/

SM^^>

JOURNAL

OF

NATURAL PHILOSOPHY,
CHEMISTRY,

AND

THE ARTS.

VOL. IX.

3lllusttrateD toitf) Cnstatiingsff

BY WILLIAM NICHOLSON.

LONDON:

PRINTED BY W. STRATFORD, CROWN COURT, TEMPLE BAR; FOR

THE AUTHOR,

AND SOLD BY HIM AT NO. 10, SOHO-SQUARE ;
AND BY
J. MURRAY, NO. 32, FLEET-STREET.

1804.

ADVERTISEMENT.

T,

HE Authors of Original Papers in the present Volume,
are Mr. John Gough; Rev. Jonathan Wilson ^ E. O.; Mr.
Wilson; Amicus; Mr. G. B. Greenough ; Hon. Robert
Clifford ; A. A. ; Mr. William Irvine ; James Thompson,
M. D.; Mr. J. Dalton; J. P. ; Sir Henry C. Englefield,
Bart. F. R. S. ; Thomas Young, M. D. F. R. S.; Mr. John
Antis; Ra. Thicknesse, Esq.; R. B; H. G.; Mr. William
Henry ; James Mai ton, Esq.; Mr. A. G. Theolden; Mr. W.
Boswell; Alexander Marcet, M. D. ; Mr. Timothy Shel-
drake; Mr. Ezekiel Walker; C.Wilkinson, Esq.; Mr.
Charles Sylvester; A Correspondent; Mr. Edward Trough-
ton; W. Jessop, Esq.; C.L. ; Thomas Harrison, Esq.

Of Foreign Works, H. Beaupoil; Count Apollos de
Moussin Poushkin ; Abbe Buee ; Abbe Hauy ; Rome de
L*Isle; M. Maunoir ; Huber; Professor Veau-de-Launav ;
Cit. Curadau; Alichael de Grubbens; Professor Prevost; M.
Seguin; M. Vauquelin; C. L. Morozzo; M. Parmentier 5
B. G. Sage; R. Prony; Bucholz; J. H. Hassenfratz; W.
D'Hesinger and J. B. Bergiius; Bode; Professor Proust;
Tromsdorff; Strauss.

And of English Memoirs, abridged or extracted; Charles
Hatchett, Esq. F. R. S. ; Benjamin Count of Rumford,
V. P, R. S. &c.; Thomas Young, M. D. F. R. S. ; Mr.
John Prior; Sir James Hall, Bart.; Mr. W. Bowler; Mr,

Thomas Willis.

Of the Engravings the Subjects are, 1. Two Plates of Ap-
paratus for Experiments on Heat ; by Count Rumford. 2.

A new

ADVERTISEMENT.

A new EleQrical Instrument, by Mr. Wilson. 3. New Fil-
tering Apparatus, by Professor Parrot. 4. Original Blow-
pipe, by the Abbe Melograni. 5. Apparatus for Filtration,
by Sir H. C. Englefield, Bart, &c. F. R. S. 6. Struaure for
purifying an entire Stream of Water. 7. Very simple striking
Part of a Clock, by Mr. Prior. 8. An Instrument for count-
ing the Number of Draughts from a Mine, by Mr. Antis.
9. An Inftrument for delineating in Perspe6tive. 10. Cheap
Apparatus for drawing Ovals. 11. Sketch of Mr. Malton's
Method of making very large Port-folios for Drawings and
Prints. 12. A Lamp for burning Tallow, by Mr. J. W.
Boswell. 13. An Evaporating Furnace, by Curadau. 14.
A Gripe for the Safety of Carriages, by Mr. Bowler. 15. A
perpetual First Mover. 16. A new Parallel Rule. 17. A
new Compensation Pendulum, by Mr. Edward Troughton.
18. An Instrument for measuring the Absorption of Gases,
by Morozzo. 19, Diagram to explain the Galvanic Energy
upon Water, by C. Wilkinson, Esq. 20. Two Plates exhi^
biting a Condenser of Force, by which the Aftion of a vari-
able First Mover is converted into a constant Pressure, by
Prony.

Soho Square, December, 1804.

TABLE OF CONTENTS

TO THIS NINTH VOLUME.

SEPTEMBER, 1804..

Engravings of the following Obie<$ls: 1, 2. Two Plates of Apparatus for Ex-
periments on Heat, by Count Rumford ; 3. A new Eleftrical Inftrument, by
Mr. Wilfon ; 4. A new Filtering Apparatus, by ProfefTor Parrot} 5. Ori-
ginal Blow-Pipe, by the Abbe Melograni.

I. Letter from Mr. John Gough, containing a Narrative of fome lefs common
Effects of Lightning, by the Rev. Jonathan Wilfon, and Remarks by the Com-
municator - . - > . - - Page 1

II. On the Computation of Tables of Squares and Cubes. In a Letter from
E. O. - - - - - - 4

III. Analyfis of a Triple Sulphuret of Lead, Antimony, and Copper, from
Cornwall. 3y Charles Hatchet, Efq. F. R. S. From the Philofophical

Tranfaaions for 3 804 . _ . - J4

IV. Defcription of a compound Electrical Inftrument for condenfing and dou-
bling} with Experiments. By Mr. Wilfon - - 19

V. Note refpe6ling the Sufpenfion of Zinc in Hidrogen, and the confequent
Ignition and Fuficn of Platina Wire. By Amicus - - '24

VI. Defcription of a Blow-Pipe zSi'mg by the PreiTure of Water, by the Abbe
Melograni. In a Letter from Mr. G. B. Greenough - i'5

VII. Outlines of the Mineralogical Syftems of Rome de Lifle and the Abbe
Hauyj with Obfervations. By the Abbe Buee. Communicated by the Hon.
Robert Clifford - - - - - 2G

VIII. Defcription of a Filtering Machine, invented by Profeflbr I'arrot of
Paris. In a Letter from a Correfpondent - - - 40

IX. Medico-Chemical Refearches on the Virtues and Principles of Cantharides.
ByH. Beaupoil - - - - - 41

X. Experimental Determinations of the Latent Heat of Spermaceti, Bees' Wax,
Tin, Bifmuth, Lead, Zinc, and Sulphur. By Mr. William Irvine. Cohi-
municated by the Author . ^ _ . 4^

XI. Strictures on Mr. Dalton's Doftrine of Mixed Gafes, and an Anfwer to
Mr. Henry's Defence of the fame. In a Letter from Mr. John Gough 52

XII. An Enquiry concerning th'e Nature of Heat, and the Modes of its Com-
munication. By Benjamin Count of Rumford, V. P. R. S. &c. Abridged
from the Philofophical Tranfa6lions for the Year 1804 - 68

XIII. Experiments and Calculations relative to Phyfical Optics. By Thomas
Young, M. D, F. R. S. From the Philof, Tranfaaions for 1804 63

OCTOBER,

ii CONTENTS.

OCTOBER, 180k

Engravlns:« of the following Ohjefts : 1. An Apparatus for Filtration, by Sir
H. C. Engleficld, Bart. Sec. F. R. S. j '2. Stiufliire for purifying an entire
Stream of Water; 3. Very fiinple ftriking Part for a Clock, by Mr. Prior j
4. An Inftrunient for counting rhe Number of Draughts from a Mine, by
Mr. Antis ; 5. An Inftrument f r delineating in Perfpeftive ; 6. Cheap Ap-
paratus for drawing Ovals; 7. Sketch of Mr. Mai ton's Method of niaking
very large Port-folios for Drawings and Prints.

I. Extraft of a Letter from Count Apollos de Mouflin Pouflikin to Charles
Hatchett, Efq. F. R. S. defcribing his Method of preparing Malleable Pla-
tina. Communicated on the Requeft' of the Count, by Charles tfa*^cliett,
Efq. F. R. S. andnowfirrtpubliflied _ _ . Page 63

II. On Pepper. By Thomas Thomfon, M. D. Communicated by the Au-
thor - ----- 68

III. Letter from the Abbe Buee on Mr. Rome de Lifle's and the Abbe Hauy's
Theories of Cryftallography - • - _ . 78

IV. Obfervations on Mr. Gough's Striftures on the Doftrine of Mixed Gafes,
&c. In a Letterfrom Mr. J. Dalton - - - 89

V. Account of the Striking Part of an Eight-Day Clock. By Mr. John
Prior, cfNefsfield, Yorkfliire. Communicated to the Society of Arts 92

VI. On the Coft of making Phofphorus. In a Letter from J. P. - 94-

VII. On the Purification of Water by Filtration; with the Defcription of a
fimple and cheap Apparatus, In a Letter from Sir Henry C. Englefield,
Bart. F. R. S. &c. - - - - - 95

VIII. Experiments on the EfFe6ls of Heat modified by Compreflion, by Sir James
Hall, Bart. Read in the Royal Society of Edinburgh, Auguft30, 1804. Com-
municated by the Author - - - - 98

IX. Atmofpherical Air not a mechanical Mixture of the Oxigenous and Azotic
Gafes, demonftrated fiom the Specific Gravities of thefe Fluids. In a Letter
from Mr. John Gough - - - - 107

X. Letter from Thomas Young, M. D. F.R.S. &c. announcing the Difcovery
of a new jnoving Star, by Mr. Harding, of Lilienthal j and on other Sub-
je^s - - - - - - 112

XI. Defcription of an Inftrument to afcertain the Number of Lifts made from
a Mine, m any given Time. By Mr. John Antis - 114

XII. On Galvanifm. In a Letter from Ra. ThicknefTe, Efq. - K'O

XIII. Defcription of an Inftrument for drawing in true Perfpeftive from Na-
ture, an^l of another of confiderable Simplicity and Cheapnefs for deline-
ating Ovals. In a Letter from a Currefpondent, R. B. - liJ2

XIV. On the Computation of Tables of Squares and Cubes. In, a Letter from
H. G. - - - - - - 123

XV. Letter to the Editor from Mr. William Henry, in Reply to Mr. Gough 126
XVi. Defcription of a very fimple and cheap Contrivance for making Port-
Folios of large Dimenfions. By the late James Malton, Efq. - 128

XVII. Experiments and Calculations relative to Phyfical Optics. By Thomas
Young, M. D. F. R. S. From the Phil. Tranf. for 1804 - 130

Scientific News, Account of Books, &c. 141— National Inftitute Prizes, lb. —
Extraft of a Lettei- from Profeflbr Bode, Aftronomer Royal, to Mr. A. F. Tho-
elden, 142— Kxtrafl of a Letter from Mr. G. B. Greenough, 143— Organic
Remains of a former World. An Examination of the Mineralized Remains
of the Vegetables and Animals of the Antediluvian World, generally termed
Ksttraneous Follils. Bv James Parkinfon, Hoxton, 143.

NOVEMBER,

CONTENTS.

m

NOVEMBER, 180k

Engravings of the following Objc61s : 1. A Lamp for burning Tallow, by Mr.
J. W. Bofwell; 2. An evapointing Furnace, by Curaudau ; 3. A Gripe for
the Safety of Carriages, by Mr. Bowler; 4. A perpetual firft Mover; 5. A
Jicw parallel Rule.

I. Defcription of a Tallow Lamp, which regulates its Supply by a fpontaneous
Movement., By Mr. John Whitley Bofwell. Communicated by the In-
ventor - - - - - - I*3ge 145

1L Account of a fuccefsful Cafe in which Deafnefs was cured by Pur.6ture of the
Membrana Tympani. By M. Maunoir, of Geneva. Communicated by
Alexander Marcet, M. D. Phyiician to Guy's Hofpital - 149

III. Letter from Mr. Timothy Sheldrake, expofing the Errors of M. Tingry
refpeding Copal Varniilies; with fine farther Inftru^ions concerning the
fame - - - - - - 1^1

IV. Reply to Mr. Dalton, on the Conftitution of Mixed Gafcs. By Mr,
John Gough - - - - - 160

V. On the apparent Size of the horizontal Moon. In a Letter from Mr.
Ezekicl Walker - - - - - 164-

VI. Defcription of thf Ship Economy, 200 Tons Meafurement, built on the im-
proved Con(lru6lion of Mr. J. W. Bofwell - - I6ii

Vff. Concluding Remarks on the Computation of Tables of Squares and

Cubes. In a Letter from E. O. - - - 171

VI U. Letter fro:n C. Wilkinfon, Efq. on Galvanifm and Ele6lricity 175

IX. Method of preventing Accidents to Hurl'es and Carriages, in going down
Hills, by a Gripe or Claip a6ting on the Naves of the Wheels of the Car-
riage. By Mr. W. Bowltr - - - - 177

X. Obfervations and Experiments to elucidate the Operation of the Galvanic
Power. By Mr. Chaiies Sylvefter. In a Letter from the Author 179

Xf. Memoir on the Origin of Wax. By Francois Huber, Member of the
Society of Natural Philofophy and Natural Hiftory of Geneva - 182

Xfl. An Enquiry concerning the Nature of Heat, and the Modes of its
Commimication. By Benjamin Count of Rumford, V. P. R. S. Abridged
from the Philofophical Tranfailions for J 804 - - 193

iXlII, Letter from Profelfor Veau-de-Launay to J. C. Delametherie, on fulmi-
nating Silver _--.._ 203
IV. Pyrotechnic Obfervations, with their Application to evaporating Fur-
naces. By Cit. Curadau, Crrrefponding Member of the Apothecaries So-
ciety of Paris, and Refident Aflbciate at the Atheneum of Arts 204

XV. An Account of a curious Phenomenon obferved on the Glaciers of
Chamouny; together with fome occalional Obfervations concerning the Pro-
pagation of Heat in Fluids. By Benjamin Count of Rumford, V. P. R. S.
Foreign Aflbciate of the National Inftitute of France, &c. &c, 207

XVI. Account of two Sketches; viz. one for a perpetual Motion, and the
other of a jointed Parallel Rule, which has no fide Deviation. In a Letter
from R. B. - - - - - 212

XVH. Familiar Account of the Method of ellimating the Value of a Steam-
Engine in Horfe-powers as they are called. By a Correfpondent 214

XVlll. Experiments proving the Neceffity of atmofpherical Oxigen in the
Procefs of Vegetation. In a Letter from Mr. John Gough - 217

Scientific News, Accounts of Books, &c. 221 — Frothing of Oil by Eleftricity,
ib. — Native Magnefia, 222 — The Experienced Mill-wrightj or a Treatife
on the Conftruflion of fome of the moft ufeful Machines, with the lateft Im-
provements. To which is prefixed a fliort Account of the general Principles
of Mechanical Powers. Illultrated with forty Engravings. By Andrew Gray,
Millwright, ib. — Praftical Obfervations concerning Sea Bathing; to which
?re added, Remarks on the Ufe of the Warm Bath. By A. P. Buchan,
M. D, of the Royal College of Phyficians, 22d,

DECEMBER,

XIV.

tt CONTENTS.

DEC'eMBER, 180 k

Engravings of the following Objefls : 1. Anew Compenfation Pendulum, by
Mr. Edward Troughton ; 2. An Inftrument for meafuring the Abforption of
Gafes, by Morozzo j 3. Diagram to explain the galvanic Energy upon Water,
by C. Wilkinlbn, Efq. ; 4. Two Plates exhibiting a Condenfer of Forces, by
which the Ailion of a variable firft Mover is converted into a conftant Pref-
furc, by Prony,

I. Defcription of a tubular Pendulum, having all the Properties of the Grid-
iron, but being more compa<Sl as well as more fteady in its Motions. In a
Letter fiom Mr. Edward Troughton, the Inventor - Page 225

II. Letter from W. Jeffop, Efq. on an Improvement in the Procefs of Blarting
Rocks with Gun-powder - . ^ - 230

III. On the Mucilaginous Matter of certain Vegetables, and their Ufc as a
Subftitute ivr Gum Arabic j by Mr. Thomas Willis; being a Continuation
of Experiments rpade upon the Subjeft by him, in Addition to thofe for-
merly pubiilhed in the Tranfaftions of the Society of Arts - 232

IV. Examination of Mr, Ezekiel Walker's Experiments and Theory of the
Enlargement of the Horizontal Moon. In a Letter from C. L. 235

V. The Method of preparing Chinefe Soy. By Michael de Grubbens 237

VI. On the Laws of Galvanifni. In Letters from C. Wilkinfon and Thomas
Harrifon, Elqrs. ----- 240

VIL Remark upon an AflTertion of Lavoifier, which has been repeated by
eminent Chemifts. By P. Prevoft, ProfcfTor at Geneva, and Correfpondent
with the National Inftitute of France - _ - 247

VIII. Account of a Memoir on chamoying of Leather. By M. Seguin 251

IX. Analyfis and Dccompofition of a Liquor employed to render Stuffs im-
permeable to Water. By M. Vauqiielin - - 252

X. New Experiments on Abforption by Charcoal, made by Means of a new
Machine. By C. L. Morozzo _ _ - 255

XI. On the Commerce of Hens Eggs, and on their Prefervation. By M.
Farmeniier - _ - - _ 264

XII. Method of giving the Colour, Grain, and Hardnefs-of Steel to Copper,
By B. G. Sage . , _ - . 267

XIII. Obfervations on Mr. Gough's two Letters on Mixed Gafes - 269

XIV. Some Account <5f a Condenfer of Forces, or a Method of obtaining the
greateft poinble Effeft from a firft Mover, of which the Energy is fubjeft
to Increafe or Diminution within certain Limits j and in general to vary
at Pleafure the Refiftance to which the Effort of the firft Mover forms an
Eciuilibriiim in any Machine whatever, without changing any Part of the
Conftruaion. By R. Prony - - - - 275

XV. Abftraft of a Memoir on the Poffibility of obtaining Pruffiate of Potafli
iree from Iron ; the Unalterability of the Fruffic Acid at high Temperatures}
and the true Nature of the Combinations of this Acid with different Bafes.

. ByBuchoh - - - - - - 278

XVI. Obi'erv;itions on the Caufe which augments the Intenfity of the Sound
in Speaking Trumpets. By J. H. Haffenfratz - - 283

XVII. Account of Cerium, a new Metal found in a Mineral Subftance from
Baftnas, in Sweden. By W. D'Hefinger and J. B. Bergelius - 290

Scientific News. 301 — Extract of a Letter from Mr. Bode, Aftronomer Royal
at Berlin, to Mr. A. F. Thoelden, ib.^-Experiment on the Heat which is
developed during the compreffion of the Air, 302 — Extra6l of a Letter from
ProfcUor P'rouft to J. C. Delametherie, ib. — Method of obtaining pure Cobalt.
By Tromfdorff, 303— Method of Coating Copper with Platina. By Straufs,
ib.

A

JOURNAL

or
NATURAL PHILOSOPHY, CHEMISTRY,

AND

THE ARTS.

SEPTEMBER, 1804.

ARTICLE L

Letter from Mr. John Go ugh, containing a Narrative offomc
ief!> common Effeds of Lightning, by the Rev. Jonathan Wil-
son, and Remarks by the Communicator.

SIR, Middlejhaw, Aug, 13, 1804^,

A HE following is a copy of a letter which I lately received
from the Rev. Jonathan Wilfon, Vicar of the parifti of Bid-
dulph, in StafFordftiire. The fa6ts and remarks contained in
it, may prove acceptable to many of your philofophical
readers, as well as to myfelf ; and by giving it a place in your
Journal, you will oblige

JOHN GOUGH.

Congleton, Aug. 1, 1804.
THE following circumftance induced me to defer my reply Stroke of light-
to your letter for a few days : On the 15th ult. I was informed 2'affe£' a
in my way to church, by the farmer of Biddulph Hall, that, circle of ao yards
on the 7th, the lightning ftruck a plain arable field of his, ^'^ «*"^«^«r'
which he ufes at prefent for a cow pafture. I went with him,
and found that the electric fluid had killed the tops of the taller
thiftles, in a circle of about twenty yards in diameter; but
Vol. IX Septkmber, 1804. B the

, 2 ON LIGHTNING.

the herbage and fmall tliiftles, no higher than the grafs, did
not appear to have been finged at all. Thofe in the centre,
for about three yards, feemed much lefs injured than thofe
nearer the circumference. In two places the foil was turned
up, a few feet in length and an inch or two in depth ; and
where the ground ceafed to be broken up, one might perceive
that the lightning had glanced, with feveral ramifications,
along the furface, but under the long grafs, leaving a track,
fuch as moles and mice fometiraes make. In one place, where
the impreffion made upon the foil was deepeft, and fomewhat
refembled the letter V, a ftraight round hole appeared at the
angle, which was about two feet deep, and about three inches
in diameter.
Probability of a After I had left the place, it occurred to me that this hole
fallen f^^hc ™'S^^ ^^^'^ ^^®" produced by a ftone falling from the clouds,
atmofphere. a phenomenon which has lately caufed much fpeculation.
The more I thought of this, the more probable it feemed.
The hole was round and perpendicular, at no great diftance
from the end of the barn, and a tall tree was alfo near the
place ; either of which was more likely to attract the light-
ning than the plain field. A very lofty tower, which was
ftruck a few years ago, was about three times the diftance of
the tree. The thunder was not fo loud as wheh the tower was
firuck, but the fmell of fulphur was much ftronger. Thefe
confiderations determined me to return the firft opportunity
and examine the place more thoroughly.
On examination From one caufe or other I could not do this conveniently
was found, before yefterday evening, when the farmer and his fan very
obligingly went with me, and dug a circular pit about four
feet in diameter, having the hole in its centre. At the depth
of two feet they came at a fhivery rock of grit, in which I
hoped to find the expe6led ftone imbedded ; but when the foil
was cleared away level with the bottom of the hole, there was
no fuch thing ; nothing appeared but fmall, oblong, fiat pieces
of gritftone, through the moift crevices of which the eledric
fluid probably efcaped. Though difappointed in the principal
part that I hoped to communicate, I refolved to fend you the
above, as I think the lightning very feldom defcends fo far into
folid ground, uniefs when guided by fome particular conduc-
tor. If the account afford you any information or amufement,

I (hall

ON LIGHTNING. J

f ftiall be glad; and fhould the fubje^ meHt any o£ yout
queries, they will be received with pleafure by
Your humble fervant,

JONATHAN WILSON.

Remarks on the abote.

THE firft part of Mr. Wilfon's letter countenances Dr. Wtethci- fairy-
Darwin's explanation of fairy-rings; for of all the thirties in- ^"^ be thus
eluded in the eledrified circle, thofe in the centre received
the leaft injury. The hypothefis of Dr. Darwin has'always
feemed to me to labour under unfurmountable difficulties ; and
this is the reafon why I point out a fa6l which eftablirties an
exaft agreement of the explanation, and natural appearances,
in one inftance.

Fairy-rings are permanent objects, the nature of which is
but imperfedly underftood ; and it is to be wiibed that Mr*
Wilfon would find leifure to obferve land defcribe the future
confequences of theele^ric difchargeatBiddulph Hall. The
herbage of the ramified figure mentioned in the letter, will in
all likelihood die in the cuurfe of a few weeks ; becaufe plants
that have fuftained ftrong electrical lliocks, feldom furvive the
operation more than a month or two. Should this change take
place in the circle, it will give a new appearance to the furface
of the ground, by expofing to view the branched path of the
lightning ; nor is it improbable but that this alteration will be
fucceeded by another of a more fingular kind. There is rea*
fon to fufpe6t, that each ramification of the track will be again
covered with a lively verdure the next fpring, being accom-
panied at the fame time by a contiguous patch of blafted
herbage refembling its own figure. This fufpicion is counte- Compartfoh wi^

nanced by certain obfervations of Dr. Hutton of Edinburgh, ^J: *^"."on's

, ,.,,/>.• A 1 . n obfervations of

who remarked, that the rairy-nngs upon Arthur s beat annu- the fairy^rings

ally increafe in diameter ; i. e, the withered circumference of °" Arthur's '

each circle becomes green in fpring, aiid is furrounded in a

fliort time by a freOi ring of a ruflfet colour. We have no

right to difpute the juftice of Dr. Hutton*s obfervations, but

the queflion is undetermined, wiiefher the appearance is con*

ftant, or refults from the nature of the foil. The peruGil of

the foregoing remarks will perhaps admonifh my friend Mr.

Wilfon, that Fortune has furniihed him with an opportunity

B 2 ^£

• OMPUTATIOlf OF SQUARES AND CUBES.

of profecuting the inquiry, fuch as (he rarely affords to perfona
of corredl obfervation. I will not trefpafs upon your pages
by a comment on the remaining fafts of my friend's letter ;
let them fpeak for themfelvesj in particular, the preference
of a thunder cloud to low ground, in the prefence of lofty
objefts, including a tall tree.

JOHN GOUGH.

ANNOTATIONT.

I BELIEVE the opinion that fairy-rings are caufed by light-
ning, is of confiderable antiquity. Dr. Prieftley gave fupport
to this conclufion by his experiment of the concentric rings
formed on a polifhed metallic furface by the explolion of a
battery. An effefl of this kind produced in Kenfington Gar-
dens, is defcribed, with an engraving, in our Quarto Series,
Vol. I. p. 546.

W.N.

On the Computaiioh of TaHles of Squares and Cubes, In a Letter
from E. O.

To Mr. NICHOLSON.
SIR,

Computation of 1 SHOULD not have troubled you with any remarks on the
fquares and method of computing fquares and cubes, if I had not feen the
paper which was printed on that fubjed in your Journal for
laft July. But as it appears, from that letter, that there may
be perfons who would like to employ themfelves on thefe cal-
culations, it is defirable that the plainefl and eafieft methods
fhould be pointed out to them.

Every one who is accufioraed to calculation, is acquainted
with the advantage of eonftantly repeating (he fame opera-
tions. When the refult of any calculation is to be made out,
in fome parts by multiplication and in others by divifion, fub-
tra£tion, or addition, it is impoffible for the moft unwearied
diligence to avoid occafional miftakes. It is right, therefore,
to iiroplify as much as poffible in this refped; and if the calcu-
lation

COMPUTATION OF SQUARES AND CUBES. 5

lation cannot be effe&ed by a (ingle operation, I believe I IhaJI Computation of.
be joined by all perfons accuftomed to arithmetical computa- ^^^^^^f* *"
tion, in recommending the ufe of addition* in preference to
fublradtion, and of multiplication in preference to divifion.
Your correfpondent H. G. does not feem to have paid fuffi-
cient attention to thefe confiderations ; and I fear that he not
only would be foon wearied, if he were to work by the me-
thod which he recommends, but (what is of ftill more confer
quence) he could not depend for any continuance upon the
accuracy of his computations.

The only method by which an extenfive table like Mr,
Councer's could have been calculated, muft have been by the
conftant addition of differences ; and the rules for this method
may be eafiiy deduced from the following confiderations : Let
x-\'3a, x-^2a, x-j-ff> &c. be any numbers in arithmetical pro-
greffion. Then by the binomial theorem.

x+3al* = a:' + 6ax ^ 9a'

x-\-2i\ 2 = X* 4- 4«x -{- 4a*
x-f.aV=:r*+2aa:4- a»

x" ^=.x^

IJl Differences.
2ax -{- 9^*

2ax -f- 3a»

2ax 4- a«

2d Differences^

2a*

2o*

It will be foreign from my prefent purpofe to enter into a
particular confideration of the manner in whjch thefe differ-
ences arife. It will be fufficient to remark, that the fecond
difference is conftant, and that its value will be always 2,
when we confider a asiz 1, or the progreffion x -f- 3a, x-f-2c,
&c. as a feries of common numbers differing from one an-
other by unity. Hence the fir ft differences of the fquares of
fuch numbers become themfelves an arithmetical progreflion,
of which the common difference is 2 ; and confequently, if
we know the firft difference between the fquares of any two
fuch numbers, we can find the difference between the fquares
of the two next.

* If this opinion wanted any argument in its favour, I might
fupport it by the authority of that able mathematician Captain
Mendoza, who has calculated his new tabks in fuch a manner as tp
^ake ajl the equations additional.

What

^ ^QDCrUTATIOM OP SftUARKS AND CUBES.

Compuutlonof What li^s been faid may be exemplified by applying it to
cubMr ^^ continuation of Mr. Councer's fquares. For

798684121 is the fquare of 28261,
798627600 is the fquare of 28260,

56521 is their difference, therefore 56523 is
iht difference between the fquare of 28261 and the fquare of
28262. By the addition in every inftance of 2, we may find
the feries of differences ; and by the conftant addition of them,
we inay eafily find the fquares. Thus

798684121 :
56523

798740644
56525

798797169 ZZ 2S263\'
56527

798853696 ZZ 28264\*
56529

798910225 IZ 282651*

By a fimilar method the table of cubes might be continued
jby the addition of differences ; but^ in this cafe, the calcula-
tion will be ^ little more complicated : Becaufe, if the terms
of any arithmetical progreffion be raifed to the alh power,
there will be n orders of differences, and the laft will be the
only one of them which will be conflant. For the cube,
therefore, where 73 iz: 3, we Ihall have one order of differences
piore th^p for the fquare.

As before, let the progreffion be x -|- 3o, x + 2^* x^a, x^

COMPUTATION OF SQVARES AND CUBES,

II II 11 II II

1. t t. "u n,
+ + + +

C9

a

«o to

8

g

^ 1

ta

t*

•• H

+

+

4- 4-

W

K>

-5 GO

»

a

e> o

M

i»

t* «•

H

H

H t,

+

+

+ +

e

^

s- ir

M

M

M M

g

§*

n

H

H

H

(*

i»

m

(*

+

+

+

to ^

».%•

H

H

H

+ 8

+

+

+

,_,

C>3 •

•«»

to

-a

S>

fe

ft

o

Computation of
fquares and
cubes.

o>

O^

Oi

^

?i

a

ft

a«

«3

+

+

+

'Si

j_^

^^

^

Oi

>o

00

o

&

ft

ri

M

M

M

9U

»£?•

%

If therefore we make en 1, the third difference will be
conftantly 6, and the fecond difference will become Sx-f- 18,
6x -f 12, 6x'\-6 ; fo that if any three numbers be taken in
an arithmetical feries (in which azz\), the fecond difference
of their cubes w^ill be conflantly fix times the middle number.

For the fake of example, we may apply thefe obfervations
to the continuation of Mr. Councer's cubes. We may confider
26559; 26560, 26-561, as part of an arithmetical feries: by
the table we could find the difference of the cubes of 26559

and

g COMPUTATION' OF. SQUARES AND CUBES.

Computation of and 26560, and, by what has been obferved above, the fecond
fquwsand difference of the three cubes will be* 6. 26560 ~ 159360;
which, added to the difference between the cubes of 26559
and 26560, will give the difference between the cubes of
26560 and 26561. So far we ftiould proceed exadtly in the
ileps which are traced out by your correfpondent H. G. ; but
I differ from him in this refpeft, that I Ihould by no means re-
commend this method for the folitary calculation of any parti-
cular cube; it is only mentioned here for the fake, of (hewing
how to afcertain the numbers by which we muft commence the
feries of differences, when we want to continue a table which
has already been calculated to a certain extent. For the third
diflference is conftantly 6 ; therefore if we take an arithmetical
progreffion, of which the terms differ from one another by that
number, and which begins with 159360 (fuch as 159360,
159366, 159372, S^c. ^^c), vve fhall afcertain the fecond dif-
ferences of the cubes which we want to find, Thefe fecond
differences mufl be added to the refpedive firft differences,
and, by that means, we fliall find a feries of numbers, which,
added to each particular cube, will give us the cubes of the
numbers next above it. Thus

26560\3 IZ 18736316416000
26559\ « ZZ 18734200194879

^KKT

2116221121 ~*26560]3 - 2655913
159360 2d Difference.

2116380481 ZZ 2656l)3 ~ 265 60]^
159366 2d Difierence.

2116539847 ZI 26562)3
159372 2d D.

2116699219 — 26563\^ - 26562] ^
159378 2d D.

2116858597 ZZ 26564)3 - 26563)3
159384 2d D.

2117017981 z: 26565)3 - 26564^3

Having thus afcertained the firfl differences, we may plo*
ceed to add them to the cubes :

♦ The dot (.) between the figures is here ufed as the iign of
multiplication. N.

COMPUTATION OF SQUARES AND CUB&S.

18736316416000 ZZ 265 60V Computation of

2I163804S1 1ft Diff. Tubes/ '"'^

18738432796481 ZZ 263 6 iV
2116539847 1ft D.

18740549336328 zr 26562V
2116699219 ift D.

18742666035547 ZZ 26563\»
2116858597 ift D.

18744782894144 ZZ 2656?)^
2117017981 Ift D.

18746899912125 ZZ 2656515

The methods here ftated are, probably, the eafieft which
can be devifed for conftruding an extenfive table : but it muft
frequently happen, that the calculator will want the fquare or
cube of fome number which is greater than any which is con-
tained in the table. It may be ufeful, therefore, to confider
the affiftance which the table may afford him in facilitating the
computation.

It is well known, that x^ x 3/" zzl]?]'". * Therefore, if we
want to find the fquare of a number which is e double of any
contained in the table, we have only to multiply the given
fquare by 4. In the fame manner, if we want to find the
fquare of a number which is exactly three or four times asi great
as any contained in the table, we may find it by multiplying
the given fquare by 9 or 16. Thus, for example,

16522531600 ZZ the fquare of 128540;

66090126400 ZZ the fquare of 257080;

16522274521 rz the fquare of 128539 ;
9

148700470689 ZZ the fquare of 385617.

* I do not know whether it is worth while to mention the cii>
cumftance, but your correfpondent H. G. has made a mlftake in
the application of this rule. For he fays that, if we " multiply
the cube of any given root by 8, the produft will be the cube of
twice the next root :^^ whereas the produ^ will be the cube of twice
the giveiv root.

Ill

IQ COMfUTATION or SQUARES AND CUBE3,

Computation of In this manner we may find the fquares of all even numbers
cu^s! *^ which do not exceed the double of the table ; we may alfo find

the fquares of numbers, to a greater extent, which are mul-
tiples of 3 : the multiples of 4 and 5 may be fquared likewife,
if we multiply by 16 and 25 ; but fquare numbers increafe
very rapidly, and confequently this method can be only ufed
(with advantage) for the fmall multiples of the tabular num-
bers. We muft, therefore, confider fome other method which
may be applicable to prime numbers and multiples of large
ones.

The fquare of 2x -f I zi 4j-« -f- 4x -f I zr 2x^ -f- 4r -f 2 -f

2j^ - 1 ZZ 2.7+71^ + 2x* - I, or 2.x -fFl' 4- x* - I.
If, therefore, we want to find the fquare of an odd number
which does not exceed the double of thofe which are fquared
in the table, we muft divide the next even number below it
by 2, and this half will be equivalent to x in the above equa-
tion ; the next number above this half will give us x-j-l*
Having thefe two fmaller numbers, we may find their fquares
by the table; and the fum of their fquares multiplied by 2,
will exceed the fquare required by 1. Thus, if it were re-
quired to find the fquare of 257079 = 2. 128539 -f 1 : Here
X = 128539, and X -f 1 = 128540; therefore, by Mr. Coun-
cer's table, the fquare of 128540 would be 16522531600
the fquare of 128539 would be 16522274521

33044806121
2

66089612242
Therefore the fquare of 257079 is 66089612241.

Inftead of examining each particular cafe, when the number
to be fquared is more than the double of thofe in the table, it
will be beft to confider the theorem, from which a general rule
may be deduced, nx -\-a\^ ZT 7i*x* -}- 2anx -{- a^ zz wx* -|-
2a«x -\-na^'{-n*^n,x^-\'l—n,a^ZZ:n . x-J-a^ -|- n . n—i, x^
-}- l-n.««— n.x-|-«\2-}-/i — 1.x*-}- l-w.a'. Hence we
TOuft multiply x« by n ~ 1 , to the produd addx-j-^V, multi-
ply the fum of thefe two quantities by w, and this laft produft
will exceed the fquare required by /»— i.a«. The only cau-
tion neceflary, is in dividing the given number by x; for as

we

COMPUTATION OF SQ.UARES AND CUBES, 1|

w:e fuppofe it equal to nx-^a, we fliould make x a>; great as It Computation of

poffibly can be, without being fo large, that when added cubes? ^"

to the remainder a (as x-\-a), it fliould exceed the numbers

of which the fquares are given in the table. Becaufe n and a

are the only numbers by which we have to multiply, and as

a muft be lefs than n, we fliall always have them as fmall as

poITible, if we take x according to the dire6lions here given.

If, for example, it be required to find the fquare of 385618,

which is greater than twice, and lefs than three times 12S540

(the greateft number which is fquared by Mr. Councer's

table) ; here 385618 ZZ 3. 128539 -f 1 ; therefore if « ~ 3,

XZZ 128539, and aZZ 1, x + a will be ZT 128540, and will be

within the extent of the table : Hence

**,or the fquare of 128539, would be by the table 16522274521
71-1, or 3-1 - - 2

33044549042
X -fu\*j or the fquare of 128540, would be 16522531600

49567080642
wor3 - - 3

11870 124 1926

and as n- 1. a« = 2, the fquare of 38561 8 will be 148701241 924

If the fquare required were that of 385619, in this cafe a=2,
and confequently, if xzz 128539, x-^-a, or 128541, would ex-
ceed the extent of the table : therefore n muft, in this cafe,
be equal to 4, xzz9 6404, and a rz: 3, and
the fquare of 96404 = 9293731216

3

27881193648
the fquare of 96407 = 9294309649

37175503297
4

148702013188; but7j~i.a*=
3.9. or 27; therefore the") ,4,070001 qifii
fquare of 385619 is | 148702013161.

From this example we fee the neceflity of being careful
that x + a does not exceed the numbers in the table : at the

fame

12 COMPUTATION OF SQUARES AND CUBES.

Computationof fame time it may be remarked, Kiat this is an extreme cafe,
cubes. which can never occur but under particular circumfiances:

for it only happens when tlie number to be fquared is lels than
a multiple of the higheft number in the table, and greater than
the fame multiple of the number next lefs than the higheft;
that is, for a table like Mr. Councer^s, it muft be lefs than
m. 12854-0, and greater than m . 128539 : under thefe circura^
ilances, if a be greater than 1, the cafe will occur which is
the fubjed of the above caution.

It remains for us to confider the method of finding the cubes
of numbers which exceed thofe given in the table.

Upon the principle to which we referred before, that x"* x
y^ = ajl*", we may find the cube of a number which is a mul-
tiple of any one contained in the table, by firaple multiplica-
tion : for the cube of any number multiplied by 8, will give
the cube of double that number ; the cube multiplied by 29,
64, or 125, will give us the cube of 3, 4, or 5 times the
number : Thus,

3368928641.271 = the cube of 14991

26951429154168 = the cube of 29982.

1045678375000 = the cube of 10150

27

731974862500©
2091356750000

28233316125000 = the cube of 30450.

But as the cubes increafe more rapidly even than the fquares,
it will flill be more necelfary in this cafe than in the former, to
efiablifli fome means c>f finding the cubes of thofp high numr
bers which are either prime or not exactly a fmall multiple of
a number contained in the table ; and by proceeding in a man-
ner fimilar to that which we ufed for the fquares, we eafily
efiablifli a general rule for this purpofe : For"^^ + «T = '^^-^^

a:^ -\-3an''-3an. X* -{-a^ ~na^ = n.x -\-a]^ -{-n .n^ ~ I .x^ -{-n.

n-l .Sax^-i-l-n.a^zznxx+^^ + n-^j.n-^l r^-fSax* -f
l—n.a^. Determine^ therefore, n, x, and «, in the fame

manner

COMPUTATION OF SQUARES AND CUBES. J <J

manner as for the fqiiare, and be equally careful that x -|- « Computation of

. fquares and

does not exceed the numbers in the table ; add « -f I . :r^ to cubes.
3ax^ ; multiply the fum of thefe two quantities by n— 1 ; to
the product add x-{-aY, and multiply this fum by n : this laft
produfl will exceed the cube required by n— I .a^.

If, for example, it be required to find the cube of 53119,
or 2.26539+1. : Then « = 2, a = 1, x = 26559, and 2- -|-a =
26560, and the cube of 53 1 1 9 = 2 X

The cube of 26560

26560)3 _|. 3 .26559)3 -j-3.26559> - I : Therefore, by Mr.

Councer's table, the cube of 26559 would be 18734200194879

The fquare of 26559 - 705380481

18734905575360
3

56204716726080
18736316416000

74941033142080
2

149882066284160

therefore the cube of 53119 IS - 149882066284159

Laftly, let it be required to find the cube of 79601, or

3.26533 4-2: here ti = 3, a = 2, x = 26533, r + a =

26535 ; therefore, by what has been demonftrated, 7960?)^

:=3 X 26535]^ -{-2X 4.26533^^ -|- 6 . 265331 ?| -- 2.8.

' 26533V = 18679234361437

265331* = 704000089
3

2112000267

37358468722874
2112000267

37360580723141
4

149442322892564
26535V = 18683458680375

Therefore the <;ube of 79601 Is

168125781572939
3

— — III m

504377344718817
504377344718801
E. O.

J^ Al^ALYSIS OF A MINERAL, &C.

III.

Analyfis of a Triple Sulphuret of Lead, Antimoni/, and Copper,
from CormualL Bij Ch/^rles Hatchet, Ef({. F. R. S.
From the Philofophical Tranfadiom for ISO^.

Hiftory of the JL HE fiibftance which forms the fubjed of this paper, has

"""" • hitherto been regarded as an ore of antimony ; it is extremely

rare, and has only been obtained from Huel Boys, in the parifti

of Endellion, a mine which, from deficiency of profit, has for

fome time been abandoned.

The fcarcity of the ore has probably been the caufe of its
being unknown to foreign mineralogifts ; indeed few even of
the Britifii cabinets poflefs it; but theraoft perfect and beautiful
fpecimens are (as far as I know) to be feen in the fplendid
colledion of Philip Rafhleigh, Efq. of Menabilly, in Corn-
wall.

To Mr. Ralhleigh we are indebted for the firft defcriptlon
of this ore* ; but no fubfequent notice had been taken of it,
until the preceding paper was written by the Count deBournon,
whofe eminent merits, as a mineralogifl: and cryllallographer,
are well known to this Society.

I. ^

Sp. gravity. The fpecific gravity of this fubftance is 5766, 65' of

Fahrenheit.

II.
Heat by the If fuddenly heated on charcoal, by the blowpipe, it crackles

blow-pipe ex- gj^j {^\\i^ j but, when gradually expofed to the flame, it
5Sdwhu!ffumes, liquifies, and, upon cooling, aflumes a dull metallic grejr
and left fulphu- colour.
»et^i!'copper. When the globule was longer expofed to heat, white fumes

(which at firft had a fulphureous odour) were evolved, and

partly fettled on the charcoal.

Ebullition prevailed during the difcharge of thefe white

fumes ; and the globule gradually fuffered conliderable dimi-

nution, remaining at length tranquil, and of a very dark gray

colour.

* Specimens of Britlfti Minerals, felefted from the Cabinet of
Philip Rafhleigh, Efq. F. R. S. &c. Part I. page 34, Plate XIX.

Upon

AI^ALYSIS OF A MINERAL, &C. J^

Upon examination, this appeared to be principally fulphuret
of lead, which, like a cruft, enveloped a minute globule of
metallic copper, fo malleable as to bear to be flattened by a
hammer.

in.

Some of the ore, finely powdered, was put into a matrafs, Digeftion with

and nitric acid diluted with an equal poison of water was acid^^«tc!Tmfica-

poured on it. Upon being digefted in a low heat, a contiderable ted fulphur, lead,

part, was difTolved, with much effervefcence. Some fulphur, *^°PP"» *"'*. f "
, . , - ' timony, with S|

which floated, was feparated ; and the clerfr liquor, which was little iron.

bluifti green, was decanted from the reliduum at the bottom of

the veflel.

A great part of the excefs of acid being expelled from the
folution, it was largely diluted with diflilled water, and fome
diflblved muriate of foda was added ; but this did not produce
any alteration in the tranfparency of the liquor. A folution of
fulphate of foda was then poured in, and formed a very copious
precipitate of fulphate of lead.

When this had been feparated, the liquor was faturated with
ammonia ; by which it was changed to a deep blue colour. A
few floccuii of iron were feparated ; and the remainder was
found to contain nothing but copper.

The fulphur which had floated, was added to the refiduum
which had fubfided to the bottom of the matrafs; and the whole
was digefted with muriatic acid. This folution was of a flraw
colour; and, when feparated from the fulphur, and poured into
a large quantity of water, afforded a plentiful while pre-
cipitate.

This precipitate was completely refolved into white fumes,
by the blowpipe; and the muriatic folution of it, when added to
water impregnated with hydro-fulphuret of ammonia, formed
the orange coloured precipitate, commonly known by the ap-
pellation of golden fulphur of antimony.

IV.

Muriatic acid did not immediately a6t upon the pulverized The fame refult*
ore ; but a folution was fpeedily effected by the addition of a ^X treatment
few drops of nitric acid : pure fulphur was feparated ; and the acid and a little
liquor, being decanted into water, yielded a copious precipitate """«•
of oxide of antimony.

4 The

1^ ANALYSIS OK A MINERAI,, &C.

The filtrated folution, by gradual evaporation, afforded
cryllais of muriate of lead ; and the lead which afterwards
lemained in the liquor, was feparated by a few drops of ful*
phuric acid.

The folution was nowofabright green colour, and, as before,
was found only to contain copper, and a minute portion of iron;
the former was therefore precipitated in the metallic flate, by a
plate of zinc.

Thefe experiments, with others which I have not thought
neceHTary to mention, prove, that the conftituent parts of this
ore are lead, antimony, copper, and a little iron, combined with
fulphur; and, when the fpecific gravity, the external and in-
ternal colour, fradure, grain, and other characters are confi-
dered, there can be no doubt but that at leaft the three firfl
metals exift in the ore, in, or nearly in, the metallic ftate,
combined with fulphur, fo as to form a triple fulphuret ; to af-
certain the proportions of which, the following analyfis was
made.

V. Analyfis.

Analvfis. Pul- A. 200 grains of the ore, reduced to a fine powder, were put
Ycrizing- Jnto a glafs matrafs, and, two ounces of muriatic acid being

added, the veffel was placed in a fand-bath. As this acid, even
when heated, fcarcely produced any effefl, fome nitric acid was
gradually added, by drops, until a moderate effervefcence began
to appear.
Digcftionwith The whole was then digefled in a gentle heat, during one
nitro-mur. acid,j,Qyf . ^^^^ ^ green coloured folution was formed, whilft a
quantity of fulphur floated on the fur face, which was colledted,
and was again digefled in another veflel, with half an ounce of
muriatic acid.
ydtfuipbur. The fulphur then appeared to be pure, and, being well waflied

and dried on bibulous paper, weighed 34- grains : it was after-
wards burned in a porcelain cup, without leaving any other
refidium than a flight dark ftain.
The green fohi- B. The green folution, by cooling, had depofited a white
tion afforded, by fj^jj^^e (ediment ; but this difappeared upon the application of
iilution, w ^ */ j^g^. g^ J ^|jg addition of the muriatic acid in which the fulphur
had been digefled.

The folution was perfe6lly tranfparent, and of a yellowifti
green: it was made to boil, and in this llate was added to three

quart*

ANALYSIS OF A MINERA^., &C. J?

quarts of boiling diftilled water, which immediately became
like milk; this was poured on a very bibulous filter, fo that
the liquor pafTed through before it had time to cool ; and
the white precipitate thus collecled, being well edulcorated
With boiling water, and dried on a fand-bath, weighed 63
grains.

C. The waftiings were added to the filtrated liquor; and theand by fubfe-
vvhole was gradually evaporated at different times, between ^"^'^^J^P^'^J
each of which it was fufFered to cool, and remain undiilurbcd/w</,
during feveral hours. A quantity of cryfiallized muriate of

lead was thus obtained, until nearly the whole of the liquor
was evaporated : to this laft portion a few drops of fulphuric
acid were added, and the evaporation was carried on to
drynefs ; after which the refiduum, being diflblved in boiling
diftilled water, left a fmall portion of fulphate of lead.

The cryftallized muriate of lead was then diflblved in boiling
water; and, being precipitated by fulphate of foda, was added
to the former portion, waswathed, dried on a fand-bath, and
then weighed 120.20 grains.

D. The filtrated liquor was now of a palebluifii-green, which Ammonia thre^r
changed to deep blue, upon the addition of ammonia; fome °^"*^^ ^^'''^'
ochraceous flocculi were colleded, and, when dry, were

heated with wax in a porcelain crucible, by which they
became completely attra6lable by the magnet, and weighed
2.40 grains.

E. The clear blue liquor was evaporated nearly to drynefs ; The Wue liquor

and, being boiled with flrong lixivium of pure potafh, until ^^^P°V ^"^ ^°^^*

. . 1 1 n J J. , r ' ,.^ , , ed with potafh

the whole was almolt reduced to a dry mats, it was diflblved and then diflbl-

in boiling diftilled water; and the black oxide of copper, being "^^^ i" ^^^'^^'^ g*^®

collected and waftied on a filter, was completely dried, and <^W^»

weighed 32 grains.

200 grains of the ore, treated as here ftated, afforded.

Grains.

A. Sulphur ... - 34.

B. Oxide of antimony - - 63.

C. Sulphate of lead - - 120.20

D. Iron .... 2.40

E. Black oxide of copper - 32.

But the metals compofing this triple fulphuret are evidently

in the metallic ftate ; and white oxide of antimony precipitated

Vol. IX,— SEPTBMBJiR, 1804, C from

Produfts.

I'e ANALYSIS OF A MINERAL, &C.

from muriatic acid by water, is to metallic antimony as 130 i»
• 100; therefore, the 63 grains of the oxide muft be eftimated
at 4-8.46, grains of the metal.

Again, fulphate of lead is to metallic lead as 141 to 100;
therefore, 120 20 grains of the former are zz 85.24 grains of
the latter. And, laftly, black oxide of copper contains 20
per cent, of oxygen ; confequently , 32 grains of the black oxide
are = 25.60 grains of metallic copper.
Component The proportions for 200 grains of the ore, will therefore be,

^^^^- Sulphur ... - 34,

Antimony - - . - 48.46

Lead 85.24

Iron 2.40

Copper . - - - 25.60

195.70
Lofs - 4.30

Ofj per ant.

Sulphur . - - - 17.

Antimony - - - - 24.23

Lead ----- 42.62
Iron - - - - - 1.20

Copper , - - - 12.80

97.85
Lofs - 2.15

Thefe proportions, I have reafon to believe, are tolerably
exad; for I did not obferve any elTential variation in the refults
of two other analyfes, which I made of this fubftance, with
every poffible precaution.

The lofs may be principally afcribed to the oxide of anti-
mony and fulphate of lead ; but efpecially to the former,
which has a great tendency to adhere to filters and glal^
veflels.

In fome of the preliminary experiments, I obtained a fmall
portion of zinc ; but, having received, through the kindnefs of
Mr. R. Phillips, of Lombard-flreet, fome pure cryftals of the
ore, I found that the zinc had proceeded from blende, which
was imperceptibly mixed in the fpecimens which I had firit
examined*

DefcHption

Compound electrical instrument. X^

IV.

befcription of a corn-pound Electrical Irifirument for condenfing
and doubling : xvith Experiments. j5j/ Mr. Wilson.

London, Augufi 10, 1804.

To Mr. NICHOLSON,
SIR,

1 TAKE the liberty of troubling you with the following ac- Compound
count and drawing of a compound condenfer of eleflricity, eleftncal can»
which I think is an improvement on Cavallo's multiplier of
ele<5lricity, defcribed in his Treatife on Ele^ricity in the

third volume, of the fourth edition, and if you think it worth
a place in your Philofophicil Journal, yoii will vfery much
oblige me by inferting it therein.

I am your obedient

Humble fervant,

W. WILSON.

The drawing is an exa6l reprefentation of the inftrument, Defcription and
about half its real fize, (Plate 3 J The plates A, B, C, D, !^''^^i"g °f, ^«
and E are fupported by glafs flicks, covered with fealing wax
at the upper part ; but the plate F is fupported by a wire,
which has a joint at the bottom, by which it may be brought
near the plate E, or thrown back away from it. 3 is a fcfew,
which Hops againft the glafs fupport of E, and regulates the
diftance of the two plates when one is brought near the other.
The plates A, C and E are fixed to the bottom board, and B
and D to the levers L 1, which move round the pins p p, and
and areconneded by the rod R. It will be feen by the draw-
ing, that when the lever L is moved, the plates B and D are
moved in contrary dire6lions> that is» they both approach to-
'Wards or recede from the plate C at the fame time, but on op*
pofi te fides* The faces of the plates are ground flat, and they
are fo adjufted that if the fcrews 2 2 did not flop the levers
when they are moved, the face of B would flop flat againft the
face of A, and fo would the face of D againft C. The fcrews

2 2 ftop them when at a very fmali diftance, which may be
made more or lefs by turning the fcrews.

C-2 '. This

SJO COMPOUND ELECTRICAL INSTRUMENT.

^o^d^"^f"* This inflrument ferves the piirpofe of a condenfer, a finglc

fingle and double ^"^ double multiplier, and a doubler of eledlricity. When it
multiplier, and a js ufed as a fingle condenfer, ihe plate B is brought as near A as
cicftricity. *'^® fcrew 2 will permit, and then the wires b and/ touch one
another and uninfulate B, which increafes the capacity of A,
As the capacity of A is increafed it will receive a greater charge
of eledricity from any electrified body brought into conta(fl
with it. Confequcntly, when B is removed, the charge on A
will be much more intenfe than it would have been if the plate
B had not been oppofed to it ; but this intenfity will not be
greater than that of the eledrified body, if its furface is not
greater than the furface of the receiving plate A ; for a con-
denfer does not increafe the quantity of eleftricity, it only col-
Ie<5ls it into a fmaller fpace than it was before. So that if the
1 eledricity of a very (mall body is required to be afcertainedf

the fimple condenfer will not anfwer the purpofe. Some other
means nluft be ufed when this is the cafe, and CavalIo*s multi-
plier is the lead exceptionable of the inftruments ufed for this
purpofe. The inftrument reprefented in the drawing forms a
multiplier, either fingle or double, for when B is near A and
uninfulatcd, A will receive a much greater charge that it would
if B had not been near. And becaufe B is uninfulated, A will
Induce a contrary flate on B, and of nearly equal intenfity;
which flate is preferved: For the infiant the lever is moved to
carry B farther from A; the contad between the wires />and/
is difcontinued, and B infulated, and as it removes farther
away from A, the intenfity of its charge will increafe the fame
as that of A will, and be ready to part with nearly the whole
to another condenfer.

Now as the plate B removes away from A, the plate D ap-
proaches C, and when at a fmall diftance from it, the wires d
and g come into contact, which operation uninfulates D, and
therefore caufes the two plates C and D to form a condenfer;
anfl at the fame inftant that d touches g, the wires h and c touch
one another, fo that nearly the whole of the charge of B is
communicated to C, which induces a contrary ftate on D, as
the charge of A did on B. D will therefore be in the fame
Hate as A is, which ftate is preferved; for the infiant the plate
B removes away from near C, the plate D alfo removes away
from it, and the contadt between the wires d and g is difcon-
tinued, and D infulated; and by continuing the motion the

plate

COMPOUND ELECTRICAL ll^STRUMENT. Ql

plate B will come near A, and D will remove away from C ^^^ yfcs as a
Ml I • 1 • 1 • n L condenier, a

till the wires b and/touch one another, at which inftant the fmgie and double

wire </ touches the wire ^. Now if the plate E and F are multiplier, and
near one another, they will form a third condenfer, and nearly ei^-^ricity.
the whole of the charge of D is communicated to E in the
fame manner the charge of B was communicated to C ; at the
fame time B recruits its charge by coming near A, which will
be communicated to C, which induces a contrary ftate on D,
and which D communicates to E, and this operation is re-
pealed every time the lever Is moved backwards and forwards;
fo that the charge on C is increafing at every motion of the
lever, while the charge on A remains the fame ; and when C
becomes fo much charged as not to be capable of receiving
any more from B (which will be the cafe in a certain number
of motions) the operation will ftill go on between D and E,
the charge on E increafing while the charge on C remains the
fame, fo that E will acquire a charge as much greater than C
as the charge on C is greater than the charge on A, which will
be manifefled by removing the plate F away from E. When
the wire a is fcrewed into the plate A, and conne6ted with E
by means of the wire 4 5; the inftrument then pofleflTes all the
properties of the double of electricity, for then all the charge
communicated to E (which is of the fame nature as that of A)
will be communicated to A, which will continually increafe the
intenfity of its charge, and that will have an increafed efFe6l
on B, &c. at every motion of the lever. There is no limits to
this accumulation, but that where the charge is fo intenfe as to
pafs from one plate to the other in the form of a fpark.

I have made many experiments with this inftrument relative On the fpon-

to its fpontaneous electricity, and I find, as a tingle multiplier ^^"?°"^ 5'^^*
,,. , ,^ •'. ^,.,7^. tricity of thjj

(that is when an electrometer is connetied with C) it has no inftrument. '

efFed on the moft delicate gold leaf eleflrometer I could make;

but as a double multiplier (that is when an eleflrometer is

conneded with E) there is fome fmalleffed if fome eledricity

had been communicated to it within an hour or two, although

it may have been difcharged by touching each of the plates with

a metal point (which I find is the moft efFedual way of dif-

charging fmall portions of eledricity,) but if it has ftood three

or four hours after being difcharged, it will not give any figns

of eledricity. When ufed as a doubler it always becomes

elei^irified with between eight and fixteen motions of the lever,

2 evj^n

2i COMPOUND ELECTRICAL INSTRUMENT.

On the fpon- even though it has not been ufed for tivo or three months.—
Sfc^rof Ui'is ^^^ ^^ ^*- ^^^ ^^^^ ^^^^ within two or three hours, the e&'eck
inftrument. will take place with fewer motions of the lever, and if it has
been ufed within a few minutes, two or three motions will be
pore than fufficient to afcertain the quality of the ele6lricity.
It is to be obferved that the inftrument was always difcharged
(by the metal point as before obferved) between each trial.

In the courfeof making the experiments on the fpontaneous,
electricity of this inftrument I found that it was always pofi-
tlve if the inftrument had not been ufed for two or three days,
U'hatever eledricity it was lall charged with. But the time it
nruft ftand unufed after it has been difcharged, to produce this
effeft, depends a great deal on the weather; if the air is very .
, humid, twenty-four hours is quite fufficient, but if it is very

dry, it w'ill require four or five days.

After I had obferved that after the inftrument was charged
with pofitive electricity its fpontaneous eledtricity was always
pofitive; and that after it was charged with negative eleftri-
city, its fpontaneous ele<Slricity was negative only within a
. , certain time after it had been difcharged, and then became

pofitive; and alfo that it required a greater number of motions
of the lever to produce a certain eftedt on the ele6lrometer
with negative eledtricity, the longer it flood after it had been
charged with negative eleftricity, and that when it became
pofitive, the longer it flood the lefs number of motions oLthe
lever it required to efFe6l the ele<5lrometer with pofitive elec-
tricity to a certain degree, and this within fome certain limits.
I was at a lofs how to- account for this change. However,
after fome confideration, I began to fufpefl that the plates (al-
though all of the fame metal, copper) had each a property
peculiar to itfelf, of acquiring a certain fmaH charge of one
kind of electricity in preference to the other; and that if they
were left to themfelves they would naturally do fo. I therefore
began a fet of experiments to afcertain the probability of this
fuppofition. Firfl, direClIy after the inflrument had been ufed
for negative eleif^ricity, I difcharged it by touching each of the
plates with a metal point, which I held in contadl with each
plate for two or three feconds. An eleCtrometer was then
connected with the plate A, and while it was in this fituation,
it was made to diverge with pofitive eleClricity ;* it was then

* The eleflrometer was made to diverge by bringing an excited
glafs or fealing wax near it.

dif-

/'

CQMPOUND ELECTRICAL INSTRUMENT. ^3

difcliarged by a flight touch with the finger, the lever was then On the fpon-
moved backwards and forwards about fourteen times, and the tjjcjty of this
ele<5trometer diverged with negative ele6lricity. This was re- inftrument,
peated feveral times with the fame effeft.

The lever was then put in fuch a petition that the plates,
could not be fuppofed to a€t as condenfers, one pair more than
another, and the whole was left untouched for twenty-four
hours. It was then tried, and with twenty motions of the
lever the electrometer diverged with pofitive electricity.

It was then left untouched for eighteen hours more, and on
trial the eledlrometer diverged with pofitive electricity. The
inftrument was next difcharged with the metal point as before,
and the eledlrometer made to diverge with negative eledlricity,
which was difcharged by a flight touch of the finger. The
lever was now worked, and with nine motions of the elec-
trometer diverged with pofitive electricity. It was then dif-
charged and left untouched for fixteen hours, after which it
diverged with pofitive ele6tricity after a few motions of the
lever. It was then left untouched for five days, after that
time it gave pofitive eieCli icity when the lever was worked,
Thefe experiments I have repeated a great many times with
the fame e(fe£t.

As it appeared from the foregoing experiments that the re-
fiduum on the eledlrometer was infufficient to overcome the
efl^eCt of the refiduum on the plates, I was induced to charge
the whole infirument with the efFe6t of the eleCtricity, I would
wifti to communicate to it, and this I did by making the elec-
trometer diverge with the defired eleCtricity, and while it was
divergent I began working the lever, to communicate the ef-
fed to all the plates. I charged the inftrument with negative
electricity firft, and difcharged it with the metal point. The
lever was then worked, and in eight motions the eleClroraeter
diverged with negative eleClricity. It was then left untouched
for five days, when eighteen motions of the lever made the
electrometer diverge with pofitive eleClricity. This has been
often repeated with the fame effeCl.

The inftrument was next charged with pofitive eleClricity,
and difcharged as before, after which, fix motions of the
lever made the eleClrometer diverge with pofitive eleCtricity,
It was left untouched for twenty-four hours, when the elec-
trometer

O^ COMPOUND ELECTRICAL INSTRUMfiNT.

On the fpon- trometer diverged with pofitive eledricity with twelve motions

tanews dec- ^f ^i^^ j^^ g^j (-^ j|. jj^j ^f^^J, j^ j^^^j ^^^^ untouched for fix

trjcity of this

inftrumcnt, days.

The probability of the foregoing fuppofition concerning the
property of the plates acquiring a charge of one eleflricity in
preference to the other, was more ftrengthened by the follow-
ing experiment, which has been repeated feveral times. The
inftrument was charged with negative eleftricity, and then left
without difcharglng for twenty-four hours, when fixteen mo-
tions of the lever made the electrometer diverge with pofitive
eleftricity.

I make no doubt if the plates were of different metals this
efted would be more ftriking, and that in fome cafes we
Ihould have the contrary ele6lricity. I intend to conftruft one
of thefe inftruments in fuch a way that plates of any metal
may be put on, and their effect tried. I think this a fubjeft
well worth purfuing as it may throw fome light on fome of the
phenomena of electricity, which have their caufes at prefent
buried in obfcurity.

Note reJpeSiing the Sufpenfion of Zinc in Hidrogen, and the con"
feqwnt Ignition and Fujion of Plaiina Wire. By Amicus.

To Mr. NICHOLSON.
Dear Sir,

Ignition and 1 EMPLOY a gajbmeter of a much more fimple conftru6lIon
fufionof platlna ^^^ much lefs expence than Lavoifier's, which that fKilful and
eazomete? °" ^ intelligent artift, Cuthhcrtfon, invented at ray entreaty, about
ten years ago. It is defcribed in your valuable Journal (quarto
feries, vol. II. p. 235.) The brafs rod or the thick wire, which
conveys the electric fire through the upper receiver, has about
half an inch of platina wire appended, to hang juft over the
aperture through which the hydrogen gas rifes at the bottom
in the brafs work. Zinc of any other fort of metal would
either be melted or readily oxided. But the other day, I was
much furprized to fee the platina wire, on becoming as ufual
. nd hot from the flame of the hydrogen gas, melt into globules

as

DESCRIPTION •F A BLOW-PIPE. ^S-

as readily as copper or brafs wire would have done, I foon —canfed by tfie
perceived from Jhe colour of the flame of the hydrogen and volauluation of
the depcfit of white clouds on the infide of the glafs, that the
rapid folution of the finely powviered zinc ufed to afford the
gas, that this metal was a6lually fufpended or diflTolved in the
gas, and hence the zinc ading to the platina fufed the latter.
It may be perhaps ufefiil to know this fadt, which occurred
during the public ledure,

Your's, as ufual,

AMICUS.
JuIj/2, 1804.

VI.

Defcripiion of a Blow-Pipe a^ing hy the Prejfure of Water, by the
Abbe Melograni. In a Letter Jrom Mr. G. B. Greenough.

To Mr. NICHOLSON.
'SIR,

No. 15, Parliament- Street,
Augufi 13, 1804.

JlT ERMIT me to make you acquainted with the principle of Blow-pipe fup-
an inftrument invented by the Abb^ Melograni, and ufed by ^^^^^1,^^^^^'
him at the Royal Mineralogical Collection at Naples, as a changing their
fubftitute for the blow-pipe. I regret that I cannot fend you P°^^*^°"*«
an accurate account of its conftru£Hon, as I made no fketch
at the time, and fpeak only from recolledlion.

Two hollow glafs globes of convenient lize were connoted
together by two brafs tubes laid along-fide each other, one of
them having a valve or flop cock, I am not fure which, at
each end, and a fide tube of the fame metal going off from the
middle at right angles. The frame was attached to the verti-
cal tubes, foas to allow the globes to circumvolve each other.
Let the lower globe be half filled with water and inverted;
Then the water in A (Fig, 2. Plate IV.) running into B
through the tube C, will force a conftant flream of air into
the tube D, and thence, the upper orifice being clofed, into
the fide-tube E, at the mouth of which the candle is placed.
When the water is nearly run out invert the globes.

If

2^ IvriNERALOGlCAL SYSTEMS.

If the principle of this inltrument fliall appear to you dc,
ferving ot the public attention, it would give me pleafure to
fee it fubmitted to the readers of your excellent Journal. I have
the honour to fubfcribe myfelf,
Sir,

Your obedient humble fervant,

G. B. Greenough.

VII.

Outlines of the Mineralogical Syjiems of Borne de Lijle and the
Abbe Haul/; uith Obfervaiions. By the Abbe Buee, Com'
viunicated by the Hon, Robert Clifford.

. , To Mr. NICHOLSON.

SIR,

Outlines of the W HEN the public mind appears at any time to direft it-
mincralogical ^ f^jf towards a particular fcience (as it does at prefent towards
de Lifle, and the mineralogy,) no perfon can feel the neceffity of removing any
AbbeHauy. erroneous opinions relating to that fcience, more forcibly than
a gentleman who dedicates his time, as you do. Sir, to pro-
pagate correft fcience by means of your Journal. Aduated
by the fame fentiments, may I requeft the infertion of the en-
clofed paper, whofe objefl is to remove feveral erroneous
opinjons relating to the mineralogical fyftems of Romc^ de
L'lfle, andof the Abb(SHauy. It was written by the Abb6 Bu^e
in French for a friend of his, but on its being communicated to
me by the author, I requefted leave to fend an Englifh tranf-
lation of it to you, thinking it might be acceptable to thofe
who are fond of philofophical purfuits. Should your opinion
coincide with mine, you will certainly afford it a place in one
of your enfuing numbers.

And I remain. Sir,

Your very humble fervant,

Robert Clifford.
Welbeck'Streef, July 1 3, 1 SOi.

A Letter

MINERALOGICAL SYSTEMS, Q^

A Letter from the Abbe BuSe to Mr. — , on Mr. Rome deUIJleh
and the Abb6 Hauy*$ Theories of Cryfiallography,

Sir,

IN confequence of your requefl-, I fend you the parallel of ^^''^V^^ between
.1 ^. • /• ^ n 11 t I • 1 r 1- . 1 the theories of

the two Theories of Cryltallography, which leem to divide Rome de I'llle

mineralogifts in this country, thofe of Mr. Rom6 de L'Ifle and and Hauy.

of Ihe Abb^ Hauy. You are perfe6lly acquainted with the

former theory, but nearly a ftranger to the latter. Having

lived for fix and thirty years in habits of intimacy with the

Abbd, I dwell with pleafure on his w^orks, and will do ray

utraoft to fatisfy your curiofity.

To Mr. de L^Ifle is due the merit of having called the at- De rifle firft
tention of naturalifts to that negleded branch of n^'neralogy, "^J'^J^^^^"'^^^
cryflallography; of having difcovered that that branch, though phy.
negleded, was perhaps the moft interefting part of mineralo-
gy, and the only part which could raife it to the dignity of a -
correal fcience; in fhort, of having difcovered order, by nu-
merous obfervations as ingenious as new, there, where a
Cronftet, a Bergman, a Buffbn, or a Kirwan could perceive
nothing but confufion; and thus feemed to refcue nature from
the charge of caprice, almoft imputed to it becaufe great mi-
neralogifts had negle6led to ftudy its unerring laws.

It was exclufively referved to the Abbe Hauy to point out, Hauy firft ex-
to explain, and apply thofe laws. He demonftrated where P['^^'^^^'^^^^^
De L'Ifle affirmed. He difcovered thofe hidden fads, which
he has fince (hewn to be the mathematical confequences of
fads obferved by De L'Ifle. If the latter furniQied a part of
the materials, the Abbd has augmented and employed them.
The difcoveries of thefe two writers force me to fubdivide
cryflallography into two diftin6t parts; defcriptive and phi-
lofophical; and under thefe two heads I will rapidly defcribe
the labours of each author.

Defcriptive, — The moft important part of Mr. de LTfle*s Defcriptive cry^
work confifts in his cryftallographical tables. In each of thefe D^^nfl^.^Luu
tables (feven in number) he defcribes one of the principal
forms affumed by cryftals, and then delineates the different
modifications of which that form is fufceptible, by means of dif-
ferent troncations (troncature) as he calls them.

For elucidation, let us take a cube, the primitive form of Modifications of
the fecond table. A- cube, it is known, has fi)i faces, eight cryftals defcribed

° by troncations.
lOha Inftancethe

cube.

2g MINER ALOGICaL SYSTEMS.

folld angles, and twelve edges. If the cube be truncated in
a parallel to one of its faces, a redangled parallelipipedon will
be produced, and the equality of the faces will be defiroyed.

If the eight folld angles of the cube be llruck ofl', eight
new faces will replace the eight folid angles, and in place of
fix fides we (hall have fourteen. If the twelve edges be taken
off, twelve new faces will fucceed the flrait lines, and the
folid will have eighteen fides. Such are De L'Ifle*s fimple
troiications. They may be then combined with each other, and
made more or lefs deep; hence an immenfe variety of new
figures. But thefe new forms again may be truncated in the
directions either of their faces, folid angles, or edges, and
(hefe new troncations more or lefs deep, called by De L'Ifle
Jur-troncatures, may alfo be combined with each other. Here
the forms mud multiply to infinity, and their boundlefs num-
bers will foon bury the primitive cube in oblivion.

It muft not be fuppofed that nature has furniQied us with this
infinite feries of forms; indeed Mr. De L*J(le in his tables has
only mentioned ihofe he had obferved, with fome few addi-
tional fuppontious figures, of which feveral have been fince
difcovered to exifi.
Account of This ingenious naturalift has given us, as I have already

Del'ine'sfeven f^i^ f^^ren cryfialloojraphical tables. In the I ft he defcribes
tables of cryftals. , , , "^ ,*. ' ,.r • • •,

the tetrahedron and its modincations; m the 2d the cube; m

the 3d the rectangular octahedron ; in the -ith the rhomboidal

parallelipipedon; in the 5th the rhomboidal octahedron; in the

6th the dodecahedron, w^ith triangular faces, and to each are

fubjoined their refpedlve modifications. The obj-ecl of the

7th table is to point out certain modifications of the o6tahe-

dron and parallelipipedon, whether reftangularor rhomboidal.

Plates accompany each table, where the figures are drawn,

and in the obfervations and notes on them are to be found the

meafuresof the principal angles.

They contain Thefe cry ftallographical tables exhibit only general repre-

general folids } fentations of folids, which Mr. de L'Ifle in the courfe of his
which are Alb- , ,. , ,.„^ -, , ,- , , , i i •

fequently applied work applies to the diHerent cryltals which had already been

tothecryftdis difcovered, and fallen within his obfervation. His work con-

fafdfjiotm, and ^^^^ of three parts. In the firft he treats of faline cryftals; in

^stctah, the fecond of ftoney (pierreux) cryftals, and in the third pf

metallic cryftals. Thofe of the firft clafs are artificial, thofe

of the two latter claflesare natural cry fta,ls, and are fubdividqd

intp genera, fpecies, and variciirs.

When

MINERALOGICAL SYSTEMS. QQ

When treating of a fpecies or of a variety, he refers his His method of
reader to the table where the figure of that fpecies or variety «lefcnptioa.
is to be found, and he then enumerates every thing relating to
minerals aduming that cryflalline form: But I cannot termi-
nate this iketch better than by the following extracl from the
Abb^ Hauy's treatife on mineralogy.

*' In (hort Romede L'Ifle reduced the ftudy of cryftallogra- Quotation
phy to principles more exa(5l and more confident with obfer- "j^'j^g""^^^
vation. He clalTed together, as much as he was able, cryftals De rifle's la-
of the fame nature. From among the different forms belong- °°""*
ing to each fpecies, he feleded one which appeared to him to
be the moft proper, on account of its fimplicity, for the primi-
tive form, and then fuppofing it to be truncated in different
manners, he deduced the other forms, and efiablifiied a cer-
tain gradation or feries of paffages from the primitive form to
that of polyedrons which would fcarcely appear to have any
connexion with it. To the defcriptions and figures which he
gave of the cryfialline forms, he added the mechanical mea-
furement of the principal angles, and he (lie wed (a molletTen-
tial point) that thefe angles were conflantly the fame In each
variety. In a word, his cryftallography is the fruit of immenfe
labour by its extent; almoft entirely new in its obje61, and of
great value for its utility." (Vol I. page J 7.)

The Abb^ Hauy in his treatife on mineralogy embraces a The mineralogy-
far greater extent than Mr. de L'Ifle. His mineralogy is not °f ^^uy is not

1 1 r • • I • • 1^1 1 -1 1 . . nierely defcrip -

only deicriptive, butitis phylical, chymical and geometrical, tive, but phyfi^
In the perfualion that a mineral cannot be well defcribed, nor "^' chemical
even in many cafes recognized, unlefs its phyfical, chemical,^" geometnca,
and geometrical charaders are clearly laid down, the Abb6
never omits any one of thofe charaders when afcertained, and
expofes with the moft fcrupulousexaflnefs every thing relating
to them that obfervation has authenticated. He has beftowed Eledlricity.
particular attention to the eledrical and magnetic phenomena, Magnetifm.
and has enriched the fcience with a multitude of new and cu-
rious obiervations. He attehtively examined the property of Double refrac-
double refradion, which feveral tranfparent minerals enjoy ;^^°^*
and here again he has extended the boundaries of fcience. A
few minerals were known to poflefs this property, and the
Abb^ has difcovered it in feveral where it had never been
furtnifed.

When we confider that writers on mineralogy have hitherto Hauy has ex-
grounded their fyftems exduftvelj/, fome on the exterior cha- thetabUudes°^

rapiers.

30 MINSRALOGICAL SYSTEMS.

ar properties of raclers, others on the chemical properties of mineral;?, and (hat
the Abbe really has, purfuant to his plan, (fee in the begin-
ning oF the volume of plates. La dijlribution methodujue des
viinernux, par clajfes, ordres. Genres et efpeces, the melhodical
diftribution of minerals intoclafTes, orders, genera, and fpecies)
united all that has hitherto been difcovered on mineralogy,
without falling into that confufion which has ever been im-
puted to other mineralogical writers, we are almoft aftoniflied
at his fuccefs. *' To clafs minerals, to furnifli the means of
difcovering to which clafs, genus, and fpecies a mineral under
examination belongs," are the two great problems which the
Abbe Hauy propofes for folution,
Clafllfication, He folves the firfl in following Bergman's method (founded

TcftTeatton W ^" chemical properties) much improved by the immenfe pro-
extetnal charac-grefs which chemical analyfis has made lince the days of that
*"'* great chemlfl. In the folution of the fecond he follows Wer-

ner's method (grounded on exterior chara6lers)but corroborated
by a multitude of new experiments, eafily made and brought
* to a furprizing degree of correflnefs by the Abba's own la*

bours on the forms of cryftals. But I perceive that the im-
menfity of matter contained in this treatife is leading me from
that point which I had particularly in view, I mean cryftal-
lography.
Haviy's defcrip- In the defcriptlon of crytlals the Abbe employs three dif-
tion of cryftals, ferent mean?. 1(1 He draws their figure; he does not give
tionJ '^^ ' cryftallographical tables as Rome de L'Ifle, which are only
general properties, but draws feparately each fpecies and va-
riety. Every form given in the plates has been examined by
himfelf; he has calculated every angle, and neverthelefs his
plates contain one third more figures than De L'Ifles tables.
2. By fymbollc 2d He makes ufe of fymbolic figns, than which nothing can be

figns defignating ^^^^ fimple, and were invented not to recall the form of the
the laws or their ' , , , , . , - i i i j

produftion. cryftal to the mind, but the laws by which it has been produced*

Yet I have met with perfons, who were foaccuflomed to thefe

figns, that at firfl fight of them they could immediately figure

to themfelves the form of the correfponding cryfials. Thefe

figns can alfo be fpoken, and much circumlocution in eonfe*

3. By nomen- quence avoided. 3d A fignificant nomenclature fubdivided

clature. into general and particular. The general is for the mineralsy

and comprifes only fubdantives; the particular for the crj/Jiahi

and is entirely cortlpofed of adjedlvesi He ftudioufly avoided

4. introducing

MINERALOGICAL SYSTEMS. 31

introducing new names, and neverthelefs has been obliged to
introduce many, where new fubftances, names capable of
giving falfe impreffions, or others void of fignification and un-
fupported by long ufage, required it. Hethenfubftituted names
taken from the Greek; a language, he fays, that eminently
enjoys the faculty of combining feveral words together, fo as
to form one reprefenting concifely the objed to be named, —
The adjedives ufed in the nomenclature of the cryftals alfo al-
lude to forae remarkable circum (lance of the cryftalline form.

1 fliall now proceed to philofophical cryftallography, which Philofophical
might be called the philofophy of mineralogy. It does not "^'^^""g'^^P'^^
confift in fearching for the primary caufes of phenomena, no- *

thing can be lefs philofophical than fuch a refearch; primary
caufes will ever be beyond the reach of the human mind!
The immortal Newton was the firft to point out to us by the
•method followed in his admirable book of the Principia, that
the only true philofophical way of treating a phytical fcience,
or of explaining a natural fad, was to demonftrate that it was The true method

the mathematical confequence of a general law, grounded °f "P. "'f'

, .\ , ,r 1 1 1. phyfics IS to ihew

on an aggregate or facts already obferved and capable that the fafts are

of correal calculation. If any one of thefe conditions are mathematically
wanting, we immediately launch out into hypothefis, expla- general law.
nations become vague, and however much we may be per- Hypothefis*
fuaded of the truth of our aflertions, we can acquire no cer-
tainty.

Let us apply thefe principles to our two writers. De L'Ifle, The method of
in declaring that the various forms obferved in cryftals of the ^gJ^J^ to be Sfe-
fame fubftance are only modifications of one conftant primitive ficient iacor-
form, certainly announced a raoft important truth. It was a'^^"^^^*
flalh of genius; but in a philofophical enquiry, to prove it and
not limply to fay it, was the necelTary ftep. On the firft in-
fpedion of his cryftalloujraphical tables, a ftudent is tempted
to think that important truth demonftrated; but on a clofer ex-
amination, the impreffion is done away. The fame order per-
vades every table. By fligh^ paflages the ftudent is led from
the fimpler to the more compound forms, and after every paf-
fage, is tempted to fay ; this can only be a modification of the
primitive; then when the real cryftals, and the figures of the
tables are compared together, and all thofe of the fame fpecies
(with a very few exceptions) are fotind in the fame table,
how eafy it is to perfuade ourlelves that nature rnuji operate by

ftmilar

32

MINERALOGICAL SYSTEMS.

fimilar paffages when producing the various forms of cryfiak;
ami the primitive of the table before us muft be the primitive of
thecr^ftal under examination. In a word it is t!ie moftfimple
form ; and firft impreffions greatly llrengthen the illufion. If
perfuafion was the fole obje^ of philofophy, De L'Ifle would
have been a powerful phiiofopher; but philofophy mufl con-
vince, demonftrate, and wreft confent, however violently op-
pofed. An enemy mufl not therefore be able to make ufe of
the fame arms, or adduce the fame proofs to eftablifli a con-
trary opinion. Ncverthelefs fuch would be cafe with Mr.
. tnd miY be De L'llle's tables and the application of them ; For it is an in-
eftabiXfaUhood.^^"^^^^^'^ ^'*^» ^^^^ by a feries of arbitrary troncations we

, may pafs infenfibly from any given form to any other. Grounded
on this principle, and feconded by Mr. de L'lOe's ingenuity,

. any form may become primitive, and any other deduced from
it. Now as t))e combinations are infinite, a multitude of tables
may be conltru<5ted, forms of the fame fpecies may be dif-
perfed in different tables: the moft fimple of each table will
be the primitive, therefore forms of the fame fpecies will have
different primitives. But when by the fame principle both
fides of thequeftion can be proved, nothing is proved.

To fay the mofl fimple form mull. be the primitive is an il-
lufion, for we know not what is the moft fimple for nature.
Wilh our feeble organs and confined fenfes we can form no
judgment of Jimple, when the operations of nature are in
quefi;ion. Nature embraces the entire univerfe, her laws are
fimple; but the combina,tions made according to thofe laws
are unbounded, therefore complicated.

Let us not forget, however, that the idea of troncations,
and the idea of taking the mod fimple form for the primitive,

,.are fo, natural that they muft have been the firft to prefent

; themfelves to the man who was opening the carreer: " Often,
fays^the Abbe Hauyi (vol. I. page 14) a more compound form
only diff(^rs from a more fimple one by certain little faces which
may be produced by feftions, either at the folid angles, or on
the edges of the fimpler form,** and in a note he fays, " this
was the obfervation which gave the celebrated Rom^ de L'Ifle
the idea of his fyflem of troncations, that he might fuccef-
fively deduce from each other the different varieties of cryftaU
line forms alTumed by the fame fubflance."

Mr.

On the njoft

fiiijple form.

TEe <>ftfm of
troncatipns is
the moft ob-
Tious.

MINERALOGICAL SYSTEMS, 33

Mr. De L'llle terminates the introdu6lion to his work by De rifle's pro-
certain axioms, as he ftyles them> the 2d and 16th are asfol-^"^ axiom*
low: ,

*' II. Every angular polyhedron, or every cryftallized fub-
ftance is a salt in the mofl: extended acceptation of that
terra/'

" XVI. Every faline fub^ance whofe confiituent parts are
perfectly faturated and combined affefts the cubic form, or its
inverfe the octahedron; whereas the falts which are not neuter,
or whofe conftituent parts are not exa6lly combined, affedt'
either the prifmatic or the rhomhoidal forms. '^

I need fcarcely obferve that, to treat thefe axiofils ohly as
doubtful, would be treating them kindly. The other axioms
are matters of fad, from which he draws no confequence, and
indeed it would have been difficult for him to have drawn any.

The Abb^ Hauy does not undertake to prove generally, that Hauy'sexhlbl-
among the different cryftafline forms of the fame fubftance, one '^'o" <>f '^he pri-

f xi • .1 • •.• 1.1 1 .1 . • ■>.' r mitive form in

or them is the primitive; but he produces that primitive form cryftals,
from each cryftal, which is always fimilar in fimilar fubftances.
He demonftrates it analytically and fynthetically ; by an ana- ^y analyfis and
lyfis which might be called mineralogical analyfis, and pointed fynthefis.
out by nature herfelf : By a fynthetis hitherto the property of
mathematicians, but here fupported by the general laws which
bis analyfis has revealed to him. The conftant accord found
between this fynthefis, and daily obfervation is a proof of the
exadnefs of his method.

Two fa6ls were the foundation of his theory : 1 . In all times Fundamental
jewellers and lapidaries have remarked that flones are more ^^*^^* '-Cry-
calily cut in fome certain directions than in others. 2. Who- in certain di-
everhas been in the habit of feeing natural cryftals muft have *"^'^ions only j
obferved, that when their forms are well determined, they are daries^are ^rigbt*
always terminated by plane furfaces. Thus, fays the Abb^, lined or plane.
** thofe foft outlines, and that roundnefs fo frequent in the ani-
mal and the vegetable kingdom, where they are inherent to
the organization, and contribute even to the elegance of the
forms, indicate on the contrary in minerals a want of per-
fedlion. The charaderiftic of true beauty in minerals is the
ftrait line, and it was with truth that Rom^ de L'Ifle declared
that line to be the peculiar property of the mineral kingdom."
The firft fad fuggefted the mineralogical apalyfis, and the fe-
cond furniflied him with the laws on which he grounded his
fynthefis.

Vol. IX. — September, 1804. D Enquiries

34» MINERALOOICAL sVStEM^.

Enquiries on thefirfi Fad;.
On the analyfis I. All cryHals that can be fplit by means of inftruraents, of-
of cryftals into ^^^ *® ^^^® vIew, if fplit in certain dire6tions, plane and fmooth
regularly formed furfaces. If divided in other diredlions, the fra6lureis rugged,
fiffurt? ''^ ^ "^"^ ^'^^ word fplit, and notfatced or cut, as the feaions of the

cryftal are not to be obtained by flow and continued efforts, but
by fudden fliocks. Patience, dexterity, and habit enabled the
Abb^ to fplit a great number of cryftals ; in all he difcovered
plane fmooth furfaces when fplit in certain dire6lions, but when
in other diredions, the fra6lure was always rugged and irregu-
lar. I requeft. Sir, your attention to this important fa<5l, it is
fundamental, and the more important, as feveral perfons of
much general information have neglected to attend to it, and,
It'iaexferttnentaij in confequence, have fuppofed the whole of this theory to be
troncations*of g^ountied on hypothefis. It would be equally erroneous 10
De rifle were confound thefe fed^ions of cryftals with De L'Ifle's troncations.
bjpotheticaU 'p|^g latter indeed warns his readers, that by the word tronca-
tions he wiflies only to figure the appearance of the cryftal ex-
amined. They are not therefore real, but only a means of
warping the imagination to the exterior form of the cryftal, and
are by their nature only defcriptive. The Abb^ Hauy's fee-
lions are real, and are pointed out to the obferver by the inte-
rior ftrudure of the cryftals ; they are experimental.
The inclinations 2. The plane fmooth furfaces obtained by the above method
cLftanu" ^* are refpedively parallel to 3, 4 or 6 planes. The mutual in-
clination of thefe planes to each other are conftant in cryftals
of the fame fubftance, whatever may be the exterior form of
the cryftal. Native antimony, phofphate of lead, and quartz
feem to fliew an appearance of more than fix planes, and the
Ahh€ Hauy leans to the opinion of only five planes in forae
cafes ; but as thefe are exceptions to the general rule, and
would only tend to complicate this ftatement, I fhall take no
further notice of them.
Explanation of Let US fuppofe the fmooth furfaces to be only parallel to three
the figures and pja^^eg^ or in other words, that the fabftance will only fplit in
cryftalsTy^the ^^^^^^ diredions, in that cafe the feclions can only produce a
meibodof Hauy. parallelipipedon, whofe nature is determined by the mutual in-
clination of the planes to each other. If the planes are per-
pendicular, it will be redangular, &c.

We next fuppofe the fmooth furfaces to be parallel to four

planes. Here adiftindtion arifes, whether three of thefe planes

4 have

MINERALOGICAL SYSTEMS. 55

have a common inlerfedion or not; and it m lift be reraem- Explanation of
bered that if the four planes have a common interfeflion, i^o formation^of"
folid can be produced, as they can neither bound nor include cryftals by the
a fpace. If therefore three of the four planes have a common*"^^ ° "^^^
interfedion, the fplittings will produce either one hexahedral
prifm, or three parallelipipedons, which will be fimilar or dif*
iimilar, according to the fimilarity or difiimilarity of inclinai'
lion of the planes, or one triangular prifm. On the contrary,
if the four planes only interfcdt each other two and two, there
will be produced either one OiSlahedron, or four parallelipipe-
dons, or one tetrahedron.

Laflly, let us fuppofe the fmooth furfaces to be parallel to
fix planes; then there arife an immenfe number of cafes.—*
But we will for the prefent confine ourfelves to the only cafe
that has hitherto been obferved in nature : Where the inter-
re6tion of the planes is two and two, then we obtain either,
1. dodecahedron with pentagonal, quadrilateral or triangular
fides, according to the fedions made, or fifteen odahedrons,
or twenty parallelipipedons, or fifteen tetrahedrons. It may
be proper to obferve here that though the fedtions parallel to
the fix planes may be clearly indicated, neverthelefs it rarely
happens they can all be executed, but it will fuffice for the
purpofes of geometry that they be clearly indicated to render
the confequences drawn from them mathematically correal.

Having laid down thefe premifes, let us proceed to the dif-
fedion of a cryfial of carbonate of lime (the fpath calcaire of
De L'Ifle) whofe primitive form is a rhomboid or a parallelipi-
pedon bounded by rhombs. Hitherto fedions have only been
obtained in the three directions parallel to its fides. If thefe
feflions be dired^ed fo as to always pafs through the center of
two oppofite fides, they will produce eight rhomboids equal
to each other, and fimilar to the original one. The fame
operation may be repeated on each of thefe eight rhomboids, and
continued fo long as the fubftance remains carbonate of lime,
that is to fay, to be a combination of 55 parts of lime, 34?
of carbonic acid, and 1 1 parts of water of cryftallization : —
(fee Bergman.) But this divifion of the cryftals into fimilar
folids has a term> beyond which we fliould come to the fmalleft
particles of the body, which could not be divided without
chemical decompofilion ; that is to fay, without an alteration

Da in

C6 MINERALOGICAL SYSTEMS.

Explanation of in the proportions of lime, carbonic acid, and water, Thefe

fonnal"oTo? '^^ pdrticles which are ftill rhomboids, are what the Abb6

cryftais by the Hauy calls the integrant particles of tlie carbonate of lime. Irt

n>ethodof Hauy. ^j^^ fuppofition therefore that a rhomboid of this fubftance can

only be divided in three diredions, by fe6^ions parallel to the

fides, it is evident that the integrant particles muft be fimilar

rhomboids.

If a cryftal can be divided by feftions in more diredions
than three, what will be the form of the integrant particles ?
For example^ in the phofphate of lime (the chryfolite of De
L'Ifle) where the fedlions are parallel to four planes, three of
which have a common interfedion. According to what has
been faid above, thefe fe6lions can produce either one hexahe-
dral prifm, or three parallelipipedons, or one triangular prifm.
It is evident that by carrying the divifion, according to thofe
fedlions, to its greateft length, either the laft hexahedral prifm,
or the laft three parallelipipedons, or the laft triangular prifm,
will be produced. Are thefe laft folids the integrant parti-
cles; are each of them fo; or is there only one of I hem en-
tilled to that denomination ; and if only one, which of them ?
My anfwer is, only one of them ; and that one, the triangular
prifm, which may be proved thus.

It cannot be denied that the integrant particle is that little
folid which contains the leaft poffible quantity of the body,
without affeding the chemical compolition of the fubftance.
This granted, let us fuppofe the hexahedral prifm to be the in-*
tegrant particle. In that fuppofition the laft triangular prifm
muft contain the laft hexahedral prifm, and is equal to the
latter more three little triangular prifms, or in other words to
nine fimilar triangular prifms, while the hexahedral prifm only
contains fix. But the laft triangular prifm and the laft hexa-
hedral prifm each contain an exa<5l proportion, and therefore
a fimilar proportion of chemical component parts; therefore
their difference alfo contain an exa6t proportion ; but it is im-
poflible to conceive how their differences can contain the ex-
a6t proportion, unlefs each of the three little triangular prifms
alfo contain it, they muft therefore contain it, and each of
them muft be an integrant particle; therefore the hexahedral
prifm cannot be one ; neither can the parallelipipedons be in-
tegrant particles, as the fame arguments will ftand good againft
them which have been applied to the hexahedral prifm ; there-
fore

MINERALOGICAL SYSTEMS. 57

fore the triangular prifm rauft be the integrant particle :* Explanation of

,*,. r. , . . . , * , * 1 1 , r 1 T *^c figures and

'* The forms ot the integrant particles, lays the Abbe (vol, I. formation of

page 30) may be reduced to three, the tetrahedron or the moft cryft^ls by the

timple of pyramids, thetriangular prifm or the mod fimple of ""^ * ^ *"^'

prifms, and the parallelipipedon or the m oft fimple of folids,

having parallel (ides two and two, and as four (ides are ne-

ceflary to circumfcribe a fpace, it is evident that the above

three forms in which the number of fides are fuccefllively four,

five and fix, are again in this point of view the mofl fimple

poffible."

The phofphate of lime or chryfolite is a fubflance that has
given rife to much curious anecdote. It fhews in what a flate
Abb^ Hauy found the mineralogical nomenclature, and points
out the accuracy of his analytical method. Achard, achemifl
at Berlin had analyfed the chryfolite, and publiflied that it con-
tained, of filex 15 parts, alumina 64, lime 17, and of iron
one. This ftartled the celebrated Vauquelin, who had feen
Klaproth's analyfis of the chryfoh'te (the apatite of Werner)
containing of lime 55 parts, and of phofphoric acid 45, (pro-
bably the water of cryftallizalion is added to the acid.) A
Frenchman of the name of Launoy fent a quantity of thisfub-
ftance to Paris, feme of it was purchafed by the Ecole des
Mines, and Vauquelin was deli red to analyfe it. The latter
foon fufpe6led Achard iiad been milled by the name, and had
not obtained the proper fubftance, a mlftake the more eafily
made as, fays Vauquelin, " the name of chryfolite was given
to a great variety of ftones, fuch a^ the peridot, the chrT/fobcril,
the olivine, (fince found to be the fame as the peridot), ar^d in
general io ftones having a yellow colour."

He foon difcovered the chryfolite fent from Spain contained
lime and phofphoric- acid. " I had no fooner made this dif-
covery, fays he, than I enquired of Abbe Hauy whether he
had compared the integrant particles of the chryfolite with
thofe of the apatite or cryftalllzed phofphate of lime. He an-
fwered me that he had not made tlie comparifon, but that he
would get his papers on primitive forms, (this was four years
before the publication of his work) fee what notes he had

* Therefore the fe6lions producing the hexahedral prifm cannot
lead to the integrant particle : therefore all feftions, though per-
fectly practicable in cryftals, will not lead to the integrant particle.

madf

38. MIVERALOGICAL SYSTEMS.

Explanation of made on each of thofe fubftanQCs, and immediately compare
the figures and them together; when with pleafure he found that there was

formation of i i o • • i i >^t i i i * i i r

cryftdsbythe "ot the lealt variation between them. Ihus had the Abbe
method of Hauy. Hauy difcovered by the help of geometry alone, (hat which was
confirmed by chemical analyfis, and this fatisfaclory accord
between two fciences apparently fo diftant from each other,
while fecuring each others fteps, ferves alfo to (hew the cer-
tainty of the principles on which they are grounded."

Journal des Mines, Kxxvl'u page 21.
A morefingular anecdote is what took place with retpect to
the emerald and the beril. VauqueUn had analyfcd the
emerald of Prerou, and read the refult of it, at a fitting of
the Erole des Mines, which is preferved in the Journal, No.
XXXVIII. page 96: viz. of filex 64, of alumina 29, oxide
of chroma 3, of lime one, and of volatile fubftance 2; I
have negleded decimals. Soon after he difcovered a new
earth, which he called the Glucine, and gives the following
account of it to the National Inftitute : ** The Abbe Hauy
having obferved a perfect conformity between the llruclure,
the hardnefs, aild the weight of the beril and the emerald,
prefled me a few months back to make an analyfis of thefe
two fubftances, to know whether they contained the fame
principles, and in fimilar proportions. In the refult, the fafl
that will raoft iniereft the Inftitute is the difcovery of a new
earth, &c. &c." Annates de Chimie, vol. XXVI. p. 137.

I am certain, Sir, that it will give you no lefs pleafure to
learn that Vauquelin, in confequence of this difcovery, made
an addition to the paper read at the Ecoles des Mines, beginning
thus, ** Since the reading of the above paper, having dif-
covered a new earth in the beril, and as this ftone, according
to the obfervations made by Hauy, contained fubltances fimi-
lar to the emerald, I have in that point of view made a new
analyfis of this latter fione." And the former analyfis was
immediately corrected, and the 29 parts of alumina became
36 parts of alumina and 13 of a iiezv earth. I hope. Sir, it is not
too much to fay that, on this occafion a new earth was dif-
covered, if not by, at leaft in confequence of, a geometrical
analyfis.

But to return to our fubjed, the Abb<$ makes a difiin6lion
between the integrant particle and the primitive form. The
former, as I have faid, is that laft particle, which preferving
an exaft proportion of the component parts, contains the leafi

number

MINERALOGICAL SYSTEMS. • 2Q

numbet of thofe parts ; it is the laft term of mineralogical Explanation of
analyfis. The primitive form, on the contrary, is its fi'ft re- ^^^^^'^^JJ^^^^^"
fiilt^ and retaining the exaft proportion of the component cryitals by the
parts, contains the greateji number of thofe parts. It is eafy "^'^thodof Hauy.
to fee that in the cafe above mentioned of the phofphate of
lime, the hexahedral prifra will be the primitive form, pre-
cifely for the reafons adduced to fhew that it is not the in-
tegrant particle. Though the Abbd does not decidedly de-
fine the integrant particle as containing the 7uinhimm of fpace
under the maximuin of furface, and the primitive form as con- ,

taining the maximum of fpace under the minimimi of furface,*
neverthelefs he makes a remark that authorifes the above de-
finitions (which. Sir, you will obferve are mine, lefl any fault
Jbe found with them.) He fays the dodecahedron with rhom^
boidal fides, which is the primitive form of the garnet (grenat)
contains the maximum of fpace under the minimum of furface ;
and if it be cut into two equal and fimilar parts, it will prefent
the fame form as the bottom of the cell of the honey-comb,
which has the fimilar property.

An objedion might be taken on the cuirre pyrileiiXf and the

, cuivre gris, or the yellow and grey copper ore of Kirwan, the
Abb6 mentioning the regular tetrahedron as their primitive
form, and not the oftahedron as in other cafes. The reafon

.may be, that all the cryfl;alline forms of their fubfiances which
he defcribes are (light modifications of the regular tetrahedron.
" The primitive forms hitherto obferved, fays the Abbe
Hauy, are reduced to fix. — The parallelipipedon, the .octa-
hedron, the tetrahedron, the regular hexahedral prifm, the
dodecahedron bounded by rhombs all equal and fimilar, and
the dodecahedron with triangular fides, formed by two right

^pyramids united bafe to bafe."

Healfo makes a diftindlion between integrant particles and

fubjlra6iive particles ; thefe latter are always parallelipipedons,
I fliall fpeedily mention whence they derive their name. They
are fubftituted for the integrant particles, to facilitate .calcula-*
tions, and it is worthy of obfervation that the parallelipipedon
can always be obtained in all difledlions of cryflals. Thus far.
Sir, I have dated the firfi: principles of miner&logical analyfis ;
I fliall now proceed to the fynthefis.

(To be continued.)

* The Inclination of thg interfering planes being the fame.

Dejcription

40 FILTERING MACHINE.

VIII.

Pefcription qf a Filtering Machine invented By Profejjfor Parrot
of Paris. In a Letter from a Correjpondent.

To Mr. NICHOLSON.
SIR,

Filtering ma- 1 ENCLOSE you a drawing of a filtering machine invented
frlTer^feSi" by Profeiror Parrot, of Paris, wliich for fimplicity and uti-
tity feems fuperior to any other I have met with. You will
perceive that from the curvature of its form, it purifies the
water both by defcentand afcent, and fs, confequently, a clofer
imitation of the operations of nature than thofe in which the
water penetrates in but one direftion. Among the advantages
which he afcribes to it, he infiances the *' prolongation of the
flratum of fand, which does not confiderably diminith the pro-
duct of the filtre, but contributes remarkably to the purity of
the fluid/* and that ** the difference of its water-level has an
eflential influence on the quantity of purified water obtained
in a given time;*' he therefore recommends an apparatus of
eighteen inches long from A to D, two inches thick, and four
broad, which, he fays, will yield fix (Paris) pints of pure
water every hour: a machine of this {\z6 requires onlyadift
ference of two or three inches in the height of the water,

I am^ Sir,

Your conflant reader,
London, Augujl 20, 1804. A. A.

Defcription of tlie Machine.

The refervoirG. Cfig- 1* P^ate IV.) may be of any form or
dimenfion which is convenient J the principal part of the ma-
chinery confiding of a fquare vetfel bent in the form of an in-
verted fyphon. The curve may be circular, elliptic, or in any
other direftion. This veflel is to be filled with fine pure fand
lo nearly the height of the dotted line x y, which denotes the
afcent of the water to D, whence it flows into the receiver.
To the part marked A B, which muft always be above this
line, a woollen bag is attached, open at the top and reaching
to the fand : this colled^s the coarfeft impurities, and prevents
the fand from becoming foul for a longer time. In large ma-

' chines

ON CANTHARIDES. 41

chines a water-tight trap-door raay be made at F, for the puF-
pofe of removing the fand when it is overcharged with impu-
rities. The fmall diameter of the machine from which the
drawing was taken, was eight inches from B to E : the per-
pendicular height from C to A B was eight inches and three-
fourths, and from C to D four inches and one-twelfth.

IX

Medico-Chemical Reftarches on the Virtues and Principles qf
Cantharides. % H. Beaupoil.

(Concluded from Page 71 of Vol. VUI.)

IaE alfo proved that the black precipitate eaiily became dry. Experiments and

obfervations
cantharides*

brittle, and friable in the air; that it reddened the tinfture of ^'^^^f ^^51°"^ o"*

turnfole; that it combined very readily with potafli, difen

gaging ammonia; that, when diftilled by an open fire, it

fwelled and yielded an acid liquor, a thick oil, and carbonate

of ammonia; and that it left a dry, fhining, friable coal in the

iretort.

Proceeding afterwards to the examination of the yellow mat-
ter remaining in folution in the alcohol, Cit. feeaupoil informs
lis, that, when it is concentrated by the evaporation of its
folvent, it retains the fame odour and the fame tafte as the
fextrafl ; that it is completely ditToIved in water, and reddens
the tin6lure of turnfole ; that it combines entirely with potafh,
without any difengagement of ammonia ; and that the refultof
Ihis combination is an homogeneous and glutinous body, foluble
in water and precipitable by a weak acid ; finally, that, dif-
tilled by an open fire, it fwells very little, yields an acid liquor,
a black and fetid oil, and carbonate of ammonia ; but that, in
general, all thefe products are in fmaller quantity than in thofe
obtained from the black precipitate.

Among thefe different refults the author thought it necefTary
to diredl his attention more particularly to the acid, which, as
has been feen, manifefls itfelf To readily in the infufion of can-
tharides, or ill the extract which they afford.

At fir ft he was of opinion that this acid was analogous to that
pf vinegar ; he alfo thought that its exiflence might be attri-
■'■ ^- , buted

4,^ 0?f GANTUAKIDC$,

Experiments and buted to the cuftom prevalent with thofe who colIe£i the Can*
canthwid^s! ^"^ tharides, of expofing them to the vapour of this acid ; but when
he found, on fubjecting fome of thefe infedts which had beetj
procured without the afliftance of vhiegar to experiment, that
they were jQmilar to tiiofe of commerce, he was obliged to re*
nounce his firft idea, and to endeavour to afcertain the nature
of the acid they offered him, by experiment. It appears that
bis endeavours have, in this inftance, been unfuccefsful ; for
he finifties by inferring that his progrefs is not fufficiently ad-
vanced to determine with certainty ; and that, although the
acid in quellion has fome analogy with the phofphoric, he, ne-
verthelefs, does not think that it poflefles all its properties, and,
confequently, is of opinion it (hould be coniidered as a peculiar
fpecies, until new experiments hAve fliewn that to which it
in reality belongs.

The third produfl of cantharides, called by Thouvenel and
by Cit. Beaupoil,. green matter, does not feem to experience
any change from the air, at leaft in its phyfical properties. It
is infoluble in cold water ; it liquefies in warm water, floating
on its furface like an oil ; alcohol and ether diflblve it, and its
folution in thefe two menftrua isdecompofed by water. Oxi-
genated muriatic acid brought into contact with this matter,
and renewed from time to time, at firft feems not to have any
a6lion on it, but at length fmall whitifli, brilliant particles are
detached from it, which fall to the bottom of the veflel : in
lefs than a week it lofes its fmell and its colour, and becomes
thick and glutinous ; and notwithftanding repeated wafhings, it
conftantly retains the odour of the oxigenated muriatic acid.

Diluted nitric acid, aflifted by heat, gives it a ruddy colour,
a rancid, penetrating odour, and alfo a confiderable confif-
tence.

Cauftic foda combines with It without the aid of heat, and
without a difengagement of ammonia. The product of tkis
union is decompofed by the acids.

Expofed to an elevated heat it fufes, and forms a liquid of an
oily appearance and flightly tranfparent, which, by cooling,
quickly refuraes the folid ftate. By a more powerful heat it is
decompofed, its colour changes, a yellowifh oil, very analo-
gous to that obtained from the diftillation of wax, and an acid
phlegm, pafs into tlie receivers, but not an atom of carbonate
of ammonia.

With

ON CANTHARIDES. ' 43

With refped to the parenchyma forming the refidue of theExperlmenteani
different macerations, infufions, and decodions in water, aJ-canth^jdwu**"
cohol, and ether, the author, after having afcertained that
thefe fluids were incapable of extracting any thing more,
treated it with caut^ic potafh, which immediately caufed a
difengagement of a very fenfible ammoniacal odour. When
this odour was diflipated, the liquor was filtered, and inftantly
mixed with muriatic acid : the mixture became turbid, and
gradually yielded a precipitate, which, dried and thrown on
burning coals, exhaled an odour fimilar to that of animal matf
ters in combuflion,

Diftilled in a retort, this parenchyma yielded phlegm, a
denfe empyreumatic oil, and a confiderable quantity of car-
bonate of ammonia. The refidue of the diflillation was a
rpecies of coal, from which a white afh was obtained by inci-
neration in the open air, in which were found carbonate of
Jime, calcareous phofphate, fulphate and muriate of lime, and,
finally, oxide of iron.

In recapitulating the quantities of each of the produdis ob-
tained by means of the experiments which have been cited,
Ihe author afTerts that one ounce of cantharides, well dried,
contains nearly

Black matter - 1 gros 2 grains ;

Yellow matter - 1 — 2

Green matter - 1 — 8

Parenchyma - 4 — 36

Acid - - An indeterminate quantity 5

Calcareous phofphate 12 grains ;

Carbonate of lime - 2

Sulphate and muriate of lime 4

Oxide of iron - 2

To complete the work which Cit, Beaupoil had undertaken,
it remained for him to determine the phyfiological properties
of cantharides, as well as thofe of the moft etfential of their
immediate materials, and he appears to have executed this
with fuccefs in the fourth part of his differtation. Among
other things, it refults from the different experiments which he
has made on this fubjedt,

IJi, That cantharides which have not undergone any pre-
paration, almoft always produce difagreeable effeifls when

taken

44 ON CANTHARIDES;

Ixperiments and taken internally ; but that Ihefe effeds, with refpcdl to their
omhlridcs!"" »"^^"^^y' are proportionate to the age, the ftrength, and the
conftitution of ihe animals, and to the dofe which has been
adminiflered to them : That the oefophagus, the ftomach, and
the fmaller inteftines, are the parts which are principally af-f-
fedled : that ihofe animals which are not overcome by it, ex-
perience a defire to vomit, very conliderable pains and vari-
ous afTedions, which feem plainly to indicate that the parts
■which have been touched by the cantharides, have a fort of
tendency to be diforganized.

2d. That the aqueous extra(5l of cantharides, in fmaller
dofes than the infedts themfelves, produces nearly the fame
effeds as they do ; and alfo, that its adion on the urinary paf-
fages is very marked.

3d. That the black matter is much lefs active than the ex-
tract; that the animals to which it has been given, are only
affected by gripings and vomitings, and yery rarely are killed
by it.

4-thf That the green matter given internally does not appear
to have deleterious qualities, fince all the animals to which
even firong dof«s had been adminiftered, did not feera to be
affedled unealily by it.

5th. Tht^t the yellow nqatter does not feem to be more ac-
tive than the green matter.

6tk. That the extrad, the yellpw matter, and the black
matter, applied feparately to the furface of the body, occa-
Tioried vefication in nearly the fame fpace of time.

^th. Th^t the green matter, applied externally, does not
feem to a6l when alone; but that its action is fpeedily mani-
fefted when it is divided by wa?:, and by that means receives
the confidence of a cerate.

I rauft not omit to i^ention, that Cit. Beaupoil was not
fatisfied with experiraents made on animals, but had the cour
rage to repeat them on himfelf. It was from having obtained
the information he fought in this manner, that he confidered
himfelf intitled to conclude, that the veficating property refides
particularly in the extractive part and in the green part of the
cantharides, but that the cxtraflive part alone a6ls on the
urinary and genital fyftem.

It will be obvious from the detail-; I have given, that the
3uthQf has carried the examination of cantharides farther than

Thouvenelv

ON LATENT HEAt. 45

Thouv6neI. But although his work is greatly extended, it ^'^per»ments and
tieverthelefs is not yet complete, fince much remains to be canthaddes^
done, particularly with refpetSl to the green matter; for it is
difficult to conceive how it Qiould have no a6lion on the animal
economy when adminiftered internally, fince, applied externally,
it produces a veficating eftb6l. This obje6lion which I have
made to the author, the importance of which he acknow-
ledges, will doubtlefs be one of the motives which will de-
termine him to renew his experiments to remove doubts, and
to (hew more clearly what is to be expefted from the employ-
ment of the different parts compofing an ingredient from
which medicine has received fuch great benefits.

X.

Experimental Determinatiom of the Latent Heat of Spermaceti ^
Bees* Wax, Tin, Bifnmth, Lead, Zinc, and Sulphur, By
Mr, William Irvine. Communicated hy the Author.

Bedford Street, Aug. 24, 1 804.

It will fcarcely be denied that the difcovery of the exigence Dlfcovery of la-
of latent heat in all fluid and vaporous bodies, is one of the^"^^"^^'^ ^^'
moft curious and important hitherto developed in the progrefs
of chemical philofophy. The merit of firft invefligating this
fubjed is univerfally attributed to the celebrated Black. By
a few fimple and clear experiments he demonftrated, that,
before any portion of ice can become water, it muft receive
or abforb as much heat as would have raifed the temperature
of an equal quantity of water by 1 40''. By other experiments,
in fome of which Dr. Black was aflitied by my father and Mr.
Watt, it was proved in a manner equally fatisfadory, that
water cannot be converted into fteara unlefs it admit a quan-
tity of heat fufficient to have heated the water 8 or 900^.
Having proceeded fo far by experiment. Dr. Black made a
general inference, and extended his theory to all cafes of fufion
and vaporization whatever.

The only other philofopher, as far as I know, who has Dr. fcyine*s ex-
attempted to determine the exadt quantity of the latent heat in amination of the
Other bodies befides water, was Dr. Irvine. Landriani made o^jhe" hol\el be-

fome fitJes water.

4<»

ON LATENT HEAT.

175 > t»n 5c

Ijtpcrlments
made by the
aatbor*

The veiTels.

fame experiments to prove that the fluidity of alum, fulphar,
and fome metals, was accompanied wilh an abforption of latent
heat ; but I believe he made no attempts to afcertain the pie-
cife quantity. In Dr. Black's lectures we are informed, that
Spermaceti Dr. Irvine found the latent heat of fpermaceti to be 143®, of

145 , ees wa^x ^^^, ^^^ ^^ ^ 173**, and of tin to be 500^. From the very
imperfed notes which I poflefs of the methods ufed to deter-
mine the two former, I believe that the 145° are meafured by
the capacity of fluid fpermaceti, and the 175*^ by that of fluid
wax: But of this fubjed I will take another opportunity to
treat more amply. I am perfedlly ignorant of every circum-
fiance regarding the latent heat of tin as determined by my
father, having been unable to find any notes of his experi-
ments for determining this point.

During the courfe of the prefent year I have turned my at-
tention a little to this fubje6l, I mean to the inveftigation of
the quantity of latent heat necefltrry for the fufion of various
bodies. I was perfuaded that an addition to our knowledge of
latent heat would at leaft increafe the ftoreof fadts, and might
perhaps give rife to fome improvement or correction of theory.
The veflels which I employed in all my experiments were
Florence flalks, ot which the neck was cut off. In thefe the
water made ufe of was contained, and the veflfel was fupported
on a flight wo®den ftand, which prefented a very fmall furface
to abftrad heat from the materials. The orifice at the fuperior
part of the veflel, was in general not more than fufficient to
permit the ready introduction of the fluid examined ; probably
from an inch and a quarter in diameter to a little more, fo that
a very fmall furface of the water was expofed to the ak. The
weight of the glafs was in all cafes previoufly afcertained.
Thefe circumflances being premifed, I proceeded as follows:
The firft fubftance which I fubmitted to examination was
*'^^ll'.'ff".'^"u bifmuth. The melting point of this metal was, by the ther*

ot fluid bifmuth , ^ . . . .

(or the numder mometer which I ufed, 480". This is fo near the point found
of degrees ^ by my father, to wit 476**, that I ftiall confider his determina-
anv'quantlty of tion as correCl, as he combined and compared the different
blitnuth would, ways of computation and obfervation, and I know the ther*
gfvesou^In con- "IOmeter which he ufed to have been made with confiderable
gelation, raife an care. Into a glafs veflel which weighed 411 grains, I put
Sl?h'"rom*'^''^2^^' ^''a^"^ of water, of the temperature of 62^. I then re*
beneath the moved from the fire a quantity of fluid bifmuth. I waited till

hot zing point of jt

iba aieta!).

Determination

ON LATENT »EAt, 47

it was partially folid, at which time I inferred that both the Blfmuth, on the

folid and fluid metal were of the temperature of 476^. I next j^g" was'poured"

poured a portion of the fluid bifmuth into the water. In one into water, the

minute tiie thermometer ftood at 86° ; in two minutes at 85| : ^"'J'/j^^^/^' ^^'

The true temperature at the moment of mixture was therefore being known j

86'|, Cuppofing equal temperatures to be loft in equal intervals. JJ*^ tratuTTas

There was alfo a quantity of fleam formed. I weighed thetalcsn.

veflel with its contents, and found that it had gained 1589

grains. This therefore ftiould be the quantity of bifmuth

poured in, if there had been no lofs. But on drying and

weighing the metal, it appeared to amount only to 1555

grains, and St grains confequently were loft. The bifmuth

was cooled 389|^, the water was heated 24|®. Then 1555

grains of water would have gained 34?. Thefe 34^, meafured

by the fpecific heat of bifmuth, as ftated in Thomfon's Syftem

of Chemiftry at .042, are equal to 810^9 : But the bifmuth,

after becoming folid, loft 389^.75, which being fubtracfed

from 810.9, there remains 421**. 15, which cannot be account-Inference of the

ed for by the cooling of the folid bifmuth, and muft therefore ^^'«"' *^^a^*

be the whole or a part of the latent heat of the fufed metal.

But the latent heat muft be greater than this, for 41 1 grains Correftion, for
of glafs were alfo lieated 24°. 25. If the capacity of this glafs ^^^ ^^^«^ >
be taken at .174, as Kirwan found flint glafs to have, and I
have found green bottle glafs to have a capacity of .173 by
feveral experiments, whence it is probable that the glafs of
Florence flalks has its capacity not very wide of thefe num-
bers; if then .174 be taken as the capacity of this glafs, thete
24^.25, which the bifmuth communicated to the 41 1 grains
of glafe in the vefl^el, are, when meafured by the capacity of
bifmuth, equal to 96°;4 : And 1555 grains of glafs would have
gained 25°.4, which muft be added to 421^.15 already found,
and makes 446*. 55 for the latent heat of bifmuth.

But this is obvioufly ftill too little ; for, as has been already and for fteam
mentioned, there was a good deal of fleam formed. The^^° "
amount of the heat thus loft is extremely difficult to aflign. I
fliall, however, make an attempt to guefs at, rather than de-
termine it. AH the 34 grains muft not be reckoned to have
been loft by evaporation. In fpite of all my efforts, I could
perceive that tome, though certainly a fmall quantity of bif-
muth went off with the water, in form of a number of fmall
particles floating in the liquid ; and perhaps alfo a fmall por,

tion

48

OK tAf £Vr HEAT.

lion of v^'ater mighl be wafted during the procefj. If we allov^
a half of all the lofs to be accounted for in thefe ways, there
remain fixteen grains of water which have been converted
into fleam. The latent heat of fleam was computed, by Mr.
Watt, to be equal to 9 VO® : But this fteam cannot be allowed
fo much heat as this ; and though it may be difficult to point
the quantity to be fairly granted, yet I Ihallexpeftto be with-
in bounds when I eftiraate it at one half of 940^, or 470°. In
this cafe we fay, 16 grains of water have been heated 470*;
fixteen grains of bifmulh would be heated by the fame quan-
tity of caloric, 11 190°. 4; and 1555 grains-}- 16 grains fup-
pofed to have gone off with the water, ir: 1571 grains of bif-
Latentheatof muth, would be heated 113*^.9. This quantity of heat, there-*

-'/T^^i!.lf "^ ^^^^' ^"g^^ ^^ ^® ^^^^^ ^^ ^^® 446*^.55 already found, and
would amount, in all, to 560.45 latent heat of bifmuth.

I am fenfible that there are feveral gratuitous fuppofi lions in
this laft part of the reafoning, and I do not therefore lay much
ftrefs on it, I endeavoured to confirm or refute the truth of
the indu6lion«, by making an experiment exaftly on the fame
principles, but where, by dexterity, I might prevent the for-*
mation of fteam wholly or in part. In one inftance I fucceeded
tolerably well, and then the latent heat, with every correc-
tion, amounted to nearly 600°.

I repeated thefe experiments for determining the latent heat
of bifmuth many times, and the refult is exprelTed m the
following

560^ degrees.

Other experi-
ments with bif-
muth.

TABLE:

Tabulated.

No. of Ex-

Latent Heat by

Correftion for

Whole Latent

periments.

firft Computa-
tion.

the Heat re-
ceived by Glafs.

Heat.

1

457

23

480

2

411

29

440

3

412

28

440

4

465

33

498

5

480

29

509

6

438

27

465

7

465

30

495

Mean

446.8

475

.1

On

ON LATENT HEAT. 4^'

On the whole, therefore, it appears that we (hall not exceed Mean refult
the truth when we eftimate the latent heat of bifmulh at 550''. tn^^^^'atof^bifl

I made, in hke manner, two experiments to alcertain the math,
latent heat of tin, and of thefe the refults were—

Experiments oa
tin.
Latent heat
S07»

This agrees remarkably well with the determination of this Latent heat of
point, faid to have been made by my father, in Black's ''"'^ ^^^
Ledures.

Zinc is computed, by Bergman, to melt at 700** of Fahren-
heit's thermometer. Taking that for granted, I made three
experiments on the latent heat of zinc, in a iiuuiar way with
that already related with bifmuth. The refults were as
follow :

Experiment.

Latent Heat by firft
Contjputation.

Correacd.

Whole L. H.

1
2
3

490
476
443

28
22

32

518
498
475

Mean

46b>

493

In thefe experiments no allowance is made for lofs by fleam, Latent heat of
which, however, by the dexterity acquired by pradice, I was ^^ *^
enabled to render very fmall.

Lead I found to melt at a point above 584®. Owing to the
Ihortnefs of the thermometric fcale, I could obferve no higher.
I fuppofe therefore that 594*^, as found by Dr. Irvine, cannot
be materially diftant from the truth. Afiuming it as true, I
proceeded to make feveral experiments on the latent heat of
lead. In doing this I was led immediately to notice, that
melted lead does not by any means produce fo much fteaai as
other metals do when poured into water, even under the mofl
carelefs management ; and of this the reafon will appear from
the followinij table :

Vol. IX.— Septemjbkr, 18Q4.

Exptriments

m

ON LATENT HEAT,

Expei'iments on the Latent Heat of Lead.

No.

Latent Heat.

Correfted.

Whole Latent Heat.

1

3

4
5

127.8
142.8
149.9
161.8
131.5

10°.3
11*>.

138*».l
153^^.8

Mean

142.7

Mean

H5°.9

In thefe experiments I have, by accident, loft the notes of
the determination of the weight of the veflfel emploj/ed in all
but the two firft inftances : notwithftanding which it may be
fairly inferred, that the mean latent heat of lead is about 150'',
a quantity certainly unexpeftedly fmall, and which, in many
more experiments than thefe related, I was at pains to exa-
mine, without being able to difcover any material inaccuracy*
In the fecond experiment, where a little fte^m was formed, I
afcertained the lofs to be four grains. If thefe four grains be
fuppofed, as in the cafe of bifmuth, to contain 470^* of heat,
the computed addition to the latent heat of lead will be 20^.3,
making in all a little more than 162**. This is certainly a very
peculiar and unexpe6led quality of this metal,
Experiments on The only other fubflance which I have fubmitted to exa-
folphur. mination for (he purpofe of afcertaining its caloric of fluidity,

is fulphur. The melting point of fulphur is commonly ftated,
in elementary works, to be at 212° : But that this is not accu-
rate any one may convince himfelf, by immerling a quantity
of fulphur in boiling water, where it remains altogether unal-
tered. By every trial which I have been able to make, I
am convinced that the fufion of fulphur takes place about the
temperature of 226®, I fay about, becaufe the communica-
tion of heat among the particles of fulphur is very flow, and
the thermometer is often encrufled with folid fulphur, which,.
jTome how or other, certainly cools below the liquid in which
• it is immerfed. In experiments for afcertaining this point,
the thermometer ought to be kept in conftant motion. The
refults of my experiments for finding the latent heat of fulphur^
are ibted in the following table*

Experiments

ON LATENT HEAT4

Expcnments to afcertain the Latent Heat of Sulphur,

No.

Latent Heat.

Correaed.

Whole Latent Heat.

1

2
3
4

144^.36
ISl*'
1 40*'
136*»

8^
7°.
4^5

132^.36
140^5

Mean

\31^S9

Mean

143^68

&l

Latent heat of
fulphur I43|*.

In thefe experiments I have fuppofed, from experiments of
my own, the capacity of fulphur to be .189, which does not
materially differ from Mr, Kirwan's determination. In thfe
other cafes I have trufted chiefly to the numbers given ill
Thomfon*s Chemiftry, though thefe are not always wholly
unexceptionable. In every inftance I have fuppofed the femi-
liquid to have the temperature of the melting point, which I
believe is generally true ; but fome practice is required to fei2e
the moment before the frozen particles float in the fluid fub-
ftancei, In experiments on fulphur efpecially, inattention to
this circumflance caufes very great inaccuracy, and was the
caufe of confiderable embarrafljuent to mq before I obferved
my error.

A comparative table follows of the caloric of fluidity of all
fubftances hitherto examined :

■
Subftance.

'Melting Point.

Latent Heat.

Ditto in Degrees
meafured by Ca-
pacity of Water.

Ice

32°

\55°,55'j

140®

Spermaceti
Bees' Wax

113^
]42<>

145°
175°

Tin

442«>

500°

33°

Bifmuth

47€o

350°

23°.65

Lead

3940

1620

5°.604

Zinc

700<>

493°

48°.3

Sulphur

226®

143°.68

27M45

Table of latent
heats.

In all thefe inftances the latent heat is exprefled in degrees General rc-
meafured by the capacity of the relative folid, excepting in ^^^'^^^
the cafes of fpermaceti and bees' wax, which are in degrees
meafared by the capacity of the fluid. I endeavoured to rec-
E 2 tify

6^ DOCTRINE OP MIXED CASES.

lify this fo as to make the comparifon more fair, by determin-
ing the fpccific heat of folid wax and fpermaceti ; but I have
not been able to fatisfy myfelf with either of thefe points,
owing to the foftnefs and confequent abforption of latent heat,
which a very low degree of heat inducer in both thefe bodies.
The numbers expreffing their latent heats are therefore too
low. On infpedion of the above table, there does not appear
any ratio by which the quantity of the caloric of fluidity feems
to be guided : it certainly does not increafe with the difficulty
of fufion, but moft probably has fome connexion with the re-
lative capacity of each body in its folid and fluid ftate. The
determination, however, of the capacity of any of the metals
in a fluid form, excepting meroury, muft be regarded as an
extremely difficult talk.

XL

StriBures on Mr. Dalton's Do6irinc of Mixed Gafes, and an
Anfwer to A/r. Henry's Defence of the fame. In a letter
from Mr. John Gough.

To Mr. NICHOLSON,
SIR,.

Ciufes of thefe X H A V E ventured to defend the chemical union of water and air,
ftnCtures. ^^ y^,gij ^^ ^j^g homogenity of the atmofpherical gas. My thoughts

on thefe fubjefts are briefly ftated in your Journal ^ ; and the
farther profecution of the enquiry compels me to make an open
attack on my friend Mr. Dalton, and his new convert, Mr.
Henry. The difpule fliall be fairly conduced on my part ;
that is, it fliall confift of arguments which I am ready to aban-
don as foon as they are refuted ; tliis promife is due to friend-
fliip, as well as the obligations of truth.
Dalton'8 a hypo- The firft thing to be afcertained is the proper appellation of
thefis not a the- ^fp. Dallon's opinions. His dodrine of mixed gafes is offered
to the public as a mechanical theory, founded on chemical
fa6ls : a little attention, however, to Mr. Dalton 's etfays, will
deprive it of all claim to the title of a theory. This is evident
from the nature of the mechanical philofophy ; every branch

* Vol. Vin. Page 243,

of

DOCTklNE OP MIXED CASES. 53

of which admits of a mathematical demonftration, derived from
Newton's definitions and laws of motion : but Mr. Dalton has
not attempted to give ftability to his new ideas, by the aid of
the mathematics ; on which account the only appellation due
to his do£lrine, is that of a hypothefis.

No philofopher ought to difregard the means which are The hypothefis
able to confirm his opinions, becaufe thefe means may be found, '^° ^^^ ^'" '
upon trial, to fubvert them. This I believe to be the cafe with
my friend's hypothefis ; fori have endeavoured to flievv fhe
fallacy of it by mathematical arguments. The refult of this
attempt will in all probability appear in the next volume of the
Manchefter Memoirs ; when the merits of the eflay will be de^
termined by geometricians, who are the proper judges of fuch
produ6lions. This want of geometrical demonfiration efcapcs
the notice of the cheraift, becaufe my friend has feemingly fup^
plied the deficiency by a number of probabilities of an expe-
rimental nature ; but it is almoft fuperfluous to remind either
him or your readers, that a myriad of fuch proofs cannot uphold
a do6lrine which is repugnant to the mechanical philofophy.

The two leading maxims which are derived from thefe proba- Conclufions
bilities, and form the bafis of the hypothefis, are thus briefly ^'^°?Jj^^M^ ?^^^
exprefled by Mr. Henry : '* mixed gales neither altradl nor repel
each other, and every gas is as a vacuum to every other gas*",
Mr. Dalton, reafoning from thefe premifes, furrounds our
globe with an independent atmofphere of vapour, the prefl^ire
of which preferves all the water on the earth's furface in a
liquid ftate, and prevents the ocean itfelf from efcaping through
the air, by virtue of its own elaftic force ; at leaft the laft is a
fair inference from his own conclufions.

Although I have demonfiraled the exiftence of an atmo-Dalton's reafon-
fphere of vapour to be a mechanical impoffibility, in the eflay ^"S i'i<^o""P^<^^<5*
mentioned above, the reality of the thing fliall be fiippofed at
prefent, for the purpofe of detecting the fallacy of the dodtrine
in the fundamental maxims of it. The truth is, Mr. Dalton
has difcontinued his train of reafoning too foon ; for, had his
arguments been purfued to their proper limits, they would
have difcovered the incompatibility of the hypothefis and na-
tural appearances. This omiflTion is eafily fupplied, and will
be as eafily comprehended, by a perfon who underflands the
laws of hydroftatics.

• Phil. Journ. Vol. VIII. Page 298.

If'

54» DOCTRINE OF MIXED GASES.

A fecond par- If a particle of vapour can pafs freely through the air, ei fe- y
ticlc may follow ^^j^^ ^^^^ j^l^^ fuccecd it at any given diftance; becaufe the
latter may undoubtedly purfue the track which the former has
already traverfed ; confequently, a feries of fuch particles, pof-
feffing the denfity of water, might be raifed into each perpen-
dicular pore of the atmofphere, by the application of a proper
Arr prefles upon force to the furface of a collection of water fupporting fuch an
water. atmofphere. Now the exiftence of fuch a force is certain ;

becaufe when air is inje6ted into either leg of an inverted
fyphon containing water, it conftantly diflurbs the equilibrium
of this fluid; that is, the gas prefles upon the liquid, notwlth-
llanding the fuppofition, that the former is a vacuum to the
Air a perforated particles conftituting the latter. If now we combine the pof-

piftoii, by the tulaies of the hvpothefis with the precedinj? fa6l, a column of
bypothefis. . , . , " T , ^ ^ J*. . .

air, which occupies the upper part or a vefl^l containing water

in its bottom, becomes a heavy piflon, having its fubflance
perforated in every diredion by pores of eafy tranfmiflion,
which are, at the fame time, feparated by partitions imper-
vious to water. After contemplating this imaginary ftru6ture
of the atmofpherical gas, let the reader inveftigate the confe-
Airnotavacuum^^^"^^^ ^^ '*> 2"^ compare them with natural events. The
tc vapour. impenetrable parts of the gafeous pifton would compel the

water to afcend along its perpendicular pores ; in which it
would be kept duly condenfed by the prefliire of the incum-
bent vapour. The fpecific gravity of this column, compound,
ed of air and water, would exceed that of the external air ;
confequently the upper extremity of it would conflantly glide
over the edges of the veflTel into the atmofphere. Thus there
would happen a double lofs of water, namely, by evaporation
and percolation : but nothing of the kind is obfervable in na-
ture ; confequently the air is impenetrable to the conftituent
particles of water not heated to the boiling point.
Impenetrability The circumftanceof water not being able to penetrate air at
noobftacle to Jqw temperatures, is no obflacle to the chemical union of the
c emica union. ^^^ fubftances ; for many aqueous folutions of falts occupy
lefs fpace, when completed, than the materials formerly did
One gas not a of which they are compofed. This fa6l has been eflablithed
vacuum to an- by the prefent Bifliop of Llandaif ; and it proves that bodies,
y"^^' ^yhich are mutually impenetrable, may be fufceptible of the

bond of chemical affinity.

After

DOCTRINE OF MIXED GASKS. ^^

After all that has been faid about the conftitution of gafes,
the notion is incorreft, ftri6lly fpeaking, which fuppofes each
gas to be as a vacuum to every other. The foregoing obferva*
tion may alfo be extended to mixtures of carbonic acid gas
with water; and the following inftances may be adduced in
confirmation of the propofition : When a particular gas is de- Proved by cxpc*
veloped in a vetTel containing common air, the firft portion *^'°**°'*
that comes over has in it lefs of the fpecific gas than the fe-
cond ; nor is the fecond equal to the third in purity. This
circum fiance fliews, that the new-formed gas does not find a
vacuum in the air of the veflel ; on the contrary, the two
fluids produce a mechanical mixture, which is gradually ex-
pelled, until no part of the air remains in the tube or bottle.
In like manner, if a bottle of highly asrated water be opened
fuddenly, the rapid expanfion of the liberated gas eje6ls a
great part of the contents, thereby proving that water oppofes
an obftacle to the dilatation of this gas. In reality, Mr. Dalton
allows one gas to be an impediment to the motions of another;
but at the fame time he maintains, that two fuch fluids finally
overcome their mutual obflruftions, and occupy the fame
fpace in a /late of perfect independence. This is a propofi-
tion which may be juftly fufpe6ted of being a folecifm in pneu-
matics, until the author of it has proved the contrary by a ri-
gorous demonftration.

Amongfl the many probabilities which have been oflfered in A new theory •£
fupport of the hypothefis, perhaps none are more ingenious ^*i^*^ ^ ''"
than the remarks of Mr. Henry ; and the part which I have
taken in the prefent letter, obliges me to place them in a new
light. This attempt muft, however, be preceded by a theory,
which will explain the relations of thofe gafes that neither
attrad nor repel each other : fuch an explanation became a
neceflary part of pneumatics, from the time when Dr. Prieflley
made his experiments upon mixtures of this defcription. The
following, then, is a flietch of a theory, having for its founda^-
tions the mutual repulfion of homogeneous particles, and ihe
reciprocal refiftance which gafes have been fliewnto poffefs.

When two fuch gafes come into conta6l, parcels of each Sketch of the j
will be detached by every flight force, and enveloped in the ^^^°^y^
fubfiance of the other. In this manner, the two fluids will be
broken to pieces, and blended in one mafs forrning a mechci-
3i «ic^l

gig DOCTRINE OF MIXED GASES,

nical mixture ; the component parts of which cannot be fe-
parated without the intervention of chemical agents, becaufe
the disjoined fragments of each gas will be prevented from re-
Exception to the uniting by their mutual repuKion. There is one exception,
however, to the general rule ; for when a liquid is found in a
mixture, the component parts will follow the law of their
fpecific gravities ; becaufe an inelaftic fluid is not a61uated by
an intnnfic repulfion, in all other cafes the gafeous fragments
will continue to be farther and farther fubdivided, and will con-
flantly aiTume a new arrangement from the fligheft agitations.
The conftituent parts of fuch a mixture exert their force in
perfect union ; and this circumftance diftinguifties it from Mr.
Dalton*s compound, the conftituent gafes of which prefs fe-
parately upon all furfaces.
Thetheoryap- The necelTary premifes being now fettled, it is time to try
gi^td to Mr. ^^^ ^j^g powers of the theory upon Mr. Henry's experiments. If,
meats, then, ten meafures of water, containing an equal bulk of car-

bonic acid gas, be prefled by a column of the fame gas, equi-
valent in force to 30 inches of mercury, the fta'LC of the aque-
ous compound will remain invariable ; becaufe the fpring of
the gas in the water appears, by Mr. Henry's experiments, to
be equal to the fpring of the incumbent gas : therefore, fliould
a gafeous particle happen to efcape from the compound, an
equal particle, from the upper part of the veflel, will replace
it immediately. But if the incumbent carbonic acid be made
to give place to a mafs of common air of the fame elaftic force,
the furface of the aqueous compound will undergo no change
of preffure ; but the gafeous part of it, meeting with no repul-
fion from the column of air, will begin to form a mechanical
mixture with it, according to the theory. The parcels of the
carbonic acid will alfo remain diftindl, according to the fame,
after their efcape from the water ; and as a number of them
will be arranged on the furface dividing the two mediums,
they will form fo many obftacles to the difcbarge of their kin-
dred gas ; the egrefs of which will be conlined to the inter-
mediate compartments of eafier tranfmillion confifting of com-
mon air. The divifion of the furface between the two medi-
ums, into compartments of eafy tranfmiflion and impene-
trable pomts, ultimately produces a fort of equilibrium, which
affigns their refpedlive portions of the elaflic acid, to the gafe-
ous

Dt)CTRINE OF MIXED GASES. 57

ous compounds. The origin of this equilibrium is eafily col-
leded from the preceding theory and the laws of pneumatics.
For the globules of carbonic acid, contained in the gafeous
compound, invariably exert the force of 30 mches of mercury;
they thenpfore prove too powerful for the rarefied gas of the
wafer, which they compref<, and infinuate part of their own
fubftances into the fluid. Whilft this operation is going on at
innumerable points in the furface, portions of the fame gas
are conftantiy forced through the companments of eafy trant.
miiCon, by the flighteft agiiations. Now the quantity of gas
which is difcharged into the air of the jar, is greateft at firft,
and continually dimini flies ; on the contrary, the quantity that
is forced into the water through the former paflat^es, is leaft at
firfl, and increafes afterwards ; confequently the two quantities
ultimately become equal, and eftablifti the equilibrium in quet-
tion, by the contrariety of their effeds.

The preceding is a general propofition, which explains a Concluding «•
variety of appearances, fuch as Mr. Henry has defcribed, by "^"^
by the well known principles of mechanics. Should the con-
fideration of it be attended with conviction on his part, he
perhaps will give a new turn to his experimental enquiries,
and endeavour to difcover the law of affinity, which coane6ls
water with the different gafes. It is almoft certain, that this
law is not the fame in all cafes, as will be feen by comparing
the experiments of M. la Saufl'ure on the folution of water in
common air, with Mr. Kirwan's obfervations on the folvent
powers of hidrogen ; which may be found at page 14 of the
lirft edition of his EflTay on Phlogifton,

JOHN GOUGH.

Middlejkaw, Aug, 23, 1804..

P. S. The following error requires corre6lion : In Vol. VIII.
page 244, line 21, before the words, as oft as uater, read
therefore, and ftrike out the fame conjunction in line 22.

An

5*^ EFFECrs OF CLOTHING, &i.C»

XII.

An Enquiry concerning the Nature of Heat and the Modes of its
Communication, By Benjamin Count of Ruwford,
V. P. R. S. Sfc. Abridged from the Philofophical Tranf
actions for the Year 1 804-.

Expcrimcntson x\FTER remarking that all difcovcries on an agent of fuch
^ extended operation as heat cannot fail to be eminently ufeful,

the author proceeds to defcribe the apparatus ufed in the ex-
periments now to be defcribed : They were the following.
Inftramcnts. I. Mercurial thermometers carefully conftrufled, having

Thermometers, cylindrical bulbs, four inches long and four tenths of an inch in
diameter, and their tubes from 15 to 16 inches long; the air
being excluded, and the graduations according to Fahrenheit,
exhibiting eight parts of degrees by means of a nonius.
Inffmments. 2. Four cylindrical veflTels of thin (heetbrafs, for afcertaining

Cylinders to the warmth of clothing. Fig. I. Plate I. The veflel isclofed
water and fuf- ^t both ends; but has a neck at the top, into which hot water
fcred to cool with js occafionally poured, and in which one of the thermometers
ol' cloSiing. ^^ fitted and placed during the time of an experiment, fo that
its long bulb ftiall occupy the axis of the velFel, and will (liew
its mean temperature. Another cylindrical neck proceeds from
the lower furface, and is lilted upon the adjuftable part of the
wooden ftem beneath. The vefiels are four inches long and
four inches diameter, and the necks are about eight tenths of
an inch in diameter, the upper one being four inches long and
the lower three inches. When the vefTel is clothed and charged
with hot water, its rate of cooling by expofure to the quiet air
of a large room, will fhew the relative warmth of each parti-
cular kind of clothing.

In fome of the experiments the ends of the inftrument were
permanently covered by the application of a thin wooden box
to each, the box being varniflied and covered with fine writing
paper, and filled with line eider down, and a cap of fur was
pulled over the box, and the projeding neck. The cloth-
ing of thefe cafes was applied for experiments to the cylindrical
furface.

Twoof the inftruraents (No. 1 and 2.) were thus covered
up at the ends, and the other two (No. 3 and 4) were left in
the flate reprcfented Fig, 1 . without the permanent coverings*

In

EFFECTS OF CtOTHlUG, &C. 59l>

In each experiment two fimilar inftruments (fuppofe No. 1 Method of oper-
and No. 2, or No. 3 and ^o. 4) were ufed, one naked i^nd the ^j^^J^'^^^J,^
oiUer covered; fo that in each experiment the naked inftrumpnt theeffcft of
ferved as the flandard of comparifon with the other. clothing.

The experiments were made and regiftered in the following
manner: the two inftruments ufed in the experiment, placed
over their wooden ftands, being fet down on the floor, were
filled to within about J| inch of the tops of their cylhidrical
necks with boiling hot water; and a thermometer being put
into each of them, they were placed at the diftance of three
feet from each other, on a large table in a corner of a large
quiet room, 24- feet long, 19 feet wide and J 3 feet high, where
they were fufFered to cool undifturbed. Near them, on the
fame table, and at the fame height above the table, there was
placed another thermometer, fufpended In the air to the arm of
a ftand, toafcertain the temperature of the air.

Every caution was ufed to prevent difturbance by currents
or agitation of the air, whether by partial heat or the intrufion
of any perfon during the progrefs of any experiment.

By the refults of a great number of experiments, it Was Scale through
found that the fame inftrument cooled through any given ^^'*^^ '^*''^"''
(fmall) number of degrees, for inftance 10^, in very nearly meafured.
the lame time, whatever was the temperature of the air of the
room; provided always that the point from which thefe 10 de-
grees commenced, was at fome conftant number of degrees
above the temperature of the air at the time being. The in-
terval chofen by the Count lay between the 501 h and the 40tfa
degrees above the temperature of the air in which the inflrtu
ment was expofed to cool; when for inftance, the air was
at 58«, the interval commenced at 108, and ended at 98**. —
When the air was at 64p it commenced at 114|° and ended
at I04f*>.

The warmth of any covering, or its power to confine heat,
was eftimated by the time employed in cooling through that
interval.

As it fometimes happened, though very feldom, in the Method of fup.

courfe of an experiment (which commonly lafted feveral hours) P^y^"?5 byinter-
aii^xi ri/y r , . . polation the ex-

that the moment ot the palTage ot the mercury through one or treme inftants of

both of thefe extreme poinls was not obferved, it was of im- time elapfed,

portance to determine the fame by interpolation from the other ^c obfcrved?

points obferved. To do this, the author availed himfelf of

the

^0 KFFECTS OF CLOTHING, &C.

the following law of cooling of hot bodies in a fluid, which be
found by experiment to be applicable without fenfible error in
the prefent cafe : It is that, if the equal portions of a right
line reprefent fucceffive intervals of time, and perpendiculars
be ereded upon the fame, to denote by their lengths the de-
grees of the excefs of temperature of the hot body beyond that
of the cold medium, at points denoting the correfponding in-
ftantsof time, the line joining the extremities of the perpen-
diculars will be the logarithmic curve. Whence if two tem-
peratures and the elapfed time be obferved, it will be eafy by
the help of a table of logarithms to determine the lime at which
any intermediate temperature took place. This is exemplied
by the Count, who then proceeds to relate his eyperiments.
Exp. T. Exp, 1. One of the veflels. No, 1. having its ends clothed

t^tllncLh^^^ before defcribed, and its poliflied fides naked, was filled
the heat to with hot water. Another velfel. No. 2. alike in all refpedts,

efcape much j^y^ having its fides clofely clothed with Irifh linen, fuch as
quicker than ./•,,. t i /-n i • ii

from a bright IS fold m London at 45. per yard, was filled in like manner,

metallic furfacc. and both were fimilarly expofed to cool.

The naked inftrument employed 55 minutes in cooling, from
9^4-° to 84' Fahrenheit (the air of the room being at 45^.) —
But the clothed inftrument was cooled through the fame in-
terval in 36| minutes, confeqtently this clothing expedited the
emiflion of heat inftead of confining it.

When both inftruments were cooled to 42** they were re-
moved into a warmer room at 62*^, and the clothed inftrument
was alfo found to acquire heat confiderably fafter than the
other.

Whether the linen accelerated the cooling by affifting the
fucceflion of frelh particles of air, or by promoting the efcape
of heat by radiation, were points to be determined.

Exp. 2. The Exp. 2. To decide this, the linen of No. 2. was removed,

fame effeft from ^^^ ^j^^ ^^^j, ^g^g thinly coated with glue. In thefe circum-
a coating 01 glue. "^

fiances, while the ftandard or naked inftrument cooled through

the interval in 55 minutes, the coated inftrument employed
only 43| minutes.

In reafoning upon this experiment, the author concluded,
that if the glue operated only by preventing the air from at-
taching and fixing itfelf to the poliflied metallic fur face, and
confequently in that manner facilitated its circulation and the
cooling; it would be of no confequence, whether the fur face.
4 was

EFFECTS OF CXOTHING, &C. jS\

was covered by one or more coatings of glue: But, on the
contrary, if the radiations of heat were facilitated and in-
creafed, it might be expelled that a greater effedt would be
produced by two coatings than by one.

Exp, 3. The experiment was therefore tried, and it was Efp; 3* Mo«
found that the inftrument ufed employed only 37|- minutes in [ncrea£i*the "*
pafling through the interval. effeft.

Exp. 4, 5, 6, 7. When the experiment was repeated with Exp. 4, 5, 6, y,
clear colourlefs fpirit varnith, the fame efFe6t was produced, ^.^^ ^^"^ ^*^'
and it was augmented as far as by four coatings. But on pro-
ceeding as far as eight coatings, the limit of the greateft effedl
was found to have been paflfed,

Exp» 8, 9, 10. Black paint (lamp black and fize) upon the Exp. 8, 9, 10.
varnini increafed the cooling effea a little. When the inQru- ""•^"'^ ^^^ ^*"

. . . . paint,

ment was cleaned and then painted, its rapidity of cooling was

nearly the fame = 35 minutes. And with white paint the dif- —and white,

ference was not contiderable, as the efFe6l was produced in

36 minutes. As the paint was laid on in feveral fucceffive

coalings, the Count remarks that little dependence is to be

placed on thefe refulls as indicating a difference from colour. '^

Exp. II. The clean infirument being fmoked black over a Exp. ir,
wax candle, was found to have cooled through the interval in ^^^ °^ fmoke
36-5 minutes, while the ftandard employed 53|- minutes. The
lamp black, when wiped off and weighed, amounted to lefs
than -j-^ of a grain, though it had completely covered 50 fquare
inches.

With a view to a more accurate determination of the velo-
city of cooling, it was neceflary to afcertain what heatefcaped
through the permanent clothing at the ends. This was done Determination of
by obferving the times of cooling with and without the cloth- ^J^^ efcape of
ing, and comparing the effe6ts with the refpe6live furfaces of ends of the in-
expofure. For the whole furface of the inftrument 85.195 ftruments.
fquare inches, is to the furface of its vertical fides; fo is the
whole quantity of heat paffed off = 10000 to the quantity that
paffed through the fame fides = 5885. And fince by obfer-
vation the naked inftrument required 45 1 minutes to cool
through the fame interval as was paffed through in 551 "^'*
nutes when the ends were covered, the author concludes that
45| : 55f : : 5885 : 7015= what would have paffed in the
later interval through the upright furface, and confequently
that the remainder of the heat zi 2985 parts rauft have pafftfd
through the covered parts of the inftrument.

02 H-FECTS or CLOTHTKG, &C.

By applying thefe refults to the numbers in Exp. 11. where
the cooling was efFedled in 36^ minutes, the Count fays as 53|
minutes give 2985 heat pafled through the covered ends, fo
will 36-5- minutes give 1942 parts. And this taken from 10000,
the whole heat loft, will leave 8058 for the heat that really
Whence the pafled through the upright fides. But it was found that 7015
xeAiits^arccor- ^^^^ through, the naked fides in 551 minutes: Whence
7015 : 551 : : 8058 : es^. And confequently, the correded
times are 36|- and 63^, which exprefs the velocities of the
pafTage of heat through the furface of the naked metal, and
that which was blackened with fmoke, viz. as 5654 to 10000
nearly.

In the fame manner the velocities of the paffage of heat in
the experiment No. 6. ar« (hewn to have been as 4566 to
10000.
A ncwcoitffeof It has been remarked that, in thefe curious inftances of the
experiments. effeds of modification of furface or clothing upon the tran-
fitions of heat, the effed may have been favoured by commu-
nication to the air, or by facilitating the procefs of radiation^
The author's reafoning upon Exp. 2. appeared not fo decifive
as to need no fapport from experiments of a different clafs.
He therefore conftru6ted an inftrument for meafuring the efFecls
of radiation, which is leea in Fig. 2, Plntel.
Inftruments for Like the hygrometer of Mr. Leflie,* (as the Count ob-
improvingradi- ferves) it confifts of two glafs balls at the ends of a tube C
**' ^^' and E. The tube is of fuch a diameter that one inch in length

*vould contain 15 grains of mercury; the balls are 1.625
inches in diameter; the upright ends of the tube C and E are
each 10 inches long; the horizontal part D Is 17 inches; and
the board A B, to which it is attached, is 27 inches long, 9
inches wide, and one inch thick. The pillar F fupports a cir-
cular vertical fcreen made of pafteboard, covered with gilt
paper on both fides, the ufe of which is to protect one of the
balls from rays intended only to act upon the other. The balls
contain only air, and a fmall drop of coloured fpirit of v/ine
is introduced by means of a (liort tube proje61ing from one of
the elbow s ; which Ihort tube is then hermetically fealed. By a
little management the bubble of fpirit is brought to reft in the
middle of the horizontal tube; and when the temperature of
*

• Philofophlcal Journal, quarto feries, lU. 4 61.

the

PHYSICAL OPTIC9.

the air in either of the balls is made to exceed that of the
other, the increafed elalHcity caufes the bubble to move to-
wards the colder ball.

By a fimple contrivance of Aiding boards, the hot bodies
were moved by rack-work and a winch to any diftance from
the thermofcope without the attention of the obferver being
taken off from the bubble in the tube, and the diftances were
alfo fliewn by a graduated fcale and nom'us. Fig, 3. Plate I.
fliews one of thefe bodies. It is a metallic cylinder having its
bafe,[which is to be prefented to the thermofcope, vertical, and
its neck obliquely placed for the purpofe of introducing the
hot Water, and alfo a thermometer for (hewing its temperature
at any required time.

The experhnents and obfervations witich covfiitute the remainder
of this 7Jiemoir will be given in our next.

XIII.

Experiments and Calculations relative to phyjical Optics. By
Thomas Young, M. D. F. R. S. From the Philofophical
TranfaBions for 1804.

I, EXPERIMENTAL DEMONSTRATION OF THE GENERAL
LAW OF THE INTERFERENCE OF LIGHT.

In making fome experiments on the fringes of colours accom- General laws of

panying (hadows, I liave found fo fimple and fo demonfirative ^^ jigj^/ ^^^^j

a proof of the general law of the interference of two portions in the produ<ftioB

of light, which I have already endeavoured to efiablifli, that I °^i^"s!" °^

think it right to lay before the Royal Society, a fhort (iatement

of the fa6ls which appear to me fo decifive. The propofition

on which I mean to infift at prefent, is (imply this, that fringes

of colours are produced by the interference of two portions of

light; and I think it will not be denied by the moft prejudiced,

that the aHTertion is proved by the experiments I am about to

relate, which may be repeated with great eafe, whenever the

fun fliines, and without any other apparatus than is at hand to

every one.

Exper. 1. I made a fmall hole in a window-fhutter, and J^^P' V Fringes
covered it with apiece of thick paper, which I perforated with fhadow"oflilip

a fine 0^ ^^^ ^^ P>^o*

|f4 fHYSICAL OPTICS,

iocedby the m- a fine needle. For greater convenience of obfervatlon, I placed
tcrferenceot ^ (maAl iookiiig glafs without the windou-Qiuttei, in i'uch a po-
hghc from both o ^ . r , , i • i- ^- i l •

ed-cs. For in- "tion as to refled the fun's Ii^ht, rn a direction nearly honzon-

terception on one (^I, upon theoppofite wa 1, and tocaufe the cone of divergmg
effeft. "S"^ ^^ P^'*^ ^^'*^'" ^ table, on which were leveral little Icreens ot

card-paper. I brought Into the fun-beam a flip of card, about
one-thirtieth of an inch in breadth, and obferved its fliadow,
either on the wall, or on other cards held at different diftances.
Befides the fringes ol' colours on each fide of the ihadow, the
fliadow itfelf wasdivideJ by fimilar parallel fringes, of fmaller
dimenfions, differing in number, according to the diftance at
which the fliadow was obferved, but leaving the middle of the
Ihadow always white. Now thefe fringes were the joint eflfe6ls
of the portions of hght paflingon each fide of the flip of card,
and infleded, or rather diffracted, into the fliadow. For, a
little fcreen being placed a few inches from the card, fo as to
receive either edge of the fliadow on its margin, all the fringes
which had before been obferved in the fliadow on the wall
immediately difappeared, although the light infledted on the
other fide was allowed to retain its courfe, and although this
light muft have undergone any modification that the proximity
of the other edge of the flip of card might have been capable
of occafioning. When the interpofing fcreen was more re-
mote from the narrow card, it was neceffary to plunge it more
deeply into the fhadow, in order to extinguifli the parallel lines;
for here the light, diffracted from the edge of the objed, had
entered further into the fliadow, in its way towards the fringes.
Nor was it for want of a fufficient intenfity of light, that one
of the two portions was incapable of producing the fringes
alone ; for, when they were both uninterrupted, the lines ap-
peared, even if the intenfity was reduced to one-tenth or one-
iwentieth.

(To be continued.)

rinloj. Joimwl. Tol.Hn.Lp. 64,

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V..S-. Jow-nal. Tol.JX,Fl.:i. p. 64.

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A

JOURNAL

OP

NATURAL PHILOSOPHY, CHEMISTRY,

AND

THE ARTS.

OCTOBER, 1804.

ARTICLE I.

£xtra6t of a Letter from, Count ApoUos de MouJJin Pou/kkin.y 0
Charles H'atchett, Efq, F. R. S. defcrihing hh ^Method of pre
paring Mallmble Plaiina. Communicated on the Reqwfi of
the County hy Charles Hatchett, Efq. F» R. S. andnozv
firji publijfiedJ

\. 1 RECIPITATE the platlna from its folution by muriate P""f ofpU^
of ammonia, and wafli the precipitate with a Htlle cold water, j^ Pf^cip. the

2. Reduce it in a convenient crucible to the well-known iol»tion by mur.
fpungy metallic texture> which wath two or three times- wirb^^^^'J^^^^^^^
boiling water to carry off any portion of fdine matter which fpongy metal,
may have efcaped the adion of the fire. ' ^"^ ^*^'

3. Boil it for about half an hour in as much water mixed 3- Boil in weak
with one tenth part of muriatic acid as will, cover the mafs ^^^rr\off'il^\ron
the depth of about haflf an inch in a convenient gbfs vetfel.

This will carry off any quantity of iron that might ftill exift ih
the metal.

4. Decant the acid Water, and edulcorate or flrongly ignite 4* EduTcprate

»u ^1 \l- ■ ' •.:^ ' '" ' idnd ignite:

the platina. . ■ ^

5. To one baft of this raetal take two parts of mercitry, and 5- Amalgamati
1 / • 1 y • T^., • I - wiik mercury i

amalgamate magtals or porphyry mortar. 1 his amalgamation '

takes place verj- readily. The proper itaethod of cOnduifting

it is totake abotit t<vT) 'drafra*? of mercary to three drams t>f

Vol. IX.-*October, l&Ot. F platina.

6Q MALLEABLE PLATINA.

platina, and amalgamate them logelher; an(TTb"^ni7s amalgam
may be added alternate fmall quantities of platina and mercurj
till the whole of" the two metals are combined. Several pounds
may be thus amalgamated in a few hours, and in the large way
a proper mill might fliorten the operation.

6. Mould the 6. After the amalgam is completely produced, it muft be
amalgam into quickly moulded in bars or plates, or any other forms that may
foon become ^^ preferred; taking care that thefe moulded pieces fliould at
^'^^'*^' leaft be half an inch in thicknefs, and of a proper length to

manage them afterwards in the fire; it is alfo requifite that
the moulds fliould be perfe^^ly even and fmooth. Half an hour
after the pieces are formed they begin to harden by the oxi-
dation of the mercury, and change their brilliant metallic co»
lour for a dull leaden one.

7. Expel the 7. As foon as the pieces have acquired a proper degree of

mercury, by ig- hardnefs to be handled without danger of breaking^, which
nition : i 1 1 • 1 • 1 • 1 ,

commonly takes place in a htlle more than an hour, place them

in a proper furnace, and keep them ignited under a muffle or
in a fmall reverberatory. No other precaution is neceflary in
this operation but that of not breaking the pieces during their
Laftly, tranfporl. The mercury flies off during the heat, and the pla-

"on iv'anf "^"^'"^ remains perfedly folid ; fo that, after being ftrongly ig-
forge or laminate nited two or three times before the bellows, it may be forged
^^' or laminated in the fame manner as gold or filver; care being

taken, at the commencement of the forging or of palling it
between rollers, not to apply too great a force till the metal has
Tofave tlie acquired all its deniity. It r . almoft fuperfluous to add that in
mercury on a evaporating the mercury from large quantities of amalgam, a
proper apparatus, fuch as in the filver amalgamation, muft be
employed to receive the volatiIize,d mercury; but for fmall
quantities, where the lofs of this metal is of no confequence,
the furnace muft have a proper chimney to carry off the metal-
lic vapours. When the platina comes out of the firft fire its
dimenfions are about two thirteenth parts fmaller every way
Remarkson this than the original amalgam from the mould. The wholeof this
procefs. operation feems to be governed by the preffure of the atmof-

phere and the laws of cohefive attradion: for the air is driven
out from between the molecules of the platina, which by their
folulion in mercury are moft probably in their primitive and
confequently uniform figure. It is very vifible and at the
fame time a very amuftng phenomenon to obferve,, (during the

procefs

Malleable platina, ^7

procefs of ignition, which is performed in four or five minutes)
how the platina contrads every way into itfelf> as if preflTed by
feme external force.*

I have alfo lately obtained triple falts of muriate of platina "triple muriatic

with muriate of ponderous earth; and alfo with muriate of ^^'^t°^Pl^f'"*»
' witn earths and

ttagnelia; and I ftrongly fufped that every other earth except x^ithmctals}

the filiceous, and even the metals, arefufceptible of fuch triple

combinations. 1 have likewife obtained a very beautiful fait —beautiful fait

of platina by the combination of foda and platina with the mu- withfoda^

riaticacid; a combination which Bergman and feveral other

chemifls deny. The beft manner of obtaining it is by diffolvi

ing the platina in nitrous acid, to which, for that purpofe, two

parts of muriate of foda and one of platina are added. The

platina mufl: be made in a retort with its receiver, and after

about four fifths of the fluid have come over, the procefs muft

be interrupted, and the whole left to cool in the fand bath.

The fait cryftallizes in fineprifms, which are fometimes four or

five inches long, and either red brown, like titanium, yellow,

like amber, or of a beautiful coquelicot colour, according to

the purity of the platina. I enclofe here my addrefs during

my abfence, and hope you will receive with indulgence the

contents of this letter.

I am with great regard. Sir,
Yourmoft humble and obedient fervant.

Count Apollos Moussin PoirsHKiNi

* In the Count's letter to Mr. Hatchett, requefting him to pub-
lifh the method in the text (communicated to Mr. H. feme years
bgo) the following addition is given : (in French.)

** As foon as my amalgam of mercury is made, 1 comprefs the
fame in tubes of wood, by the preflTure of an iron fcrev^r upon a cy-»
linder of wood, adapted to the bore of the tube. This forces out
the fuperabundant mercury from the amalgam, and renders it folid.
After two or three hours I burn upon the coals or in a crucible
lined with charcoal, the flieath in which the amalgam is contained,
and urge the fire to a white heat; after which I take out the platina
m a very folid ftate, fit to be forgtd.''*

t^ On

^ , ON PEPPER,

II.

On Pepper, 5^* Thomas Thomson, M.D, Communicated
by the Author.

VegetaWeche. NOTWITHSTANDING the great number of labourers
who have engaged in the caltivation of chemiftry, the field
of that alluring fcience h too extenfive to be fully occupied.
While many fubdivifions are left entirely wafte, and others
exhibit here and there only faint traces of improvement, fome
fortunate fpots, either from their fuppofed importance, or from
the influence of fafliion or accident, have been crowded with
workmen, and cultivated with enthufiaftic eagernefs. The
mineral kingdom has probably engaged the exclufive attention
of nearly two thirds of the whole body of pra6tical chemifts:
The animal kingdom, in confequence of th^ intimate connec-
tion between chemiftry and medicine, has enjoyed a confi-
derable fhare of cultivation; but the vegetable kingdom, though
furely not inferior in importance, and apparently rather more
alluring, has till lately been greatly neglefled, at leaft in
Britain.
Reafons why Indeed it is not likely that vegetable chemiftry will ever

this branch muft arrive at the precifion which we have a right to look for in
accurate^ than ^^^ analylis of minerals. The conftituents of the latter feem
mineral che- fcarcely fufceptible of altering their ftate; but thofe of vegeta-
"'^ ^^* bles run progreffively through a regular fuite of changes. —

Thus the fubftance, which in the embryo ear of corn polTefles
the properties of mucilage, appears in the ripened grain under
the form oi' ftarch. Between thefe two extremes there exift*
an indefinite number of intermediate ftates, through allof
which the vegetable matter fucceffively runs. The rapidity
and completion of thefe changes depend upon a multitude of
circumftances. In no cafe can they proceed exadly in the
fame order and at the fame rate unlefs all the circumftances
tally. Without this the conftituents of two vegetables even of
the fame fpecies, cannot be in the fame ftate, and of courfe the
analyfis of each, though conduced with the moft perfect ac-
curacy, will by no means exhibit an exatl coincidence.
Changes in ve- But even fuppofing the conftituents of two vegetable bodies
fftctufeTand ^" ^^^"^^ refped the fame, ftill the analylis of each may lead
by reagents. tO

ON PEPPER. (J3*

to different refalts. Vegetable fabftances not on!)' pafs through
a fuit of changes while they conftitute a part of the living
plant, but many of them are dill fufceptible of continuing the
fuit even after they are feparated from the parent that produced
them. Thu^ gluten when kept moift runs into cheefe; oil when
long expofed to the fun and air hardens into tvax, or refcu, and
the milky juices of plants into giim-refms . Our analyiis fre-
quently accelerates or occafions thefe changes, and even pro-
duces others altogether new. Hence the principles which we
exlra6l from vegetable bodies are not always the conftituent<J of
thefe bodies; but a new fet of principles formed during the
analyfis, and of courfe varying according to the nature and
circumftances of the experimental inveftigation. Hence we
are feldom able to form again the old vegetable compound by
uniting together all the ingredients which we have extracted
from it.

Thefe difficulties increafe with the complicated nature of the Complication of
vegetable body; for the greater the number of conftituents isjP"'^^*^^ '
the more liable are they to undergo alteration during an analy-
fis. Indeed fome vegetable principles feem incapable of ex-
ifting except in combination, and are decorapofed or new mo^
dified the inftant we attempt to feparate them.

The variety of fiates in which the vegetable principles fuc- Loofe nomen-
cellively exift, together with the difficulty of examining ^^^*^''' tables! ° ^^^'
properties without altering their nature, has rendered it necef-
fary for chemifls to apply the names of them with greater lati-
tude than is ufual in other departments of the fcience. A ger
neral refemblance, indeed, in the moft ftriking properties,
feeras to have been thought fufficient to entitle vegetable prin*
ciplesto the fame name. If we examine all the bodies termed
gum, we Qiall find them running on the one hand into ^^mch,
and on the other intoyi/^or; and forming a pretty long feries,
having fugar and flarch at the two extremities: no two of the
fubftances conftituting the feries are exadly the fame; but the
fame name is ufiially applied to all thofe that have a general
refemblance. This will be eafily feen by the following table,
jn which I have fubdivided the feries into five genera.

ri. Common sugar Inftancesin

Genus I. Sugar . - 4 2. Sugar of grapes ftTch.^^'

Ls. Sugar of beet,

II. Sarcocoll

70

OK PEPPER,

Ih Sarcocoll

m. Qum

IV. Gluten

V. Starch

■I
-(

1. Manna

2. Liquorice

3. Common farcocoll

4. Saccharine of malt.

1. Mucilage of roots

2. Cherry-tree gum

3. Gum-Arabic

4. Gum of barks.

Gluten of barley
Gluten of wheat
Cafeous principle.
Gum tragacanth
Gum of lichens.
Common ftarch.

Sabjeft intro-
duced :
Fej>per,

Defcrlption.

Thefe terms arc The terms gum, jiarch, f agar f &c. in vegetable chemiftry
generic. ^^.g ^^^ j.^ ^g underftood as the riames of peculiar fubftances,

nor even 2l% /pedes ; but merely as ge/^era, and nearly fimilar
to the terms metals, acids, alkalies. Sic. in the other depart-
ments of chemiftry.

The preceding obfervations will ferve, I truft, as an apology
for the imperfe^ion of the following remarks on pepper, I
offer them to the public not as an analyfis of that vegetable fub-
flance, but as an account of forae of the properties of its moft
remarkable conflituents.

I. Black pepper is the fruit of an Eaft Indian plant, the
piper nigrum, and is too well known to require any particular
defcription. The outer coat of the pepper-corn is brown,
and a good deal fl^rivelled. Its tafte is not nearly fo pungent
as the inner part ; of courfe it contains lefs of the peculiar prin-
ciplt; to which pepper owes its tafte and fmell.

II. When pepper is macerated in cold water it does not
Jofe its (hri veiled appearance; a proof that the corns are im-
pregnated with an oily fuhflance, which prevents them from
abforbing water. The liquid very foon acquires a fine deep
reddifli brown colour, but retains its tranfparency, Whiiepep-
pert which is known to want the outer coat, communicates no
fuch colour to water; the colouring matter then muft refide in
the outer coat.

The watery irifufion thus obtained pofleffes the fmell and
tjifle which are peculiar to pepper. Like moft other extrads,

Maceration in
cold water.

OJT PE^PEK.^ 71*

it has the property of giving a red colour to vegetable blues.

A very great quantity oF water fuccenively applied is necelTary .

to exhauft the pepper of its colouring matter: but the fmell

and tafte of pepper become lefs and lefs ftrong in thefe infu-- ^

iions, and at lad altogether imperceptible, leaving the infufions

infipid, or flightly fweetilh.

1. Thefe cold infufions contain a peculiar extraSiive matter, Peculiar extraSi-
which feems to retide in the outer coat of the pepper-corn. ^*'^ "^^"^'^*

In the firft infufions their matter is united to the fubftance, in
which the tafte and fmell of pepper reiide, and occalions its
folubility in water. In the laft infufions, if we jud^e from'
their appearance, it feems to be mixed with a mucelaginous
fubf^ance.

2. If we mix the infufion of nut-galls with the cold infufion Cold and hot

of pepper, no fenlible change is produced; but in a deco6tion ^^1"^°"^ a'' ^
of pepper, it produces a copious flaky precipitate. Hence with jnfuf. of '^
we learn that there is a fubftance in pepper infoluble in cold ^^"l* f*"^<^'P*

. 01 Ji arch t

water, but feparated by means of boiling water. This fub-
ilance, as fliall be afterwards fhown, is a fpecies of Jiarch.

3. When pepper is macerated in alcohol it communicates a Maceration of
light yellowith green colour to the liquid, which becomes at P^PP*'''^,*".j!^°'
the fame time fully impregnated with the peculiar hot princi- tion leave Wiz/i/c
pie which charadlerizes pepper. By dillilling this t'indlure in "'^^

a retort, the alcohol is obtained colourlefs, but of a decidedly
peppery flavour. Towards the end of the diflillation, the
liquid in the retort becomes muddy, and depofites a greenilh 7rM%'^

matter, part of which may be obfervedalfo trickling down the
fides of the receiver like drops of oil. The refidual liquid is
yellow, but nearly infipid. T'his green matter is the fubflance
to which pepper is indebted for its tafte and fmell. Its pro-
perties are analogous to thofe of the volatile oils.

4. Thefe three bodies, namely, exiraSiive, fiarch and oil, I
confider as the mofl important ingredients of the pepper-corn.
Let us examine the properties of each, beginning with the oil,
which is obvioufly the effential ingredient.

III. The colour of the oil of pepper is grafs green. When Charaflers of
firll obtained it is of the confifience of turpentine, but it gra- "'^ °^ pepp«r.
dually hardens by expofure to the air. When moderately
heated, it gives out a liquid oil of a yellowifh green colour,
and leaves a folid mafs, fimilar nearly to a refin. When thrown
into water, it finks to the bottom of that liquid.

Its

Y2. eif TtffttL.

Taftcandfmell Its taft« is intolerably hot, and preciWy fimilar to that of

itrong, and that ^ r • '^ /- n

of ihf pepper. P^PP^"^- So is Its fmell.

corn. When heated to 100®, it foftens; it melts at 148'', evapo-

Iilfli'able. '^^^^ ^ ^'^^'^ ®^^^^ 212° in a white fraoke, which fmells like
tobacco fmoke, irritating the throat and exciting coughing.
Evaporated to drynefs on a glafs plate, it leaves a yellow trace
behind it. When fuddenly heated, it boils violently, and the
Vapour burns with a clear white flame without any fmoke.

Volatile by jt gives agreafy (lain of a green colour to paper. At 500°

the greafy appearance is removed, but the green mark fiill con-
tinues, unlefs the heat be fufficient to char the paper. Hence
I think it follows, that the colouring matter of this oil is a fub-
flance entirely diflinfi from the oil itfelf.

Soluble in alco- fhe oil of pepper is infoluble in water; alcohol and ether

hoi and in ether, ,.». , . i-i ,i r i • • i- , . ■ , > , ,•

but notinw-iter, a»"^ive it readjly; the lolution is light green: alcohol holding

&c. it in folutipn, acquires a very fragrant odour, precifely iimila.'

to that of oil of lavender. When water is added to this folu-

tion, the whole becomes milky, and pafles in that (iate through

the filter. On /landing fome weeks, light green flakes fubfide,

but the milky opacity is permanent.

Aaionofal- Alkalies have no fenfible a6lion on this oil while cold,

icalis*

When thrown into liquid potafti it fwiras on liie furface. If

the liquid be heated, the oil becomes brown and acquires

greater confiftence. At the fame time it evaporates partially,

diffufing around the peculiar odour of pepper.

•-- of nitric acid. Nitric acid difiblves it with effervefcence, the folntion is yel-

lowifh browri, and a waxy matter (wims on Uie furface. This

acid 2t^-< in the fame manner on other volatile oils.

— and of ox. The oXygenij?ed mqriatic acid dertroys the green colour and

mur. acid. ^^akes it yellowifl) white. But it ftill retains its former taHe.

It is a vol. oil Tliefe properties are fufficient to authorize us to refier this

with col. natter green m^^tter to the genus of volatile oils It is not however

*^ ^^ "* a pure oil, for befiJes the colouring matter already mentioned,

it obvioufly contains a fubftance which approaches to thegenus'

of refins in its properties.

Bstr-'iSii'dt ai IV. The EXTRACTIVE of pepper is j>rocured by ipacerat-

P-PP-<^» ing ({,e pepper-corns in cold water. Like the other fpecieu of

this difhcult genus of vegetable principles, it is fcarce poffible

to ob'ain it in a ftate of ablolute purity. But if we macerate

the pepper-torns whole in fucceffive portions of water, till the

liquid Ipfes the peppery flavour, and then pour on them frefli

i 4 water,

ON PEPPER.' 7^^

water, we obtain an infufion which I believe holds in folu-
tion fcarcely any thing butextrafiive. If this infufion be eva-
porated flowly in a fteam heat, it leaves a brown refiduum,
which Iconfiderasextra6^ive of ftarch not far from purity.

1. The infufion is infipid or flightiy fweetifli, and of a fine Aq. folution
reddilh brown colour. As the evaporation advances, the co- ^y evap. leave*
lour deepens, andthe hquid acquires an acrid flavour, fimilar

to that of fcorched vegetable matter. This flavour, which in-
dicates a commencement of decompofition, is evolved at a
very moderate temperature.

2. If the evaporation be conducted rapidly the extradive is
opaque, dark brown, and has a perceptible tafte, and dele-
quefces or at leaft attrads moifiure when firft expofed to the
atmofphere. But by very flow evaporation I have obtained
it in fine femi-tranfparent brown fcales, which are infipid,
brittle, and not altered by expofure to the air.

3. This extradlive diflblves readily in water, but not in al- Soluble in water,
cohol. If it be repeatedly diflblved in water, and the folu- |^^f "ot in alco-
tions evaporated to drynefs, a fmal! portion of it becomes in-

foluble in that liquid; but the greater part continues foluble
after the procefs has been repeated occafionai ly even for
months.

4. Thisextradlive is precipitated from water by moft of the Precipit. by
pietallic falts and by feveral of the earthy folutions. metallic falts.

It is thrown down in brown flakes by lime-water ftrontian
water and alum. Barytes water deepens the colour, but oc-
cafions no fenfible precipitate; nor is any precipitate pro-
duced by filicated potafs or the magnefian falts.

It is precipitated brown red by the nitro-muriate of gold,
the nitrate of filver, mercury, lead and bifmuth, and by the
muriate of tin and antimony. When mixed with the infufion
of litmus, the colour becomes red. Ammonia reftores the ori- • ^

ginal colour, and at the fame time throws down a copious blue
Jake.

5. When a current of oxymuriatic acid is paflTed through —by ox. mur.
the infuficfli of pepper, the brown colour is fpeedily converted "^^
into a pale yellow, and the extractive precipitates in white

tiakes. The eafiefi method of making this experiment is the
following: Put a quantity of the hyperoxymuriate of pofafli
into a fmall retort, having a long neck (or a flafli provided
with a bent glafs tujbe ground into it) and pour upon it a por-

-tion

74 O^ PEPPER.

tion of muriatic acid. Let the infufionof pepper be put info
a tali glafs veflel, and plunge (lie beak of the retort to the bot-
tom ot it, A current of oxyniurialic acid is difengaged from
tlie fait, and patfesin bubbles through the inlufion for a conli-
derable time.

When ammonia is added to the infufion thus made while,
the original red colour is rellored. The white flakes precipi-
tated by oxymuriatic acid gas are infolubie in cold water.
Deco4ftion of V. That pepper contains a fpecies oF (larch, I conclude

pepper affords f^.^^^ ^j^^ following experiment, which I have frequently re-
with tattf a pre- . . . -^

cip. foluble in peated. When the decoction of pepper is mixed with the in-

^u ^^^ "°' ^ fiifion of nut-galls, a copious precipitate falls in reddidi brown
flakes. If this liquid be heated to the temperature of about
120°, the precipitate is re-difiblved, but appears again when
the i'olution cools. Now the only fubftance which poifetTes
the property of forming with tan, a precipitate nearly infolubie
in cold water, but very foluble in hot water, is ftarcb. Tan
indeed throws down gluten, but the precipitate is not re-dif-
folved in the application of heat. It tlirows down caoutchouc
and fome of the gum-refins, but the precipitate is fcanty and
probably owing to the extraneous matter. The precipitate,
which it forms with gelatine and albumen cannot even by the
mottcarelefs obferver, be confounded with the compound of

Tfcis property is ftarch and tan. But befides this property, which I coiilider as;

^aradlenftic of ^.^gj-jj^^^fif^jf,^ j|jg ftarch of pepper, agrees with com'.non
ftarch in the phenomena which it exhibits with the different
chemical reagents.

Phenomena of As thefe phenomena have not yet been detailed by chemical

ftarch with re- writers, it may be necctfary to give a fliort Iketch of them in

•gents. ,, . , ^ ^

this place. •

Starch noteafily *• Starch is one of thofe vegetable bodies that are leaft li-
iccompofcd. at>ie ^o decompofition. It conftitutes one of themoft import-
ant articles of food, and acts an important part in the produc-
tion of fermented liquors. The obvious properties of com-
mon fiarch are too well known to require any defcription.
Not foluble in 2. Neither alcohol nor elher nor water are capable of dif-

alcohol, ether, f^i^ing it. The laft liquid when affifted by a boiling heat,
or water. ° . . . . .

readily unites with it, and forms a kind of jelly, which may

be diffufed through boiling water; but when the mixture is

allowed to ftand afufficient time, the flarch flowly precipitates

Forms a jelly ^q i\^q bottom. By drying the compound of flarch and water,

with hot water ^ ^ u x i • i

which is little ^ brittle

changed.

ON PEPPER. ' 15'

a brittle fubftance is obtained, differini^' in appearance from
common ftarch, but exhibiting nearly the fame properties with
re-agents. The apparent difference is probably owing to a
portion ot" water remaining united to the ftarch.

* 3. When ftarch is triturated with the hot infufion of nut-^-Completely
galls, a complete folution is effeded. The folution is ^^^''^-InM^of gzUs,
parent and rather lighter coloured than the infufion of galls, and precip. by
When cold it becomes opaque, and a copious curdy precipi-^°^'^*
lateralis.

The infufion of nut-galls, which I am accuftomed to em- The infufion of
ploy in all my experiments, except when the contrary is ^'^-^^.^^fa^,^'^^^^^^
prefsly mentioned, is made by boiling together one part of
galls in coarfe powder and two parts of water in a glafs retort.
When cold, the liquid part is decanted into a glafs phial. It
is at firft muddy, and opake ; but on (landing, a fediment falls,
and a tranfparent liquid remains of a deep brown colour,
which conftitutes my infufion. An ounce meafure of this in-
fufion, when evaporated to drynefs in a glafs velTel placed on
a tin-plate box, heated by fteam, leaves a brown refidue,
which weighs 68 grains. This refidue confifts chiefly of tan;
for thegreatefi part of the exlradive gradually feparates from
the infufion in the fiate of a brown, tough, imperfectly folu-
ble membrane. Neiiher*extra8ive nor pure gallic acidh^^ any --"^

effed upon the decoction of ftarch. Hence the precipitate is
obvioufly produced by the fole adion of tan upon the ftarch.

4. Twenty-four grains of fiarch were triturated with half an Experiment of
ounce meafure of the infufion of galls, and mixed with about ^^^j.^'J^'^^^j °
five ounces of hot water. A complete folution took place;
but on cooling, the liquid became opaque, and a precipitate
fell, which dried by a fteam heat, weighed 35 grains. The
refidual liquor had a light yellow colour and an aftringent tafte.
When evaporated to drynefs, it left a refiduum that weighed
17 grains. This refiduum contained ftarch, for it was not
completely foluble in alcohol. In this experiment feme lofs
muft have been fuftained during the trituration. For the folid
matter obtained weighed only 52 grains; or fix grains lefs than
the 21' grains of ftarch and the 34 grains of folid matter in the
infufion of galls. The following is more to be depended on:
After various trials, I found that ftarch and tan are capable of
uniting in diflFerent proportions. But the precipitate is leaft
foluble when | oz. meafure of infufion of galls is ufed for
every 24 grains of ftarch, — I took 24 grains of ftarch, boiled

them

7(J ON PEPPER.

Ihera in a flafk with Hve ounces of water, and then added |6z.
menfare of the infufion of galls. On cooling, a copious pre-
cipitate fell, and the liquid remained only faintly coloured.
The precipitate dried in a fteam heat weighed 31 grains, and
iht refidual liquid left 11 grains of refidue. The whole
amouiited to 42 grains; which is very nearly equal to the 24«
grains of i\?,rch and 17 of tan employed; the compound in this
cafe confilU of

58. 5 ftarch, or nearly 3 (larch

41.5 tan » - . - 2 tan

100,0 5

The compound of ftarch and tan is of a light brownifti yel-
low colour, femi-tranfparent and brittle^ and has a good deal
of refemblance to common farcocoll. Its tafte is aHringent ;
it feels glutinous between the teeth, like gum. It is very im-
perfectly foluble in cold water, but hot water difiblves it abun-
dantly. Alcohol digefted on it acquires a brown colour; but
is incapable of feparating the whole of the tan from the ftarch.
When heated, it froths, fwells and melts, and then burns with
a clear flame, leaving like ftarch a fmall portion of white aflies
behind it.
Infufion of ftarch 5. To afcertain the effeft'of the earths and metallic oxides
toeatoijwith ^^ flarch, an infution of it was formed by triturating 24 grains
of ftarch with 4f ounces of water, and then boiling the miX'
ture for fome time. The decodion thus formed, is nearly
tranfparent, and of a flight opal colour. When fet afide, at
leaft a month elapfes before the ftarch begins to fubfide.

When lime water is mixed with this decoction, no change
is produced; neither is any perceptible alteration occafioned
by ftronti^ water; but barytes water throws down a copious
white flaky precipitate. This precipitate is re-difl>)lved by
muriatic acid, but appears again on ftanding unlefs a confider-
able excefs of acid has been added. Vet muriate of barytes
occafions no change in the decodlion of ftarch.
—with metallic No metallic fait feems to have the effedl of throwing down
felts : no cffca. ^^^^^ ^^^^ j^^ jecoaion. The following were tried :
Nitro-muriate of gold, platinum;
Nitrate of filver, mercury, lead;
Muriate of tin, acelite of lead;
Salts of copper, iron, zinc;
Ammoniated nickel and cobalt.

6. When

^: ON PEPPER. 7T

, 6. When polafs is triturated with ftarch, and a rmall quan-
tity of water added, the whole adumes on ftanding the ap-
pearance of a femi-tranfparent jelly. On adding water, an
opal coloured folution is obtained, from which the ftarch is rea-
dily thrown down by an acid. When muriatic acid is em-
ployed, a peculiar aromatic odour is exhaled.

When the infufion of galls is dropt into the folution of ftarch
in potafs, a yellowifti white precipitate appears, but is imme-
diately re-diflblved, and the liquid remains opake and of a
dark brown colour. On adding muriatic acid, a copious pre-
cipitate falls, refembling the compound of ftarch and tan. —
Nitric acid occafions no precipitate, neither does ammonia.

The decoction of ftarch is neither altered by potath, carbo-
nate of potafti, nor ammonia.

7. Sulphuric acid diffolves ftarch, and abundance of char- Treatment of

coal is precipitated. Diluted fulphuric acid, when aflifted by ^^'^^ '^'g'jj^

heat, diftblves it without decompofition. Sulphureous acid tion. Separation

has no effea upon it. >y ^^'^'' The

I-.M , 1 .. • • 1 /- o 1 n , . , - 1 . infufion of ftarch

Diluted nitric acid nrft reduces ftarch to powder, and then not affeded by

difTolves it, with the exception of feme waxy matter, which ^'^^^'"•.

fwims on the furface. During the folution, fome nitrous gas by the ancient

is exhaled. mineral acids.

Strong muriatic acid diflblves ftarch flowly, and without ef-^^^"°°*^"**
fervefcence. When the ftarch does not exceed ^ of the
acid, the folution is colourlefs and tranfparent, but if we con-
tinue to add ftarch, a brown colour foon appears, and the acid
lofesa portion of its liquidity. Its peculiar fm ell isdeftroyed,
and replaced by the odour which diftinguiflies corn mills.

Acetic acid does not diftblve ftarch.

8. Alcohol feparates ftarch in part from its deco6lion. Potafti Expenments
<li(rolved in alcohol occafions a copious white precipitatCj^* '^ **'
which is re-diftblved on adding a fufficient quantity of water.
Alcohol digefted on fulphuret of potafs, occafions a flaky
precipitate in the deco6tion of ftarch; this precipitate has
fometimes an orange colour.

Such are the properties of common ftarch: the ftarch ofstarch of pepper
pepper poflefles them, excepting only that the colour of its '^^^ 'he preceding
precipitates is peculiarly modified by the other Ingredients offsTni7e?to an
pepper, from which it is not poflible to free the ftarch com-^^ inthepepper-
pletely. <=°'^"-

A very confiderable portion of the pepper-corn feenis to
x2onfift pf ftarch, chiefly united to the oil of pepper. When a

pepper-

"^j THEORIES OF CRYSTALLOGRAPHY.

pepper-corn is'cut in two, we find it compofed of two coats*

The outermoft brown ftirivelled coat is eafily feparated by
ileeping the pepper in water. The fecond coat is much
thinner and hghter coloured ; it does not feparate by macer-
ation. Beneath this coat is a thick zone of pale green mat-
ter, apparently ftarch united to oil. This is fucceeded by a
thin yellow zone, feemingly of nearly the fame compofition.
Within this is a fmall fpherical fpace, fometimes hollow, but
moft commonly filled with a foft white fubftance like the pith
of trees. All the zones have the peppery tafie. The outer
coat has the flavour, but little of the heat of pepper.

III.

Letter from the Abbe Buee on Mr. Rome' de Lisle's and
the AbbS Hauy's Theories of Cryfiallography ,

(Concluded from p. 39.)

OYNTHESIS is grounded, as I mentioned, on the fad, that
all well formed cryftals are terminated by plain furfaces.
Primitive forms: Since there exift primitive forms, there mufi alfo be fecond-
ary forms, for the one fuppoles the exiftence of the other.
SecoHdary, The fecondary forms are fuch, that fedions can be made only
parallel to the fides of the primitive ; and when the primitive
has been produced by Ihefe fc(5lions, the divifion being conti-
nued the integrant particles are obtained.
Laws of the 'The mineralogical analyfis defcends from the fecondary to

ftruftureof (he primitive form, and from the latter to the integrant par-
SorVthenae ^'^^^ » J"^'' ^^ ^^^ mineralogical fynthefis afcends from the inte*
refuiting, grant particle to the primitive, and from thence to the fecond-

ary forms. A cryfialline edifice is therefore raifed by means of
the integrant particles. What are the laws of this extraordi-
nary architedure ? By laws I mean the difpofition of the la-
minae, not the means employed by nature to execute the
curious ftrudure.

Laws mud exift. Hi, for the formation of the primitive,
and 2dly, for the conftruclion of the fecondary form. I'he
primitives are either fimilar to their integrant particles, or
they are not. If they are not, their forms niuft be parallelopi-

pedon?>

•THSORIES OF CRYSTALLOGRAPHY'. 76

•pedons, and their laws of formation very fimple; for there Laws of the ^^
will be the fame number of integrant particles in each row, as ^ ^^j^^ ^^^
there are rows in each lamina, as there are laminae in the pri- theory thence '
mitive form. It is eafy to conceive that all the joints perfedl) ^efultrng.
coincide witH each other, and form continued planes ; neither
will there be any vacuity left between the particles. If the
primitive be not fimilar to the integrant particle, then the fim-
plicity of the former cafe difappears. I have already fiated
-that there are three forms of integrant particles; the telra-
edron, the triangular prifm, and the parallelopipedon. There
are alfo fix primitive forms ; the parallelopipedon, the odtae-
dron, the tetraeclron, the regular hexaedral prifm, the dode-
-caedron bounded by rhombs all equal and (imilar, and the
dodecaedron with triangular fides and formed by two right
-pyramids united bafe to bafe. Of Ihefe fix primitive forms
there are only the parallelopipedon and the regular hexaedral
prifm that can exadly fill up a fpace without leaving any va-
cuity. The integrant particles of the former are parallelopi-
pedons; of the latter, triangular prifms. As to the other four
primitive forms, their integrant particles are tetraedrons. The
dodecaedron bounded by rhombs is produced by twenty-four
fimilar tetrnedrons without any vacuity between them ; the
o£lae Iron and tetraedron are formed by tetraedrons leaving
octaedral vacuities ; and the dodecaedron bounded by tri-
angles, to be formed of tetracvlrons, mufl imply fedions pa-
rallel to more than fix planes; which perfectly coincides with
obfervation.

Thefe vacuities, whofe exifience muft be admitted in the
integrant particles, as well as between thofe particles when
forming a primitive, give rife to the following reflexions :

When the elements of a fubfl:ance are chemically combined,
that fubfiance is homogeneous. Let us fuppofe a cryfial of
fuch a fubftance to be fubdivided into fmall parallelopipedons
equal and fimilar ; as the fubftance is homogeneous, and thefe
little parallelopipedons having no vacuities between them, it
is evident the elements that compofe them are equal in number
and proportion. We will next fuppofe the cryftals of this fub-
ftance can be divided by fections parallel to fix planes. In
ihat fuppofition, nineteen or twenty diiFerent fpecies of pa*>-
rallelopipedons can be produced. Among thefe fpecies (bme
-will be fimilar, others not ; but none of the fpecies will be ex-

aaiy

^WB

^ TRSORIBS OP CRVSTAttOGRAfHY*

l«wi of the ilftTy parallel to each other. We will proceed on two fimllar
wftalT^and cryftals of the fame fubftance and equal in folidit)', dividing
theory thence the firll into one fpecies, the other into a different fpecies, of
jtfulting. parallelopipedons, equal in folidity but not in furface; and let

the diviilon of each be pulhed to its lalt term. But as we are
come by fmooth fedliohs to parallelopipedons of different fpe*
cies, thofe fedions have alfo produced their differences : but
by fuppofltion thefe parallelopipedons are the refult of the lall
poflible term of divifion without defiroying the chemical com*
portion, and being equal in folidity, though not in furface,
they cannot contain each other ; therefore if their differences
are not integrant parts of both, thefe differences muft ceafe to
be homogeneous, and we come to a fort of chemical decom-
pofition. It is true we cannot execute this exceflive divifion,
but we can form a very corretSl idea of if» If the little paral*
lelopipedons contain two forts of elements, their differences
will alfo, but alfo in different proportions; and, fir, if you
will turn to Berthollet's Bejhmxhes on the Lwjjs qf Affinities^
you will fee him in all his experiments proving, that however
perfedly a chemical decompofition may have been made, the
refults will always contain a certain portion of thofe fubflances
from which it was the objed of the operation to feparate them»
If thefe reflexions, Sir, are well grounded, do they not give
us hopes, and perhaps fliow the poffibility, of defcending from
the integrant particles to the conftituent particles ? This fe-
cond refearch is of the fame nature as the firfl. It is more
than probable that the conflituent particles themfelves are di*
vifible, having no determined figure, but are aggregations,
fubje£t to the fame laws as the integrant particles. The objeft
of the natural philofppher is not to difcover the forms of the
ultimate particles, but to determine their refpedlive pofitions ;
which, if ever they could be determined in the integrant par^
tides and their component parts, the grand problem of chemi-
cal affinities would be fully folved; and fliould fuch ever be
the cafe, to the Abbe Hauy's theory would be due the merit.
The Encydop<£dia Britannica, under the article Chemijliy, in
the Supplement, p. 396, fays :

" This theory, to fay no more of it, is, in point of ing6»
nuity, inferior to few ; and the mathematical fkill and induflry
of its author are entitled to the greatefl applaufe.

♦' But

TrtECyRTES OF CRYSTA'LXOGRAFMV, ^l

" But what we confider as the mod important part of that Laws ^ftlie
philofopher's labours, is the method which they point out ofcryftals, and
difcovering the figure of the integrant particles of cryftals ;theory thence
becaufe it may pave the way for calculating the affinities oi^^ ii"in&»
bodies, which is certainly by far the raoft important part of
chemiflry. This part of the fubje6t, therefore, ddferves to
be inveftigated with the greateft care."

But I return to the point whence this digreffion carried me,
to the vacuities left between the integrant particles in the con-
ftru6tion of a primitive form. The Abb^ confiders them as
filled either by the water of cryflallization or by fome oth^r
iubftance. It is not an admiffible fuppotidon that this other
fubftance is compofed of the fame elements as the integrant
particles, but in different proportions? At leaft, fuch is the
conclufion I fliould be tempted to draw after reading Berthol-
Jet's excellent Refearches on Affinities.

I fliall now proceed to the laws of formation in fecondary
cryftals. It is eafy to deduce them from thefe two fa6ts : viz.
1(1, That the tides of the fecondary cryflals are planes ; 2dly,
That they divide by fmooth fe6tions parallel to the fides of
their primitive form.

Let us take a rhomboid of carbonate of lime for example.
If on one of the (ides of the rhomboid I wilbed to raife a
pyramid, I fliould lay laminae of rhomboidal particles upon
each otlier.^ Thefe laminas would decreafe in furface until
the laft is reduced to a tingle rhomboid. Thus the fecond.
lamina contains fewer particles than the firfl, the third fewer
than the fecond, and fo on. As the faces of thefe pyramids
are always to be planes, the fucceffive decrements of the la-*
minae muft be eqtial ; that is to fay, the fecond lamina is lefs
by one range in every dire6tion than the firft, and the third
than the fecond, &c. If the decrement is more rapid ; that
is to fay, if two or three ranges are fubtrafted in the fecond
lamina, the fame number will be fubtra61ed from the third,
-and fo on fucceffively till the pyramid is completed. As the
fe6^ions are to be fmooth, the joints muft form one continued
plane ; therefore the ranges and even the particles at the
joints muft not encroach on each other: hence it follows Mai
the number of ranges fuccejjlveli/ fubtra6ied from each lamina can
"never he incotnmenfurahle ; that is to fay, the decrement, naay
'bel,2, 3, 4, &:c.; but never <y/ 2, v^3, &c.
';. Vol. IX.— October, 1804. G Tijefe

82

Laws of th«
ftrufture of
cryflals, and
theory thence
rcfulting.

THEORIES OF CRYSTALLOGRAPHY.

Thefc are the decrements parallel to the edges, or, as the
Abb^ calls them, decrements on the edges. But they may
take place in a parallel with the diagonal of the faces of th6
primitive ; they are then called decrements on the angles, be-
caufe the diagonals are drawn from one angle to the oppofite
angle. This fecond fpecies of decrement follows the fame
laws as the firft.

There is a third, fpecies, called by our author intetmediatc
decrements. In this cafe they are neither parallel to the edges
nor to the diagonals of the faces, but to intermediate lines,
which if prolonged would interfe6l both the edges and dia-
gonals, but otherwife they follow the fame laws as the two
firft. It is a general law, therefore, that in all cafes the lamince
decreafe in arithmetical progrejfion, and its ratio or the number
of ranges fubtraBed is alivays commeiif arable.

The particles of which the laminae are compofed are to be
conlidered as parallelopipedons ; not that the integrant par-
ticles always have this figure ; but if they have it not, they
niuft leave vacuities between them, and each vacuity being
added to its correfponding particle, will complete the paral-
Iclopipedon. If this was not the cafe, the faces of the fecond-
ary cryllals would not be planes, nor could they be fpiit
fmoothly in any diredion. Thefe little parallelopipedons
which compole the fubtra6led ranges are what I called above,
alter our author, fubtra^ive particles,

I fuppofed the conftrud^ion of the fecondary form only to
take place on one of the faces of the rhomboid ; but what was
faid relative to that face is applicable to all the others. It is
alfo to be remarked that different laws of decrement may affe6t
the different faces ; even further, different laws may fuccef-
lively affeft the fame face. Hence a diverfity of forms arife
fcarcely credible to a perfon unacquainted with the do^^rine of
combinations. The Abbe Haiiy has calculated, " that con-
. fining one's-felf to decrements by 1, 2, 3, or 4- ranges, and
not taking intermediate or mixt decrements into account, the
rhomboid is capable of 8,324,60 !• varieties of cryflalline forms.
It is an important remark, that whatever may be the variety
of form, the forms (in complete cryftals) will always be fym-
metrical. There are two forts of fyrametry, the perfect alid
imperfefl. In the pcrfed, the right is fymmetrical with the
. left, and the top with the bottom ; but in the imperfed, the

top
3

tHEORIES OF CRYSTALLOGRAPHY. 83

top is not fymmetrical with the bottom. This latter fpecies of taws of the
fymme(ry appears, by general obfervation, to be exclutively cryftals, and
appropriated to cryftais that become ele<5lrical by heat; that theory thence
is to (ay, which being expofed to the heat of the fire, or '"'^^"^""S*
plunged into hot water, acquire th j eledric power. Thefe
cryftals, the tourmaline, for example, acquire a pofitive elec-
tricity on one fide, while on the fide diametrically oppofite
their electricity becomes negative ; and all obfervations hi-
therto made give us reafon to conclude that thefe fides are
never fymmetrical, and are always produced by different or
fewer laws of decrement. " Hence,^' fays the Abb6, *• by
mere infpedlion it is eafy to point out which is the fide that
will give the pofitive and which the negative eledlriclly."
(Vol. i. p. 237.)

The aftonifiiing variety in the cryftalline forms leads us
naturally to afl<:. What can be the caufe of this variety ? This
queftion has not been treated by the Abb^ : allow me. Sir/
to fubmit a few ideas on the fubje6l for the opinion of mathe-
maticians.

Firft caufes, I repeat, are not the obje6t of this difcuflion.
I ftate the queftion thus : Why does the fame fubje<5t cryftal-
lize in fuch a variety of forms, always fymmetrical and always
terminated by planes?

The folution of this queftion feems to require three condi-
tions: 1ft, That the particles of the fubftance diflx)lved in the
fluid all leave the ftate of reft at the fame inftant, to form the
cryftal by their aggregation : 2dly, That, while thefe particles
are in the ad of drawing near to each other, no foreign power
(hall imprint on them any other motion than a common motion,
whether it be in a ftraight line, or rotary round their common
centre of gravity : 3dly, That the particles all arrive at the
ftate of reft at the fame inftant, which takes place when the
a6t of cryftallization is finithed. The fecond condition is ne-
ceftary, and infers the firft and third. The natural confe-
quence of thefe conditions will be, that the aggregation of the
particles will only take place conformably to a law ading
equally on all of them, whatever may be the law.

Since they all leave the ftate of reft at the fame inftant, they
are in equihbrio previous to ihat inftant. Since they all arrive
at the ftate of reft at the fame inftant, they are in equilibrio
after that inftant : but when particles that are aded upon by

G 2 no

u

THEORIES OF CRYSTALLOGRAPHY,

Laws of the
ftrufture of
ciy'ftals, and
theory thence
refultirig.

no other force than that which they exercife on each other,
are in equilibrio, thej are in the clofeft poffible union that
concomitant circumftances will permit. If the particles were
in equilibrio previous to their leaving the flate of reft, fome-
thing niuft have obftru6led their approach. Let us fuppofe
that fomeihing to be the interpofition of another fubftance, and
that fo long as the interpofition remains equilibrium is main,-
"taihed. But this can only be the cafe, in as much as the whole
of the particles of the interpofed fubftance are in equilibrio
with the whole of the particles diflblved and about to leave the
ftateof reft, which in the future I ftiall call the proper particles.
If by any caufe which a6ls uniformly on the whole furface of
the diflblving fluid any of the interpofed particles are fub-
tracted, the proper particles muftceafeto be in equilibrio. A
ftep toward aggregation will immediately take place, and the
equilibrium will be reftored, A further fubtra6lion will pro-
duce a further ftep toward aggregation, and a confequent
equilibrium; and thefe operations will be repeated fo long as
the caufe of fubtradion continues, and the longer its duration
the larger will be the refulting cryftalline mafs. If the above
mode of reafoning be admitted, it will fuffice to apply the
laws of equilibrium to deduce the laws of cryftalH«e forms.
The laws of equilibrium to which I allude, are thofe of the
equilibrium of fluids, with certain modifications which ftiall
hereafter be explained. According to thefe laws, that the
preceding conditions may take place in the formation of a
cryftal, it will be neceHary that they take place in the forma-
tion of each and every part of it, whatever may be the figure
or the fmallnefs of thofe parts. They muft alfo take place in
thofe laft cryftals which contain the leaft poflible number of
particles; and as thefe particles are in equilibrio, and in the
greateft poflible ftate of proximity to each other which cir-
cumftances will permit, it muft follow, to fulfil all the condi-
tions, that thefe particles form a fymmetrical polyedron. This
peculiar difpofition of the cryftalline particles conftitutes the
modification, to which I alluded, in the laws of the equili-
brium of fluids ; it being neceflary in this cafe to lake the num-
ber of cryftalline particles into account, which is not the cafe
when treating of the particles of a fluid. In a fluid, the par-
ticles and their reciprocal diftances are fuppofed infinitely
imall J but the cryftalline particles and their diftances to each

other

THEORISS OF CRYSTALLOGRAPHY, ^5

Other muft be fuppofed finite. This material diflference will Laws of the
neceffarily caufe a difFerence between the forms of their aggre- f^'yi^rs^and
gates. Thofe formed with the particles of a fluid will be theory thence
bounded by curved lines; the cryftalline aggregates, on the "^^^"^^'"S*
contrary, will be terminated by ftraight lines; and when thefe
ftraight lines are not too fmall, the boundaries will be fenfibly
rectilinear.

To afcertain what the power is that holds the particles in
the ftate of refl, though not in clofe contaft, is not the quef-
tion ; but the form of the polyedrons which they produce,,
The clofer adhefion of the particles to be obtained by the fub-
tra6tion of caloric, fufficiently demonftrates that the particles. ,
^re not in clofe contad with each other, and the conftancy of
the cryftalline forms equally proves that they are in equilibrio.
We will now proceed to the conftrudion of a cryftal with
thefe cryftalline particles. That the conftancy of the form in
tJie large cryftal be preferved, the particles muft be in equi"
librio. That the equilibrium be preferved, the forces that fo-,
licit the particles to motion muft mutually deftroy each other.
That the mutual deftrudion of thofe forces be effedled, thefe
forces after having been decompofed into other relatively pa-
rallel to three axes perpendicular to each other, and having a
common point of interfe6tion, muft each meet in its.direftion
another force equal and diametrically oppofed to it. This will
be obtained if the fimilar particles are arranged on ftraight
lines parallel two and two at equal oppofite diftances from the
common centre, and bifedted by lines pafling through that
centre ; but if the particles are thus arranged, they muft pro-
duce fymmetrical folids bounded by planes; and they are thus
arranged : for if a foreign force, an excefs of caloric for ex-
ample, does not impede the free arrangement of the particles
in the formation of the cryftal, their exterior difpofition will-
follow as much as poffible their interior arrangement j but their
interior arrangement muft be on ftraight lines, or the cryftal-
would ceafe to be homogeneous; their exterior difpofition
will therefore be on ftraight lines.

As the circumftances giving rife to the approach of the par--
tides maybe in the higheft degree variable, it muft follow
that the forms .produced may be diverfified in the extreme.
Such, Sir, is the anfwer I fliould fubmil for the folution of
the queftion propofed,

5 When

85 THEORIES OF CRYSTAtLOOR A PHY.

Laws of the When fpeaking of the approach of the proper particles, I

fr "fSir^aid ^^'^ ^^^^ '^ might be occafioned by the fubtradion of certain
theory thence interpofed particles which obftruded the approach of the pro-
rcfulting, p^j. particles. The former are generally water, caloric, or

any fluid elallic or not. Their exit may perhaps make place
for others, fuch as light, eledlricity, &c, &c. ButtheeflTen-
tial point is, that whatever thefe particles may be, they are
in perfe6t equilibrio with the proper particles, otherwife they
would become perturbing forces. Hence it follows, that not
only the integrant particles of the cryftal, but all thofe that
are mixed with them, the chemical or component particles
and even the vacuities, rauft follow the fame laws. It alfo
follows, that if each fpecies of particle (even the chemical)
that enters into the formation of the cryftal be feparately con-
iidered, each fpecies will have its diftind fymmetrical and
polyedral form. The forms will penetrate each other, while
the particles will not only not penetrate, but not even touch
each other. All forms would fland in the fame predicament
as the regular odaedron, which contains, as the Abb^ Haiiy
has demonftrated, fix regular odtaedrons and eight regular
tetraedrons, each tetraedron containing one odaHdron and
four tetraedrons. It will further follow, if the chemical ele-
ments can be looked upon as particles which are not in con-
- tact with each other, that we may from thence mathematically
determine chemical affinities.

I have now. Sir, but one talk left ; to fpeak of the appli-
cation our author has made of algebra and geometry to cryf-
tallography. Many perfons complain of the difficulty nccef-
farily refulting from it in the ftudy of mineralogy ; and dare
not engage in it, uncertain whether they will find a compen-
fation for their trouble. Our author has therefore adopted a
double plan, and begins by expofing his theory by a feries of
reafonings and arguments which will fuffice to make the reader
underftand it, or any difcoveries made in confequence of it.
He then expofes the theory in the moft corred of all languages
— mathematical analyfis ; by far the mod interefting, and the
only means of making difcoveries oneVfelf : and who can be
caHous to the pleafure of difcovering an unknown truth ? If
the folution of a problem gives fo much fatisfadion, though
thei data be only imaginary, what mufl be the fenfations of
thofe who are happy enough to folve problems whofe data are

fet

THEORIES OF CRYSTALLOGRAPHY. 87

fei by Him whom the ereateft of pasan philofophers calls the ^='^s of the
Eternal Geometrician? This recalls reflections to my mmdcryHais, and
which I cannot fupprels. Converfing one day with the Abb6 theory thence
Haiiy, he was taking a curfory view of all the modern difco-^^ " ^*
veries ; when he could not help remarking, that there was
not one of them but what furniftied victorious arms to the
caufe of religion. My anfwer was, that in future the nam«
of God would be as diftindlly written on a cryftal as it had
hitherto been in the heavens. The obfervation of this moft
religious and ingenious man reminds me of the faying of lord
Bacon : '* A little philofophy eftranges us from religion, but
a great deal reclaims us again." Even d'Alembert could not
help faying, ** An atheift in the Cartefian fyftem is a philo-
fopher miftaken in the principles; but an atheift in the New-
tonian fyftem is fomething worfe, an inconfequent philofo*
pher."

But to return to the mathematical part of our author's the-
ory : the branch of mathematics, and the manner in which he
treats it, are almoft new. The theory of polyedrons had been
nearly negleded by geometers, both on account of the diffi-
culty to reprefent a polye<Iron on a plane, and becaufe they
did not feel the utility of the purfuit. Neverthelefs, ftrange
to fay, all the regular figures that are to be found in one of
the three kingdoms of nature are polyedrons. In this point of
view, the branch of mathematics illuftrated by the Abb6 be^
comes very interefting ; and it is not a little fo, to fee with
what ingenuity he extricates himfelf from the difficulties
he meets with in his refearches. He forms all the polyedrons,
however complicated, of little equal rhomboids or parallelo-
pipedons, and by that means he reduces the theories of every
poffible polyedron to that of the rhomboid, which is extremely
fimplified by two very limple remarks : 1ft, That in all equi» . ,
lateral rhomboids, whatever may be the fpecies, their projec-^ , .
tlon on a plane perpendicular to their axes will always be a
regular hexagon : 2dly, That the axes will always be trifeded .
by perpendiculars drawn from all the lateral folid angles.
His theory has alfo led him to difcover in a variety of cryftals
geometrical properties, which muft be highly gratifying to .
geometers. But the great advantage to be derived from it is,
that it enables us with the feweft poffible data to calculate
the cryftalline forms juft as aftronomers do the motions of the •

heavens.

88'

Laws of the
ftrufture of
cryftals, and
theory thence
re(ulting.

THEORIES aV CRYSTALLOGRAPHY.

heavens. By the very means by wliich the latter determine?
the future motions of the heavens, the Ahh6 decides which
forms are poflible and which are impolTible. It is thus by his
fimple and general law of cryftallization, ** the number of the
ranges of the fubtradive particles muil always be a coraraen-
furable quantity," that he has demonftrated the regular dode-
caHdron and the regular icofaedron to be im poflible forms in
mineralogy. As the immortal Newton, by having difcovered
the law of attra6lion to be *' in the inverfe ratio of the fquares
of the diftances," explained and calculated every thing in the
vaft regions of the firmament ; fo at the other extremity of the
creation the Abbe Haiiy, by means of a fingle law which he
has difcovered, explains the irregularities and calculates thofe
problematic formations with which the mineral kingdom had
hitherto aftonillied the natural philofopher.

Laws, Sir, that refult from the ftudy of nature, enjoy this
ineftimable advantage, that they always lead to equations ; and
it is only by the help of equations (exprefled or underftood)
that quefrions can be lolved which relate to objects that can
be either counted or meafured.

Of late, Sir, the word nature has been fo much abufed,
that I mu(i beg leave to ftate the prccife fenfe in which I wifli
to be underftood whenever I made ufe of that word in the
courfe of this letter. The Abbe Haiiy found it neceflary to
take a fimilar precaution at the beginning of the excellent
work (Traile de Phyjlque) he has lately publiflied. He fays :
** This word Nature, fo frequently in our mouths, can only
be looked upon as an abridged expreffion, either for the refult
of thofe laws which the Great Creator has imprinted on
the univerfe, or for that aggregate of beings the works of his
hands. Nature, thus viewed in its true light, is no longer a
fubjed of cold and Herile fpeculation. The ftudy of its pro-
ductions, of its phaenomena, ceafes to be a mere exercife of
the mind ; it moves the heart, and ftrengthens the moral vir-.
tues in man, by awakening in his mind fentiments of refpedl
and admiration at the fight of fo many wonders bearing the
vifible characters of infinite power and wifdom."
With thefe fentiments I remain^^ Sir, your's,

A. Q. BUEE.
y«/jf 13, 1804.

OhfervatioM

ON THE OQCTaiNE OF M1XEI\ GASES. 39

IV.

Obfcnations on Mr. Cough's StriSiures on the Doctrine of
Mixed Gqfes, 5)C\ Jn a Letter from Mr. J. Dalton.

To Mr. NICHOLSON.

SIR,

Jr ROM the formidable manner in whicli Mr. Gough opens Introduaion.
the campaign, I might exped him to bring a hoft oi fa6iii
and flr^M.///dn^A' to his affiftance ; ihe faSts^ however, he pru-
dently keeps in referve, and it is to be feared feveral of the
arguments too, as thofe already drawn out are fcarceiy of
forc'e futficient to provoke refiftance.

Mr. Gough's firll argument is, that the fubje6t in difpute
is more properly denominated hypotliefis th^n tlieory. Thia
is certainly not worth contending about.

Mr. Gough's next argument is, that the hjpothefis is not
mechanical ; but as this cannot be made good, it feems,
without a geometrical difquifition of length much exceeding
an ordinary letter, the philofophical world are to w^ait till
the fame fliall appear in due courfe. I might therefore, for
the prefent, wave any remarks on this head, as a long and
equally abllrufe defence might be expefted. But as I think Whether the
geometry has nothing to do in the bufinefs, and that all that ^Jj^/cha^^^i^al!** '
can be faid effedually, either for or againft the hypothefis,
being confiftent with mechanical principles, may be com-
prized in one fliort paragraph, I (hall difcufs the argument
here.

Oxigen repels oxigen, but not azote : This is a poflula- Poftulate. The

turn: and bein*^ admitted, it follows, that if a meafure ofP^^^^^^S^^

' ^ ' ... repel each other,

oxigen be put to one of azote, the oxigen finding it porous, but not thofe of
mult enter the pores, and -vice verfa, till the two gafes feve- other gafes.
rally making their way into the interftices of th^ other, at
laft obtain a perfed equilibrium, and then prefs with equal
force on all the furrounding bodies, and no longer prefs on
each other. This is fo plain and obvious an inference, and
fo little involves any mechanical confideration, that I ihould
have juftly incurred blame for infulting my readers with the
appearance of mathematical demonftration in tbe.cafe. As
well might I have attempted, from the elements of Euclid,

to

g(^ ON THE DOCTRINE OP MIXED GASES,

to demonftrate to a cottager, that if he put a iieve-over his
chimney the fmoke would ilill efcape, though interruptedly ;
or to a chemift, that if he drilled holes in an exhau-fted re-
ceiver, it would in time be completely filled with air.
Ontheaftionof Mr. Gough next remarks upon my opinion, that the at-
aqueous vapour jjiofphere of aqueous vapour is fufficient to prevent the ocean
from efcaping into the air, which he fe«ms to think wonder-
ful : Upon this I may remind him of another wonderful fad,
which I confider the fame in effed ; that is, the pretTure of
like vapour on a cup of water in an exhaufted receiver, pre-
vents the water from efcaping out of the cup. When Mr.
Gough fhall explain how this fad is to be accounted for, I
may avail myfelf of his explanation to apply to the other.
He proceeds, however, to demonftrate the impoflibility of
an aqueous atmofphere ; but inftead of that, he demonftrates
the impojfibilit^ of an atmofphere of an^ kmd prejjing on water,
without at the fame time forcing the water up into its pores.
Luckily, as Mr. Gough obferves, the fads do not counter
nance the conclufion ; and therefore, however rigid the de-
monftration, it thews that the previous data are not corredly
alTuraed. The confideration of this fubjed is^ notwithftand-
ing, an important one ; it is more than a year fince I urged
iVlr. Goug^ to pay attention to it, and to attempt a folution.
of the ditficulty which perplexes all theories of the atmo-
fphere alike : I did it the rather, becaufe I thought him well
qualified for a fubjed of this nature, where the aid of ma-
thematical fcience muft be of fubfervience. The fubjed^
has never been at all explained that I know of. I have
made an attempt w^hich has not yet been publithed, except
in a ledure laft winter ; but J (hall ftill be glad to avail ray-
More particular felf of any affiftance I can obtain. Suppoiing that in the
ftatementof thej^^gf^ ftratum of an atmofphere incumbent on water, there
tion.' ^" is one particle of gas for one hundred of water, (which may

be the cafe, conlidering their relative deniities as one to a
thoufand) ; query, How does the air diffufe its pretlUre over
all the hundred particles equally, in fuch fort that no co-
lumn of particles of water is forced up into the interftices of
the atmofphere by the inequality of the prelTure ? If Mr.
Gough will explain this, either for. his new theory or for
any other, I will engage to remove all diflkulty on this
head which attaches to my hypothefis,

Mr.

OK THE DOCTRINE OF MIXED GASES. Ql

Mr. Gough next wants a rigorous proof of the propofition. Impediments af-
that one gas affords an impediment to the motion of another, [^''^^^ diffUfiol"
but that two fuch fluids finally overcome their mutual ob- of another,
ftrudlions, and occupy the fame fpace in a fUte of perfect
independence. No one acquainted with the experimental
part of pneumatic chemi^ry would have required proofs of
fuch fads, becaufe he daily experiences them. Take two
phials filled with different gafes ; apply the mouth of one to
that of the other for a few moments ; upon withdrawing it,
the two phials will be found to have interchapged verv little
of their contents. This is a mpft unqueftionable prQof that
gafes afford impediment to each other's motion ; for, into a
perfed vacuum the air ruflies inllantaneoufly. Again, let
the phials remain in connexion for a few minutes, or at
moff, hours, and they will be found to have both gafes in
the fame proportion ; and this ftaie will continue in perpe-
tuity afterwards. That they are ultimately independent on
each other, is fufficiently marked by the circumftance, that
any fubftance having an affinity for one of them will with-
draw it from the mixture, if it will take it alone.

Mr. Gough proceeds to give a neiv thtori/ of mixed gafes : Mr. Gough'*
At the commencement of this contro-verfy he came forth to "^^ theory of
defend the all-fufficiency of the old dodtrine of the chemical
union of water and air, and the homogenity of the atmo-
fphere, and to attack the new do61rine, which profcribes
chemical union in thefe inftances, and places for its funda-
mental and diftinguifbing maxim, that " mixed gafes iipK/'^^ .
ther attract nor repel one another :" It was therefore with
no fmall furprife that I found, upon his advances, that a
new theori) was Hill requifite ; but this furprife became afto-
nifliment, when I found the preamble admitted the exigence
of certain, " gafes that neither attract nor repel each other/*
The only clear information I could obtain from this fudden
revolution was, that Mr. Gough ufes the terms theory and
hypotliefm in a contrary fenfe to what philofophers in general
do. When I brought my hypotltefis (as he calls it) forward,
it was fupported by an extenfive train of facts, the refult of
long and careful inveftigation, none of which, that I know
of, has fince been controverted ; I mean what Mr. Gough
alludes to as a " number of probabilities of an experimental
nature:" Whereas Mr. Cough's theory is propofed without

a fmgle

go NEW STRIKING PART OF A CLOCK.

a finglc fa6l to corroborate it, merely to try how far it may
be found to agree with facls already known. Leaving Mr.
Gough to develope his theory, which I confefs I do not
comprehend, and therefore cannot follow him in the appli-
cation, I proceed to his concluding remarks on the law of
affinity, which connects water with the difl'erent gafes.
Waicr fufpended Saufllire, to whom Mr. Gough refers, in the ninth chapter
or diiJufed alike ^f j^-g fgeond eflay inftruds us, that the folvent powers of
common air, carbonic acid, and hydrogen, are the lame as
far as his experience goes. The refults of Kirwan's expe-
riments I am unacquainted with. Clement and Deforme,
in the forty-fecond volume of the Anmles de Chimie ior 1802,
have clearly fhewn, that all gafes take up the fame quan-
tities of water, alcohol, and ether, in like circuinftances ;
and I think 1 have fliewn, that thefe quantities are precifely
the fame as a torricelliam vacuum of the fame capacity takes
up: So that unlefs Mr. Gough can hold out fome further
encouragement to the refumption of the enquiry, it feems
hardly likely that any one will undertake to inveftigate the
diverfities in the law of affinity between gafes and water,
when there does not appear a tingle fadt that points out any
affinity at all in the cafe.

I am your's, &c.

J. DALTON.
Manchejier, Sept. 8, ISO't.

V.

' Account of the Striking Part of an Eight'Day Clock, By Mr,
John Prior, of Nefsjitld, Yorkjhire. Communicated to
the Society of Arts. *

To CHARLES TAYLOR.
SIR,

New ftriking J. HAVE taken the liberty of fending to you a new flriking-

part of a COCK. ^^^^ ^^^ ^^ eight-day clock, of my own invention and work-

manlhip, which I finiQied laft April; **■*■***. I beg

♦ Extrafted from their Tranfa61ions, 1803. A reward of thirty
guineas was given by the Society, who have a model of the fame.

leave

^* E W gf BfrtC KK G PART OP At CO'CIC .•' '^ }p3

leave to inform the Society of fome of the advantages New ftriking

• re xi • • *• part of a ciock.

anling irom this new invention. ^

Firft, it confifts in a wheel and fly, with fix turns of a
fpiral line, cut upon the wheel, for the purpofe of counting
'the hours'. The pins below^ this fpiral elevate the hammer,
and thofe above are for the ufe of the detent.

This fingle wheel ferves the purpofe of count wheel, pin
wheel, detent wheel, and the fly wheel, and has fix revo-
lulions in ftriking the twelve hours.

Permit me to fuppofe a train of wheels and pinions, ufed
in other ftriking parts, to be made without error, and that
the wheels and pinions would turn each other without fliake
or play. Allowing the above fuppofition to be true, which
every mechanic knows it is not, my ftriking part will be
found fix times fuperior to others, in ftriking the hours
»'l, 2, 5) 7, 10, 11, and twelve times, in ftriking 4, 6, 8,
and eighteen times, in ftriking 3, 9, and 12,
• I have defignediy made a defedl in the model herewith
fent, in ftriking 2 and 3 o'clock, to fliew thit What I have
now advanced will, upon the trial, be found to be true.

In ftriking 2, I have purpofely made an imperfe^ion,
equal to the fpace of three teeth of the wheel; and, in
ftriking 3, an imperfeftion of nine or ten teeth ; and yet
both thefe hours are ftruck perfeftly correct.

The fly« in clocks turn round, at a mean, about fixty times
for every knock of the hammer, but mine turns round only
three times for the fame purpofe ; and fuppofe the pivot«
were of equal diameters, the influence of oil on them would
:be as the number of revolutions in each. *

It would be better for clocks if they gave no warning at
all, but the fnail-piece to raife a weight fomcwhat fimilar
to the model now fent for the infpeclion of your refpectable
Society.

Reference to Mr, V rjo iC s Siri/dng Part of his Clock.
Plate VI. Fig. 1.

A. The large wheel, on the face of whieh are funk or cut
'<Jlhe"(ix turns of a fpiral.

B. The fingle worm fcrew, which acts on the above wheel,
und moves the fly C.

* See Curamings's Elements,

D.

g4} ^J^ THE COST dy MAKING tKOSPHORlTS-^

New ftriking D. The fpiral work of the wheel A. The black fpoti
part of a clock, q^^^^, ^^iq grooves into whicii the detents drop, on ftriking
the hour.

E. The groove into which the locking piece F drops,
when it ftrikes one, and from which place it proceeds to
the outward parts of the fpiral in the progre Tive hours, be-
ing thrown out by a lifting-piece H, at each hour; the
upper detent G being pumped off with the locking-piece F,
from the pins in the wheej A .

In ftriking the hour of tzvehe, the locking-piece, having
arrived at the outer fpiral at H, rifes up an inclined plane,
and drops by its own weight to the inner circle, in which
the hour one is to be flruck, and proceeds on in a progreffive
motion through the different hours till it comes again to j
twelve. M

J. The hammer-work made in the common way, which ■.
is worked by thirteen pins, on the face of the fpiral.

Fig. 2. — K. The thirteen pins on the face of the fpiral,
which work the hammer-work.

L. The outer pins, which lock the detent.

M. The pump-fpring to the detent.

VI.

On the Cnft of making Phojphorus. In a Letter from J. P.

To Mr. NICHOLSON.

SIR,

Brijiol, September 16, 1804.

XJlAVING lately been led io confider the various procefTes
by which phofphorus might be oblained, with a view to deter-
in Ine the moft eligible, I thought that a very ihort fketch of
what had occurred to me on the fubjeft, might be not im-
properly introduced in a fpare corner of your Journal; if you
fiiould be of that opinion, the contents of the following pages
are much at your fervice, from a very refpedful admirer of
your unremitting exertions in the caufe of Science and Phib"
fophy.

J. p.

I. In

(

I. -In'iheufual method of procuring pliofpliorus from tone- Eftimate of
duft, and fulphuric acid, the value of the ingredients is very ta'imnrphofpho-
fmall, the labour of the procefs, with the fuel employed for ms from bones.
the evaporation and diftillation form the principal confideration *^""^t 3s. per oz.
in eftimating the value of the product.

One pound of bones calcined and pulverized with half a
pound of fulphuric acid, will produce, according to Fourcroy,
about three quarters of an ounce of piiofphorus; if the labour
and fuel be eftimated at two fiiillings, and it cannot be pro-
bably much lefs, the phofphorus would then coft the manufac-
turer about three (hillings an ounce.

2. If to the acid folution obtained by the above method be The additional
added l|lb. of acetiteof lead, value three thiHings, th6 phof- P^^^P^orus ob-

, , . . t> ' f tamed by addi«g

phate of lime will be decompofed, and two ounces of phof- acetite of lead,

phorus fhould be produced from the precipitate, (vide F oar- *^ '^^^^^^ '^^^^P'

croy.) • This appears then to bean improvement, fince i|oz.

of phofphorus is procured for three fhillings. But perhaps the

following procefs may be preferable to either.

3. To one pound of phofphate of foda, value two fliillings The procefs of
and fix-pence; add l|lb. of acetite of lead^ value three ftiil- «^ecompofing
lings; above one pound of phofphate of lead will he immedi- byacet! of lead
ately precipitated, and about one pound of acetite of foda may affords phofpho-
be eafily obtained by evaporation. If this (hoald be valued at^"^ ^'*^* pero».
two fliillings and fix-pence, the original coft of the ingredients

will be reduced to three fliillings, add one ftiilling for fuel and
labour, and two ounces of phofphorus will be procured for
four {hillings. It is needlefs to remark the great fuperiority of
the laft method in point of facility, neatnefs and fimplicicy.

VII.

On the Piirifieation of Water hy Filtration ; with the Defcription
of a fimple and cheap Apparatus. In a Letter from Si a
Henry C. Englefield, Bart. F, R, S, Sfc,

To Mr. NICHOLSON.

SIR,

1 CANNOT but think the filtering machine of Profeifor Obf. on P. Pa>
Parrott, publiftied in your laft Journal, a very inconvenient ^achiM ^at/.
form of a very common inftrument; but as the filtration of the

water

^^ PURIFICATION or WATER.

water with which the metropolis is fupplied contributes mate-
rially to the health and comfort of thofe who ufe it, and in fa<5l
renders it purer than almoft any known fpring water, a very
cheap and commodious apparatus for the purpofe may be con-
fidered as an obje6t of general utility. I therefore fend you a
fe'^ion of a machine whicli I conilru6led feveral years fince,
and which any common carpenter can make for a very few
fliillings, which may be thoroughly cleanfed at any time, dnd
jwhich occupies very little room.

As you have already honoured feveral of my fhort eifays,
publithed in other colleftions, with infertion in your Journal,
you will, I truft, not be difpleafed that we (liould become im-
mediate correfpondents.

I am. Sir,

Your obedient Servant,

H. C. ENGLEFIflLD.

P.S. I will not anfwer for it that the machine I fend you
has not been already introduced into ufe. If it has, you will
of courfe fupprefs my letter; but if it has, ProfelTor Parrot's
filtre is quite nugatory.
Arrangement A molt excellent arrangement for the purification of river

for purifying , water On a large fcale is mentioned in the writings of De Luc
fcaie, or De SautTure, but I cannot turn to the pafTage in their works.

It was applied with complete fuccefs by the inventor, to the
ftream which fupplied a large town in Switzerland. The ma-
chine (if it may be fo called) was as follows:

A is the upper furface of the flream to be purified, B the
bottom. Acifiern isfunkof fix or feven feet in depth, and of
a 43roper breadth, divided by parallel partitions, alternately
rifing above the furface level of the ftream and open at the bot-
tom, and level with the bed of the river, and clofed at the
bottom. It is obvious that the courfe of the water mufl be in
the dire(5lion of the arrows, and in this repeated and flow af-
cent and defceni, all floating impurities will be left at the top,
and the heavier mixtures will fubfide. The ciftern may be
eafily cleanfed, either by taking out the partitions, if it is on a
fmall fcale, or by fending perfons down between the walls, if
it is built permanently for a great ftream. Perhaps, indeed,
a box having the partitions filled half the way up with fand or
gravel, may on this plan be the bell of all liltres for domeftic

J)efcnpHon

p

f URIFICATION- O^ V/ATER. ' Q'J

Defcription of the filtering Apparatus, Plate V. Fig. 1 .
A B The exterior tube, two feet high and fix inches fquare Filtering appa-
Within. . ratusdcfcribed.

C D The interior tube, four inches fquare at the top and
three inches at the bottom. It reaches within about three
inches of the bottom of the exterior tube, and is covered at
the bottom with a coarfe h'nen tied round it. The ufe of this
i& to prevent the weight of the water from diflurbing the fand.
The upper end of this tube is formed into a funnel, for the
cpnvenience of filling it with water, and it refts on the outer
tube, E a fpout for the exit of the filtered water.

Both tubes are filled with clean waihed fand up to the dot-
ted line juft below the fpout. A bag for flopping the coarfer
impurities may be adapted to the funnel. If this machine be
placed under the cock of any common water ciilern, which is
opened juft enough tofupply the funnel without running over,
it will require no attendance," and will very feldom want clean-
ing. It is obvious that every part of the machine, when the
two tubes are taken afunder is vifible to the eye, and eafily
reached by the band. The fand, when waftied, will ferve
jnany times.

If inftead of a funnel, a larger refervoir of water at the tpp
is ufed, which may fometimes be convenient, it will be bed
to fill the upper part of the inner tube for a few inches with
clean fmall pebbles, as the pouring in water diliurbs the upper
lurface of the fand.

It may be made either of wood or tin, but not of lead, for
fear of impregnation. It is alfo evident that the rapidity of
adion of the filtre will be in a great degree regulated by the
diflTerence of level between the fpout and the furface of the
water in the funnel, and by fupplying the funnel with a greater
or letfer flream, the machine may be made to a6l as quick or
as flow as is wiflied.

As the water which fupplies the metropolis is often tainted Whether char-

with vegetable or animal fubftances putrified in it, it might be *^°^^ ^^'^"^^ K

,. , 1 ., . , /-iv I • 1-1 advantageous m

well worth while to try whether tillmg the mner tube with a filtering appa-

powdered charcoal might not tend to free the water filtred"*"*^^'^ ^**^*

through it from the difagreeable tafte and fmell communicated

by the caufes above-mentioned. It will alfo be advantageous

to place the receiving vetTel at fome diftance belaw the fpout,

that the flream may fall through as much air as it conveniently

can.

Vol. IX. — October, 180-i. H Experiments

^ EFFECTS OF HEAT*

VIII.

Experiments on the Ejects of Heat modified hy Comprejfion, hy
Sir James Hall, Ban, Read in the Royal Society of Edin-
burgh, Augnjl 30, 1 804-. Communicated by the Author,

Experiments of ^ BEG leave to announce to this Society the refult of a feries
heat, modified of experiments which have occupied my attention almoft ex-
ycompre ion. (,iQfjygjy during feveral years. Thefe experiments relate to
the effe(5ts of heat modified by compreffion, and are intended
to inveftigate the peculiar and chara6leriflic principle of the
Huttonlan theory.
Dr. Huttrn's Dr. Hutton, in common with many former geologifts, has

Smpo^nd^'n^* afcribed the formation of all mineral fubftances chiefly to fire.
turally produced But, according to him, the influence of this element has been
m this way. ^^^^ much modified by compreflion, occafioned by the weight
and flrength of a vaft fuperincumbent mafs, which then preflfed
upon what is now the furface of our globe. In this manner
he has anticipated the natural objedlion to all igneous theories
which muft arife from a comparifon of various mineral fub-
ftances with the produds of fire in our furnaces; for he con-
ceives that prefl'ure by repreflSng volatility would occafion the
prefence, in high temperatures, of many fubftances which
efcape in our fires, on a flight application of heat; and that
thefe by their chemical relations would give rife to a fiate of
things untried in any experiments hitherto publiftied, but fuch
as to afford a fatisfadory explanation of all the natural pheno-
mena upon his hypothefis, even of thofe which are the moft
incompatible with the common a6lion of fire.
Thefaftsare The two fundamental pojiulata required in this theory,

^^^^ ^^^t has (o naniely, thea6tionof heat, and the prefence of a fuperincum-
globejbutthe bent mafs are certainly allowable; fince the volcanos furnifli
efFears have Hot yg ^jih a proof that internal fire does a6l occafionally and in
expenment. ^ the irregular manner which this fyflem requires; and fince th6
fragmented and perturbed fiate of our ftrata enables us to fay
with certainly that great changes have taken place, that enor-
mous mafles have been removed, and that what was once
placed at a great depth is now highly elevated.

But a third pnpdaliun is involved in this theory, which feems
to be of more difficult admiflion. Granting that heat did a6|

on

KFtECTS OF HEAT'. ^9

on fubdances con drained by prelfure, would its a6lion be mo*
dified? Would that modification be fuch as is aflumed in the
Huttonian theory?

To thefe queftions Dr. Hutton has replied by arguments Dr. H. has en*
founded on general analogy; and has refted the proof of hishy- efliabJrfh thefe
pothefis on its agreement with the phenomena of nature* In efFefts from gc*
that refpeafew philofophical theories have been fo fortunate; J^°£/^^^'"
for its univerfal application to every department of the mineral
kingdom, and its folution of all the difficulties, afford a con- '
currenceof probabilities in its favour which prefs on the mind
with almoft irrefi(!ible convi6lion. Still it muft be owned that
the batis of the fyftem is hypothetical; and a with has been ex*.
prefled by every man of fcience who has attended to the fub-
je6t, that this bafis fliould be fubmitted to the teft of experi-
ment.

My objefl has been to accomplifti that end, and to bring '^^'^ ^"^^^^f

^1 • n- ■ . -r^ 1 • ^ , «urs to aftmal

this great queltion to an experimentum crucis. By placmg tub- experiment*

fiances in the predicament afligned to them in the Huttonian

theory, I have endeavoured to imitate the fuppofed procefs of

nature. In this attempt I have met with great and numerous

difficulties, but I have at laft fucceeded beyond ray original

expe^ation, and have obtained refults, which, if I am not

greatly deceived, eftablith as a law of chemiftry the mod pa^

radoxical of Dr. Hutton's pofitions.

My experiments Ihevv, that when pounded carbonate o^ ^^^^f^^te of
lime, produced by the trituration of chalk, of marble, of the (at 22^ Wedg-
fliell of a fifti, or of calcareous fpar, after being rammed into wood) in ftrong
a fmall tube of porcelain, is expofed in velTels of fufficient becomes ilai-'^
flrength and tightnefs to the heat of 21 or 22 of Wedgwood's ftone.
pyrometer (that is to the heat in which pure filver melts,*)

the

* I take this opportunity of mentioning that a very material er-
ror feems to prevail with refpeft to this point of the pyrometrical
fcale. The error is the more formidable that it has been introduced
and fanftioned by the highett authority poflible in fuch a cafe j I
mean that of Mr. Wedgwood himfelf. In his account of the
pyrometer he gives a table, expreffing the efFefts produced at va-
rious points of temperature, and ftates 28 as the melting heat of
filver. Now it confiits with my knowledge that pure filver melts at
22. I learned the fa6^ from Dr. Kennedy, and I have had occafion
to confirm the truth of it in numberlefs trials.

H 2 Thif

100 EFFECTS OP HEAt.

th« carbonate (brinks upon itfelf and agglutinates into a firtfl
mafs, which in point of hardneis and fperific gravity ap-^
preaches very near to common lime-flone, an.I foraetimes equals
it, and whicii has frequently acquired the fj)arkling frafture,
the femi-tranfparency, the flifceptibility of polifli, and tiio
general afped of marble. The fame refult is obtained when
a folid piece of chalk is treated in a fimilar manner, and the
Oi-Mt eontrac- chalk being previonfly meafured in Wedgwood's gage, is
*hjdk ^ ^ found to contra6t during the action of heat three times more
than the pyrometer pieces do in the fame temperature. During
the action of heat, the carbonate is found to have loft very lit-
tle of its weight; that lofs amounting in many cafes to lefs
than one per cent, and in fome experiments it has urtdefgone
no fenfible lofs at all, or fo very fmall a one, that it may be
negledled without fear of error. When thrown into an acid,
this artificial limeftone effervefces violently as it ditTolvcs, the
difcharge of gas continuing whilft the fmalleft atom of carbo'
jiate remains viiible.
Irnperfcft fufion I have been in poiTeffion of this fadt fince the year 1801, and
of the chalk. I long attempted in vain to carry the experiment farther, fo as
to accomplifl^ the fufion of the carbonate. In one folitary and
accidental inftance, I had fucceeded in obtaining it in a ftale
of real froth, which could not have been produced without
previous liqiiefadion; but being unable to repeat this refult, I
was unwilling to publith it or any of the fads already ftaled,
till I could do fo in a more fatisfaclory manner. In thecourfe
of laft winter, with the help of many improvements in my
mode of operation, and of ftronger apparatus, I at lafl ac-
quired the power of performing repeatedly and even with
tolerable certainty, what at firft had been the effed of chance.
Aftual fufion* In thefe experiments carbonate of lime has not only been ag-

Tliis obfervatian relates to the pyrometer pieces fold by the late
Mr. Wedgwood, which were formed of a mixture of aluminc
with Cornifli porcelain clay. This let having been the only o»e
ever diftrlbuted amongft cheniifts, muft certainly be looked upon as
the ftandard. Other fcts had previoufly been made by him of
Cornifh clay alone, which had never been fent abroad, or at leaft
only given to fbme friends. It is poflible that the difcordance ah
laded to in this note, may have been occafioned by experiments
made with thdfe firft Pets, which may have pofTefled different pro-"
perties from thole afterwards fold.

glutinatedj

EFFECTS OF HEAT. -101

^luti'nated, but aftually fufed; the fubftance Gnking upon itfelf
with a round and glofly fiirface, and exhibiting every proof of
a vifcid fluidity, fiinilar to that of melting fealing wax. Iti
general the fufion has been accompanied with a flight ebulli-
tion, which has fometime.s changed the mafs to a kind of froth,
and fometimes has merely produced fome fcatiered air bubbles.
The wiiole externally and in its fradure fliines much; thi«
fliine, arifing in fome cafes from numberlefs facettes of cryftal- '
Jization, and in others from a fraooth and continued glofs, like
that of glafs. In many fpecimens the cryftallization of newly Sparry cryftala
formed fpar is diftinc^ly vifible; the cryftalline mafs confiding bonat^, u e ca •
of parallel plates, which reflect together with one glofs. Some
of thefe are difcernible by the naked eye, though in general to
fee them well we require the help of a lens. As foon as the
carbonate becomes foft, it begins to act powerfully on the tube
of porcelain (generally formed of pure Cornifh clay) in which
it rs confined; the compound fliewing itfelf to be much more AiVionofthc
fufible than the pure carbonate. It penetrates the minuteft day veflcl^"
crevices, and fpreads along the cup to a confiderable diftance
from the point of contadt between the carbonate and the tube;
its termination being marked by a black line, the caufe of
which I have not difcovered. Previous to this ftage of fufion
no acljon whatever feems to take place between the carbonate
and the porcelain, the former receiving from the latter an ac-
curate imprelTion of its fliape, acquired doubtlefs when the
powder was rammed into the tube. In this cafe the carbonate
remains quite loofe, and is often heard to rattle before the vef-
fel is opened. Where pounded filex has been rammed into Union of the
the tube in contadt with the carbonate, an union has fometimes ^,1^3^^
taken place, producing a fubflance having fomewhat the ap-
pearance pf chalcedony, bijt which thews evident proof of
fufion, it having flowed fo as to form little flaladliles and tla-
lagmites. This fubftance effervefces feebly in acid, in fome
cafes it leaves a femi-tranfparent cloud of undilfolved matter,
in others diflblves entirely the folution, yielding a jelly when
evaporated to a certain pitch. This affords proof of a real
ijnion between the carbonate and the filex.

in all the experiments alluded to in this paper, the vefllsis When the vef-
,- . • I , r r L . • I fels have failed,

pave been expoled to a violent expanlive torce, by which a- the carbonate has

great number of them have been deftroyed, and the experi- fl»ewn different

ments have often been loft or refalts obtained only of partial j^^^^^J aaid.

3 f^^ccef^ ,

10«

Eri^ECtS 0¥ HEAT.

--•being Iff*
fufible, &c.

An apparatus
refembling that
of Count Rum-
ford,

•-^and regulated

PrcfTure 3 or
^ hundred at-
mofpheres.

Similar experi-
ments on bitu-
minous matter.

fuccefs. But thefe have frequently been of value, by bring*
ing into view important collateral fa6ls. Thus I have found
that under certain circumftances, a partial calcination has taken
place by the feparation of forae of the carbonic acid from the
lime, though enough ftill remained to preferve many of the
Jeading properties of a carbonate. When a lofs is fuftained,
amounling only to two or three, or even four per cent, I find
the fubllance ftill fufceptible of agglutination and fulion, but
its fufibility is greatly diminiilied, a heat of 40 or 50 being re*
quired to accomplifli what would have been done in 22 or 25,
had the earth continued to be completely faturated with car-
bonic acid, and the carbonate thus obtained is apt to fall to
decay by attra6ling moiflure from the air. Thefe differences
afford a good illuflration of the influence exerted by the acid as
^ flux on the earth.

Having thus afcertained the fufibility of the carbonate under
prelfgre of indefinite amount, I became defirous of affigning
its limits, and of difcovering the leaft force neceffary for this
purpofe. In this view, in addition to my other devices, I fol-
lowed thofe ufed by Count Rumford in trying the explofive
flrength of gun-powder.*

By means of a great w^eight prefling upon a fmall opening,
and regulated by a counterpoife adjufted at pleafure, I was able
to conftrain the carbonate to any given amount. In this man-
ner I found that the preflTure of 80 atmofpheres, anfwering
nearly to half a mile of fea in depth, was requifite to produce
any etfe6l of compreflion on the carbonate of lime, and that
to execute the bufinefs vv'ell required a force four or five times
greater.

I have likewife made fome experiments with coal treated in
the fame manner as the carbonate of lime, but I have found it
much lefs tractable, for the bitumen, when heat is applied to
it, tends to efcape by its fimple elaflicity, whereas the carbo-
nic acid in marble is in part retained by the chemical force of
quick lime. | fucceeded, however in conftraining the bitu-
nienous matter of the coal to a certain degree in red heats, fo
as to bring the fubllance into a complete fufion, and to retain
its faculty of burning with flame. But I could not accomplifli
this in heats capable of agglutinating the carbonate; fori have
fpiind, vyhere I rammed them fucceflfively into the fame tube,

* Philof. Journal, quarto feries, I. 45?»

an4
4-

EFFECTS OF HEAT. \Q3

and where the veflel has withftood the expanfive force, that

the carbonate has been agglutinated into a good lime-ftone, but Remarkable fa£l

, ,n • ■ 1 1 • 1 - of a Droduttion

that the coal has loft about half its weight, together with «ts refembling
power of giving flame when burnt, remaining in a very com* blind coaU
pad ftate with a (hining fra6ture. Although this experiment
has not afforded the defired refult, it anfwers another purpofe
admirably well. It is known that where a bed of coal is crofled
by a dyke of Whinftone, the coal is found in a peculiar ftate
in the immediate neighbourhood of the Whin, the fubftance in
fuch places being incapable of giving flame, it is diftinguiftied
by the name of blind coal. Dr. Hutton has explained this
fad by fuppofing that the bituminous matter of the coal has
been driven by the local heat of the Whin into places of lefs
intenfity, where it would probably be retained by diftillaiion.
Yet the whole muft have been carried on under the aftion of a
preflTure capable of conftraining the carbonic acid of the calca-
reous fpar which occurs frequently in fuch rocks. In the laft
mentioned experiment, we have a perfe6t reprefentation of the
natural fad lince the coal has loft its petroleum, whilft the chalk
in contad with it has retained its carbonic acid.

I have made fome experiments of the fame kind with ve- Animal and ve-
getable and animal fubftances. I found their volatility much f^uttreTted?'*
greater than that of coal, and I was compelled with them to
work in heals below rednefs; for even in the loweft red heat
they were apt tadeftroy the apparatus. The animal fubftance
I commonly ufed was horn, and the vegetable faw-duft of fir.
The horn was incomparably the moft fuftble and volatile of the
two. In a very flight heat it was converted into a yellow red
fubftance like oil, vvhicli penetrated the clay lubes through and
through. |n thefe experiments I therefore made ufe of tubes
of glafs. It was only after a confiderable portion of the fub-
ftance had been feparated from the mals that the remainder af-
fumed the clear black peculiar to coal. In this way I obtained
coal, both from faWrduft and from horn, which yielded a bright
flame in burning.

The mixture of the two produced a fubftance having exadly ProbabiHty that
the fmell of foot or coal tar. I am therefore ftrongly inclined ^^^^ ^^ ^^ ammat
to believe that animal fubftance, as well as vegetable, has con- j^ble origin.
tributed towards the formation of our bituminous ftrata. This
feems to confirm an opinion advanced by Mr. Keir, which has
l}een mentioned, to n)e fince I made this experiment. I con-
ceive

104

EFFECTS Oy BEAT.

Horn totally vo»
latilized under
ftrong but not
extreme pref-
fure.

Exhibition and
4efcription of
the refults of
carbonate ex-
pofed to heat
under ftrong
preffurc.

ceive that the coal which now remains In the world is but a
fmall portion of the organic matter originally depofited, the
mod volatile parts having been driven off by the a6lion of heat
before the temperature had rifen high enough to bring the fur-
rounding fubftance into fufion, fo as to confine the elaftic fluids
and fubjeft them to compreflion.

In feveral of thefe experiments, I found that when the pref-
fure was not great, when equal, for inftance, only to 80 at-
mofpheres, that the horn employed wasdiffipated entirely, the
glafs tube which had contained it being left almoft clean, yet
undoubtedly if expofed to heat without compreflion, and pro-
teded from the contact of theatmofphere, the horn would leave
a cinder or coak behind it, .of matter wholly devoid of volati-
lity. Here then it would feem as if the moderate preffure, by
keeping the elements of the fubftance together, had promoted
the general volatility, without being ftrong enouglj to refill
that expanfive force, and thus, that the whole had efcaped.
This refult, which I fhould certainly not have forefeen in the-
ory, may perhaps account for the abfence of coal in Situations
where its prefence might be expefled on principles of general
analogy.

I have fhewn feveral fpecimens of thefe refults to my friends,
in particular to Lord Webb Seymour, Mr. Play fair, and Mr.
Davy, who have agreed in thinking that the inveftigation is
now brought to fuch a flage of advancement, that the refult
ought to be made public.

I propofe in the courfe of next winter to lay before the So-
ciety a particular account of all thefe refults, and of the me-
thods followed in obtaining them. In the mean time I fliall
now fubmit a few of them to the infpe^ion of the gentlemen
pre fen t.

Nos. 1, 2, 3, 4, 5, 6 and 7, were all produced in feparate
experiments from pounded carbonate of lime. No. 1, was
amongfl the firft of myfuccefsful refults, having been obtained
in 1799. It is a firm (lone, requifing a fmart blow of a ham-
mer to break it. It was inclofed in a cartridge of paper, the
mark of which it ftill bears. The other fix are Hill harder and
more compaft, approaching nearly in thefe qualities to com-
mon lime-ftone. Nos. 2, 4, and 7, poflefs a degree of femi-
tranfparency moft remarkable in No. 4, and all of thefe fpeci*
mens exhibit an uneven fraflure, approaching to that of bees-
wax

fitFEOTa ^F. -KEATr 195

wax and marble. Their cofours are varloufly though fllghlly
tinged with yellow and blue; ill particular No. 3, which though
produced from common white chalk, refembles a yellow mar^
ble. Nos. 3, 5 and 6 have taken a tolerable polifii. No. 7
contains a (hell introduced along with the pounded chalk, and
now clofely incorporated with it.

Nos. 8, 9, 10, H, all formed from pieces of chalk ex-
pofed unbroken to heat and prelfure. No. 8 is remarkable for
a fliining grain and fern i-t ran fparency. Nos. 9 and 10 (hew
parallel planes like internal flratification which has often ap-
peared in chalk, in confequence of the a6lion of heat, though
nothing of the kind could be ken in the native maf^. No. 11,
very com padl, and of a yellow colour.

By various trials, to be given in detail hereafter, it appears Great lacreafe of
that the carbonate in all thefe experiments has undergone a ^.fg'y^gf*"
* great diminution of bulk, amounting in forae cafes to more
than y of the original mafs; and that its denfity has been pro-
portionably increafed. At the fame time the porofity of the
iiibftance has diminifhed in a ftill higher degree. Thus it is
found that chalk in its natural flate abfojfbs and retains from 20
toi*5 per cent, of water; but after being expofed to heal un-
der Gorapreffion, that it does not abforb quite 0.2 per cent, or
tiie 500 part of its weight. . .

Nos. 12, 13. Examples of vtrelding, in which the pounded Other fpecimens
chalk has been -incorporated with a lump of chalk, upon wi)ich pofe^ roheat
it had been rammed, fo that their joining is hardly vifible in under ftrong
the fraaure. ' P"^'^"'^'

- - Nos. 14, 15, 16. Shewing the fuiion of the carbonate well
advanced, with a confiderable a6iion on the porcelain tube, in
No; 15, the rod of chalk is half melted, and a yellow fub-
ilance produced by a mixture of the carbonate with the porce-
lain. No. 16 is a lump of chalk, in a ftate indicating foftnefs ;
a piece of porcelain, which lay in conta(5l with it, having fuok

' a little into the fubftance of the carbonate.

KTos. 17 and 18, being delicate, are inclofed in tubes of
^lafs. No. 17, formed from pounded chalk, (hews in one
part the moft complete formation of fpar with its rhomboidal

- fradure I have ever obtained. The carbonate having loft fomc
of its carbonic acid, had crumbled to much in its elTential parts
by the aftion of the air, that the cryltallization was no longer
vifible, and I had given up the fpecimen for loft till within

thefe

I^OdJ EFFECTS OP HEAT.

Other fpecimens thefe few days. When employed in examining tliefe refults,

pofed to heat ^ ™*^^ ^^ ^^^ Carbonate broke in two, and exhibited the frac-

under ftrong tare now before us nearly in as good a ftate as it was originally.

preffure. j immediately inclofed it in a glafs tube, and fealed it up with

' wax, fo that I have hopes of preferving it. In the mean time

I am happy tofliew it entire to the Society. No. 18, likewife

from pounded chalk is perfedly frefh and entire, though made

more than a year ago; it thews fome beautiful clear cryftals of

fpar in parallel plates, but is fo fmall as to require the ufe of a

glafs.

Nos. 19, 20, 21, fliew examples of fufion and a6tion on the
tubes. In number 19, a fhell is finely united to fome pounded
chalk. In No. 20, the mafs originally of pounded chalk is
iinking upon itfelf, and afting at the fame time upon the tube.
The pure carbonate in its fiadiire (liewing brilliant facettes of
cryftallization. In No. 21, the carbonate in a ftate like the
laft; the compound of porcelain and carbonate fliewing its li-
quidity by penetrating the tube fo as to form a diftind vein,
and then fpreading on its outfide to a confiderable extent, teri"
minating with the black line above alluded to.

Nos. 22i 23, 24, give proofs of entire fufion. In No. 22,
we fee two porcelain tubes inclofed for prefervation in a glafs
tube, the fealed end of which muft be held downwards, to
Ihew the pofition in which the experiment was made. The
innermoft porcelain tube ftands with its muzzle upwards, and
the outermoft covers it in the inverfe pofition ; the carbonate
was contained in the inner tube. During the aftion of heat,
the barrel failed fuddenly, and the carbonate has boiled over
the lips of the inner tube, running down, as here appears,
almoft to its bottom ; thus proving that immediately previous
to the failure of the apparatus, the carbonate had been in a
liquid ftate. No. 23, two mafles of carbonate, welded toge-
ther in a complete ftate of froth. The fubftance fliining and
tranfparent. No. 24-, two feparate maffes expofed together to
heat; one from pounded chalk, now in a ftate quite like the
laft; the other put in as a lump of chalk dreflfed flat at both
ends, and a letter cut on each end (as done in many of the
experiments.) It is in a thining and almoft tranfparent ftate;
at one end the flat form and the letter are ftill vifibie; the other
end is completely rounded in fufion, with a glofly ftrrface.

Nos.

ON ATMOSPHERICAL AIR, |^7

Nos. 25, 26, refults of coal. No. 25, produced by the
fufion of common coal under preffure in low red heat. It
gave flame powerfully. No. 26, coal produced from horn.
It is a fliining black fubflance, exadly refembling pitch or pe-
troleum, and burns with a bright flame,

JAMES HALL.

IX.

Atmofpherical Air not a mechanical Mixture of the Oxigenovs and
Azotic Gajh, demonjlrated from the Specific Gravities of thejh
Fluids, In a Letter from Mr. John Gough.

To Mr. NICHOLSON.
SIR,

JL HAVE already attempted to prove common air not to be a Introduftory re-
mechanical mixture. The arguments which I ufed for the^^*^^^*
purpofe, were drawn from the properties of refrafled light
and the motion of founds through elaftic fluids. Such proofs
are of an indire6l nature; and though the mathematician may
fee the force of them, they may not carry an equal degree of
convidion to the chemifl, who ought alfo to be convinced.
The following obfervations apply more immediately to the
fubjedl ; and I do not perceive how they can be refuted, unlefs
this be done by difputing the accuracy of the experiments on
which they are founded. The prefent enquiry has the re- Experlmenbfl
commendation of being ftatical, and the data of my calcula- '^^^^^
tions are borrowed from certain experiments made by Mr.
Kirwan and M. Lavoifier. According to (he former gentle-
man, if the weight * of atmofpherical air be denoted by 1000,
that of an equal bulk of carbonic acid gas will be 1500, of
oxigenous gas 1103, of azotic gas 985. An attempt to dif-
cover the comparative weights of a number of gafes is a diffi-
cult undertaking; but the preceding ratios may be ufed with
fome degree of confidence, becaufe they have been eftabliflied
by a philofopher of the higheft reputation. Then in order to
apply them to the bufinefs in hand, we will fuppofethe weight
of 100 cubic inches of common air to be denoted by unity;
though the real weight of the quantity may be ftaled at 3\ Equations to

♦EffayonPhlogiflon. baV.'''"^'^

g

rams.

\0$ ON ATMOSPHERICAL AIA.

grains, according to Mr. Kir wan. Alfo let the charadlers
zv, T, and y, exprefs refpedively the cubic inches of the caiv
bonic acid, the oxigenous, and azotic gafes, which compofe
the mixture contained in 100 folid inches. Now w + j: -j-y
=;= 100 inches by hypothecs. But if 100 inches of air be de^
i)oted by unity, the fame bulk of carbonic acid gas will be
exprelTed by the fraction -Jl^ff, by the experimental dala ;
confequently the weight of this gas in the mixture will be
found by the following proportion ; i, e. as 100 : 4-§^§ : : zv :
tV^%%^-* I" J'^^6 manner, the weight of the.oxigen is found
to be tVcV^* and th^t of the azote is t^tI^Io. Now the
fijra of thefe weights is equal to unity by the premifes of the
calculation ; if then the equation be multiplied by 100000 on
the common denominator of the unknown quantities, itaflumes
the following form ; i, e. 1 500 w -{-\\03 x -\~9S5 y= 1 00000.
Thus it appears that we have only two equations, when the
quantities to be determined are three ; this circumftance leaves
the problem unlimited ; that is, the value of one of the quan-
tities mull be difcovered without the aid of calculation.
Air contains car- M. Chaplal takes no notice of the carbonic acid in his ob-
bonic acid. fervations on the conliitution of common air ; which appears

to be an overfight, at lead in a general view of the fubjecl ;
for various procelles of nature as well as art conftantly dif-
charge this gafeous acid into the atmofphere, whe^e its pre-
fence is alfo indicated l)y quick -lime being CDnverf.ed into a
carbonate, when placed in open (ituations. Thefe fa6ts
amount to more than a probability, that the lower parts of the
atmofphere contain a flight admixture of the carbonic acid :
this fraall portion, however, was undoubtedly retained, in a
great meafure, by the azotic gas which Mr. |Cirwan ufed in
his experiments ; becaule he prepared it from common air,
which was confined over mercury, together with a pafte of
fulphur and the filings of iron.
u and j> deter- This fmgle confideration induces me to follow the example
mined. ^f jyj^ Chaptal in making w of no value; and the ftep may be

taken with the greateft fecurity in the prefent inftance, be-
caufe it increafes the value of x, if it alter it at all ; that is,
the amount of the oxigenous gas, as found by calculation, will
exceed the truth, on the fuppofition that the carbonic acid
remained in the azotic gas, which Mr. Kirwan weighed. If^
tlicn, w be put equal to nothing, the preceding. equations al'

' ' ■ fume

ON ATMOSPHERICAL AtR. 100

fame the following forms ; i.e. x +5/ = 100, and 1 103 r +
9833^=100000. Multiply the former by 985, fubtrad the
produd from the latter, and you will have the following equa-
tion ; i.e. 118jt:=1500: Hence by dlvifion, a:=:12,|^;
and the excefs of 100 above this number gives j/ = 87,|^.
The ftep<; of this procefs have been detailed minutely, with a
view to enable the chemical reader, who has the leall know-
ledge of algebra, to confider the grounds of the following
•conclulions, and to form his own judgment refpe6ling the
weight of them.

It is evident from the foreproinpr calculation, that if 1 00 parts Air not a mix-

r • r , • . .• r u • .» ture of oxigen.

or a mixture of Ine oxigenous and azotic gales, having the ^^yg g^^ ^^otic
fpecilic gravity of common air, were deprived of their oxigen ga^es.
in a graduated tube, the reliduum would meafure foraethin*
more than 87 fuch parts, ?'. e. S7 ,\^. But when an equal
bulk of the atmofpherical fluid is treated in the f^me manner,
the portion of it which remain*; unabforbed, is much lefs than
the preceding quantity ; M. Chaptal makes it to be 72 fuch
parts, and fome writers call it 78, the mean of which is 75.
Now if we fubtra6l any one of thefe numbers from the refi-
duum fixed by calculation, a difference will be found, which
cannot be referred to the unavoidable imperfections of eudio-
meters, becaufe it could hardly efcape obfervation in any in-
ftrument of the kind, the leaft excefs being more than nine
parts, or nearly a tenth, of the whole fcale of 100 parts. On
the other hand, a mixture of 72 parts azote and 28 oxigen, or
• of 78 of the former and 22 of the latter, exceeds an equal bulk
of common air in weight ; confequently the atmofpherical
fluid is not a mechanical mixture of the two gafes in queflion,
if any credit be due to the experimental data.

Though air has been fliewn not to coniifl of the oxigenous Air a gafeous
and azotic gafes Amply mixed together, it is certainly a com-*'*"*^*'^"*'^^'
pound that maybe refolved into thefe two principles: For
betides fupporting refpiration and combuflion, it converts me-
tals into oxides, and the nitrous gas into nitric acid; therefore
it contains the oxigenating principle. On the other hand,
when air is employed to oxigenate bodies, the refiduum of
it is azotic gas of greater or lefs purity; confequently the at-
mofpherical fluid is a gafeous oxide of azote, which can be
decompofed by art, though chemifts have not as yet difco-
vered a certain method of producing it at pleafure, by uniting
the oxigenating matter to th^ azotic bafe.

Fafls

IIQ ON ATMOSPHERICAL AIR,

Statical analyfis Facts have obliged me to give a name to common air, which
•fair. has been hitherto exclufively applied to the dephlogifiicat«d

nitrous air of Dr. Prieftly. This remark being made for the
fake of perfplcuity, I will endeavour, in the next place, to
give a ftatical anal) fis of the atmofpherical fluid. If 100 cubic
inches of common air weigh 31 grains, the weight of an equal
bulk of azotic gas will be 30.535 grains; becaufe as 1000 : 31
: : 985 ; 30.535 ; in like manner the weight of 100 cubic
inches of oxigenous gas will be found to be 34.193 grains.
The quantity of azotic gas in 100 cubic inches of air, will be
flated at 75 inches in the prefent calculation, for the following
reafons : Fiiji, Becaufe 75 is the mean of 72 and 78 ; fecond,
Becaufe M. Lavoifier found, that four inches of oxigenous
gas and 16 inches of air faturate equal quantities of the nitrous
gas. Thefe premifes being fettled, we fliall find the weight
of 75 inches of azotic gas to be 22.90125 grains; confequently
the weight of the oxigen gas in 100 cubic inches of common
air, is the excefs of 31 above the lafl number, or 8.09875
grains ; therefore as 34.193 : 100 inches : : 8.09875 grains
: 23.685 inches, which is the meafure of the oxigen gas in lOQ
cubic inches of common air, when the azotic gas is Hated at
75 inches. Thus it appears, that if 100 parts of the atmo-
fpherical fluid were decompofed, the elementary gafes would
occupy together no more than 98.685 fuch parts; and a dif-
ference of a like nature will be obferved, if the azotic gas be
called 72 or 78 per cent.', hence it follows that the denfity of
air is lefs than that of the mechanical mixture of its elements.
This pofition may appear paradoxical at the firft view, but
chemiflry can furnifli various inflances of compounds, which
are fpecifically lighter than the aggregates of their ingre-
dients.
Theoxigcnof This anal} fis muft remain incomplete, until the powers of
the air compared the oxigen of the atmofphere have been compared with the
^'^^ ^^® °*'^^"' correfponding effed of an equal weight of the oxigenous gas.
Such an attempt, however, is liable to great uncertainty ;
becaufe the experiments which fliould fiipply the necefl^ary
data, are varioufly reprefented by different writers. M,
Lavoifier fays, that four parts of oxigenous gas and nearly 16
of common air, oxigenate equal bulks of nitrous gas, namely
17,-|- part?. On the contrary, M. Chaptal found by repeated
«xpetiments, that 12, or at ni9ll 13, parts of air were fuffi-

cient

ON ATMOSPHERICAL AIR. HI

clent to faturate the fame quantity of nitrous gas. The data
of the following calculation are taken partly from the one and
partly from the other author : I have fuppofed with M. La-
voifier, that three inches of the oxigenous will acidify 13
inches of the nitrous gas : M. Chaptal is followed in other re-
fpeds^ namely, the atmofphere is imagined to contain 72 per
cent, of azote, and S9 inches of air are made equivalent to 52
of nitrous gas. The calculation, which is formed upon thefe
fuppofitions, will in all probability prove incorred j but I have
ventured to infert it, as being a novelty, which is likely to
excite enquiry. If 39 inches of air can faturate 52 of nitrous
gas, 100 inches of the former require 133.333 of the latter.
Again, if 13 inches of nitrous gas demand three of oxigen,
133.333 of the former will require 30.303 of the latter. But
the weight of 30.303 inches of oxigen gas amounts to 10.361
grains, which is equivalent in effect to 100 inches of air.
Now 72 fnthfef of azotic gas weigh 21.985 grains, which
being taken from 31 grains, leaves 9.015 grains for the weight
of the oxigenous part of 100 inches of air; in round numbers,
90 grains of the latter kind of oxigen are equal in effedl to
103 of the former..

I know that M. Lavolfier, in fpeaking of the conflitution
of nitric acid, makes 100 grains of it contain 64 grains of the
nitrous and 36 of the oxigenous gas ; or 173 inches of the
former and 105 of the latter. Had the data of the preceding
calculation been taken from this ratio, the comparative fupe-
riority of atmofpherical oxigen would have been much greater
than it appears to be by the lafl paragraph. A preference,
bowever, has been given to the preceding hypothefis, becaufe
I defire to excite enquiry, rather than exped to eftablifh any ,
thing of a permanent nature concerning the fubjed.

The preceding arguments, in conjun6lion with others of a The origin of
kind more uncertain than themfelves, fiiggefted to me the ^j^^ phlll^ro^r.
probability of atmofpherical oxigen pOiTeffing a greater degree vol. viii. p. 246.
of efficacy than an equal weight of vital air. This idea oc-
curred to me feveral months ago ; and I at length refolved to
propofe it to the public in a number of hypothetical queftions,
which appeared in your Journal for Auguft. Thefe queries
are evidently borrowed from fome ingenious fpeculations, that
were publiflied in the eighth volume of the fame work*; for

' ' * Page 8S. v"'--

the

112 ^^EW MOVING STAR, StC*

the queries imply, in common with the remarks here allflded
to, that the oxigenating matter is tvater chemically united to
the pofitive power of the galvanic pile. In order to accom-
modate this notion to the cafe of common air, I have fuppofed
that the oxigen of the almofphere receives a Wronger charge
of the power in queftion, than that which is imparted to vital
air; in confequence df which it takes up an additional quan*
tity of water, upon being diliinlted from the azotic bafis, and
is thus converted into oxigenous gas. Should future experi*
ments difcover that bodies, which are oxlgenated by given
portions of common air in contafl with water, acquire more
weight than the air iofes, the difcovery will undoubtedly open
a wide field for enquiry,

JOHN GOUGH.
Middkffui'X, Sept. 5, 1801'.

Leftcrfrom Tkomas YotrvG, M. D. F. B.. S. ^c, announcing
the DifcoverT/ of a new moving Star, by Mr. Harding, fff
Lilicnthal; and on other Subje^s.

To Mr. NICHOLSON.
Dear Sir»

New planet 1 HAVE juft received a letter from Dr. Gaufs of BrunfwicJt/
ktelydifcoveicd.p^^ R. S. dated September 11, in which he informs me that,
a few days before, Mr. Harding at Lilienthal had difcovered
*' a new moving ftar, moft probably another new planet of
our folar fyftem." Dr. Gaufs is certainly a perfon on whofe
judgment much dependance mrvy be placed : He has fent
fome further particulars of the difcovery to the Aftronotmet
Royal.
Maximum of I lake this opportunity of making a criticifm on a work of

deafity of water, gj.^^^ experimental merit which has lately appeared. It re-
lates to the apparent expanfion of water in a velfel of glafs.
Mr. Leflie calculates, from the fuppofition that the expanfion
of water is proportional to the fquare of the degrees of tem-
perature above the freezing point, and from the expanfion of
glafs meafured by General Roy, that the apparent maximum

of

bf ' denfity ihould be at 6** of the decimal fcale : but be has
taken in this calculation the mean rate of expanfion from the
freezing to the boiling point, inftead of the expanfion at tb«
boiling point, which, upon the fuppofitton, is twice as great;
hence the apparent maximum, on the fame grounds of calcu-
lation, ftiould be at 3® of the decimal fcale, or at 37.4^ of
Fahrenheit* Mr. Dalton attempts to avoid this difficulty by
fuppofing that the thin bulb of a thermometer expands more
than the glafs tube employed by General Roy.

The fame ingenious author has made experiments on the TElaftlcity of Imn*
elafticity of different fubftances, by meafuring the depreffion '^^*
of -the middle of a bar fupported at its extremities; but if I
am not much miftaken, his inferences from them are by nO
means accurate. Mr. Leflie gives 67 1625 feet for the height
of a column of deal equivalent to its elaflicitj' ; the true height
refulting from his experiments, taking into confideration alfo
the inequality of curvature, appears to me to" be 4664000
feet; which is ftill little more than half as much as would bfe
inferred from the experiments of Chladni on the longitudinal
founds of fir wood. There mufl: have been fome inaccuracy
\v\ Mr. Lellie*s experiments on fieel differently tempered : for
it appears from the direct experiments of Coulomb on the
flexure of bars, as well as from thofe of Chladni, and fome
of my own, upon found, that the ultimate elafticity of fteel
in fmall tenfions is the fame, whether it is harder or fofter.
This may appear at firft fight paradoxical, but it admits of a
fufficient explanation, which, together with many other illuf-
trations of various parts of natural philofophy, will probably
before long be laid before the public.

Your very obedient fervant,

THOMAS YOUNQ,
J^^Mbeck Street, Sep, 22, 1804,

Vol. IX.— OcT«BfiR, 1804-. I Vefcriptiort

114

SKSTRUMENT FOR COUNTING THt LIFTS FROM A MINE.

Inflrument for
counting the
lifts from a

XI.

Vefcription of am Injirument to a/certain the Number of Lifts
made from a Mine, in am/ given Time, Bj/ Mr, John
Antis*.

SIR,

A HAVE lately been encouraged by fome gentlemen engaged
in fome coal mines in this neighbourhood, to invent a machine,
which would infallibly tell the number of boxes of coals drawn
out of a pit in the courfe of a week, or any given time. I
havejuft now completed a model, which I think would anfwer
the purpofe extremely well.

Before, however, I make it known, I thought I would
inquire of you, whether fuch an invention might be of a more
extenfive ufe, and as fuch would deferve the attention of the
Society.

The machine Is very limple, and need not be expenfive;
its properties are as follow :

1. It is of no confequence if the pit be ten, twenty, forty,
or more yards deep. It will, notwithftanding this difference,
only point out one box at once ; and, fuppofing the pit to be
feveral hundred yards deep, the principle will remain the
fame, and the machine could be eafily adapted for it.

2. It is likewife of no confequence if the coals be drawn up
by a hand windlafs, or any other machine turned by horfes or
other powers.

3. No account is neceffary to be kept for a whole week, or
any given time, as the machine can be calculated for any
quantity of coals whatever, that can be drawn up in a given lime.
Only allowance muft be made for the number of perfons that go
down and up in the fame way.

l have not yet heard of any contrivance of this kind ; and
therefore, if there be any fuch, it is unjknown to me. Who-
ever knows the fraud, which is but too often committed by
bankfmen, in accounting for the quantity of coals procured
from a pit, will readily admit the utility of fuch a contrivance.
And it may raoft likely alfo be ufeful in tin, lead, and other

• From the Tranfaftions of the Society of Arts, 1803.

mme^.

INSTRUMENT FOR COUNTING THE tlPTS PROM A MINE, J 15

mines. Should the Society be of the fame opinion, then I Inftrumcnt fot
will fend you a ftill more complete model than at prefent. 5ifb"froLV
Your fpcedy anfwer will very much oblige mine.

Your moft obedient Servant,^

- JOHN ANTIS.
Fulneck, March 6, 1802.
Charles Taylor, Efq.

SIR,
I HEREWITH fend you a model of my machine, which I
have before mentioned to you, for pointing out any number of
boxes or bafkets of coals, or other minerals, whicli are drawn
out of a pit in any given time. I (hall be much obliged to
you, if you will lay it before the Society for the Encouragement
of Arts, &c, for their infpedion, and fhall be glad that thej
find it of public utility.

It will ealily be perceived, that by enlarging the wheels
and multiplying the cogs of them, the number of yards re-
quired for the depth of a mine, as likewife the number of boxes
which are wanted to be pointed out may be carried to any
extent.

I am fo little acquainted with coal-pits, or any other mines^
that I do not know the technical terms by which the different
parts are called, nor all the methods now ufed to draw up thofe
materials ; I muft therefore beg the indulgence of the Society,
if I do not always exprefs myfelf with accuracy.

By inventing this machine, I aimed at afcertaining the
number of boxes, my ideas relpe^ing which I will endeavour
to defcribe, to the beft of my abilities.

Firft, the rope muft be fo long, that it can be faftened at its
middle to the windlafs, and that each end thereof may reach
to the bottom of the pit. This precaution will not be neceflary,
if it can be prevented by any other means from lliifting or
Aiding, which I leave to others, more acquainted than I am
with the prefent practice, to effed.

The roller A, Plate VII. Fig, 1, in the model, with the endlefs
fcrew, reprefents the gudgeon in full fize of a hand windlafs,
fuch as are ufed in this neighbourhood, particularly where the
pits are of confiderakble depth. As no great (Irefs is laid upoa
this fcrew, it may be made, in order to fave labour, of brafs,

I 2 aod

11^ INSTRUMENT FOR COUNTIKG THE LIFTS FROM A MiKt;

Ihftrumcnt for and driven, or otherwife fattened, upon any gudgeon. I
mts"fiom^a* fuppofe the windlafslo be one yard in circumference; and
mine. • confequently forty revolutions of the windlafs are required
before the firft wheel B, upon which the brafs catch C is fixed,
turns once round. The pit, therefore, may be only ten yards,
or from feventy to feventy-five yards deep, yet it will make no
difference. All that is required to regulate the machine to the
depth of the pit, is as follows: — It' the pit be little more or
lefs than ten yards, the firfl wlied muft be fo placed in the end-
lefs fcrew, that the brafs catch C may be at the beginning, but
yud efcaped from the cogs of the fecond wheel D. It will
then only want five or fix revolutions of the windlafs backwards,
before the faid catch is ready to operate again. But fuppofing
the pit to be feventy yards deep, in this cafe, the catch G
imift be placed fo as nearly to be ready to a€t. By turjiing
■backwards, the wheel may very nearly make two revolutions;
and as it can be ft ill turned as far (he other way, the catch will
only zQ. once, provided the faid wheel does not quite make
two revolutions.

The model is about the fize required for a common hand
windlafs. The index will at orice (how how many times fifty
boxes, and how many above and below that number, have been
drawn up: not one of them can efcape. Allowance, however,
muft be made for the number of perfons who go op and down
in the fame way. Befides this, fince one box is always coming
up, whilft the other is going down, the numbers pointed at
muft be doubled, except a perfon was defirous to have a ma-
chine a6ling both ways, which would hardly be worth while.
As the machine is at preferU, though it points out a thoufand
boxes only, yet it will ferve for two thoufand.

The fame mechanifm, with very little variation, may be
fixed to a horfe machine, called a gin, in this neighbourhood ;
viz. as a gin may be ten yards or more in circumference, the
a6lion would be too flow, if moved by an endlefs fcrew ; a
.pinion, with four leaves, will be found much more convenient.
This pinion is fixed to the end of the upper gudgeon, which en-
ters the box containing the machinery. As fome accuracy is
required to make fuch a pinion work well, and thefe machines
are often coatfely conftru6ied, it will be neceifary only to make"
about one inch and a half of the end of the faid gudgeon ex-
adly round, namely, that part of it which goes through the

. . bottom

1

INSTRUMENT FOR COUNTING THE LIFTS FROM A MINE. 117

bottom of the box, and then faften the latter {o, that it can Inftrument for
give way to any remaining inaccuracy of the other parts ofj^^f^j^fj^^ ^'
the gudgeon. mine.

I have fent a drawing* x)f fuch a machine, which will be
eafily underftood, fmce the principle is the fame as in the
mode!. But as gins are commonly made ufe of in deep mines,
I have made it upon a larger fcale; viz. the firft wheel has
fixty-four cogs ; and this, with a pinion of four leaves, will
require fixteen revolutions of the gin, for one of the wheel.
Allowing ten yards for the circumference of the gin, it will
make one hundred and fixty yards of rope ; and confidering^
that the faid wheel can nearly make two revolutions, and that
the catch will ftill a6l only once, it will confequently ferve
for a pit of three hundred yards deep, as well as for one of ten
or twenty.

In this machine, the three wheels are placed one on another,
and the index is divided ; viz. the fifty on the fecond, and the
1000 on the third wheel. As the wheels move, the two hands
are flanditig, which will point out the numbers as exa6tly as
thofe in the model. Indeed, machines for hand windlalfes
may be made in the very fame way, and thereby be more
fimple, though the difTerence is but fmall ; viz. the box would
require but one hd and lock, and th,e two fmaller wheels be-
come unnecefTary. .

Though in fetting the machine fo as to begirt counting wilh
one, it may eafily be effected by lifting out the fpring, and then
turning the wheel with the other hand, till both hands fland
upon one, yet, in the double index, the upper hand muft only
be fet thus with the wheel, and the lower may be moved rOund
on its focket.

. In my humble opinion, my machines may be ufeful in two
ways; firft, to the honed- bank^sman, as they will fave him
t)ie trouble of noting down each box which is drawn up, and
prevent miftakes; fecondly, in the prevention of fraud, which
will be their greatelt and mofl important ufe. To. obtain this
end. It is necefllary that the machine be fo contrived, that
nothing etfentially wanted can be difengaged. I have there*
fore made the model fo as to fruftrateany fuch defign. All is
within Xhe box J and neither the endlefs fcrevv'can be difen-

-♦ Thisddrawing is in the Society's ppfleflion.

gaged

118 INSTRUMENT FOK COUlfTING THE LIFTS FROM A MINI.

Inftrument for gaged from the wheel, nor the fpring; nor can the number on
liftTfio^ t* ^^^^ '"^^^ ^^ altered without firft opening the box. This latter
mine. can be made of iron, if found necelTary, with a good lock to

it ; otherwife, the ftrefs is fo very little, that even one of wood,
made in all refpeds like the model, would anfwer, if it could
be fecured from the efFeds of the weather. In the machine
likewife, reprefented by the drawing, nothing can be altered,
except the box be firft opened. This machine is faftened to
the beam in which the upper gudgeon turns. To effeft this, the
bottom of the box muft have two projefting ends with holes in
them, larger than neccflary to receive a ftrong pin or rivet j
which pins muft have large heads, fo that when properly driven
or riveted in, the box may be able to give way to any remain-,
ing inaccuracy in the lower parts of the gurigeon, as I before
obferved. Thofe machines for hand windlafles, like the model,
are fixed to the fide of the poft into which one of the gudgeons
. -turns ; but perhaps tiiefe might likewife be contrived fo, that
the gudgeon with the endlefs fcrew may be a piece by itfelf,
9tlached only to the windlafs by a fquare, or otherwife, as is
pften pra6lifed in other machineries, fuch as cotton.-mills, ${c,
I am. Sir,

Your obedient Servant,

JOHN ANTIS.
Fulnech, Mai/\8, 1802.
Charles Taylor, Efq.

JJeferenc^ to the Model fent by Mr. Ak ris to the Society*

Plate Vll. Fig, 1. A. The roller, with an endlefs fcrew,
to be the fize of the gudgeon of a hand windlafs.

13. The firft wheel, of forty teeth, with a brlls catch C.
It may be moved backwards or forwards by the endlefs fcrew.

D. A ratchet wheel with fifty teeth, which, when the wheel
B is put in motion one way, the catch will Hide over the teeth
of it ; but, on turning it the other way, the catch will drop
into and forward this wheel one tooth, in which fituation it is
prevented from returning by the fpring E, placed on the fide
of the box which holds a tooth on the fide of the wheel.

F. A fmall pinion of four teeth, on the back part of the#'
axle of the wheel D. This pinion moves a large wheel on tlie
other fide of the bon.

INSTRUMENT FOR CdUNTINC THE LIFTS PROM A MINE« {JQ

Fig. 2. G. The large wheel laft mentioned : it has eighty Inftrument for
, . counting the

*®^^"- lifts from a

H. A fmaller wheel of fifty teeth, fixed fafl on the face of xni^e.

the wheel G ; which wheel H works a wheel I, of the fame
number of teeth, fliown by dotted lines behind the figured
dial-plate.

K. The fhort hand, or finger of the dial, is placed upon an
arbor or collar of this wheel I, and moves with it.

The long finger, or hand of the dial-plate, goes upon a
Iquare on the end of the fpindle on which the above arbor
moves; which fpindle moves forward this long finger one
divifion in fifty of the outer circle marked on the dial-plate,
every time the rope, or any thing attached to it, has been
down to the bottom of the mine, and returned to the top.

The inner circle of the face of the dial is marked in divi-
lions of fifty each. When therefore fifty draughts up and
down have been made from the mine, the fliorter hand will
be found, if both hands were originally fet correctly at the
top, to have moved to the firfl interior divifion marked 50;
and fo on, in proportion, will advance as more draughts are
made.

K, Is a board placed under the wheels B D, in Fig, 1 , and
which feparates them from the other wheel-work in Fig. 2,
where only a few teeth of the wheel B appear behind it.

L L, Show the temporary handles in both figures ; and
the pofition of thofe letters denote that the gudgeon of the
windlafs, when the machine is in adual ufe, fliould be there
joined to, or make a part of the roller A.

Fig. 3, Shows, on an enlarged fcale, the form of the catch
C. The fleel fpring M preffing againfl the pin N, returns
the catch to the tooth of the wheel D, when it has been forced
back ; and a pin fixed underneath the catch moves in a groove
O, made in the wheel B, to prevent the catch being prelfed
too far back, or thrown out improperly by the fpring,

A door is fixed on each fide the box, and fhould be locked,
to prevent the hands being altered unknowingly.

The drawing of a machine for fimilar purpofes, intended
to be ufed with a gin or horfe-wheel, alluded to in Mr. Antis's
letter, is in the Society's poffeflion, if a reference thereto be
thought necelTary.

120

©N GALVANISM*

XII.

On Gakanifm. In a Letter from Ra. Thickness^, Efq.

SIR,

To Mr. NICHOLSON.

Wi^an, Sept, 20, 1804.

On the caufes
which retard
difcovery.

xILTHOUGH the produ6Hon of the elearic fluid by the
galvanic pile has never yet been fatisfaclorily accounted for,
it appears to me fomewhat eafy to be explained, from a con-
fideration of the principles of chemiftry. This, I am aware,
is a very bold opinion from a man who is a mere dabbler in
philofophy ; but as it muft be allowed that the ableft philofo-
phical inquirers and experimentalifls have been guilty of ex-
traordinary overfights, I truft my prefumption is excufable.
When an ardent mind has once entered a wrong path in pur-
fuit of knowledge, it is too intent upon the objeds before it ^
to turn afide, and too anxious to proceed to be induced to
look back. Thus chemifts fifty years ago thought they ob-
tained earth from water, becaufe they omitted to weigh the
veflek in which they made their experiments ; and thus, per-
haps, the profeflfors of galvanifm at the prefent day, being of
opinion, as I believe they all are, that the electric fluid pro-
ceeds from the metals, devote little of their attention to the
fluid employed in the pile, confidering it almoft as a mere
eondudlor. Nothing can be more obvious to a chemift now
than the neceflity of weighing the matter he fubjects to expe-
riment, and alfo theprodu6t; yet the difcovery alone of this
necefllty overturned the opinions, and falfified the wifdom,
of all the previous ciiltivators of the fcience, and led to the
modern theory of chemiflry and its improvements ; an omifllon
how trifling in itfelf to keep men (philofophers too) poking
in the dark for ages !

Water, we are told, is compofed of certain parts of oxigen
and hidrogen ; but, a$ to form thefe bodies, from a ftate of
^fed of oxigen, g^s at lead, into water, it is necetfary to pafs lan eiedric
fpark through, or rather irito them (no matter whether the
procefs of formation be combuftion or not), and as water owes
its fluidity to heat, the matter of heat and the eledric fluid
being probably the fame, or modifications of the fame body,
I think it reafonable Xo atlume that water is compofed of
oxigen, hydrogen, and tlie ekSlric Jluid,

The

Argument or
inference that

pole

hidrogen,

eledlricity

and

ON IG^LVANISM. , 121'

The experiments by which M. Volta and others have en- Decompofition
deavoured to (hew that piles compofed of metals only afford ^^ ^.f^^ '" S»*-

*^ n - f • I I vanilm afcribedL

the galvanic fluid, are fo little demonitrative ot it, that they not to the aftioii

feem to me equally illuftrative of the contrary ; and I believe of elearipity,

that all galvanic piles muft, with the intervention of fluids, be^^^^^^

compofed of two metals, or other fuhfiances, which have an

affinity, the one for oxigen and the other for hidrogen ; for

water and other fluids made ufe of in galvanic piles, are de-

compofed; and not, I conceive, as hath generally been ima-.

gined, by the eledtricity of the metals ; but by the adion of

affinities. For inftance, in a pile formed with zinc, copper,

and water, the oxigen and hidrogen of the water having a

ftronger affinity for the zinc and copper (the oxigen for the

zinc and the hidrogen for the copper) than for each other,

unite with them, the water being confequently decompofed,

and the eledHric or galvanic fluid, which was contained in it,

confequently fet at liberty.

In fupport ipf this theory I* may alledge as fa6ts, that the firft Fuller explana- .
fliock from a galvanic pile is generally the ftrongeft, when J-!^^/'^**'"
the energy of the affinities is the greatefl; that for a repeti-
tion fqme interval of time is requifite, whilfl: the decompoti-
tion is taking place; that the metals in the pile aft, not ac-
cording to their quantities, but according to their furfaces— •
the greater thefe are, the greater being the quantity of water
adled upon; that the zinc is always oxidated, and the copper
(or filver) always aded upon by the hidrogen, being rendered
more brittle, &c. ; that any alteration in the arrangement of
the pile, which brings two pieces of the fame metal to the fame
fjratum of water, inftead of one piece of each metal (one to
ad on the oxigen and the other on the hidrogen), interrupts
the procefs, and, no decompofition taking place, there is no
eledric fluid produced; and it may alfo be added, that this
lafl is a fad which cannot otherwife be accounted for,

I am not ignorant that a flream of the galvanic fluid from Objeaion, that
the pile, pafled through water, decompofes it; but it is no *^^ galvanic
proof, I prefume, that water contains none of this fluid, be- pofes water
caufe it is decompofed by a greater quantity than will chemi-*"^wered,
cally mix with it. If we pour a fmall quantity of water im-
pregnated with carbonic acid gas into lime-water, the lime is
precipitated, or compofed, the lime-water becoming turbid;
• but

r

[122 rERSPECTIVE INSTRUMEMT, EtLIPTIC INSTRUMEMT*

but if we add a further quantity, the lime is again decom-
pofed, and the lime-water becomes again perfectly clear,
I am. Sir,

Your moft obedient fervant,

RA. THICKNESSE.

XIII.

Defcription of an Injirument for drawing in true PerfpeStive
from Nature, and of another of confiderahle Simplicity and
Cheapnef^i for delineating Ovals, In a Letter from a CorrC'
fpondent, R. B.

To Mr. NICHOLSONf ^
SIR, ^

introduaion. J\s I obferre that you are willing, in your capacity of Jour-
nalift, to lay before the public any (ketch or outline of inven-
tion that may promife to be ufeful, whether in its ultimate
flate of improvement or not, I am encouraged now and then
to fend my thoughts, queries, obfervations, or news, as they
may occur. The following inftruments are offered to your
notice, in hopes they may appear in your excellent col-
ledion.
Inftrument for Fig, 1, Plate VIU, is a Iketch of an inftrument for per-
drawmg in per- fpe^c^iyp^ made fome years ago by Dolland, and of which I
know not the inventor. A telefcope or camera is fufpended
vertically on a frame by an univerfal joint or jimbals. Hori-
zontal rays A, are diredted down the tube by a plane mirror
B, and are again rendered horizontal, and turned to the eye
through a fide hole in the tube, by another mirror C. At the
lower end is a pencil E Aiding in a well-fitted focket, and
preffed gently downwards by a weight or fpring ; or ftill better,
by the hand only. The refult or ufe is, that while the images
are in fucceffion brought into apparent contadl with a point
in the field of view, the pencil may be employed in tracing
them in true perfpediive upon the table beneath *,

* There is an omiflion of the grey or rough glafs, if the drawing
be meant for a camera} or of the eye-piece, if it be a telefcope.
The firft focal convergence muft be made in thcfe, and not at the
eye— N.

5 Fig^

COMPUTATION OF SQUARES AND CUBES. 123

Fig. 2 reprefents a iimple rale and firing for drawing ovals Inftrument for
«u paper. A C B is a filken thread, fixed at A, and capable ^'^^wing ovals,
of being letigthened, fhortened, and fixed b)' a fcrew B at the
other end. This fcrew B can be placed, by a longitudinal
groove in the ruler, at any Hi fiance from A, and can be made
to pinch the thread upon any one of the divifions of the rule.
At C is a pencil to be moved in the bend of the thread. It
mad be held upright, and it would be eafy to contrive means
of keeping it fo ; but it does not feem an object of fufficient
neceffity to add to the price of the inflrument.

In the ufe, (et A at one focus of the intended oval and B
at the other. Allow the firing to extend till the pencil marks
the extremity of the conjugate diameter. Draw the femi-oval
by moving the pencil along in the flretched thread: Then
reverfe the points A and B, placing them refpe^ively on the
foci occupied before by each other. Draw the other femi-
oval, which completes the figure.
I am. Sir,

Your obliged correfpondent,

R. B.

XIV.

On tite Computation of Tables of Squares and Cubes. In a Letter
from H. G.

To jyrr. NICHOLSON.
SIR, Sept. 8, 1804-.

l\S I can employ my time in a more ufeful, pleafant, and Introiuftioa.'
advantageous way than by making tables of any kind, I have
no defire on ray own account to trouble your readers with the
following remarks, and fhall therefore leave it entirely to your
choice to notice them or not in your Journal.
I am. Sir,

Yooj humble fervant,

H. G.

YOUR correfpondent E. O. in his note, p. 79 of your On die compa-

Journal for this month, has very properly pointed out an error '^''°" °^ "'''*=•

''*''* .of fquarcs and

«n cubes.

]|24 COMMUTATION OF saUAREf AND CITBES;

On the compu- Jn the rule laid down by me in p. 150 of your Journal for July
ff i^uafestld' ^»'^' w^'<^^ ^''^ ^® correaed by fubftituting the, word given
c»k9« for the word next.

But he does not feera to be aware that the rule I propofed
for finding the fquares of roots in an arithmetical progreffion
of thofe roots, is^ precifely the fame as that he has ufed and
elucidated in pages 5 and 6 of your Journal for this month.

Neither has he made me a convert to his dodlrine, that ad-
dition ftiould be ufed in preference to fubtradion ; for the one
appears to me as eafy an operation as the other, for all the
purpofes to which it is applied in the conftrudion of the tables
in queftion.

, With refpedl to the conftru6lion of the table of cubes, I
will barely ftate my method of computing the cubes of the
fame roots E. O. has calculated, in pages 8 and 9 of your
Journal for this month, and will leave it to thofe who may be
inclinable to enter on the inveftigation, to determine which
method will be raoft advantageoufly pra6lifed, his or mine,
only obferving, that E. O. has a continual repetition of the
firft differences, which I have entirely avoided without adding
any figures, \n other refpe^ls, to thofe he has ufed.

I ftill think my method of computing the table of cubes is
not more liable to inaccuracy than that E. O. has adopted ; but
in order to avoid almoft the poffibility of error in my computa-
tion, and at the fame time to add to, examine, and corred
Mr. Councer's table, I would place the cubes of half the given
roots X 8, at fuch diftances under each other, as would en-
able me to interpolate my calculations of the cubes of twice
thofe roots, as it is done in the left hand part of the following
« elucidation ; and then it is evident, every other cube obtained

by the calculation muft be the fame as that obtained from the
table; and thus a proof of the accuracy of Mr. Councer's
tablei and of the continuation of it, would go hand in hand.

TABLE.

o

COMPUTATION XJFSaVARES AKD CUBES.

II II 11; II

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Letkr

126 MI^ED CASKS,

XV.

Lelitr to the E^tor from Mr, William Henry, in reply td
Mr, Gough.

Manchejler, September 13, 1804.
SIR,

Previous re- iSloTHING was farther from my intention, when I com-
municated to you the " Illuftrations of Mr, Dalton's Theory
of Mixed Gafes," than to enter into controverfy refpeding a
do6lrine, to the defence of which I may naturally be fuppofed
to be much lefs competent than its author. Yet it is certainly
required of me, both by the refpe6lful attention due to your
correfpondent Mr. Gough, and to others of your readers,
either to explain and fupport, or to relinquifli, if erroneous,
the opinions refpefting which I have publicly exprefled a coin-
cidence with Mr. Dalton. The laft alternative I do not, at
prefent, feel difpofed to adopt, becaufe I am far from being
convinced by Mr.G.'s reafoning; and in the explanation, which
I am about to offer, I Ihall confine myfelf to thofe proofs of
the new theory of mixed gafes, which are furniflied by my
own experiments; leaving to Mr, Dalton the more important
office of eflablifliing its fundamental evidences.
The quantity of It is by no means clear to me, whether or not Mr. Gough
gas abforbed denies the principle, ** that the relation between gafes and

being as the • i i i • i »jt. rr^ i •

preflure, the laft water IS altogether a mechanical one. * To me this appears
is taken to be as legitimate an inference, as can poffibly be deduced in phy-
* fics; for the quantity of every gas, abforbed by water, follows

exactly the ratio of the preiTure: And, fince it is a rule in phi-
lofophizing, that efre6ls of the fame kind, though differing in
degree, are produced by the fariie caufe, it is perfectly fafe to
conclude, that every, even the minutefl portion of any gas,
in a flate of abforption by water, is retained entirely by incum-
bent preflure. There is no occafion, therefore, to call in the
aid of the, law of chemical affinity, when a mechanical law
fully and fatisfaClorily explains the appearances. And when
the effed ceafes, it is equally conformable to juft reafoning to
infer, that this happens, in every cafe, folely in confequence

* Certain acid gafes, the muriatic for inftance, are obvioufly ex-
cluded.

of

MIXED CASES*

127

t»f the relaxation or removal of that mechanical power, which
feeld (he gas in its fituation. Under all circumftances, there-
fore, when a gas efcapes from water, whether by placing the
aqueous mixture under an exhaufted receiver, or in an atraof- »

phere of a different gas, the caufe operating its efcape, muft
be one and identical, viz. the diminution of mechanical pref-
fure. Before we account for any effed by comparifon of af-
finities, the affinities themfelves fliould be proved to exifl.
But with refpcd to the relation of gafe« to water, the proof
fails in every in (lance; for how can that efFed be fairly afcribed
to chemical affinity which is deftroyed, as is the connexion of
every gas with water, by an unmixed mechanical caufe; and
is it not abfurd to compare powers which have no exiftence in
nature?

Admitting (hen the conne6lion between gafes and water to —and the pref-
be entirely dependent on phyfical prefTure, there naturally o"her'gas than
arifesout of this law an explanation of the curious fa6t, which that abtorbed.
I have afcertained, that each gas, when abforbed by water, is
retained in its place by an atmofphere of no other gas but of
its own kind. Under any other atmofphere, the abforbed gas
efcapes, even without agitation, though this certainly acce-
lerates the event. Now the fubaqueous gas can only accom-
plifh its change of place by virtue of fome a<5live principle or
power inherent in it, and caufing its movement; and this
power is its elafticity, which is not countera6ted by that of an
incumbent gas of a different fort. The fa6l affords, therefore,
fomething further than ** probability,'* that the particles of
gafes prefs only on thofe of their own kind ; for to fay that the
elafticity of the fubaqueous gas is not counteracted by any in-
cumbent one of a different fort, is to affert in other terms, that
the one is not preffed by the other, — the principle which I am
folicitoiis to eftabliHi.

The above remarks are the only ones which I deem It within Jhe theory Is aa
my province to urge in reply to Mr. Gough. Before doling J-^^" . 'capable
this letter, however, I muft exculpate myfelf from the charge of mathematical
of attempting to uphold a mechanical theory, by probabilities J^^^fj^^^^"^^'^^_
drawn from chemical fa6ls. This ftatement is notcorred; the fervatioji.
fa6ls which I have alledged are purely ftatical, and my obje6t
has been to prove that they were before erroneoufly included
winder the laws of chemical affinity, with which, in reality
they have no connexion, Thefe mechanical phenomena, I

have

12S jORt-fOtlOS.

hare bronght in fupport of the general principle " that the
particles of gafes prefs only on thofe of their own kind;" and
in fo applying them, I trufl I have conformed to the rigorous
laws of philofophical induction. Such general principles are
not uncommon in natural fcience; and though, like the law of
gravitation and f )me other iefs comprehenfive ones, they may
be mathematically purfued and inveftigated, yet the^y are not
derived from mathematical reafoning, but from a method of
enquiry which Newton himfelf did not difdain (o employ,—
that of induction on the bafis of experiment and obfervation.
Tiie fpeculations of Mr. Dalton, being founded on wellafcer-
(ained fa6ls, appear therefore to me to be fairly entitled to the
appellation of theory, and not to be included within the defi-
nition of hypothefia* handed down to us from the father of ex-
perimental philqfophy. I remain, very truly. Sir,

Your's, &c.

WILLIAM HENRY.

XVL

Defer iption of a very fimple and cheap Contrivance for making
Fort Folios qf large Dimenfions. By the late James Mal-
TON, Efq.f
SIR,

Method of con- Jl\S I well know the great inconvenience experienced hy
ftruaing large artifts and collectors of prints and drawings, from the want
^' ' of portfolios of dimenfions capable of inclofing large fubje^s,

and as I alfo well know that the means ufed by the Society for '
the Encouragement of Arts, &c. to promulgate knowledge
and ufeful information are earnefl as they are extenfive, I am
induced to lay before that body a port-folio of my conflru6lion,
which I perfuade myfelf pofleiTes every advantage that can be
withed.

The difficulty, or rather the impoffibility of obtaining cafes or
port-folios, as large as are fometimes requifite, has given rife
to many expenfive contrivances, to the fame end ; or larger

* " Quicquid ex phaenomenis non deducitur, bypothefis vdcand*
eft." Princ. LIII. in Bruckeri Hift. Crit. Phil. Tom. IV. p. 646.
fSacicty of Arts, 1803.

prints.

I'ORT-I'OLrOS.

i29

prints, &c. muft be kept in rolls, to their almoft certain de- J^^^^?^ °[ ""^^^
ilrudlion, by frequency of rolling; or at leaft they are thus pQ^-foiios. '
expofed to the danger of being cruflied by accident. Milled
pafteboards, of which port-folios are made, are not raanufac-
tured above a certain moderate fize: to exceed ihat fjze in a
,|)prt-folio, is an undertaking of no inconiiderable trouble, in
parting, glueing, and preffing them together. On inquiring
of Mr. Newman, of Soho-fquare, (a raanufadlurer of thefe
articles) how he managed to make port-folios above the ordi-
nary dimenfions, he informed me, it was an undertaking of
trouble, and related his having made one for a gentleman, by
attaching fixteen of the largell milled boards together; that
the materials alone cod five guineas; and that its weight was
greater than one man could lifl.

My method of conftrudtion obViates all difadvantages —
weight, expence, and trouble; and port folios of any dimen-
iions may very readily be manufa6lured by the fimple appli-
cation of two ftraining-fraroes, covered on both fides w'llk
canvas, and papered; and connected, as all port-folios are, by
leather at the back, or with wooden backs, the fides being
connected by hinges. Thus a port-folio may be made capable
of holding the largeft cartoons, maps, and prints; and pofTefT-
ing another great advantage, befides that of not bellying or
fwagging, when laid againft a wall, as thofe conftrudted of
pafteboard do, to their own deftrudion, and material injury
of the things they contain,

A frame of four feet by three will be ftrong enough, if made
of deal. The ftiles are four inches wide by half an inch
thick; and they have a middle upright ftile of the fame width,
with angle pieces at the corners, as is fliown in the engraving.
Fig. I. A frame of much greater dimenfions may require
two middle upright ftiles; and, if very large, a middle longi-
tudinal flile, as is thown in the engraving, Fig. 2.

If the frames are made of mahogany, they need not ex-
ceed 3-16ths of an inch in thicknefs; but, of whatever wood
they are made, it muft be well feafoned, or they will warp.
A padlock may be applied to fuch cafes, for the protection of
their contents.

On this conftru6tion I have made two port-folios, one of
which I have had in ufe thefe ten years. A handfome one,
of tolerably large dimenfions, I have fent with this paper, for
. Vol. IX.— October, 1804-. K the

I

Method of con- the infpcftlon of the Society. The outer fiiles of It are of
port-fo"k)$r^* mahogany, which, beaded, forms the out edge in a neat man-»
ner. Its fimple formation, its lightnefs, and its firm flatnefs,
mil ft be obvious to every one; and I am of opinion the Society,
w#|.l obtain the thanks of all c(^lle6lorss and artifts (if they think
it worthy of inferlion in the Volume of their Tranfaftions) by
making (his iimple matter publicly known. For my own part,
I (hall be highly gratified in having contributed to the comfort
of artifts and coilcdlors, in preferving their valuable refearches*
I am. Sir,

Your obedient Servant,

JAMES M ALTON.
Norton-Jlreet, June 25, 1802.

Reference to the Engraving, Plate VIII.

Fig. 4. One of the fides of the frame for a port-folio, the
tlimenfions four feet by three: it may be made of deal or fit
wood. The ftiles, four inches wide by half an inch thick ;'
the middle upright ftile to be of the fame width. It fliould
have angle pieces within the corners, to keep them firm.

Fig. 3. Shows a fide of another frame, where much larger
dimenfions are required; it fliould then have two upright ftiles,
and a middle longitudinal ftile, all within the frame, and angle
-pieces at the corners. U it is made of mahogany, inftead of
deal, the ftiles may be reduced nearly one-fourth in breadth and
thicknefs; the wood, in either cafe, fliould be well feafoned,
that it may not be liable to warp.

XVII.

Experiments and Calculations relative to Phyfical Optics, By
Thomas Young, M. D. V. R. S. From the PhilofophiccA
TranfaSiions for 1804-.

(Concluded from p. 64.)

g^ Exper. 2. 1 HE crefted fringes defcribed by the ingenious
like Wife the and accurate Grimaldi, afford an elegant variation of the
crefted fringes ' preceding experiment, and an intereftine example of a calcu-
of Grimaldi. J . , , -, ttt. n j • r j 1 1

lation grounded on it. When a Ihadovv is formed by an ob-
ject which has a rectangular termination, befides the ufual ex-
ternal

J^iv^tCAL OPTICS, ^ I'Sl

Ifernal fringes, there are two or three alter nations'of colours,
beginning from the line which bifefls the angle, difpofed on
each fide of it, in curves, which are convex towards the bi-
fedting line, and which converge in fome degree towards it, as
they become more remote from the angular point. Thefe
fringes are alfo the joint efFed of the light which is inflefled
diredlly towards the fliadow, from each of the two outlines of
the object. For, if a fcreen be placed within a few inches of
the objedt, fo as to receive only one of the edges of the fliadbw,
the whole of the fringes difappear. If, on the contrary, the
redlangular poinf of the fcreen be oppofed to the point of the
fliadow, fo as barely to receive the angle of the ftiadow on
its extremity, the fringes will remain undifturbed.

ir. COMPARISON OF MEASURES, DEDUCED FROM VARIOUS
EXPERIMENTS,

If we now proceed to examine the dimenfions of the fringes, Comparifoii ot
under different circumftances, we may calculate the differences incaf"^^'
of the lengths of the paths defcribed by the portions of light,
which have thus been proved to be concerned in producing
thofe fringes ; and we fliall find, that where the lengths are
equal, the light always remains white; but that, where either
the brighteft light, or the light of any given colour, difappears
and reappears, a firft, a fecond, or a third time, the differences
of the lengths of the paths of the two portions are in arithme-
tical progreflion, as nearly as we can exped experiments of this
kind to agree with each other. I ftiall compare, in this point of
view, the meafures deduced from feveral experiments of New-
ton, and from fome of my own.

In the eighth and nmth obfervations of the third book of
Newton's Optics, fome experiments are related, which, toge-
ther with the third obfervation, will furnifti us with the data
necetfary for the calculation. Two knives were placed, with
their edges meeting at a very acute angle, in a beam of the fun's
light, admitted through a fmall aperture ; and the point of con-
courfe of the two firft dark fines bordering the fhadows of the
refpedive knives, wasobferved at various difiances. Therefults
of fix obfervations are expreffed in the firfl three lines of the
firfl Table. On the fuppofition that the dark line is produced
by the firft interference of the light refledted from the edges of
the knives, with thelight pafling in a ftraight line between them,

K2 we

132

PHYSICAL OPTICS,

Comparlfon of we may aflign, by calculating the difference of the tw^o paths,
mea urcj. ^^^ interval for the firft difappearance of the brightefl hght, as

it is exprelTed in the fourth line. The fecond Table contains the
refults of a (imilar calculation, from Newton's obfervations on
the (hadow of a hair ; and the third, from forae experiments
of my own, of the fame nature : the fecond bright line being
fuppofed to correfpond to a double interval, the fecond dark
line to a triple interval, and the fucceeding lines to depend on
a continuation of the progreffion; The unit of all the Tables
is an inch.

Table I. Obf, 9.

DItlance of the knives from the aperture
Diftances of the pa-

N.

per from the knives

Diftances between
the edges of the
knives, oppofite
to the point of
concourfe

li

.012, ,020,

8f

.034,

32,

96,

101.
131.

.057, .081, 087.

Interval of difappearance .ooooiaz, .0000155, .coooiSa, .0000167, .0000166, .0000166.

Table II. Obf, 3. N.
Breadth of the hair ...

Diftance of fhe hair from the aperture
Diflances of the fcale from the aperture -
(Breadths of the (hadow . - -

Breadth between the fecond pair of bright lines

Interval of difappearance, or half the difference
of the paths . - - -

Breadth between the third pair of bright lines

Interval of difappearance, | of the difference

Table III. Exper. 3.

Breadth of the objed

Diftance of the object from the aperture

Diftance of the wall from the aperture

Diflance of the fecond pair of dark lines from each other

Interval of difappearance, \ of the difference

-

^1-5'

-

144.

150,

252.

I

f)

tV

.0000151,

.0000173

tV

1^.

.0000130,

.0000143,

.434.

-

- 125.

-

250.

)ther

1.167.

_

.0000149.

Exper,

PHYSICAL OPTICS,

133

Exper. 4.

Breadth of the wire - , - - - ,083«

Difiance of the wire from the aperture ... 32.

Diflanceof the wall from the aperture - « - 250.
(Breadth of the (hadow by three

meafureraents - - .815, .826, or .827; mean, .823.)

DiHance of the firft pair of dark

lines - . - - 1.165, 1.170, or 1.160; mean, 1.165.

Interval of difappearance - . - - .0000194.

Diftanceof the fecond pair of dark

lines - - - . 1.402, 1.395, or 1.400; mean, 1.399.

Interval of difappearance - - - - .0000137.

Diftance of the third pair of dark

Hnes .... 1.594, 1.580, or 1.585; mean, 1,5&6.

Interval of difappearance _ - - . .0000128.

It appears, from five of the fix obfervallons of the firft Table,
in which the diftance of the (hadow was varied from about 3
inches to 1 1 feet, and the breadth of the fringes was increafed
ill the ratio of 7 to I, that the difference of the routes confli»
tuting the interval of difappearance, varied but one-eleventh
at mofi; and that, in three out of the five, it agreed with the
mean, either exactly, or within ^^ part. Hence we are war-
ranted in inferring, that the interval appropriate to theextinftion
of the brightefl light, is either accurately or very nearly
conflanf.

But it may be inferred, from a comparlfon of all the other
obfervations, that when the obliquity of the refledlion is very
great, fome circumflance takes place, which caufes the interval
thus calculated to be fomewhat greater ; thus, in the eleventh
line of the third Table, it comes out one-fixth greater than the
mean of the live already mentioned. On the other hand, the
mean of two of Newton's experiments and one of mine, is a
refult about one-fourth lefs than the former. With refpedl to
the nature of this circumfiance, I cannot at prefent form a de-
cided opinion; but Iconje61ure thit it is a deviation of fome of
the light concerned, from the redilinear direftionalligned to it,
arifing either from its natural diffraclion, by which the mag-
nitude of the fiiadow is alfo enlarged, or from fome other un-
known caufe. If we imagined the fliadow of the wire, and the
5k fringes

13^ PHYSICAL OPTICS,

Comparifon of fringes nearcft it, to be fo contracted that the Tnotion of the
mc4urcs, light bounding the fliadow might be redlilinear, we fliould thus

n^ake a fufficient compenfation for this deviation ; but it is dif-
ficult to point out what precife trad of the light would caufe
it to require this correftion.

The mean of the three experiments which appear to have
been leaft affefled by this unknown deviation, gives ,0000127
for the interval appropriate to the difappearance of the brighteft
light ; and it may be inferred, that if they had been wholly
exempted from its e|Fe6ls, the meafure would have been fome-
vvhat fmaJler. Now the analogous interval, deduced from thes
experiments of Newton on thin plates, is .00001 12, which is
about one-eighth lefs than the former refult ; and this appears
to be a coincidence fully fufficient to authorife us to attribute
thefe two clafles of phenomena to the fame caufe. It is very
eafily (hown, with refpe€l to the colours of thin plates, that
each kind of light difappearsand reappears, where the dlffer-
, cnces of the routes of two of its portions are in arithmetical

progreflion ; and we have feen, that the lame law may be in
general inferred from the phenomena of diffra^led light, even
independently of the analogy.

The diflribution of the colours is alfo fo iimilar in both cafes,
as to point immediately to a firailarity in the caufes. In the
thirteenth obfervation of the fecond part of the firft book,
Newton relates, that the interval of the glaffes where the rings
appeared in red light, was to the interval where they appeared
in violet light, as 14 to 9 ; and, in the eleventh obfervation of
the third book, that the diflances between the fringes, under the
fame circumftances, were the22d and 27th of an inch. Hence,
dedu6ling the breadth of the hair, and taking the fquares, in
order to find the relation of the difference of the routes, we have
the proportion of 14 to 9^, which fcarcely differs from the pro-
portion obferved in die colours of the thin plate.

We may readily determine, from this general principle, the
form of the crefted fringes of Grimaldi, already defcribed ; for
it will appear that, under the circumftances of the experiment
related, the points in which the diiferences of the lengths of the
paths defcribed by the two portions of light are equal toacon-
ilant quantity, and in which, therefore, the fame kinds of light
ought to appear or difappear, are always found in equilateral
hyperbolas, of which the axes coincide with the outlines of the

ihadow.

PHYSICAL OPTICS. J25

ihadow, and the afymptotes nearly with the diagonal line.
Such, therefore, muft be the diredlion of the fringes ; and
this conclufion agrees perfe<5lly with the obfervation. But it
muft be remarked, that the parts near the outlines of the (ha-
dow, are fo much (leaded off, as to render the chara6ler of the
curve fomewhat lefs decidedly marked where it approaches to
its axis. Thefe fringes have a flight refemblance to the hy-
perbolic fringes obferved by Newton ; but theUnalogy is only
diftant.

III. APPLICATION TO THE SUPERNUMERARY RAINBOWS.

. The repetitions of colours fometimes obferved within the Applicatjon of
common rainbow, and defcribed in the Philofophical Tranfac-*Jj^ ?^^""e of
tions, by Dr. Langwith and Mr Daval, admit alfo a very eafy of light to Xt^
and complete explanation from the fame principles. Dr. Pern- fupernumerary
berton has attempted to point out an analogy between thefe co-Lanewith° d
lours and thofe of thin plates; but the irregular refledlion Daval.
from the pofterior furface of the drop, to which alone he attri-
butes the appearance, rouft be far too weak to produce any
yifible effe6ls. In order to underftand the phenomenon, we have
only to attendto the two portions of light which are exhibited
in the common diagrams explanatory of the rainbow, regularly
refleded from the pofterior furface of the drop, and croffing
each other in various directions, till, at the angle of the great-
^ft deviation, they coincide with each other, fo as to produce,
by the greater intenfity of this redoubled light, the common
rainbow of 41 degrees. Other parts of thefe two portions
will quit the drop in dire6lions parallel to each other; and thefe
would exhibit a continued diffufion of fainter ligiit, for 25**
within the bright termination which forms the rainbow, but
for the general law of interference, which, as in other fimilar
cafes^ divides the light into concentric rings; the magnitude
of thefe rings depending on tiiat of the drop, according to the
(Jifference of time occupied in the paflTage of the two portions,
which thus proceed in parallel directions to the fpe6tator\s eye,
qfter having been differently refracted and reflefted within the
4rop. This difference varies at firft, nearly as the fquare of
the angular diftance from the primitive rainbow: and, if the
Ijrft additional r-ed be at the diftance of 2^^ from the red of the
TAinboNy, fo as to interfere a little with the primitive violet,
the fourth aclditiqnal red will be at a diftance of nearly 2*^

more ,

13«

Application of
the doftrine of
the interference
of light to the
fupcrnumerary
rainbows of
Langwith and
D4v4.

rirysicAt optics.

more ; and the intermediate colours will occupy a fpace nearly
equal to the original rainbow. In order to produce this effed,
the drops mull be about -^ <^ an inch, or .013, in diameter :
it would be fufficient if they were between -jq and -3%. The
reafon that fuch fupernunierary colours are not often feen,
mufl be, that it does not often happen that drops fo nearly
equal are found together: but, that this may fometimes
happen, is not in itfelf at all improbable : we meafure even
medicines by dropping them from a phial, and it may eafily
be conceived that the drops formed by natural operations may
fometimes be as uniform as any that can be produced by art.'
How accurately this theory coincides with the obfervation,
may beft be determined from Dr. Lan<>with's own words.

** Auguft the 2 1 ft, 1722, about half an hour paft five in the
evening, weather temperate, wind at north-eafl, the appear-
rance was as follows : The colours of the primary rainbow
were as ufual, only the purple very much inclining to red,
and well defined : under this was an arch of green, the upper
part of which inclined to a bright yellow, the lower to a more
dullvy green : under this were alternately two arches of reddifli
purple, and two of green : under all, a faint appearance of
another arch of purple, which vaniflied and returned feveral
limes fo quick, that we could not readily fix our eyes upon it.
Thus the order of the colours was, i. Red, orange-colour, yel-
low, green, light blue, deep blue, purple, 11. Light green,
dark green, purple, ui. Green, purple, jv. Green, faint
vanifiiing purple. You fee we had here four orders of colours, -
and perhaps the beginning of a fifth ; for I make no queftion
but that what I call the purple, is a mixture of the purple of
each of the upper feries with the red (f the next below it, and
the green a mixture of the intermediate colours. I fend you not
this account barely upon the credit of my own eyes; for there
was a clergyman and four other gentlemen in company, whom
I defired to view the colours attentively, who all agreed,
that they appeared in the manner that I have now defcribed.
There are two things which well deferve to be taken notice of,
as they may perhaps dired us, in fome meafure, to the folution
of this curious phenomenon. Tlie firft is, that the breadth of
the firft feries fo far exceeded that of any of the rell, that, as
near as I could judge, it was equal to them all taken together.
The fecond is, that I have iiever obferved thefe inner orders

of

PHYSICAL OPTICS.- 137

of colours in the lower parts of the rainbow, though they have
often been incomparably more vivid than the upper parts,
under wliich the colours have appeared. I have taken notice
of this fo very often, that I can hardly look upon it to be ac-
cidental ; and, if it fliould prove true in general, it will bring-
the difquifilion into a narrow compafs; for it will (liow that this .

efl'ed depends upon fome property which the drops retain,
whiKi they are in the upper part of the air, but lofe as they
come lower, and are more mixed with one another." Phil.
Tranf. Vol. XXXII. p. 243.

From a confideration of the nature of the fecondary rainbow,
of 54'', it may be inferred, that if any fuch fupernumerary
colours, were feen attending this rainbow% they would necelfa-
rily be external to it, inftead of internal. The circles fometimes . ,

(ieen encompaffing the obferver's (Imdow in a mift, are perhaps
more nearly related to the common colours of thin plates as
ieen by reileclion.

IV. ARGUMENTATIVE INFERENCE RESPECTING THE
NATURE or LIGHT,

The experiment of Grimaldi, on the crcfled fringes within Argumentative
(he (liarlow, together with feveral olhers of his obfervations/
equally important, has been left unnoticed by Newton. Thofe
who are attached to the Newtonian theory of light, or to the
hypothefes of modern opticians, founded on views ilill lefs en-
larged, would do well to endeavour to imagine any thing like
an explanation of thefe experiments, derived from their own
do6lrines; and, if they fail in the attempt, to refrain at leaft
from idle declamation againft a fyftem which is founded on the
accuracy of its application to all thefe fads, and to a thoufand
others of a (imilar nature.

From the experiments and calculations which have been Homogeneons
premifed, we may be allowed to infer, that homogeneous ^'g^^. I^^soppofitc
light, at certain equal diftances in the diredion of is motion, jiftances along its
is poflelfed of oppofite qualities, capable of neutralifing or coi'r^e, by which
deftroying each other, and of extinguifliing the light, where extinalon of"
they happen to be united ; that thefe qualities fucceed each the light may be
oiher alternately in fuccelfive concentric fuperticies, at dif- ^ '

tances which are conflant for the fame light, palling through
the fame medium. From the agreement of the meafures,
and from the fimilarityof the phenomena, we may conclude,

that

138* PHYSICAL OPTICS.

th^t thefe intervals are the fame as are concerned in the
produ6lion of the colours of thin plates j but thefe are fliow n,
by the experiments of Newton, to be the fmaller, the denfcr
the medium ; and, fince it may be prefumed that their num-
ber mull neceflarily remain unaltered in a given quantity of
Ughtmovfs light, it follows of courfe, that light moves more flowly in a
deafer mediums. ^^^^^^' than in a rarer medium : and this being granted, it
muft be allowed, that refradion is not the effe6l of an attrac-
tive force direded to a denfer medium. The advocates for
the projedile hypothefis of light, muft confider which link ir^
this chain of reafoning they may judge to be the moft
feeble J for, hitherto, I have advanced in this Paper no ge-
tight and found neral hypothefis whatever. But, fince we knpw that found
ftrongly refemble diverges in concentric fuperficies, and that mufical founds
confid of oppofite qualities, capable of neutralifing each
other, and fucceeding at certain equal intervals, which are
different according to the diiTerence of the note, we are
fuJly authorifed to conclude, that there muft be fome ftrong
refemblance between the nature of found and that of light.
There is pro- I have not, in the courfe of thefe inveftigations, found

^n'-'Ledii^^'^" ^"^ reafon to fuppofe the prefence of fuch an infleding me-
dium in the neighbourhood of denfe fubftances as I was for-
merly incliped to attribute to them; and, upon copfidering
the phenomena- of the aberration of the fi:ars, I am difpofed
to believe, that the luminiferous ether pervades the fubr
ilance of all material bodies with little or no refi fiance, as
freely perhaps as the wind palTes through a grove of trees,
Praftical appli- The obfervations on the effeds of ditfraciion and inter-
cation ot" the ference, may perhaps fometimes be applied to a pradical
purpofe, in majcing us cautious in our copclufions relped^ing
the appearances of minute bodies viewed in a microfcope.
The fliadow of a fibre, however opaque, placed in a pencil
of light admitted through a fmall aperture, is always fome-
what lefs dark in the middle of its breadth than in the parts
on each fide. A fimilar efied may alfo take place, in fome
' degree, with refped to the image on the retina, and impreis

the fenfe with, an idea of a tranfparency whi^h has no real
exiftence : and, if a fmall portion of li^ht be really tranf-
mitted through the fubllance, this may again be deftroyed
by its interference with the diflraded light, and produce an
appear&nce of partial opacity, inftead of uniform femitranf-*
3 parenty.

PHYSICAL OPTICS, J39

parency. Thus, a central dark fpot, and a light fpot far-
|-ounded by a darker circle, may refpe6tively be produced
in the images of a femitranfparent and an opaque corpufcle ;
and imprefs us with an idea of a complication of firu61ure
which does not exift. Jn order to deted the fallacy, we
may make two or three fibres crofs each other, and view a
pumber of globules contiguous to each other j or we may
obtain a flill more effectual remedy by changing the magni-
fying power ; and then, if the appearance remain conftant
in kind and in degree, we maybe atfured that it truly repre-
fents the nature of the fubftancc to be examined. It is na-
tural to inquire whether or no the figures of the globules of
blood, delineated by Mr. Hewfon in the Phil. Tranf. Vol.
JjXIII. for 1773, might not in fome meafure have been in-
fluenced by a deception of this kind : but, as far as I have
hitherto been able to examine the globules, with a lens of
one-fiftieth of an inch focus, I have found them nearly fuch
as Mr. Hewfon has defcribed them.

REMARKS ON THE C0L0UE.S OF NATURAL BODIES.

Exper. 5. I have already adduced, in illuftration of New- On the colours
ton's comparifon of the colours of natural bodies with iho{e°^' ^^^^^^^o^<^^
of-tliin plates. Dr. Wollaflon's obfeyvations on the blue light
pf the lower part of a candle, which appears, when viewed
through a prifm, to be divided into hve portions. I have
lately obferved a limilar inftance, flill more ftrongly marked,
in the light tranfmitted by the blue glafs fold by the opti-
f ians. This light is feparated by the prifm into feven dif-
tin<5l portions, nearly equal in magnitude, but fomewhat
broader, and lefs accurately defined, towards the violet end
of the fpectrum. The firfl two are red, the third is yellow^.
i Hi green, the fourth green, the fifth blue,- the fixth bluilh
violet, and the feventh violet. This divifion agrees very
nearly with that of the light refleded by a plate of air ^^\^
of an inch in liiicknefs correfponding to the 11th feries of
red and the 18th of violet. A fimilar plate of metallic oxide,
would perhaps be about Tji's-G ^^ ^^ ^^^^ ^" thicknefs. But
it mufl be confeiFed, that there are ftrong reafons for believing
the colouring particles of natural bodies in general to be in-
comparably fmalier than this; and it is probable that the
"linalogy, fuggeflyd by Newton, is fomewhat lefs clofe than
' "'- he

l40 PHYSICAL OPTICS.

he imagined. The light refle61ed by a plate of air, at anic
thickncfs nearly correfponding to the 11th red, appears to
the eye to be very nearly white ; but, under Favourable cir-
cumftances, the 11th red and the neighbouring colours may
/till be diftinguiflied. The light of fome kinds of coloured
glafs is pure red ; that of others, red with a little green :
fome Intercept all the light, except the extreme red and the
blue. In the blue light of a candle, expanded by the prifm,
the portions of each colour appear to be narrower, and the
intervening dark fpaces wider, than in the analogous fpedrum
derived from the light refle^led from a thin plate. The light
of burning alcohol appears to be green and violet only. The
pink dye fold in the (liops, which is a preparation of the car-
thamus, affords a good fpecimen of a yellow green light regu-
larly refle(5ted, and a crimfon probably produced by tranfmiffion.

Vf. EXPERIMENT ON THE DARK RAYS OF RITTER.

Dark rays of Exper, 6. The exigence of folar rays accompanying light,

ifoT^^Dr^'^^ more refrangible than the violet rays, and cognifable by their
WoUailon. chemical effeds, was firtl afcertalned by Mr. Ritter : but Dr.

Woilaflon made the fame experiments a very fhort time after-
wards, without having been informed of what hsc] been done
on theContinent. Thefe rays appear to extend beyond the violet
rays of the prifmatic fpeclrum, through a fpace nearly equal ta
that which is occupied by the violet. lu order to complete the
comparlfon of their properties with thofeof vifible light, T was
They are re- defirous of examining the effect of their reOedion from a thin
thin platr^' air plal^^ ^^^ air, capable of producing the well known ring^ of co,
>^ith the fame lours. For this purpofe, I formed an image of the rings, by
modification of ^p ^^^^ j-^l^^ mlcrofcope, with the apparatu?^ which i

rings as v ft bis ' ' ^

light IS. have defcribed in the Journals of the Royal Inftitution^ and I

threw this image; on paper dipped In a folution of nitrate of
filver, placed at the diftance of about nine inches from the
microfcope. In the courfe of an hour,, portions of three dark
rings were very dlfh*n6tly vifihle, mucli fjnaller than the bright-
ell rings of the coloured image, and coinciding very nearly,
in their diaienfions, with the rings of violet light that appeared;
upon the interpofition of violet glafs. I thought the dark rings
were a little fma:ller than the violet rings, but the difference
vvas not futficiently great to be accurately afcerlained ; it might
be as much as ^^ or ^^ oi" the diametwj§, but not greater. It

is

SCIENTIFIC NEW^. '141

is the lefs Turprjfing that the difference fliould be fo fmall, as
the dimenfions of the coloured rings do not by any means vary
at the violet end of ihe rpe<5lrum, jo rapidly as at the red end.
^ ;For performing this experiment wilh very great accuracy, a
heliollale would be neceffary, ftnce the molion of the fun
.caufes a flight ch.ange in the place of the image; and leather,
impregnated with the muriate of filver, would indicate the
efte6l with greater delicacy. The experiment, however, in
its prefent (late, is fufficient to complete the analogy of the
jnvifible with the vitible rays, and to (how that they are
equally liable to the general law which is the principal fub-
je6l of (his Paper. If we had thermometers fufficiently deli-
.cate, it is probable that we might acquire, by (irailar means,
information dill more interefiing, with rei'ped to the rays of
invifible heat difcovered by Dr. Herfchel; but at prefent there "*'

is great reafon to doubt of the pra6licability of fuch an expe-
riment.

SCIENTIFIC NEWS, ACCOUNT OF BOOKS, Syc,
National Injiitute.

i- HE clafs of mathematical and phyfical fciences of tbe National Infti-
French National Inftitute had a public fitting on the 6th Mefli> ^''^^ P*"''"*
dor (June 25.) The fubje^ts appointed for prizes were the
following;

Mathematics. " It is required to give a theory of the per- Planet Pallas,
turbations of the planet Pallas, difcovered by M. Olbers.**

The prize will be a gold medal, weighing one kilogramme,
'(35^oz. avoirdupois.)

Natural Philofophy. The clafs had propofed for tTie fubjefi Carbon in vegc-
of a prize the following queftion. '* To determine by expei-i-
ment the different fources of carbon in vegetables.'* The
concurrence is prorogued until the 1ft Germinal in the year 13
(March 22, IS05.)

Tlie concurrence for the prize upon the following queftion Torpid ftate of
is alfo prolonged to the fame period. *' To determine by ana- *^^'.?P**^'^* ^^*
toraical and chemical obfervations and experiments, what are '

the phenomena of the torpid ftate to which certain animals*
fuch as marmots, dormice, &c. are fubjed during the winter,
with refpedt to the circulation of the blood, refpiration, and
irritability ; to inveftigate the caufes of this fleep, and why
it is peculiar to thefe animals.'*

The

142 SCrENTIFIC NEWS;

The value of thefe two prizes is doubled, and confifts itt
two kilogrammes of gold about 6800 francs each (c£289.)

The clafs had propofed for the fecond time, the 15th Ger-
mmal of the year 10, as the rubje6l of a prize to be decreed
in the public fitting of Meflidor, the following queftion.

Ferments. *« "What are the charaders which diftinguifli, in vegetable

and animal matters, thofe bodies which ferve as ferments from
Ihofe in which they produce the ftate of fermentation,"
' The memoirs received not having anfwered the conditions
of the program, and the clafs confidering that this queftion
has been four years before the public, the fubjeft is now with-
drawn.

Aftronomy. Aftronomy. Mr. Piazzi of Palermo has obtained the prize

PUMi^^""'^^^ founded by IVl. De Lalande, in favour of the perfon who fhall
have made the nioft interefting obfervation, or written the
inoft ufeful memoir to the progrefs of aftronomy. Mr. PiazzJi
is the difcoverer of the planet Ceres.

Readings. The readings delivered during the fitting were as follow:

1. Notice of the labours of the clafs during the year; the
mathematical part by M. Deiambre. 2. Notice of their la-
bours; the phyfical part by M. Cuvier. 3. Account of a
phytico-mathematical theory of currents of water, by M.
Prony. 4. A note refpe6ling the amelioration of Iheep in the
foulh of France, by M. Teffier. 5. General reffedtions on the
produ61ions of the vegetable kingdom in the Pyrenean moun-
tains by M. Raymond. 6. Refleflions on heat, by Count
Rumford*. 7. Extra6! of a memoir tending to illuftrate the
occonomical hiftory of vegetables, cultivated or naturally grow*
ing in the Canaries, by M. Brouflbnet.

ExtraB f^f a Letter from Professor Bode, Ajlronomer Jtoj/al,
to Mr. A. K Thoelden,

Datied Berlin, Sept. 1 8*

Place of new ON the firft of September Mr. Harding difcovered, at

pluiets. Lilrenthal, a new moveable ftar ; it appears to be of the eighth

magnitude; its motion retrograde towards the South. Proba->

bly this may be another new planet m the orbit of Ceres and

Pallas.

I ft Sept.

1ft Sept.
5 —

10\-1
11 8'

8 —

8 11

10 —

8 15

SClENtlFlC NEWS, ^C. 143

Lven. RA. 2^ 24.' Decl. 0^ 37'— N.

S.

1

.H

51''

- 0

11

26"

1

29

28

- 0

47

19

1

12

55

- 1

11

5^

The two laft obfervations were made by Dr. Olbers, at
Bremen. I received this intelligence yefterday, but at prefent
this fmall planet (there are now three) is not d.ilboverable, on
account of the moon-fliine.

Extract of a Letter from Mr. G. B, Grenough.
* ♦ * * There is an overfight in the hafty account I fent Correftlon of a
you of the Abbe Melograni's blow-pipe. No provifion is ^o[f^['V^ f "
made for admitting the external air. This may be done by grani's blow-
feveral means. It may be admitted through that part of the P'P^'
axis which is oppofite the nozel; but as this would require
forae contrivance which would render it defe^live in fimpli-
city, I fliould prefer the addition of a fmall val\fe opening in-
wards at that part of each veffel which is immediately oppo-
fite the neck that joins them. Whether this method was ufed
in the adual inftrument I cannot, at this diflance of time, re-
collect.

Organic Remains of a former IVoi'ld. An Examination of the
Mineralized Remains of the Vegetables and Animals of the An-
tediluvian World, generally termed extraneous Fqfds. Bj/
James Parkinson, Hoxton, Vol. I, containing the Vege-
table Kingdom, ^to, pp. 4^71. with 10 Plates {£2 2 0)
Robfon, Sfc.

AS it would be impradicable in the general announcement Parklnfon's or-
of a work of the magnitude and importance of the prefent to ^^"^"^ remains,
give the reader any well filled outline of the plan, I muft con-
fine myfelf to ftate in few words, that the defcription and elu-
cidation of organic foffil bodies, though in many points of
view of the higheft intereft, has not yet conftituted the fub-
je6l of a general treatife; notwithftanding the various confi-
derations refpedling the local, the individual, and the chemi-
cal hiftory of thefe wonderful bodies have occupied the re-
fearches of many able philofophers in detached memoirs; and
that the compofition of fuch an hiftory demands a great ex-
ertion of labour, in confulting and digefting what has been

dons

:144' ' ACCOUNT OF BOOKS.

Parkinfon*s or- done by Others, an accurate, p:eological, and chemical view
game remains, ^p ^^^ ^^^^ ^p^^^ which fcientific conclufions or deda61ion!4
may be grounded, and above all, an ardent curiofity, with
adequate leifure and means to become acquainted with the
fpecimens themfelves: — And, after this preface, I muft add,
that fortunately for the advancetnent of this brancli of know-
ledge, the author of the prefent work, has amply vindicated
hisciaim to thefe requifites.

The work is written in the form of letters, and enlivened
by an adoption of the ftyle and fome of the incidents of a
traveller. Much of ufeful fcience and clear explanations of
the fubje6l are to be found in tlie pages of this volume. The
abridgements from other authors are full, and the quotations
always given with the volume and page, which I mention
more readily, as a flovenly iiabit of loofe quotation, or not
quoting at all, is but too common, even with our wTiters of
merit. Nine plates of the fubjeds are given, which do the
higheli credit to the defigner and engraver, Springfguth, for
their delicacy and beauty, and conliderable pains have been
taken in colouring them. The frontispiece, reprefenting the
Ark upon Mount Ararat, dellgned by Cotbould, is happy and
appropriate; though the artill has taken a pi6lorial licence to
reprefent the fun and the rainbow nearly on the fame azimuth,
for which neither opticians nor correal obfervcrs will be dif-
pofed t» excufe him.

The volume yet to be publiHied will contain the animal king-
dom; a fubjecl perhaps ftill more attractive than the vegeta-
ble. In the remains of extind vegetables, we appear to con-
template the phyfical economy of a world long ago obliter-
ated; but in thofe of animals, we feem to behold fomething
that gives a glimpfe into the moral relations of thofe beings of
palt ages who exifted upon its furface.

ThLUjj-. Jbiinuzl.TolJX.2^. Kp. 244.

WW

~y--y

J'hiZo^: Joio-nal,. VolJZ.Tl. W.p.

«B^^''

,7os. Journal. VolJZJ^. VUpJM-

^

§

<<3

■I

4

i^

PhUos. Jovnial,Fl.yni.Vol.II.pcua44.

T.

■■^■^GUR N A L

OF

NATURAL PHILOSOPHY, CHEMISTRY,

AND

.■•ndi tiUz.u 1

THE ARTS.

'■■ NOVEMBER, 1804,

- :f

ARTICLE I.

Defcription of a Tallow Lamp, xvhich regulates its Supply hy a
' fpontaneous Movement. By Mr, John WhitlkyBosw ell^
Communicated by the Inventor,

To Mr. NICHOLSON.
' SIR,

•1 HE conftant attention which candles demand frotn the'Defcrlptlonof a

frequent fnuffing they require, and the conlinued variation^**™? fo*'»«'""S

of their light in the intervals of this operation, on the one

hand, and on the other the expence and trouble which oil

lamps becafion, together with the difagreeable fcent they in

gener-al proddce; have rendered the contrivance of a good

lamp for burning 'tallow, a defirable obje6l to feveral for a

Jong time.

^ I hope, therefore, the defcription I fend of a lamp for this

purpofe, which pofleiffes fome valuable properties; will be

acceptable to you.

The beft lamp for burning tallow which I had feen before
I contrived this, was one invented by Mr. March, of Barn-
llaple, in which the tallow kept continually melted in a veflTel
fufpended over the flame, was admitted by a fmall pipe to the
burner, and th.e fupply r'egulated by a kind of cock attached
' Vol, lX:r-NovfiMBER, 1804. -^ - to

14(5 TALLOW LAMP.

Pcfcriptlon of a to the pipe : But this method occafioned a wafte from the
{*Jj'Pj°'' ''"'"'"« evaporation of the melted tallow, and befides, required much
attendance to regulate the cock and keep the tallow veflTel at a
proper diftance from the flame ; for the alteration of the tem-
perature of the melted tallow, which was very frequent from
many caufes, continually changing its degree of fluidity,
caufed it to vary in its fupply through the pipe propor-
tionally.

It occurred to me fome time after I faw this lamp, that one
might be contrived in which the tallow ftiould only be melted
as it was confumed, and other of the inconveniences be re-
moved to which the firft was fubjecl; and X made then a
rough drawing of a lamp for this purpofe, but other more
interefling matters prevented my having one made on that
plan before laft December : It confifted of a trough fupported
in an inclination of about 45 degrees, fimilar to the one in the
figure, which held a fquare prifm of tallow ; under this was
placed a little oblong veflel of tin, formed fo as to move for-
wards and backwards like a drawer, in front of which was
placed a burner : a couple of wires placed acrofs the lower
pcirt of the trough, prevented the tallow from Aiding down
beyond them, as it otherwife would from the obliquity of its
fupport; but as it melted by the heat from the burner, it
fell in drops into the little drawer, fo as to fupply the flame,
while the degree of this fupply was regulated by moving the
drawer in or out, fo as to bring the burner nearer to, or fur-
ther from the tallow. In this Hate, though it formed a very
, ufeful lamp, it was not fo perfect as I could wifli ; every al-

teration of temperature of the apartment (which in cold wea-
ther happens frequently) required a proportional alteration in
the diftance of tlie burner from the tallow, to prevent the
little drawer being either overflowed by a fuperabundance of
V melted tallow, or the flame cealing from a deficiency of fup-
ply. The attendance this circumftance requh-ed induced me
to contrive the prefent lamp, or rather to improve the former,
in manner following.

I conceived that if the little pan, which held the melted
tallow and the burner, was placed on the arm of a balance
inclined from 30 to 45 degrees from the perpendicular, and
its weight corapenfated by a counterpoife at the extremity of
the; other arm, that when more than a certain quantity of tal-

lovr

-TALLOW LAMP. 147

low ran into ft, it would fink lower, and, in doing fo, move Defcription of a:
Ihe burner farther forward from the trough at the fame ^>"^6, ^^^J^'*^ urnuij
and lice vofUf and thus regulate the fupply fponlaneoufly :
But as it was neceflary that the pan (holding a fluid) (hould
always maintain an horizontal pofition during its movement, I
imagined this might be effeded by placing another arm be-
neath the balance-arm, and fixing a perpendicular piece,
fo jointed to the extremity of each as to move frefli and
fteadily, which piece fliould fupport an horizontal (land for
the pan.

I had a lamp made in this manner, and found it anfwer my
intention perfedly. It required no attendance whatfoever,
but regulated its fupply with precifion ; and afforded, like-
wife, an agreeable fpedacle, having in its movements fome-
what the air oF thofe of an animal, from their exaiSt rela-
tion toxan evident object, and adopting themfelves to all its
changes.

The lamp thus made atTumed the form in the figure, PI. IX.
where Treprefents the inclined trough for holding the tallow; P
^- the pan for catching the tallow as it melted, and holding the
burner ; F the flame and burner j R the perpendicular piece
fufiaining a fupport for the pan ; B the balance moving freely
on its center in the ftand S, and jointed to R as before de-
scribed ; c the parallel arm ufed to keep R perpendicular, and
by its means horizontal ; id the counter weight, placed fo as
to move on the extremity of B by a fcrevv. The firfl frofiy
night fliewed me the neceffity of the addition of another part
to remedy an inconvenience I had not forefeen ; the dropping
tallow affuming the fcm of an ificle, joined the pan to tl.e
trough, and thus flopped its movement : As it was tfouble-
fome to break this oflT as it occurred, I contrived the follow-
ing means to prevent its formation : A little oblong fliding-
piece, the fame breadth as the trough, vyas placed clofe un-
derneath its lower part ; the extremity of this Aide was made
angular, that the melted tallow might fall from a fingle point;
a wire reprefented at L, moved it back or forwards as re-
quired : By this Aide the drop may be made to fall as clofe
to the flream of burning air from the flame as Is thought fit,
and all congelation prevented. 1 afterwards added a fort of
refledor to the lamp, which confiderably improved the light
not merely ading as its name implies, but alfo occafloning an

L 2 incrtaf©

148 TALLOW LAMP.

pefcription of a incrcafe in the current of air which paffed the flame, ren-
tallow^ "'^"'"^ ^^rcd it fomewhat more bright, and confiderably more fteady.
This part is reprefented at D in the figure, and confifls of two
fide-pieces placed before the trough, but fo as not to obftrufl
the tallow, and bent forward to form an angle with its fides.
To improve the light, I alfo ufe in the lamp five fmall diftindl
wicks, of three threads each, inftead of one large wick, placed
near each other in a row, which renders the flame clear and
free from fmoke, and thereby alfo prevents any unpleafant
fcent. I ufed this lamp for more than three months, and
found it very convenient for reading or writing by, as when
once lighted it required no farther attention, and kept its
light at nearly the fame height at all times, and of the fame
degree of intenfity ; and I can further recommend it, as
yielding the greateft light at the fmallefl coft, in proportion,
of any invention yet made public which is applicable to do-
meftic ufes,

I have had two lamps of this kind carefully made by Mr.
Lloyd, No. I7S, Strand, and left with him as models: In
one of which the chief object is cheapnefs, as far as confident
with perfection and neatnefs ; in the other, to form an elegant
utenfil for the ftudy, office, or chamber; and any gentleman
may be fupplied with them there, made exadly to my plan,
on reafonable terms ; and as Mr. Lloyd is the only perfon
at prefent appointed to make them, and inftructed fully in the
mechanifm, they can be had perfed from him only.

It is probable wax might alfo be burned in this lamp as
well as tallow : of this I cannot fpeak from experience, but
mention it, as I know fome v/ould prefer to ufe it.
I am. Sir,

Your very humble fervant,

J. WHITLEY BOSWELL.

Oa. 1, 1804..

AccourU

DEAFNESS CURED. 149

II.

Account of a fuccef^ul Cafe in lohich Deafnefs was cured by
Pundure of the Memhrana Tympani. By M. Maunoir, of
Geneva, Comm unicated i'j/ Alexander Marcet, M.D,
Phyfician to Guy's Hofpital.

To Mr. NICHOLSON.
SIR,

A HE inclofed communication on the efFeds produced in a Introduftory
cafe of deafnefs by the perforation of the tympanum of the ^"'®*^'
ear, is extrafled from a letter which I have juft received from
Mr. Maunoir, an eminent furgeon at Geneva. The hiftory of
this cafe, drawn up by fuch an intelligent and accurate ob-
ferver, appears to me curious, both from the phyiiological re-
marks which it contains, and from the llriking illuftration
which it affords of a new mode of pradice lately propofed in
tliis country. And, as this fubjed feems fully as interefting
in its philofophical point of view, as in its connexion with
practical furgery, I (hould with, if you think it proper, that
you would give it a place in the next number of your valuable
Journal. I have the honour to be. Sir,

Your obedient humble fervant,

ALEXANDER MARCET.
St, Mary Axe, Oa. 16, 1804.

Extrad of a Letter from Mr. Maunoir, furgeon at Geneva,
dated 5th September, 1 804.
"Mr. F. of Geneva, aged forty years, had loft his hearing, A gentleman
feveral years ago, in confequence of a long affedion of the ^la been^feveral
pofterlor part of the internal fauces, and it was evident, that, years extremely
in this cafe, the euftachian tubes were obliterated. In con- ^^ *
denfing the air in his mouth and noftrils, he was totally unable
to diftend the membrane of the tympanum, a thing which is
yery eafy to do for any one who enjoys a perfed fenfe of hear-
ing. He could fcarcely hear, even when you (houted in his
ears, and although fo long deaf, he had not acquired the fa-
culty of under ftanding by the motion of the lips. After pe-
rufing the paper which I lately publilhed in the Biblioth^que
Britannique, Mr. F. conceived that he might be oneof thofe
in whom the hearing could be recovered by the perforation of

the

150

Punftiirc of the
tympanum of
one ear.

Inftant reftqra-
tion of hearing
with extreme
fenfibility.

DEAFNESS CUREB.

Some founds
more audible
than others.

The other ear
punctured with
out effe<a.

Caufe of this
failure.

the tympanum. On the Ulh of July laft, I performed that
operation on his right ear, in prcfence of Mr. Jurine, with a
very fmall trocar, about one eighth of an inch in diameter. At
the inftant that the inftruraent was withdrawn, we fpoke to
him in a low voice; but inftead of anfwering, he remained
immoveable in his chair, and feemed (lupified. — Then he ex,
claimed *' For God's fake gentlemen, don't cry out fo loud;
you hurt me!" I then began to walk about the room, — The
fqueaking of my boots made him fliudder and jump in his chair ;
and he covered his ear with his hand. The fnapping of the
fingers quite diftracted him, and feemed to produce upon him
an efFe6l fimilar to that of a piftol fuddenly fired in the ear of
a perfon not aware of it. When fpoken to, though in a whif-
per, he complained that we fpoke too loud. Yet in fpite of
this exceffive fenfibility to very inconfiderable noifes, there
were other founds, not lefs diftin6t, which he did not hear,
even at a very little di fiance; fuch for inftance as the ticking
of his watch. So that his hearing feemed to be fometimes too
dull, fometimes too acute ; becaufe, no doubt, the organ had
loft the faculty of adjufting itfelf to the different modulations
of found. A week after this, however, Mr. F. had loft that
excefliive fenfibility which rendered acute founds almoft in-
tolerable to him, and in fa6t he had already again learnt to hear.
He then wiflied to have the other ear perforated in the fame
manner. I performed this operation, but without effed.—
Twenty days after this fecond operation, Mr. F. called upon
toe. I examined his ears in a fine fun fliine, and could fee in
' the right ear the membrane of the tympanum traverfed in its
exterior part by a fmall cicatrix, having in its center a fmall
hole which was hardly perceptible. Yet the hearing was
fcarcely diminiflied fince the firft operation. Fearing that this
fmall aperture might clofe itfelf entirely, Mr. F. defired that
I would perforate a'gain the membrane of that ear, an opera-
tion which was repeated without giving him any pain, but not
without a flight increafe of fenfibility in his hearing. I after-
wards examined the left ear, and having placed the meatus in
the dire6ti()n of the fun's rays. I diftinclly perceived a falfe
membrane adhering to the whole circumference of Ihepaflage,
and perfedly fimilar, in its form and fifuation, to that of the
tympanum, the diftance between the two membranes being
fcarcdy one fixth part of an inch. I took ofl^ at once this
4 falfe

ON COPAL VARNISHES. 151

falfe membrane with a pair of tweezers, and difcovered be*
hind it, the tympanum, quite found and entire, I thought it
probable that, in the fecond operation, I had only touched
this falfe membrane. I immediately perforated the true one, Repetition of
and was furprized (as well as my brother who attended this jJj^j^^P^^^^'^^"^^
operation), to find tliat, although Mr. F. had already learnt fimilgr pheno-
again to hear with the right ear, yet the reftoration of his hear* "*^"^«
ing in the left, occafioned in him the fame eiFeds of wonder,
and of exceffive fenfibiUty to the lead unexpected noife, which
he had experienced after the firft operation. This inconveni-
ence, however, has not been of longer duration in this ear,
than it had been in the other."

III.

Zetter from Mr. Timothy Sheldrake, expofing the Errors
of M. Tingry refpeding Copal Varnijkes; with fame farther In-
J!ru6iions concerning the fame,

(Received OB, 16, 1804-.)

To Mr. NICHOLSON.
SIR,

TINGRY, profeflbr of chemiftry, &c. in the academy Tingry in his
of Geneva, has publiOied a treatife on the art of making and y^^l^^^^""^
applying varnifhesj with new obfervations and experiments
on copal, &c, &c. A tranflation of that work has lately
appeared here, and at p. 157 of that tranflation I find the fol-
lowing paflage.

" Mr. Timothy Sheldrake mentions camphor as a medium
for difTolving copal in eflfence* and alcohol. He gives alfo an-
other procefs, in which ammonia (volatile alcaline fpirit offal
ammoniac) in the proportion of an eighth part of the eflence
employed, is fubftituted in the room of camphor.

*' Exper, I, Of the three procefles which he defcribes, I repeated Shel-
repeated two: thofe which regard the folution of copal in ef-f" dH^lving^
fence and in alcohol by a mixture of camphor. That with ef- copal in eflence
fence did not fUcceed. The author himfelf announces that he ^5/'!,"°'^"*'

♦ Throughout the book this word islifeil to defcribe what we call
fpirit of turpentine.

always

152

ON COPAL VARNISHES.

Bor with alcohol.

He infers that
the compounds
tnuft be imper-
feft and not
varnifhes.

Obfervations
in replyt

Mr. Tingry
ought not to
have oppofed
fpeculation againft
faHi,

always failed, except when he obtained the eflence from apo*
Ihecaries hall. It appears that this eflfence had by chance all
thofe effential qualities which we endeavour to give it by time,
and ftill more fpeedily by the influence of light.

" Exp. II. The fame experiment repeated with pure alco-
hol was attended luith too little fuccefs to make the refult be con-
Jtdered as a varnijh. The alcohol appeared milky, and the
copal formed at the bottom of the veflel a mafs which did not
feem to have decreafed in volume. Next morning the inter-
pofed part of the copal, which altered the limpidity of the al-
cohol, was precipitated, and adhered to the (ides of the glafs.
The procefs I have defcribed for fpirituous tindure of amber
would give more hopes of fuccefs without any intermediate
fubftance."

" In regard to the means propofed by the medium of am-
monia, the faline nature of that liquid, if the procefi fucceeds,
will not admit of the produ6l being placed in the clafs of var-
niflies deftined for delicate painting. It is a kind of faponace-
ous compound, the ufe of which is not to be recommended in fuch
cafes,"

The paflTage above quoted undoubtedly relates to a paper
which I communicated feveral years ago to the Society for the
Encouragement of Arts, &c.

This paper was wholly tranfcribed * into fome periodica]
publications, and parts of it into others; it may therefore be
neceflary to obferve that when reference is made to the original
paper, it muft be underftood to mean as it was printed in the
Society's Tranfadions, and not to any imperfect extracts that
may have been made from it.

Mr. Tingry (hould have been fenfible of the danger in op-
pofing a conje<3ure or opinion purely fpeculative , to what is de-
fcribed as a fadl that had been demonjirated by experiment. Since
it is more probable that the conjecture fliould be unfounded, or
the opinion untrue, than that a man Ihould forfeit his reputation
with the public by relating that, as having been demonftrated
by experiment, which the perfon who contradicts him fays
cannot, in the nature of thjngs be true, even if the procefs
Jucceeds : As it is the intention of your valuable Journal to pro-
mote the caufe of fcience, and as that caufe will be as etfe6^-

* Sec our Journal, I, 250.

ually

OK COPAL VARNISHES. 153

oally ferved by the detedion of errors, as by the promulgation
of new fa6^s, I Iruft you will favour me by fuferting the follow-
ing obfervations on thofe pafTages which I have quoted from
Mr. Tingry's work; beginning with that in which he attempts
to demohlh one part of difcovery (if it may be fo called) with*
out ufing one experiment as the inftrument of deftru6tion.

*' In regard to the means propofed by the medium of am-
:inonia, the faline nature of that liquid, if theprocefs fucceeds,
'Will not admit of the produ^ being placed in i//e class of var-
jNishes, deftined for delicate painting; it is a kind oi' fapona-
• ceous compound, the ufe of which is not to be recommended injuch
-cafes"

In oppofition to all this I have but a (imple fad to produce: Inftances of
viz. It is many years fince I diffolved copal by the procefs al-g^ withthecopi
luded to; and adually varnithed feveral pi6tures with the folu- many years ago,
tion fo prepared: thofe pidures appeared to fliine, or bear out, J"^ ^^^^cd-'
!as artifts call it, as well as if they had been covered with any lent condition*
other varnifti; the colour of the varnitli has not changed in the
leait, which raoft other vamifhes would have done in the fame
time; they have ftood in a fraoky houfe in London the whole
time, have been repeatedly waflied with warm water, and
cleaned withfpiritof turpentine; and notwithftandingall this,
ihey ftill preferve their glolTy appearance undiminiflied. If a
folution which is proved by the experience of many years tp
potfefs thefe properties in an eminent degree, does not deferve
to be admitted into the clafs of varnithes, it is not eafy to tell
to what fubftance Mr. Tingry will grant that diftindion.

Having faid thus much for the faft, we may venture to pro- The ammonia
ceed to the theory : When ammonia and copal were mentioned, P'o^^^^y fo^nis
the combination of both thofe fubftances with the fpirit of tur- compound; but
pentine appeared to Mr. Tingry to be fo much a matter of '^ss of no
courfe, that he took it for granted, and drew all the conclu- q^gncg^
lions from it without making a (ingle experiment to prove the
reality of the fa6l, had he done fo, even he, with the ftrong
prejudices he evidently has upon this fubjed, might have
doubted if ths ammonia entered into the compofitinn at all; to me
it appears, after attending carefully to the phenomena of the
folution, that it does not', but without determining pofitiveiy
on the fubjed, I (hall defcribe thofe phenomena, and leave
your readers to judge for themfelves.

The

154' ^^ COPAL VARNISHES.

Particular de- The copal niu(l be grofsly powdered and put into a conve*
^"^r^c^sfof ct^l"'®"*^ S'^^* veflel; the fpirit of turpentine and ammonia muft
in fp. of turpcn-be well fliaken together, and the mixture poured upon the co-
^ by ammo- j^i. ^^^ ^^ff^] clofed, and To much heat applied as Hiall, as
^^ fpeedily as poffible, make the fpirit boil fo ilowly that the bub-

bles may be counted as they rife to the furface; if this is IkiU
fuUy performed, the folution is feen to take place in the follow-
ing manner; the mixture has a milky appearance when firll
applied to the copal; the upper furface firfl becomes clear, the
cloud gradually fubtides, and attaches itfelf to the copal, which
fwclls and becomes opaque ; a portion oF it in a diflblved ftate
gradually exudes with the air bubbles, and diffufes itfelf in the
fpirit, and this continues till it has taken up as much as can be
The fuccefs fufpended in it ; no more is then diflblved: It is on the (kilful

depends on the jnanagement of thefe circumftances that the fuccefs of the

management ot o

thccircum- procefs depends; for, if lefsheat than the degree required be

ftan^cs. given, the folution flops ; if more, the bits of copal inftead

of being opaque and adhering together at the bottom of the
veflel, refume their tranfparency, and are agitated feparately
by boiling of the fpirit ; and when either of thefe accidents
happened, I could never afterwards diflblve the fame portion
of copal either in the fame or any frefti portion of fpirits. If
I might venture to explain thefe phenomena, I fhould fay, that
the ammonia gradually quits the fpirit of turpentine, and unites
with the copal, and reduces it to fuch a ftate, that with the
afliflance of the peculiar degree of heat that I have defcribed,
the fpirit of turpentine is enabled to diffolve fo much as will
form a varnifh ; but, if either more or lefs heat is applied, the
copal cannot be diflfolved, and then the operation is abortive,

Excellence of Whether this explanation be falisfaflory or not is of fmall

* *^"**» confequence, the exiftence of pidlures in my pofleffion, which
wc^re varniflied with this folution many years ago, and ftill re-
main more perfeA than they would have been if covered with
any other varnifh, is fufficient to prove that all Mr, Tingry has
faid on this fubjed has not the fmalleft foundation in truth.

Hint which pro. I had examined all the books which I had accefs to, without

duced the dif- getting any information refpe61ing the folution of copal for the
purpofe of making varnifh, till in Lewis's tranflation of Neu-
man's works I found the following. Vol. II. p. 27. " Solutions
of copal have been greatly efteemed as varnifties, and the me-
thod of making the folution kept a fecret'in particular hands:

Junker

ON CO^AL VAUVISHES. J55

Junker infbrms' us that it readili/ fucceeds, iffpirit of faUammO"
Iliac, mixed with a due proportion of oil of Jpike or oil of tur-
pentine, be ufed as the menftruum." Upon this tint I pro-
ceeded till I had difcovered the procefs I have defcribed ; but,
though the varnifti anfwered every purpofe I could wifti, the
trouble of making it being great, and the /ailure of the procefs
fo frequent that I determined to feek for fome more convenient
method.

Having found that copal, when powdered and rubbed in the Invention of
mortar with a fmall quantity of camphor, became foft, and in a ^gJJ^^ ^j^*
few minutes, united in one coherent mafs, I conjectured that by than aminonia.
means of camphor, copal might be diffolved in alcohol, and
upon trial found that it might be fo dilTolved, and rendered fit
for the purpofes of varnith ; this I did, not by way of experi-
ment, but in confiderable quantities and at various times ; fo
often, that I am authorifed to fay, that if the materials are
good, and the procefs I have defcribed in the Tranfaftions of
the Society for Encouragement of Arts be followed, there can
be no difficulty in making a colourlefs fpirit varnith from copal ;
and as a proof that this may be done, I fend you a fmall quan-
tity that I made fome time ago, and which will enable you to
judge whether it deferves to be "placed in the clafs of vamijkes.**

But as it is improper, for many reafons, to varnifti pictures Sp. of turpen-
with any fubftance diffolved in alcohol, I tried to diffolve the ^j^^^iPJ^^J""''
copal in fpirit of turpentine by the intervention of camphor,
and fucceeded ; not fo eafily indeed as in alcohol, but always
with the certainty of fuccefs, when the precautions I have de- /
fcribed were obferved; this has been uniformly the cafe with
myfelf for feveral years, as well as feveral artifts who have
made the trial ; and it has now been proved by many years ex-
perience that copal diffolved, by means of camphor, in fpirit of
turpentine, is as colourlefs as the refin itfelf and perhaps as jj^j^ ^j^r^j^ jg
durable, tince pictures that have been varniflied many years alfo excellent,
with it have been preferved without the leaft change even in
the colour of the varnifti, which would not have been the cafe
had any other fubftance been ufed.

As Mr. Tingry's experitnents lead to very different conclu-
fions, I am compelled to fuppofe, either that they were inac-
curately made, or that the copal, camphor, alcohol, and*

fpirit

* Mr. Tingry himfelf, as be fays, tried to diffolve copal in fpirit
of turpentine, and the procefs did not fucceed : his notion that the

fpirit

J56 •" COPAL VARWUHEJJ,

fpirit of turpentine in his country are very different from ih&
fubftances which are fold hy the fame names in this.
General My intention in communicating thofe papers to the Society

Ttmir . ^^g j^ ^^^ thofe who are engaged in the practice of the arts,

by making public a method of making a vainifti that muft be
valuable to them : and I have been induced to trouble you with
this, in hopes that, by printing it, you may prevent thofe falfe
notions, which might be formed upon Mr. Tingry's experi-
ments from gaining credit; to which you will allow me to add
fuch hints and improvements as may prevent difappomtment to
thofe who undertake to prepare this varnifli for themfelves in-
ilead of depending upon thofe who make it for fale ; this every
artift (hould do if he refolves to have it perfect ; for, though
I do not mean to fuppofe that every maker of varnith will fub-
ftitute inferior articles, yet it is certain ihat where the price of
cne article is higher, becaufe it is really valuable, and difficult
to make, many dealers will fubftitute fomething inferior that
produces more profit to himfelf, without confidering whether
it may not be injurious to thofe who are to ufe it.
Narrative of an J had feveral times given fome of my varnifh to an artift,
not fJc'^eedln who liked it fo well that he requeued I would inftruft him to
the procefb. make it himfelf, inftead of making frequent applications to me
for it : I procured him the neceflary apparatus, and gave him a
written account of the procef*, with fuch verbal inllrudions
as I could add to it, and left him to procure his own materials
and proceed to work by himfelf; he did fo, and did not fuc-
ceed in dilTolving the copal ; he tried a fecond and third time
with no more fuccefs; he then brought his materials to me,
requefted that I would try if I could diflfolve them ; which ex-
periment would determine whether his materials were bad, or
whether there was any defedl in his manner of attempting the
procefs : this I refolved to undertake; ufing the fame fpirit

fpirit I ufed had by chance obtained thofe powers fordiflTolvrng copal
which he endewvaurs to give it by timsy &c. is perfeftly ridiculous.
You and yoor Englifli readers will know that in faying I did not
fucceed when I ufed fpirit of turpentine from the colour /hops, but
always did when I got the fpirit from Apothecaries Hall, I meant
that at the latter place I always obtained the beft article of the kind,
inftead of the inferior ariicles which are fold by the fame ?iame in
other places, though totally unfit for this purpofe.

4nci

ON COPAL VARNISHES. 157

and copal which he had thrice attempted in vain to diflblve;
and at the fame time fubjeftihg another portion of ray own
materials to the fame procefs in every particular : I fucceeded
in both inftances : the only difference was that the folution
which I produced from the materials which had been tried by
my friend was not fo vifcid as that which was obtained from
the freih materials.

As the procefs which I have ufed for fome time pad is dif- Improve*!
ferent from and better than that wliich I communicated to the ^'^^
Society, and has been pubiiftied in their Tranfa^ions, I truft
you will excufe me for defcribing it here; it is fuch an one as
may be fuccefsfully ufed by any perfon upon a common fire,
without any danger, and which any man of fcience, or who
may chufe to adopt in a large way, may eafily modify fo as to
anfwer his purpofe. ' '■'

Provide aflrong vefTel made of tin or other metal, it fhould Safe and eafy
be fhaped like a wine bottle and capable of holding two quarts ; ^ ^.^ j ^^^^l
it will be convenient to have a handle ilrongly rivetted to thenifli.
neck; the neck fliould be long and have a cork fitted to the
mouth, but a notch or fmall hole fliould be made in the cork,
that, when the fpirit is expanded by heat, a (mall portion may
force its way through the hole, and thus prevent the velfel from
burfting.

Diffolve half an ounce of camphor in a quart of fpirit of tur-
pentine, and put it into the vefTel ; take a piece of copal the
fize of a large walnut, reduce it to coarfe powder or very
fmall pieces ; put tliem into the tin bottle, faften the cork down
with a wire, and fet it as quick as poffible upon a fire fo brifk
as to make the fpirit boil almoft immediately; then keep it
boiling very gently for about an hour, when fo much of the
copal will be difTolved as will make a very good varnifli ; or,
if the operation has been properly begun, but enough copal
has not been diflblved, it may be again put on the fire, and by
boiling it (lowly for a longer time, it may be at laft brought to
the confiftence defired.

The rationale of the operation I believe will be nearly as Explanation of
follows : copal and camphor have fo firong an affinity for each ti^« procefs j
other, that when feparately powdered and th6n rubbed toge-
ther, the copal abforbs the camphor, fwells, foftens, and be-
comes one coherent mafs; nor when once united do they eafily

feparate

153 P^ COPAL VARKISHES.

feparate again *. When the camphor Is diflblved in the fpirit,
the finall bits of copal thrown into it and inftantly made to boil,
the motion of ebullition keeps the camphor fufpended, moves
the copal about in the fpirits, the furface of each bit of copal
is diflblved, and the whole of it foftened and enlarged, and by
—and why Mr. continual boiling may be diflblved ; but ray friend did not pro-
S.'s friend failed, ceed in this way ; he reduced his copal to a very fine powder,
thinking, perhaps, that would facilitate the folution ; he then
added the camphor, diflblved in the fpirit of turpentine, but
fearful of giving too much heat, fet it by the fide of his fire
till it was warmed, then moved it into a warmer place, and
at lad made it boil ; the confequence was that the camphor + left
the fpirit and united with the copal to form one folid coherent
mafs at the bottom of the veflel ; the thicknefs of this mafs
prevented the heat from penetrating to the fpirit fo foon as i'
otherwife would have done ; and, when at laft it did boil, the
camphor had entirely left it, and of courfe it was impoffible
that any folution (hould take place.

Three times was the folution attempted in this manner, but
when on a fourth trial by myfelf a fufficient quantity of cam-
phor was added and the boiling heat immediately applied, the
folution went on, but not fo favourably as in my other attempt,
becaufe the copal was united into one mafs at the bottom of
the veflel, and no more could be expofed to the a6lion of the
folvent than the furface ; but, in the other experiment the
copal was broke into very fmall bits and the furface of each
expofed to the full adion of the folvent ; of courfe a greater
quantity was diflx)lved in the fame fpace of time.
Thelnftanccof Had this gentleman been fatisfied with the experiment he
failure here ^^jg^ jjy hm^fgif he might have reported, from his own expe-
mentioned might . •^, ,7 , ,.S , r

have been urged rience, that copal could not be diflblved by the procefs I had

againft the defcribed ; and yet in point of fa£l, nothing could have been

more untrue : from this it may be fairly deduced that when
perfons who are unufed to fuch experiments do undertake them
they (hould be fcrupuloufly exa6l in following the directions

* Six montlis ago I reduced fome copal to this ftatej it has re-
mained ever fince expofed to the open air in a hot room, and ftill re-n
mains foft, the particles adhering to each other.

f When the fpirit of turpentine was poured off from the copal
it was perfeftly colourlefV, and by the fmcU did not in the leaft ii
dicate the prefence of camphor.

giv<

ON COeAL VARNrSMES. 25^

given to them, and on any apparent failure, refort to thofe
whofe experience may enable them to detect any fallacy there
may be in the proceeding.

As it is well known that folUtion of copal is the mod valu- Remarks and
able of thofe varnifhes which can be ufed for the finer works of^*"''^'*^'
art, and as it is proved that by the procefs I have defcribed,
thefe folutions may be eafily made by any one in almoft any
fituation, it only remains to mention fome cautions which are
necefTary to enfure fuccefs.

Firft, That the fpirit and camphor fhould be united before
the copal is added.

Secondly, That the copal fhould be grofsly powdered before
it is added to the fpirit, the whole (hould then be made to boil
as quicklj/ aspojfibk, but not violently, and that ebullition Ihould
be kept up regularly till the folution be compleat.

There feems to be no difadvantage in ufing too much cam-Effeas of an
phor if it (hould fo happen ; but it is difadvantageous to put overdoie
in too little copal; becaufe a certain quantity of fpirit will of copal,
take up a given quantity of copal; and if more is added than
will be diffolved, the fuperabundant copal will abftradt more
camphor from the liquid, and thus render the folution more
tedious and difficult, and fometimes, perhaps, entirely pre-
vent it.

The advantage that attends the ufe of glafs veflels is that theciafs veffels an*!
folution may be feen all the time it is going on ; the difadvan-^^^^*^ of metal
tage is that perfons who are not accuftomed to fuch purfuits,
may inadvertently give too much heat, and thus fubjedl them-
felves to ferious accidents; but by ufing veflels of metal with
the precautions I have given, no accident can happen ; the
only difadvantage is that they cannot fee what they are doing ;
this is of fmall confequence, as it may alv/ays be determined
with fufficient accuracy by the ear whether the fpirit boils> and
to what degree ; and as no accident can happen, without very
grofs neglect, from the ufe of them, they certainly fhould be
preferred.

As I have written more than I at firfl: intended, I fhall con- Condufion.
elude with a requeft that you will ufe your difcretion in omit-
ting any part or rejedling the whole of what I have written,
if you think the publication will not anfwer any ufeful purpofe.
I fend with it afuiall quantity of copal dilTolyed ia alcohol, and

another

IQC) CONSTITUTION OF MIXED GASES.

another in fpirit of turpentine, which will enable you to falisfy
yourfelf and your readers whether thefe folutions deferve to he
placed in the clq/i qf varnijhes, and remain

Your raoft obliged fervant,

T. SHELDRAKE.

No. 5, Montague-Street, -
* Rujfel-Square,

IV.

Reply to Mr, Dalton, on the Confiitution of Mixed Gafes^
By Mr, JoHii GovGH»

CJiarafter of
Mr. Dalton*s
reply.

Mr. D.'t de-

monftration rc-
Tiewed.

To Mr. NICHOLSON.

SIR, MiddleJkiWy Oa. 16, 1804.

1 DID not attack Mr. Dalton's opinions openly, until he had
invited roe to do it ; the attempt has been made on my part
purfuant to his requefl: ; and he has replied, but in a manner
which feems better calculated to amufe the fuperficial reader,
than to convince the reafoner : For he treats the fubjecl,
fometimes with acrimony, and fometimes with ridicule ; in
the mean time his arguments are but few, and thefe appear to
be negligently condu6led. A bare infpedion of his own letter
will fupport the two firft charges, and I will now enter upon
the defence of the third.

Mr. Dalton begins by pronouncing the diftin^ions which I
make betwixt a mechanical hypothefis and theory, to be nu-
gatory ; notwithfianding the caufes of thefe diriin6iions arc
fully llated in my Stridures. Now controverfy is of a nature
which always obliges a man to point out the fallacy or futility
of his opponent, when he can do it with fuccefs ; but this has
been negleded by Mr. D. in relation to my diftindlions, and I
leave him to draw the inference which refults from thefe ob-
fervations,

Mr. D. proceeds, in the next place, to demonftrate the fun-
damental propofition of his hypothefis ; namely, the mutual
penetrability of gafes which do not attract nor repel each other.
For this purpofe he remarks, that oxigen repels oxigen, but

not

COXSTITUTJON OF MIXJSD GASES. IQ\

not azote. This afTumption is fairly allowed to be a poftulate
byMr. Daltonj and he then proceeds to obfervc, that this
being admitted, it follows, that if a meafure of oxigen be put
to one of azote, the oxigen finding it, viz. the azote, porous,
enters its pores, and vice vcrja, &c. But here a fecond and
an eflfential poftiilate is flily introduced into the fyllogifm, un-
der the form of an inference ; becaufe no ft rid logician will
venture to fay that a body. A, muft be porous of neceffity,
becaufe it repels a body B ; on the contrary he muft conclude,
that this miftake in his art deftroys the demonftralion, and
does not retrieve the dodrine from the imputation of being an
hypothelis. The fimile of the philofopher, cottager, and fieve, Mr. D.'s fimile
may be calculated to promote ridicule, but it is badly chofen ; '"^^^^^^^^ •
for it is impoffible to demon ftrate the propofed problem froai
Euclid's Elements, becaufe this work confines its fpeculations
to abftra6l figures and magnitudes. But a mathematician
might demonltrate the fame to a brother mathematician, from
the elements of the mechanical philofophy ; and he ought to
have his demonftration ready upon demand, which is not the
cafe of Mr. D. in the inftance of his fundamental propo-
rtion.

It is a matter of forae furpHfe, that Mr. D. has drawn his The fecond pof-

demonftration from the mutual affbaions afcribed by him to ^"^^^^ £''^^^ '" -

J the m fiance of

oxigen and azote; feeing I had profefledly attempted to fliew vapour and air.
the fallacy of his fecond and eflential poftulate, by afcribing
the fame affections to aqueous vapour and the permanent gafes
of the atmofphere. This unfortunate choice obliges my oppo-
nent to be content with a diflant fide-view of the arguments
which have been brought againft him ; whereas a fl;ri6ter ob-
fervance of the path* chalked out for him in my Strictures,
would have given him an opportunity to confront them, and
defend his atmofphere of fteam. The thing however has
turned out, for fome reafon or other, as it is here reprefented;
and Mr. D. arrives very briefly at the following fingular con-
clufion ; that though the demonftration of my propotition re-
fpedling air and vapour, be rigid, the previous data are not
correftly aflfumed. Now this is the point which I endeavoured
to eftablifli in the propofition alluded to above; for his fecond
poftulate makes one of the incorred data; in fact, they are all

* Phil. Journ. Vol. IX. Page 53.
Vol. IX,— November, 1804* M bis

i

\Q^ CONSTlTUtlON OF MIXED GASES. '

bis 6\vn except this: If a particle of vapour can pafs freefy
through the air, a fecond can alfo fucceed it at any given
diftance. My antagonift will certainly grant me this con-
ceffion ; becaufc the falvation of his aqueous atmofphere obliges
him not to fufped it. Should this indulgence be extended to
my Stridures, the demonftration in queftion muft be re-exa-
mined v^^ith greater diligence by Mr. Dalton ; for if it cannot
be refuted, it will manifeftly do away his atmofphere of free
vapour, by proving the abfurdity of his fecond poftulate in the
cafe of air and water ; and the fame obfervation may alfo be
extended to all the permanent gafes which are not abforbed by
water ; becaufe no fluid of this defcription forces water to pafs
through its pores by preffing upon it.

The ufeof the After all, if we may judge from Mr, Dalton's reply, he ap-

anafyfis^ *^'^* pears not to comprehend my arguments on this fubjed : they
have however nothing of novelty in them ; for the bell rea.
foners in all ages have not hentated to admit a hypolhefis is for
the fole purpofe of difcovering its worth, by comparing the
confequences refulting from it with known fads. This kind
of argumentation was in great efteem with the Greek mathe-
maticians, and Pappus of Alexandria has defcribed and re-
commended this fpecies of logic under the name of the con-
templative analyfis.

Faftsoppofing Mr. Dalton fays, he is acquainted with no fads that con*
ypo e }s. ^^g^jj^ what I call his experimental probabilities. I can fur-
niih him with one to which perhaps he is a ftranger, and re-
mind him of another, which he will not difpute : it will there-
fore be his bufinefs to reconcile them to the hypothecs of an
aqueous atmofphere.

An experiment Fifji, Mr. Kirwan, in the courfe of his flatical experiments
y r. irwan.Q^ ^j^.^ conftantly found a given bulk of it to be lighter, ccEtens
paribus, when De Sauflure's hygrometer was at 90"^, than
when the atmofphere was lefs humid. Now according to
Mr. D.'s hypothefis, all the permanent gafes, of this given
bulk, had the fame weight both in the dry and moift ftate of
the air ; becaufe they were of the fame denfity on account of
the ccettris paribus : but the aqueous vapour was moft abun-
dant when the weight of the aggregate was leaft ; that is, the
weight of vapour dirainifhes, while its denfity increafes. Will
Mr. D. admit the truth of the preceding conclufion, to the
detriment of his own dodrine; or will he refute the infer*
ence, by denying the fad ?

4 StcQtid,

CONSTITUTION OF MIXED GASES. J^J

- Second, If the latter alternative fliould be preferred, the An experiment
rollowing experiment, with which Mr. D. is already ac- ^'^jj^* ''^'
iquainted, remains to be explained by the principles of his
hypothefis, due attention being at the fame time paid to the
axioms of Dynamics.

A moid bottle, which I had found would contain 7794
grains of water of the temperature of 59**, was placed in
water heated to 126°, having its mouth elevated about two
inches above the furface. This aperture was covered by my
hand ; which was occafionally removed for an inftant, that the -
warm air might efcape. At the end of two minutes the bottle
was inverted in cold water, the mouth of it being firft fecured
in the manner defcribed above ; in which fituation the tem-
perature of it was again reduced to 59**. The air remaining
in it after refrigeration, occupied 6172 of the 7794 parts con^
ftituting the capacity of the bottle. From this fad I infer,
that 6172 parts of air of 59^, will occupy *7794< fuch parts
after being raifed to 126'* in contact with moift glafs. But
6172 parts of dry air of 59®, will only occupy 6992. C6 parts»
after being heated to 126® in a dry tube; Thus it appears
that the prefence of water augmented the bulk of the air
which I ufed; how is this difficulty to be explained i We
have no ftopple of mercury in this experiment, by help of
which Mr. D, explains the appearances of the manometer;
confequently, as nothing was in the way to prevent the free
egrefs of the vapour, it expanded itfelf in the bottle, and
aded on the air contained in the fame, juft as it does in the
atmofphere. But it increafed the bulk of this air, which could
not be effeded on Mr. D.'s prirvciples, otherwife than by dif-
tending the pores of it. Now his own tables of the force of
vapour will (liew this to be impradicable, if there be any truth
in the axioms of Dynamics. On the contrary, nothing oc-
curs in the two laft experiments repugnant to chemical union ;
and as water makes a part of the atmofphere, it muft be at- /

tached to air by the rnediation of affinity.

I have now done fomething more than anfwer all Mr. RecapItulaUop;
Dalton*s objedions : the demonftration of his fundamental
propolition has been (hewn to be no demonftration at ail ; his
fecond populate has been proved to be falfe, by his own data^
in the cafe of air and vapour ; laftly, two fad^ have been
advanced which are inexplicable by my opponent's prin-
M2 cipit

les;

5[§4 '^'-'^ ^^ "^"^ HORIZONTAL MOON.

cipleis : After perufing thefe obje6tIons, can he blame me for
reje6iing his hypothefis. As for Mr. D.*s remarks on my
theory of mixed gafes, they require no anfwer ; becaufe he
profeffes not to underftand it. I am willing, however, to
fubmit the merits of it, as well as its claim to the title of a
'theory, to thofe mechanical philofophers who happen to com-
prehend it.

JOHN GOUGH.

V.

On ilte apparent Size of the horizontal Moon, In a Letter from
Mr. EzEKiEL Walker.

DEAR SIR^

Enlarged appear,
ance of the ho-
rizontal moon.

Attempts to ac-
count for it.

To Mr. NICHOLSON.

HEN the full moon is juft rifing above a clear horizon,
(he is an object that pleafes every eye : But at the fame time
that (he pleafes the eye of the philofopher, fhe embarrafles his
reafon, to affign the caufe of her apparent magnitude's being
fo milch greater near the horizon, than at higher elevations.
■ When men in former ages began to reafon on this phenome-
'non, they imagined that the angle fubtended by the moon, was
Yeally increafed, by arefradion of her rays, in paffing througli
the vapours contained in the air, near the earth's furface. But
when it became known that the fubtended the lead angle at the
eye, when her apparent magnitude was greateft, philofophers faid
that the eye was impofed upon by the long feries of objeds
interpofed between the eye and the extremity of the fenfibfe
horizon. And after It was difcovered that the fame pheno-
menon was bbferved at fea, where no land obje6ts could be
Teen, they blamed the clouds for deceiving them ; and when
the clouds fle>)v away, the fpirit of inquiry flew after them,
to feek for information in the apparent concavity of the Iky.

Such were the erroneous opinions maintained by men of the
greateft celebrity, both in ancient and in modern times. To
mention any more of them would be ufelefs labour : a fingle
quotation from Dr. Smith's Optics will, I prefume, be quite
fufficient to fhow how little was known of this matter at the
time when he wrote.

After

SIZE OF THE HORIZONTAL MOON. f ^^

After Ihe ProfefTor had finifticd his celeftial exjilanation of

uiis phenomenon, he juftiy acknowledges that, at diflTerent^

imes, the moon appears of very different magnitudes, even in

the fame horizon, and occafionally of an extraordinary large

fize, which he is not able to give a fatisfadlory explanation of.

Smith's Optics, Vol. I. pa. 63, &c. Remarks, pa, 53.

It is really aftonifliing, that this phenomenon fliould have re- Explanation of-

mained fo long without an explanation founded on a better P""~po^ntion^that th

ciple than that of mere opinion. That the dimenfiorjs of the images on the

pupil of the eye alter by the ftimulus of light, has long been retina vary with
1 \ ^ , . , , , , thefizeotthe

known; but I believe it ftill remains to be proved, that the pupil.

pidure of the moon formed upon the retina is not pejmanent,

but varies as the dimenfions of the pupil vary. The following ^^ ^^ ^ r^

experiments will, I hope, remove every doubt refpecling this " »

law of vifion.

To imitate the eye upon a large fcale, I took an achromatic Experiment.

lens of 1.6 inches in diameter, and 17 inches focal diftance, to placed bef^e^a

reprefent the cryftalline humour. This I fixed upon a fland in achromatic lens,

a perpendicular direction, with a moveable white fcreen be- ^"^ '^^''^^ ^P""
, • 1 • r 1 • • 1 • r I- , 1 ., tures were pro-

hmd It for the retina, to receive the image of a lighted candle, vided.

which ftood before it, at the diftance of 40 inches. To imitate

the pupil, I took three cards, and numbered them 1, 2, and 3,

In No. 1, I made a circular hole half an inch in diameter, in

No. 2 a hole of -^-^ of an inch, and in No, 3, a hole of -^

of an inch.

After I had moved the fcreen until the image of the candle Focal image by
appeared diftindly upon it, I found that the length of this f Ij^'^^hi,""
luminous picture meafured 1.82 inches. Jong.

When the card No. 1, was applied clofe to the lens, with Half an inch

the centre of the hole againft the centre of the lens, the in- aperture gave an

*=• , image of 1.46

verted image of the flame of the candle, upon the fcreen, inch.

meafured 1.46 inches.

When the card No 2, was applied to the lens, in the fame Three tenths
manner as No. \, the image of tlie flame meafured 1.3 gave 1.3 inch,
inches.

And with No 3, the picture of the flame meafured only 1.2 Two tenths gave
inches. 1.2, inch.

Thefe experiments lliow us, in thecleareft manner, thecaufe Application of

of that variation which obtains in the apparent raajinitudes of ^^^ "P"''"^"*^.

^ to the moon ana

ODjetls, other obiefts.

That

If^ IMPROVED METHOD OF CONSTRUCTING SHIPS.

That the pupil contra6ls as the quantity of light which falls
upon the eye increafes, is well known.

And that the magnitude of the pi6ture of a luminous object
upon the retina, decreafes as the pupil contrads, is evident
from the experiments.

Therefore, the magnitude of the picture upon the retina,
decreafes, as the quantity of light falling upon the eye in-
creafes.

Hence the apparent magnitude of the moon is greateft at the
horizon, and decreafes as (he afcends ; for the magnitude of
her picture upon the retina is inverfely as the quantity of light
which (he gives us.
^d to the fun. The fun appears larger at the horizon than at higher altitudes,
for the fame reafon ; and terreftrial objeds feen through a mift
appear larger than in a clear day_, in confcquence of the famq
operation of the eye.

I am. Dear Sir,

With much refpefl.

Your humble Servant,

E. WALKER.
lynn, Oa. 13, 1804.

VI.

Dejbription of the Ship Economy^ 200 Tons Meafurement, built
on the improved ConjlruSiion of Mi\ J. W. Bos well. ^

-a- HE plan adopted in the formation of this (hip is that defign-
ed for large (hips of 500 tons and upwards, and the third men-
tioned in my fpecification f.

Its external appearance is nearly the fame as that of any other

veflel of the fize, and the outward planking done in the ulbal

Tnanner. Jt»is the internal conftrudion alone to which the patent

relates, and that is as follows ;

Dcfcription of a The beft general idea of it will be obtained by conceiying a

vefftl framed in ^gfl-^j j^^jif with timbers, or ribs, much fmaller than ufuai, with

a new method.

♦ For which he has a patent.

•f- See Vol.11. Second Series, p. 31, of Repertory of Arts.

an

IMPROVED METHOD QF CONSTRUCTING SHIPS. 1^7

an internal framing, fo contrived as to give every requifitefiip- Defcrlptioa of a
port and ftrength both to them and the entire veflel, with ^ ^^^^ method.
the leaft timber, and of the cheapeft form, and without any
knee-timber.

The floor-timbers are molded feven inclies, and fided fix{
thefe, with four futtocks and two top timbers at each fide,
form what is called a frame of timbers. Thofe fmal! timbers
are laid down fo that their terminations all fall out in fair lines,
which are nearly the fame as the ribband lines, when below the
wales. Along thofe lines infide are laid fore and aft ribs, from
flem to ftern poft, fo as to fupport the extremity of every one
of the fmall ribs in the fliip. The fore and aft ribs are fix in
number at each fide; one diredlly under the water ways, an-
other at the level of the lower beams, and the other four placed
nearly at equal diftances between thefe laft and the kelfon : each
pair uniting in a breaft-hook at the ftem.

The pieces of timber which form thefe fore and aft ribs are
fcarfed at tJieir extremities with hook fcarfs, and fo placed that
the fcarfs fall out in fair vertical fe6lions of the Ihip, where
they are fupported, and firmly bolted to tranfverfe framings>
contrived fo as to unite the greateft ftrength with the leaft ob-
llrudlion, and which are five in number in the whole (hip.

Thofe tranfverfe framings laft mentioned rauft be confidered
as the great fupport of the veflTel, and the foundations, as it
were, on which all the other parts reft, as the beams of a .

wooden bridge are fupported by the piers. Thofe tranfverfe
framings are each formed by one upper and one lower beam,
two pair of futtocks, a floor timber, two pair of top timbers,
and four bracing pieces ; the whole conne<Sted into one firni
framing, felf-fupported, independent of any other part.

The four bracing pieces form each framing into a fet of tri- The leading
angular compartments : which triangular framing gives the principle is that
greateft ftability poflible, as a triangular frame cannot be made frSigrc»nnot
to give in, or alter its figure, by any force which is not fufii- vary,
cient to tear its connecting parts through the timber of which it
is compofed ; a property which no other figure pofleflfes.

Thefe tranverfe framings (beftdes fupporting the fore and aft
ribs, arid by them the fmall vertical timbers) tie and unite the
veflTel together acrofs fhip, fo as to give much greater ftrength
than hanging-knees, whofe place they fupply, at a much ^

cheaper rate.

168

Framing of the
deck.

IMPROVED METHQD OF G^NSTRVCTINO SHIPS.

The framing of the deck, is alfo divided into triangular com-
parlments, as fpecified in my patent, as to preclude the ufe
of lodging-knees entirely ; which compartments are formed by
fix pieces of timber, which proceed obliquely at each fide, from
the top of each beam to the fore and aft rib ne>tt adjoining, into
which they are dovetailed and bolted ; long carlings from beam
to beam, at each fide of the hatchways, with thefe pieces,
fupport fmall ledges, on which the deck is laid in the ufual
manner.

The vcflel in coming round from Southampton water failed
remarkably fad, and flayed and fleered admirably well.

Advantages of
the method :

ih price of tim-
ber}

ufe of ftorter
pieces, &c.;

knees fupcr-
fededi

Advantages of this Mtthod of framitig Ships.

1ft. Timber of lefs than one fourth of tiie ufual girth can be
ufed, in this method, in conftru6ting large veifels, for nearly four-
fifths of their frames.

This will be a direft faving in the difference of price of fmall
timber and large for the quantity ufedj for large veffels this
will be confiderable, and, according to the [)re(ent contract
prices for naval timber, not lefs than from two to four pounds
per load. Befidcs this, it is a great national benefit in another
point; for, by this means, timber of half the number of years
growth, or lefs, can be ufed for naval purpofes ; and thus forty
or fifty years, or even lefs, be fufficient to produce timber fit
for the navy, inftead of the vaft period of near a century, now
neceflary ; by which the land will not only produce a double
crop in tlie fame time, fit for this purpofe, but all danger be
removed of there being a ftoppage of building, lor want of a
fupply of timber, at any future period; an event extremely
probable to take place, from the increafing difficulty of getting
the large kind ufed at prefent in the Royal Dock Yards.

2d, Much (horter timber may, in forming the futtocks, be
ufed, without any danger of weakening the fliip, on account
of the great fupport given to them by the fore and aft ribs, and
other internal framing, before defcribed.

The advantage of this is, that it renders the compafs timber
for futtocks eafier to be procured, and prevents any neceffity of
ufing any timber cut acrofs the grain.

3d. The ufe of kneeii of every kind h fuperfeded by this

mode of building, as the triangularframing of the decks gives

5 all

JNffttOVEDr METHOD OP CON STRUCTI JTG SHIPS. 159

all the eifecl 'of lodging-knees, and that of tiie tranrveffe
frames more than fupphes the fupport given by hanging-
knees.

Tliis would occafion a confiderable faving in large vefTels,
on account of the great price of knee-timber fit for them;
which, for that of 30 feet meeting, is near ten pound per load
and for the fmalleft kind, taken at the dock-yard, not lefs than
SI. I5s. ,

4th. Plank of half thfeufual thickneis may be ufedfor lining; thinner plank-
the great fupport given by the fore and aft ribs rendering any*^^^'^
life of infide plank, to ftrenglhen the velfel, needlefs, and con-
fining its purpofe merely to prevent ballad, or other matters,"
from getting between the timbers, fo as to reft on the outfide
plank.

This will al fo caufe a faving of confequence in large yeflels ;
plank of all kinds, but particularly that' of great thicknefs^
being the next deareft article to knee-timber.

5th. It is probable a much lefs quantity of limber might be leCs quantity of
ufed with fafety ih this method, on account of the great ftrength "^^'^^"^'^>
produced for the timber ufed. ift. By the triangular framing.
2d. By every timber having a folid fupport at each extremity.
3d. By the increafe of thicknefs from in to out all along the
fore and aft ribs, being very great in proportion to the tim-
ber ufed.

6th. It is probable, veflels built in this method will laft durability,
many years longer bef6re decay; becaufe the ufe of fmall
timber admits of a kind more fpiny and durable than the large,
which is often dotard, and never lafts fo long; and alfo becaufe
this conftrudion admits of a free circulation of air among the
timbers, than which nothing is known to contribute fo much to
their prefervation. It is moreover conceived, that the timbers
being prevented from working by the folid fupport each has at
its extremities, will caufe the vetfel to wear lefs, and at the
fame time render it fafer, by diminithing the danger of ftarting
planks, or otherwife caufing bad leaks,

7th. The timber of confiderable ilze ufed in this method is
almoft all nearly ftraight, or of very little curvature, on account
of its running fore and aft.

This kind is much eafier to procure than large compafs
tiaiber.

8th.

J70 IMPROVl^O MBTirOD OF CONSTRUCTING SHIPS.

8th. Short-top timber and coarfe butts can be worked up
to advantage, inftead of being fold for lefs than half coft,
or burned ; as this kind will do fufficiently well for the
i)umber of thort ledges in the deck frames, and to fupport
the lining at the floor, which are wanted in this mode of
building.

9th. VefTels built in this manner will not be fo liable as
others to hog, or have their backs broken, on account of
the great flrength length-ways, caufed by the fore and aft
ribs.

lOLh. Veflels fo built will be drier, from the circulation of
air before mentioned, and having the floor-lining detached from
tjie timbers ; which quality renders this conftru6tion parti-
cularly valuable for the fliips ufed in the Eafl and Weft India
trade.

The advantages above recited relate to vcflels entirely form-
ed in this manner. It fiiould be known alfo, that parts of this
plan may be applied with profit. The mode of framing the
decks, for inftance, might be ufed to fave lodging-knees in
veflels built in other refpeds in the ufual mode. Other parts
of it might be applied to the ftrengthening old veflels, which, by
this means, might be made to laft many years, after they would
other wife have been unferviceable.

The principles of this method of building are capable of
being extended ftill further than they are in the veflel here de-
fcribed ; the triangular framing may be even adopted to the
conftruflion of fore and aft ribs, fo that thefe could alfo
be conftrufted of fmall timber, if required. Thus, by this
means, the former barrier to the increafe of fize in fliips is re-
moved, as it no longer now depends on the fize of timber ;
and fliips of any dimenfions required may be formed, of any
firenglh requiflte, of fmall timber.

J. W. BOSWELL,

Concluding

POMFUTATION OF SQUARES AND CUBES, 171

VII.

Concluding JRemarks on the Computation of Tables of Square*
and Cubes. In a Letter from E. O.

To Mr. NICHOI^SON.
SIR,

1 AM ferry to trouble you again on a fubjeft which I fear On the compu.
can afford but little intereft to the generality of your readers; ^^^ cubes,
but I niuft requeft the admiffion of a few remarks upon
the letter which you publiftied in your laft number from
p. G.

Your correfponderit is certainly miftaken when he aflerts
that our methods of calculating fquares are ** precifely the
fame :" Both, indeed, are derived from the principles of the
binomial theorem ; but I conceive that there is a material
difference in our manners of applying thofe principles to prac-
tice. As we find the fquare of the given number by adding a
certain quantity to the known fquare of the number next be-
low it, it follows, that in both methods the quantity fo added
muft be the fame ; but there is a confiderable difference in the
operations by which we find this number : I do it by the re-
peated addition of the fmall number 2, whereas H. G. finds
the fame quantity by the repeated doubling of a number,
which is conftantly changing, and may poffibly confift of many
figures. To fhew the difference more clearly, I will calculate
feveral fquares according to the direftion given in P. 150,
Vol. VIII. and I will take for my example the fame which I
Jiave taken in P. 6, Vol. IX. that your readers may the more
eafily form the comparifon for thenafelves.

28261
2

2.28261

28262
2

56522 =

56524. =

798740644 =

1

2.28262

798684121 ==
1

2826 iV

282621 «

798740644 =

28262>

798797169 =

28263^'
28263

272' COMPUTATION QF S<^yA9BS AND CUBES,

On the compu-
tation of fquares
and cubes*

1
798

.28253
2

56526 ■;:? 2.282^3

28264.
2

56528 == 2.2S264.

797169 .=; 282631''
1

798853696 = 28264V-
1

798853696 = 2826-40* 798910225 = 282651'^

Perhaps it may be obje6led to my ftatement, that the calcii,
later would be aware that 28264.. 2 =: 28263 .24-2 = 2826:2
.2 -j- 4, &c. or that he muft (oim difcover this law of conti-
nuation ; and therefore, that he would not proceed in every
iaftance to the adtual mulliphcation of tlie root by 2. Such
an objection, however, will avail nothing again ft my argu-
ment, for in tl)at cafe he will no longer work by the rule
given by H. G. in P. 150, Vol, VIII.; but if he proceeds to
find the difference by addition, he muft virtually purfue the
method which I recommend : the only difference will be, that
the pra^ice of calculation will have (uggefted to him an im-,,
provement which he might have originally derived from firft
principles.

I ftiali not enter into the queftion, whether addition is, or
is not, a iimpler procefs than (ubtradion. The prefent quef-
tion may be decided Independently of it. For grantir^ that
there is no reafon to prefer one to the other, yet the two me^,
thods by which we lind the firft differences of the c\jbes,
might be; fairly put to iffue upon the number of figures ufed in
e.ach. To find them according to the mcfthod recommended
by H. G. in p. 150, Vol. VIII. we muft fubtra6t the whole
of one cube from the whole of the other ; whereas I find them
b,y theconftant addition of the fecond differences, which muft
neceffarily be much frnaller no^mbers. Thus to find the fitft
difference between the cubes of 26561 and 26560 :

According to H. G, According to E. O.

18738432796481 2116221121

~ 1873^316416000 + 159360

21163804S1 2116380481

It is ftated, indeed, by H. G. that he avoids the continual
repetition of firft differences; By this we muft not underftahd

that

COMPUTATION OF SQUARES ANB CUBES. 173

"that his method lii&kes it unneceflhry to calculate them ; for On the compu-
by mere comparifon of p. 9 with p. 125, it will be feen that ^jj^^^^j^^^^**"^'^*;^
we both ufe (he fame numbers. In this inftance, asjn that of
the fquares, the real difference between the two methods
confiils in the manner of finding thefe additional quantities.
H. G. mufl therefore mean, that he avoids the neceflity of
^Calculating the table given in p. 8. Now in this I do not
'tlirnk that any advantage is gained. For if the firft differ-
'Hfences are to be found feparately, 1 have (hewn that they can
he more eafily found by the method which I have recora-
raended ; and much expedition will be obtained by making a
feparate table of them, which is impoffible if we work accord-
ing to the diredions of H. G. I may, with fome reafon,
complain, that H. G. has not made his example a fair parallel
to mine ; for I have fet down every figure which need be ufed,
while he has declined printing any of the operations whereby
he determined his firfl: differences. It is poffible, indeed,
from long pra6lice in arithmetical computations, that he may
be able to cafl his eye from one cube to the other, and fo , .

find the firft differences, without copying them out on the
fide of his paper for fubtradion. I ftiall not dwell upon the
danger of miftake in fuch a procefs : the quickeft and mod
accurate eye could hardly avoid frequent errors, and the com-
mon arithmetician will find it attended by confiderable diffi-
culty. But granting that all this difficulty could be com-
pletely conquered, ftill it would give no fuperiority to the
method recommended by H. G. ; for it might be applied to mine
with equal, if not greater eafe and advantage. Thus, in the ex-
ample given in p. 125 ; if F were computed by the addition
of C and D, inftead of the fubtraftion of A from E ; if we
confider I =r F -1- G infiead of = H - E, M = I -f- K in.
ftead of z: L — H, &c, we (hould have the differences com-
puted according to my rules. We may remark likewife, in
this fliorter method of calculating, that, according to the ar-
rangement given by H. G. himfelf in p. 129., the ,e)'e mufl
neceffarily pafs over two intermediate lines of .figures in fub-
trafling one cube from the other, whereas the two. rows of
figures which I would have added to one another, may
always be placed contiguous. This certainly is an advan-
tage ; but at the fame time I only mention it to fhew the

grounds

174 COMPUTATION OF SQUARES ANO CUBES.

On the compu- grounds on which I prefer my method to that of H. G; ;
tation of fquarcs f^,. j fjin confider the plan which I firft Jaid down as the
and cubes. ^ n ^ r r,

eafielt and fureft. . .

I have faid, that if the differences are confidered in p. 125
as found by addition inftead of fubtra<5i:ion, the example;
would fuit with my method, becaufe the fecond differences
are ftill additional, and will be found, upon comparifon, to
be added in exaftiy the fame order as in pp. 8 and 9. The
only variety is by making two tables: I add the fum of the
two numbers which are feparately arranged under each cube.
I have only to add on this part of the fubje6t, that H. G. has
adopted my method in feme meafure ; for he fays that K ==
G -[- 6» as well as = 6d. It is true (as I remarked with
refpe<5l to the fquares, that this equality would moft probably
occur to the calculator; but at the fame time we rauft recoi-
led, that it is different from the rule laid down in p. 150,
Vol. VIII.

I (hall not add any thing to what I have ftated in p. 5,
with refped to the miftakes to which either method is liable;
but I fliall conclude by affuring you, that it is not my inten-
tion to trouble you any more on the prelent fubjed. I
thought it might be ufeful to publifli the letter which I firrt
fent you, and having done fo, it became neceffary to remove
any obfcurities in it, and to anfwer any miftaken objedlions
which might be raifed againft it: but this having once been
done, there can be no occafion for further controverfy ; and
I have only to thank you for the indulgence which you have
granted me.

I am. Sir,

Your obliged humble fervaiit,

E. O.

P. S. I take this opportunity to beg you will mention two
or three prefs errors which occur in my former letter.

P. 9, line 20, dele the Italic e.

P. lo, line 12, X + lY , read in both inftances, x -^ i\*
p. 12, line 1 6, 29 read 27.

Letter

ON GALVANISM AND ELSCTRIClTTrf 175

VIII.

Letter from C. Wilkinson, Ejq. on Gakanifm and EUBricily*

Dublin, Oa, 8, l&O*.

To Mr. NICHOLSON.
SIR,

HEN at Liverpool a few days (ince, at the Athenaeum Obfervatlons oa
I found a paper of Mr. Thicknefle of Wigan in your valuable galvanifm, &c.
Journal, and which has induced me to trouble you with the
following obfervation. Mr, T. ingenioufly conjectures that
the galvanic phenomena depend more upon the decompolition
of the water employed than as to any chemical change eflFeded
on the metals. Mr. T. obferves that two metals are requifite
to the production of galvanic phenomena : this is no ways the
cafe, it is well known that a fingle metal fuffices, or even brain
and mufcle, according to the experiment of La Grave, or
nerve and mufcle according to Aldini. Mr. T. further ob-
ferves that hydrogen mixed with copper always renders it brit-
tle. I fliould wifti to know this gentleman^s authority for fuch
an aflbrtion : he alfo fets out too hypothetically as to eleClricity
being a modification of caloric. It has always appeared to me
that the galvanic phenomena entirely depend upon the difen-
gagement of eleClricity from the metal undergoing a chemical
change,

Galvani has afcertained that gold, filver, copper, iron, tin,
lead and zinc, conftitute the feries of metallic bodies; that
when two metals the moft remote in the feries are united, the
mod powerful galvanic combination is formed; thus gold and
zinc, filver and zinc, copper and zinc, &c. and laflly, lead
and zinc, form the weakeft galvanic combination. The difpo-
lition to oxidation is in the inverfe order, thus zinc will become
oxidated even by expofure to the air, whilft filver and gold
undergo this change with the greateft ditficulty.

Hence a metal which is oxidated with the greateft difficulty
combined with a metal which oxidates with the greateft faci-
lity, form the moft powerful galvanic combination. The pro-
duction of galvanic phenomena is always proportionate to the
degree of oxidation,

AU

7d'$ 0» GALVAJiIISM AMD ELECTltlClTY.

Obfervations on All fubfiances wliich are condn6lors. of ele6lricity, if they
galvainfm, &c yntiergjo any change as to their conducing power, fo as to
become diminiflied as conduftors, always in the change lofe a
portioa of ti>eir natural eledricity, T^ms metals which are
the bed condiidors, when oxidat<^d, become non-condu6lors
irt this change, the coftibined electricity is loft.

If a plate of zinc is ufiiverfaJly immeifed in a fluid which
will produce ciiemical changes upon it, no galvanic plienome-
non will be produced becaufe the metal in every alfignable
point, being equally a6ted on, the contrary ftates of cleQricity
cannot then be produced.

If only one fide be afted on.everyaffignabie point on that fide
undergoing a chemical change, by which it isdifpofed to part
with its combined eledricity, there will be a general tendency*
of the eledricity in the fubftance of the metal towards the fur-
face aded on ; the fame as if in a vetfel filled with water, a
fmall aperture be formed, there will be a general tendency or
current of the water towards the aperture, fo of eledricity.

Dr. Wollafton has proved by very ingenious experiments,
that when two difiimilar metals are placed in a fluid which will
ad upon one of the metals and not upon the other, when the
two metals are put into contad in the fame fluid, that thus che*
mical changes are effeded on both ; thus that gold and filver
thus arranged, will be aded on. by the nitric acid. — When two
metals are placed in a fluid which will ad upon either of them
feparately, if the two metals are preferved in a ftate of fepa-
ration while in the fame fluid, chemical changes will only be
effeded upon one. Thus zinc and copper placed in nitrous
acid and water, only the zinc will be aded on.

Thefe principles point out the neceflity in our galvanic
troughs to have our cells perfedly infulated, and that there be
no communication between the refpedive plates.

Mr. T. has by miftake obferved that tJie fenfation is in pro-
portion to the furface aded on; the experiments of the French
philofophers proved that the adion of galvanifm on animal
fubftances is in the ratio x)f the number of plates employed,
and not the fur faces expofed.

In all my experiments in town with my own eledrlc battery
I never fucceeded.in giving the flighted charge with my gal-
vanic apparatus; In forae coaverfation 1 had with you, Mr.
I^itor, you conjedured that an extenfive feries of fmall jars

>vould

^^

GRIPE FOR CARRIAGES*

Would be the beft arrangement. When at Liverpool, I met
with fuch at the houfe of Mr. Dalton, a very ingenious lec-
turer on ele6lricily. The galvanic battery I employed con*
fifted of 200 eight-inch plates, which had fufed at the time
near five feet of fteel wire ; this communicated a very flight
intenfity to the eleftric battery, containing forty feet cofated
furface, juft fufficient to convulfe a frog,and although the eleftri-
cal battery was in the beft ftate of preparation, we could not
fucceed in producing any intenfity as even to affed the tongue*
At another period, I (hall do rayfelf the pleafure of tranfmit-
ling to you an account of fome ingenious experiments of Mr.
Dalton, on eledricity, he finds a cylinder, when exhaufted of
air, or when one atmofphere is condenfed into it, will not thea
be capable of excitation.

I am. Sir,

Your's fincerely,

C. WILKINSON".
No, 19, SohO'Square,

ix.

Method of preventing Accidents to Horfes and Carriages, in going
down Hillsy by a Gripe or Clafp aBing on the Naves of the
V Wheels of the Carriage. By Mr, W. Bowler,*

SIR,

JL HE invention I hjlvenow fent you is, I thinks likely to be Apparatus to
of great ufe, and I therefore offer a model thereof for your JjP^^^J^*^^^^®^*
infpe6tion. In the firft cafe, this cart may be ftopped in an
inftant, in going down the fteepeft hill with a load, without
Hopping the horfes, by the carter only prefling his hand upon
a lever. This plan would likewife be highly advantageous in
cafe of a horfe taking fright, as the carriage may be inftantly
ftopped by the brace clafping the wheels. It may alfo, with
little alteration, anfwer for a broad-wheel waggon with a
heavy load. By the prefent method, a coachman, whilft fit-

* Tranfaflions of the Society of Arts. A bounty of ten guineas
was given to the inventor, and the Society have a model.
V^L, IX.-— November, 1804. N ting

GRIPE FOR CARRIAGES,

Apparatus to ting Oil his hnK, may. confine or releafe the wheels of his car-
of^ carriages. ^i^ge at pleafure, dntl prevent accidents in defcending hills, or
in managing reftive horfes.

I am. Sir,

Yoiir humble Servant,

WILLIAM BOWLER,
Fivjhury-Street, May 1 3, 1 803 .

To Mr. Charles Taylor, Sec,

Iteference to the Engraving of Mi\ William Bowler*s Gripe for
the Wheels of Carts and Carriages, Plate X.
A B. The extent of the body of the cart. C D. The two
(hafts. E. The front ladder of the cart, part of which pro-
jects over the fliafts, and is fupported on them : the other part
is fattened to the upright piece F. G. The handle of the le-
ver. Aiding betwixt two uprights, and moveable on an iron
bar and pivot at H, in the upright piece F. By preffing dow^
this handle, the moveable joints I K raife upwards the lower
part of another lever L, fo as to prefs againft the lower part
of the nave of the wheel, and at the fame time the moveable
joints prefs down the lever O, and caufe this lever to a6l againft
the upper part of the nave of the wheel ; thus compreffing
the nave of the wheel betwixt a double brace, and either re-
tarding wholly the motion of the wheel, or allowing it to move
a little, as may be thought requifite. The circle of the nearer
wheel is ftiown by the dotted lines P; but this wheel is not
added, as it would prevent this gripe from being clearly feen.
The handle of the lever G produces at the fame time a fimilar
efFeft on the further wheel R, by means of the bar of iron
which croflfes the cart at H, and a6ls in the fame manner on
fimilar double joints at the other fide of the cart, as may be
feen at S, where the further double gripe is ihown preffing on ^
the nave of the further wheel. T. A fmall catch, which, by 1
falling into the notches or teeth of the lever, when it is prefled
down, holds both the gripes in one certain pofition.

When the wheels are to be fet at liberty, the catch T is re-
moved out of the teeth of the lever ; then the lever G mk
raifed above the hole V, and kept from Aiding down by an
iron pin attached to the Chain U, being put underneath the
lever, through the hole V.
'•^"' The

CALVANIC POWER, ^^^

The Iron-work is not any inconvenience in the loading or
unloading of the caii/ nor ocddpies any room withiii it; and,
what is of material confequence in new inventions, it rhay be
managed by the carter with much lefs time and trouble than
the common hook and drag chain. It is alfo much more fe-
cure in its a6tion, as it binds on both wheels at once> and gives
a uniform fteady draught for the horfes, which prevents them
from falling down.

Obfervatiom and Experiments to elucidate the Operation of the
Galvanic Power. By Mr. Charles Sylvester, In «
Letter from the Author »

To the Editor of the PHiLOSbPiiic Jouri^al.
SIR, r

1 HAVE for fome time read and admired your valuable pub- 'f

lication, but have not before this time ventured a communica- .^^^

lion on any fubjeft. If you think the following thoughts and
experiments worthy the attention of your readers, I (hall feel
myfelf honoured if yoii give them a place in your Journal.
I remain, Sir,

Your obedient fervant,

CHARLES SYLVESTER,
Sheffield, Oa, 16, 1804-.

The decompofition of water, or at leaft, the prefence of ^Vhether water
bxigen and hidrogen, is obferved in all the modes by which ^^^ \n xhT°rS\unc
galvanic energy is excited. I obferve that fome of yout* cor-procefsj
refpondents are inclined to doubt the truth of water being a
compound body, from obferving in its decompofition that the
oxigen and hidrogen are given out at fo great a diftance from ^

each other. Though thefe philofophers have more iimply ac-
counted for fome of the phenomena by making water a fimple
fubftance, their affumed data, that pofitive and negative elec-
tricity are two diftinfl bodies, is by far more gratuitous than
the pofition, that water is a compound, Belides this hypothe- -*-<w pof* and
fis will only account for a few of the faas, while it abounds tfaVS'^'^
with contradidlion when applied to the reft of the phenomena bodies,
of galvanifm,

N2 They

180

The latter lefs
probable.

The oxidation
contraidids the
hypothefis of
two eleftrie
bodies*

Variation of Dr.
Afh's exptri-
xnent.

When a long
copper wire was
conneded at the
end with zinc
(under weak
iiUph. acid)
hidrogen was
earlier given out

GALVANIC POW£R.

They tell us of two kinds of eledtricity coming from thegaf-*
vanic apparatus one from the zinc end, the other from th«
copper end: the former being pofitive, the latter negative.

Two diftindl fluids moving in contrary dire£iions could not
pofliblyexift in the galvanic trough; by reafon of that fluid
proceeding from the zinc meeting that coming from the cop-
per in each of the cells, and confequently eftabJifl^ing a con-
flant equilibrium, without producing any effeft. When lh«
decompofilion of water is only taking place in one velfel (ad-
mitting the above objedion to be of no weight) the phenomena
admit of an eafy explanation by this hypothecs; but when two
veflels are ufed connected by a wire arch, it cannot in any
(hape be adequate; for as we have in each veflel both oxigen
and hidrogen gafes, there muft alfo be both pofitive and nega-
tive eledricity ; thefe two contrary fluids would of courfe have
to meet each other in the connecting arch, and according to
another part of this theory form fenlible heat *.

The pofitive wire, if a bafe metal is always oxidated; this
effect is known to be facilitated by the electrical agency. Ac-
cording to the principles in queftion, it would be retarded by
the power of affinity exifting between water and pofitive elec-
tricity. When the wires of a galvanic apparatus are brought
into a metallic folulion, no hidrogen is given out at the nega-
tive wire, but the metallic oxide is reduced. Now if metal-
lic oxides be compofed of water and the metal, the negative
eleftricity would combine with the water, and hidrogen ga»
would be evolved — the very reverfe of the fa6l.

My reafon for being thus particular in the examination of
the hypothefis of Mr. Richter and Dr, Gibbs, is to prepare
the mind of the reader for fome experiments which I think
will contribute to the firmnefs of the hypothefis, which fup-
pofes water to be a compound, and that the hydrogen is car-
ried from the pofitive to the negative wire by the electricity.

The well-known experiment of Dr. Ath (with the plate of
zinc and fiilver in a dilute fulphuric acid) I had occafion to
vary in the following manner. I took a copper wire abou^
eighteen inches long, and bent it in the middle fo as to form

* They are of opinion that thefe two fluids combined form calo-
ric. They alfo hold with Dr. Prieftly that what are now termed
metallic oxides are the refpe^ive metals combined with water.

tw9

GALVANIC POWER. 181

two parallel legs, about two inches diftant from each other. »' ^'^^ '}^"^^
This I laid in an earthen difli filled with dilute muriatic acid, (bended) wire;
I then brought a piece of zinc in contadl with one of the ends :
bubbles of hidrogen were immediately given out by that part
of the copper. After bubbles had appeared for about two
inches down this leg, I obferved bubbles on the end of the other
leg, — they now proceeded down the two legs till at laft they
appeared on the part where the wire was bended. I after-
wards laid a piece of zinc at one end of the fame dilh and a
piece of gold at the other. I prepared a metallic arch with
two pieces of wire, one of gold, the other zinc, foldered to-
gether. The zinc end I conneded with the piece of zinc in— and fo like*
the diih, and the gold end with the gold. After the eontad "^^^^^^^"^^^"^^'^^
had been made about ten feconds, bubbles appeared on the between gold
piece of gold. The diflance was about twelve inches. I now ^^'^ ^^^^*
placed the pieces of gold and zinc at half the diftance, and
made the communication with the fame arch. The bubbles
now appeared upon the gold in about half the before-mentioned
time. Upon bringing the pieces ftill nearer together, the gold
gave out gas alraoft inftantly, but yet in all the three inftances
I had time to obferve that the bubbles always appeared firft on
that fide the gold next the zinc.

I think from the above experiments that the difengagement Whence it Is
of hidrogen from the gold dops not depend upon its negative d]fgngage„fgnt of
l!ate, for this quality muft have been produced on the gold in hidrogen does
every one of the three inftances in the fame time, from the JJ^^^ ^^j" . °^^^
communication being always made by an arch of the fame that the elec-
length. On the contrary, it proves that the eledricity difen- ^.^nica'tea""*'
gaged from the jzinc is communicated to the gold through the through the in-
intervening liquid. If we obferve the length of time taken up *^T>ofed liquid,
in its palTage through this medium, we Ihall fee that it does not
agree with the laws of ele<5iricity. Is it not therefore proba-
ble that when the oxigen of the water combines with the metal,
the hidrogen combines with the eleftricity of the metal, and a
compound of this kij)d obferves thofe laws confiftent with the
phenomena.

In each of the cells of the galvanic trough a quantity of this Probability that
compound is diffufed through the liquid. The moment a com- [n^ombination
munication is made between the two ends, the elediricity en- with cle^ricity,
ters each of the copper-plates, leaving the hidrogen in bubbles

Oft .

182 GALVANIC POWER.

on the furface *. As this eledrated hidrogen (if I may l)«

allowed the expreflion) does not move through the liquid with

the facility of the ele£lricity itfelf, the neceffity of a furface of

copper equal to that of the zinc is obvious. It is plain that

only a proportionate quantity will be carried through the whole

Olgeftion to the feries. This fad I have afcertained in attempting to render

Jcnb?d^nour the apparatus propofedby Mr. Wilkinfon ?ind yourfelf ufeful

Vol. VIII. p. 3. for all experiments. The (liock is even lefs when the furfiace

of Voita'!"'°"''*' ^^ ^^PP^^ '^ '^^' ^^^^"^ ^^"^""^ '"^^^•

How the e'cc- The quantity of ele6trated hidrogen in each cell increafes

tricitv increafes f^^^ ^j^^ copper end to that of the zinc in an arithmetical pro.,

the hidrogen in , . . . .

.the eyct^rior gremon. The eledricity only exifts in its fimple form while

f5^» it is paffing from the copper furface through the two metals tq

the zinc furface. It there combines with another portion of

hidrogen, which it le^aves at the next copper furface,, and fo

on accumulating in quantity the longer the feries it has to pafs

through. In the decompoiition of water by the galvanic

trough, the veffels in which this is performed may be confidered

as one cell in the feries. The eleflricity feizing the hidrogen

at the pofitive wire and giving it out at the negative.

XI.

Memoir on the Origin of Wax •\'. By Francois Huber,
AJ ember of the Society of Natural Philofophy q,nd Natural
Hijiory of Geneva.

IT has been thought flrange that the word wax fhould feldom
occur in a book which treats of bees alone : but neverthelefs as
in the courie of my obfervations, I had not attended to the
products of their induftry, I could only have repeated what
had been faid by Swammardam and Jleauraur, and that did
not feem to me to be neceflary.
Mechanical I knew that thefe infe6ls colleded abundantly upon the an-

operations of therx of flowers, that they are acquainted with the method of

the bees, . ■ • [

•This faft is very obvious when the copper furface is very clean.
The hidrogen under contrary circumftances is employed to reduce
the oxide.

f From Journal dePhyfiquc, &c. Pluviofe, An. XII.

opening

ON BEES WAX, J§^

opening them, of gathering their duft, keeping it in the ca-
vities of their hind legs, and carrying it to rfieir hives.

It had been obferved that the particles of this duft fwells in Examination of
water, and that, when one of them burfts, an oily liquor runs ^^ pollen of
out, which floats on its furface, but did not mix with it ; from
thefe experiments, repeated on the duft of a great number of
flowers, it was concluded that they contain the principles of
wax, but it was admitted that thefe muft undergo a peculiar
elaboration in the body of the bee, fince, according to the
experiments of Reaumur, a flexible wax could not be made
from the duft of the antherae.

It will be feen from feveral patfages in my work that I had The true origin

adopted this opinion : a fingle obfervation of Burnens * changed °^ ^'^^ J^:

^, . . . . - mamed fo long

all my ideas. The true origin of wax might have been fooner unknown from

known, had there been any fufpicion that it was not already ?" °P'"/1''^ ^^^\

itwasdifcoveredj
difcovered. I (hall now ftate how I was led to doubt, and what

I have done to verify my new conjectures.

I was in Switzerland in 1793; the farmer of the eftate on Obfervations
which I refided had many bees, and the greater part of his^"^^ ^^? ^^
hives having been ftocked in former years, the combs with
which they were filled reached to the ftands, confequently
there was no room to conftru6l new ones. We remarked,
however, that the working bees carried in a confiderable quan-
tity of this fecundating powder.

There was alio in the fame apiary fome fwarms of that
year, the hives having only been ftocked a day or two ; in
fome of them the combs were only began, in others they were
larger, but in all of them there were vacancies to fill up, and
much work to do. We obferved with aftonifhment that the
bees of thefe fwarjiis did not carry in the pollen, and that,
neverthel«fs, they worked with activity in the conftru(5lion of
new combs, and in lengthening thofe already commenced.^
Where, therefore, did they procure materials for their edifices?
After thefe obfervations, we fufpeded that it was not from the
duft of the ftamina, and that they had a very different ufe for
it than that for which it was believed to be intended. We - .

however found that it was not impollible to explain thefe ex-
traordinary fads, without abandoning the hypothefis of Reau-

* The name of M. Huberts fecretary j which deferves to be
Kn owi\ to the cultivators of natural hiftory.

mur.

Uf ON BEES WAX.

iBur, hy fuppofing that the bees of the old hives flored up fo
much pollen in their combs for their future wants, while thofc
of the new fwarms did not carry it outwardly on their legs, in
the infancy of their eftablifliment, becaufe they had no cells in
which they could depofit it: it might be fufficient to enable
them to conftru6l their combs, if they were at liberty to fly to
the-flowers, procure their pollen, and return to their hives after
having filled their ftomachs, where it muft be elaborated and
^converted into perfed wax. It vyas to obviatQ thefe doubts
^hat I undertook the following experiments,

FIRST EXPERIMEINT.

On Bees in Confinement with Honey alone for their Nourijiment^

^xp- 1* Muft bees eat pollen to be in a ftate to produce wax? Thi?

fary VSie pro- ^^^ ^^^ ^^^ queftion which I thought it neceflary to inveftigate ;

dudlion of wax? the meihod of trying the experiment was obvious; it was only

required to keep the bees within their hives, and thus prevenj:

them from colle(5ting or eating the fecundating powder.

On the 24th of May, Burnens lodged a fwarm in a ftravy
hive, with 51s much honey and \yater as \yas necelTary for their
Confumption, and he clofed the doors fo that the beqs could noj;
get out and the air be at the fame time renewed.

At firft the bees were very uneafy, but became calm on re-
moving the hive to a cool dark place ; their captivity lafted
five days; they were permitted to come out in a room, the win-
dows of which were (hut: we then examined tjie hive mor^
Wax from conveniently. We firft noticed that there was no honey left
honey alone. |„ jj^g ^gj|e| vvhich had been filled vyith it, with tjie fole inten-
tion of feeding the confined bees; and were more aftoniftied
to find five combs of the moft beautiful wax, fufpended from
the roof of the hive; they were perfe6lly white, and very
brittle. This refult vyas very remarkable; however, before
forming a conclufion from it, that the honey with which thefe
bees were fed had enabled them to produce the wax, it was
neceftary to enquire whether it could not alfo be explained in
another manner.

The bees which J had employed had doubllefs collefted the
duft while they were at liberty.

They might have done fo the evening before, or on the very
day of their confinement, and might have enough in their fto-
machs, and in the cavities of their legs, to extra6| from it aU
the wax which we had found in their hive.

But

•N BEES WAX. JL^

Bat if it was true that it had been obtained from the fecun-
dating powder previouily obtained, this fource was not inex*
hauftible, and the bees being unable to procure any more,
they would foon ceafe to conftrud combs, and fall into the moft
complete inaction. It was necelTary therefore to continue the
fame trial to render it decifive.

The 28th, Burnens returned this fwarm into its hive, after
having taken out all the combs; he fliut them up as before with
a freth fupply of honey.

This experiment was not long, for on the evening of ilie
fecond day we perceived the prifoners working with new wax.
The next day the hive vkras infpeded, and we found five combs,
as heavy and as regular as thofe made during their firft capti-
vity.

We afterwards repeated this experiment five times fuccef-
(ively, with the fame bees, and the fame precautions: weal*
ways found that the honey had difappeared, and that new wax
was produced. This refult was fo invariable during this long
feclufion that we could no longer doubt that the honey alone
had fupplied them with all the elements of their wax, without
ihe afliflance of the fecundating duft.

SECOND EXPERIMENT.

On a Hive from Viihich Honey was excluded, and in which only
Pollen and Fruits for the Nourijhment of ihe Bees were left,

I thought it would not be ufelefs to make the inverfe of the Exp. II;
prececjing experiments : it would fiiow me whether the pol-
len could not fupply the want of honey when the bees were
deprived of it, and enable them to produce wax.
. I therefore enclofed a fwarm in a bell-glafs, in which had
J)een placed a comb whofe cells contained only pollen, and the
folenourifhment of the bees was fruit.

Thefe bees did not make wax, nor did they form a fingle
cell during eight days, which was the time of their capti-
vity.

I was going to repeat this experiment, when Burnens re- Bees fed on
mark*;{J th^t the free bees were, in fome meafure, in the faraeP?"^" ^"'^ ^'"'^*
ftate as thofe we had confined ; there being no honey at that wax!° ^^ ^^
time in the flowers, they found only pollen, and did not work
in wax.

I may

UQ

ON" BEES WAX,

Wax«maklng
bees.

Nurfing bees.

Operations of
the bees during
an intemperate
fpring.

I may perhaps be aiked howl was fatisfied of this, to which
I anfvver, bees-wax is white at firft, the cells foon become yel-
low, and in time, this colour grows browner, and in older
hives the combs have acquired a blackifti tinge. It is there*
fore very eafy to diftinguifh the new cells from thofe which
have been fome time formed, and confequently to know whe*
ther the bees are really making combs, or whether that work is
fufpended; it is fufficient to raife the hives, and to notice the
lower edges of the combs.

The odour exhaled by the hives, and the ftiape of the bees,
are indications by which it may always be known whether there
is honey in the flowers; if they are combined, there can be
110 further doubt, and, particularly, if a great number of bees
return to the hive, which are remarkable for the bulk and the
form of« their bellies. Thofe which are filled with honey have
the abdomen cylindrical ; the name of wax-making bees be-
longs to them exclufively: the bellies of the labouring bees
which have other functions, always preferve their ovoid form,
and their volume is never fenfibly augmented; the name of
nurfing bees is proper for thefe.

The farmers of the neighbouring villages kept their bees in
balkets, or in cafes of difterent forms; and I was able to vifit
a very great number without going to any great diftance from
my habitation.

In 1793, an intemperate fpring had retarded the feparatlon
of the fwarms; there had not been any in the country before
the 2 Uh of May ; but towards the middle of June there were
feveral in the vicinity of my reiidence. At that time the fields
were covered with flowers, the bees collected much honey, and
the new fwarms worked at the wax with vigour.

Oh the I8th, Burnens vifited fixty-five hives; at the en-
trances of all of them he obferved waxrmaking bees. Thofe
which returned to old hives, not baring to conflru6l cells, de-
pofited their honey in the combs, or diftributed it among their
companions; thofe belonging to the fwarms converted their
honey into wax, and haftened to conflru6l combs for the re-
ception of their young bees.

It was (liowery on the 19th: the bees went abroad but
brought home only pollen. The weather was cold and rainy
until the 27th. We were defirous of knowing if this had pre-
vented their working. On the 28lb, all the hives were lifted:

burnens

ON BEES WAX. 187

Earners found that the work had been ftopped ; the combs
which he had meafared on the 19th, were not at all increafed,
and were of a citron-yellow, nor was there a fingle white cell
in any of thefe hives.

On the 1ft of July the chefnuts and limes were in bloflbm, —and a dry
the thermometer indicated the 20th degree; the wax-making ^'^"^^•
bees re-appeared, they carried away great quantities ot honey,
which, as we had before obferved, was employed in aug-
menting the provifions of the old hives, and in enabling the
young fwarms to conftrudt new combs.

The greateft aftivity was obfervable among them : the ga-
thering of honey, and the produiftion of wax continued until
the middle of this month.

July 1 6th, the heat remained the fame : the field flowers, as
we]l as thofe of the chefnuts and limes, were completely-
withered; they yielded no more honey; their pollen alone at-
trafled the working bees, and they colleded it abundantly,
but there was not any wax produced; the combs were not
lengthened ; thofe of the young fwarms did not fill more than ^

two thirds of their hives.

Auguft 9th. It had not rained for fix weeks, the heat was,
very powerful, nor was there any dew to allay it during the
night: the black wheat which had been in flower for fome
days, did not offer any honey to the bees; they found only
pollen.

On the 10th, it rained for feveral hours; next day the black
wheat had the odour of honey ; in fad it might be feen glit-
tering in their expanfed flowers. The bees found enou^^h to
feed them, but too little to induce them to work at new wax.

On the I^th, the drought re-commenced, and lafted to the
end of the month: no more honey appeared upon the flowers,
and when we vifited the fixty-five hives for the lafl time, we
found, 1ft, that the bees had not produced any wax after ths
middle of July ; 2d, that they had ftored up a great quantity
of pollen ; 3d, that the fupply of honey was much leflTened in
the old hives, and that hardly any remained in the new fwarms,
that which they had collected in the fpring having been em-
ployed in the preparation of wax; the pollen, therefore, has
not this property, and no further doubt remained on this head.

This year had not been ftormy, and I have fince afcertained. Weather moft

by a great number of obfervations, that eledtricity is fingularly favourabe to the
•^ ° . r 1 1 labour of bees.

4> lavourable

J88 ON BEES WAX.

favourable to the feeretion of honey by the flowers : the bees
never colleft it in greater abundance, nor is the preparation of
wax ever more a6live than when the wind is in the fouth, the
air humid and warm, and a florm gathering.

Heat too long continued, and the drought which Is the con*
fequence of it, cold rains, and principally a north wind, faf-
pend it entirely.

THIRD EXPERIMENT.

On the Ufe which the Bees make of the fecundating Powder,

Jxp. UU In the fecond experiment the bees did not touch the pollei^

which I had placed within their reach, and, as its quantity was
not fenfibly diminithed during this trial, I was induced to be-
lieve that it was not an aliment proper for them.
What is tbe ufc I alfo knew that the new fvvarms were liable to perllh from
of pollen . hunger in the middle of fummer, and even when the country

was covered witl) flowers, if a particular temperature, which
is too uncommon in our climate, did not favour the fecretion of
honey in their neflaria. What, therefore, is the ufe of the
pollen which they colle6lwith fuch avidity during eight months
of the year, and of which they lay up fuch abundance?*
This queftion remained to be inveftigated.
I had a hive, in divifions, the queen of which was barren;
its combs did not contain any pollen, but they had much ho-
ney : the two narrowed fides of this hiye were formed of panes
of glafs, through which the furfaces of the exterior combs
might be feen, and the condu6t of the bees obferved.
The queen, bee I took away the queen on the 16th of July, but to confole the
taken away. working bees I removed the firfl and the twelfth combs, in
which there was not any thing to intereft them, and I fupplied
their places with two combs, the cells of which were filled
with eggs, and worms of all ages. I carefully cut away all
the cells in which pollen could be perceived^ and (hut up the

* Reaumur was of opinion that the bees of a well-ftocked hive
might colle6l at leaft a hundred pounds of this fubftance in the courfe
of a year i but, having remarked that the weight of wax, fabricated
in the fame time, did not exceed two pounds, he concluded f* that
Jthe bees extrail only a very Tmajl portion of the true wax from this
native wax, that the greateft part of it is required for their nourilh-
men^, and, that the reft is difcharged from their bodies in the forni
of excrement."

hive

ON BEES WAX* ^ J g(J

hive with a grating. My intention will be gaefied: I wi(hecl
to know whether thefe infe^ls could fupport their young with*
out this fecundating powder.

The next day nothing extraordinary occurred j the bees fat
on their eggs and Teemed tonurfe them.

On the 18th, after fun-fet, a great noife was heard in the
hive. Anxious to fee what occafioned it, we opened the fliut*
ters, and obferved that all was in confufion: the incubation was
flopped; the bees ran over the combs in diforder; we faw
thoufands precipitate themfelves on the ftand, thofe which
were neareft to the mouth eagerly gnawed the grating; their
intention was no longer doubtful, they wiftied to get out of
their confinement.

I was fearful of deftroying them by continuing to prevent
them from yielding to their inftinft, they were therefore fet at
liberty : the whole fvvarm came out, but the hour was unfa-
vourable to their collecting, the bees did not go far from the
hives, the darknefs, and the chillinefs of the air, foon compel-
led them to ffeturn, and probably calmed their agitation, for
we faw them quietly reafcend their combs, and order appeared
to us to be re-eftabliflied. This moment was taken to clofe
the hive again.

On the 19th, we faw two royal cells begun on one of the Other royal celb
combs of the nurfery (couvain)', the evening of this day, and ^^'^^>
at the fame hour as the day before, we heard a great tumult in
the clofed hive, it was in a general confufion, and we were
again obliged to permit the fwarm to come out.

The 20th was the fifth day of their captivity ; we thought
it had been of fufficient duration, and were alfo very impatient
to examine the nurfery, and to fee what was the caufe of the:
periodical agitation of thefe bees : Burnens therefore opened
the firtl and twelfth windows, and drove the bees from the
combs, fullering them to take their flight in a room, the win-
dows of which were iliut.

He firft noticed that the royal cells had not been continued',
that they did not contain any worm, and that there was not gn
atom of the jelly which ferves for the nourifliroent and the cra-
dle of the larvse of the queens.

He fought in vain for eggs, for worms, and for the liquid in —but the pro-
thd corara«n cells; all had difappeared. Had lhef« worms *^*^^* *!'? "°' 8^

*^* on Without pol-

dltid lea.

1^ 9V JEfiS WAX*

died of Imnger ? Had we, by withdrawing iht fecundating
powder, deprived the bees of every means of nouriibing
them ?

. To afceiiain this it would be fufficient to reftore them theif
pollen, and obfcrve the ilTue. Tiie bees were therefore again
returned to tlieir prifon, after having fubftituted young worms
for thofe which had been fuffered to die.

Oa the 22d, we found that the bees had faftened thefe combs,
and that they were again in a ftate of incubiation ; we then gave
Uiem fome pieces of combs in which other bees had ftored up
the fecundating powder, and, the belter toobferve what they
did with it, we took fome of the pollen out of the cells, and
laid it expofed on the ftand of the hive. In a few minutes the
bees difcovered the pollen in. the combs, and that which we
had taken out; they took it grain by grain in their jaws, and
conveyed it into their mouths; thofe which had eaten mofl vo-
racioufly re-afcended the combs, and placed themfelves, af
firtl, upon the cells of the young worms, which they entered
with their heads foremoft, and remained there a greater or lefs
length of time. One of the windows of the hive was now
opened cautioiifly, Burnens powdered the bees which ^at the
pollen, and watched them for fome hours; he obferved that the
marked bees always re-afcended to the nurfery, and immedi-
ately entered the cells of the young bees-.

The 23d, we> found the royal cells begun.

The 24th, we drove the bees from off the young worms,
and we remarked,

1ft, That all of them had the jelly, as in the common hives :

2d, That the worms had grown larger, and were forwarder
in their cells :

3d, That others had been. (Imt up again: And,
.. 4th, That the royal cells had been lengthened.

The 25th, we withdrew the pieces of comb which we had
placed on the ftand, and found that the quantity of pollen was*
fenfibly diminiflied; we afterwards replaced them in the hive
Yr^h other cells filled with the fecundating powder*

The 26th, the royal cells had been clofed diiring the night,
as well as feveral of the common ones.

The 27 Ih, I reftored thefe bees to liberty ; Burnens examined
the cells with the greateft attention, and found jelly in all thofe

which

ON BEES WAX/ X^X

tdhich ftilV contained worms, but moft of them were fhut with
• lid of wax : he examined (bme of the latter, and found the
worms employed in fpinning cocoons of (ilk,
- All the worms had therefore been tended as in the natural
hives. In this fecond trial we did not perceive any diforder
in this hive; there had not been the leaft agitation: it is true
fome of the working bees attempted to go out in the courfe of
the day, but finding it impoffible, they re-afcended the combs
quietly, which were never left for an inftant. The hive being
abundantly fupplied with honey, and with the pollen necelfary
for their young, left them nothing to wifh for; and they were
ftill more happy when a queen was born, who afterwards be-
came pregnant, and laid a great number of eggs.

After ihefe two experiments there could be no more doubt ThepoUenis
that the fecundating duft was the aliment proper for the young ^^^^^^^^^^^^
bees, and that the want of this fubftance was the caufe of their bees,
death, and of the evident anguilh of their nurfes during their
firft captivity,

FOURTH EXPERIMENT.

On Bees deprived of Honey and Pollen^ and which it was at-
tempted to feed mth Sugar,

I wiftied to know ii^ it was the faccharine part of the honqy Exp. IV.
which enabled the bees to produce wax. ^j^^ ^J^^^^y ^^^^

Burnens confined a fwarm in a glazed hive: one pound of tains the princi-
Canary fugar was their fole aliment. P^" °^ '^^ «'" ■

He put a fecond fwarm into another hive, and endeavoured
to feed them with very eoarfe raw fugar; and to obtain a term
I of comparifon, a third fv^arm was fnut up in the fame manner,
Pand fed with honey.

The bees of the three hives produced wax; thofe fed with
the different qualities of fugar produced it iboner than the
fwarm which had only had honey, and they produced it in
greater quantity.

A pound of Canary fugar reduced to fyr up, and clarified Wax made from
with white of egg, yielded 10 gros, 52 grains, of a wax not dXrenr^u'^aU,
fo white as that which the bees extract from honey. ties.

An equal weight of raw fugar gave 22 gros of very white
wax.

Maple

Jgg mV BEES WAX;

Maple fugar produced the fame effefl. Tins experiment
having been repeated feven times fucceffively^ always employ/
ing the fame bees, we could not doubt that fugar contains the
principles of wax, and we concluded that it was the faccha-
rine part of the honey which had this property.

CONCLUSION.

Coaclafionss Thefe obfervations iihew,

1 ft. That the wax comes from the honey i

2d, That the honey is alfo a food of the firft neceffity to the
bees:

3d, That flowers do not always contain honey, as has bees
imagined ; that this fecretion is fubje6l to the variations of the
atmofphere; and, that the days in which it is abundant are
very rare in our climate :

4th, That it is the faccharine part of the honey which en-
ables the bees to produce wax :

5th, That raw fugar yields more wax than honey, or refined
fugar:

6th, That the daft of the ftamina does not contain the prin*
ciples of wax :

7 th, That this diift is not the food of the adult bees, ar^l that
they do not collect it for themfelves t

8th, That the pollen affords the only aliment which is pro-
per for their young, but that this fubftance muft undergo a pe-
culiar elaboration in the ftomachs of the bees to be converted
into an aliment, which is always appropriated to their fex, their
age, and their wants, fmce the beft microfcopes do not (hew
the particles of pollen^ or their coverings in the liquor pre-
pared by the working bees.

I fliall fpeak of the economical confequences of thefe ob-
fervations on another occafion. By ftiowing the breeders the
real wants of the bees, they will be podetTed of the means of
aflifting them in time, in all their neceffities, and of prefer v-
ing them in climates in which nature has not placed them, and
in which they could not profper without our aid.

An

»N tHE NATURE OF HEAT* J93

tit

An Enquiry concerning the Nature nf Heat, and the Mode 'i 6/
^ its Communication. By Benjamin Coimt of Rumkord;
' V. P. R: S, S^'C. Abridged from the Philofophicdl Tranf-
• daionsfor 180'K

(Concluded from p. 63.)

Exp. 12. Jt WO equal cylindrical veflfcls of flieet brafs po-Exp. 12. Bo-
iiflied very bright, each three inches in diameter and four '^'^ ^^'^^ *" ^^^

• ■^ ° • i • 1 • • refpects and

inches long, fuipended by their oblique necks in a horizontal {seated, do, at
pofition, beins: placed on their wooden ftands, were filled ^^^'^^ dutances,

. . ■ n ^n 1 f • • in affed the ther-

with water at the tentperatnte of 180^ ; and their circolar flat mofcope equally.
bottoms were prefented, in a rertical pofition, to the two
balls of the thermofcope; at the diftance of two inches.

When thp two hot bodies were prefented, at the fame mo7
ment, to the two balls of the infirument^ or what was ftill
better, when two fcreens were placed before the two balls,
at the diftance of about an inch, and, after the hot bodies
were placed, thefe fcreens were both removed at the fame
inftant, the bubble remained without motion in the middle
of the horizontal part of the tube of the inftrument.

If the diftances of the equally hot bodies were rendered
unequal, the bubble always moved towards the mofl remote
of the two; and if a fingle hot body was prefented to one
of the balls, the bubble was driven from it, and might have
been carried quite out of the tube; which, however, wa? "
always avoided, as the inftrument would have been by that
means quite deranged. ' , ,

Exp, 1-3. The flat circular bottom of one of the cylii>drical Ex-p. 13. A cy.
veflels was blackened by holding it over the flame of a wax lender blackened

r- I • - 1 • I 1 /• w . w^" imoke,

candle; the other vetlel remaining pr'ght as before. Both gives out moi;e
were then filled with water at 130^, and prefented at equal radi.nt heat thin
diftances to the two oppoflte balls of the inftrument, as de- furfac?.
icribed in the laft experiment.

The bubble was inftantly driven out of its pl^ce by the
i'uperior adion of the blackened furface; and it did not return
io its former ftation until the blackened furface had Leen re»
moved to more than eight inches from the ball to which it was

Vol. IX. — November, 1804. O prefented j

194 ^^' ''"* NATURE OF HEAT,

prefented ; tlic other, which had not been blackened, re-
maining in its tirft pofition, at tiie diHance of two inches.
The other coat- Other limilar experiments were made to (hew whether
acSlelJated the thofe coatings or clothings which, in the former experiments
cooling, were alfa with the large vefl'els, had accelerated their cooling, did alto
thHadTation." '^ ^"^"^^^^"^ ^^^''" P^^^'" of radiation, as (hewn by the procefs and
inftruments laft defcribed. And the refalts invariably proved
that this is the cafe.

It was alfo a queftion deferving to be inveftigated, whether
any peculiarity belonging to the metallic furface hitherto ufed,
namely of brafs, might have influenced the refults.
Exp. 14, 15. Exp. 1 4, 1 5. The two large cylindrical veflels No. 1 and 2,
faces radiate " ^^'^''^ covered with a lingle coating of oil varnilh, and on this,
equally, \viien fufficicntly dry, was laid a covering of thick gold leaf

upon No. I, and thick filver leaf on No. 2. Thefe veflcis
were cooled through the interval of 10 degrees, in the fame
time as the naked vefTel ufed as the ftandard. Similar expe-
riments with vefi'els of tinned iron and of lead, (liewed that
the radiation from all thefe metals, though fo different in theif
conducing power, is the fame.

'* Is not this," fays the Count, " owing to their being all
equally wanting in tranfparency r And does not this afford us
a ftrong prefumption that heat is, in all cafes, excited and
communicated by means of radiations or undulations, as I
fliould rather choofe to call them ?"

And he proceeds to obferve, that another very important
queftion alfo muft be decided before thefe points can be deter-
mined, and that is. Whether bodies are cooled in confequence
of the rays they emit, or by thofe they receive ? The celebrated
experiment of Piflet has (hewn, in our author's opinion, that
rays or emanations proceed/rowi cold bodies, which may be con-
centrated by concave mirrors, and will affedt a delicate air
thermometer,
Exp. 16, 17. Exp. Id, 17. The horizontal cylindrical veffels (Fig, 5,

A cold body dc- p/^g /^ of the prefent volume) were made very clean and
pcraure o^f other bright, were duly fixed, and left for feveral hours in a room
bodies by radia- j^gar the thermofcope ; and when each veff^l was in fuccetlion
Metal horizon- -prefented to that inftrument, with every precaution to pre-
tally placed, vent irregularity from external circumftancGs, it was not found
to be affcdcd by them. One of the veffels was now taken
away and filled with ice and water, and then prefented, at th^

> diftance

ON THE NATURE OF HEAT. iQ^

rlidance of four inches, to one of the balls of the thermofcope.
The bubble immediately moved towards the cold body, and
palFed through the fpace of one inch. A nearer approach of
the cold body produced a tlill farther motion itt the fame di-
rection.

- Exp. 18, 19. Though this refult appeared to the Gount to Exp. 18, 19.
prove mdifputably that cold bodies emit riys capable of gene- J^^J^^^"^^^^-^^"^"^
rating cold in warmer bodies, yet* from the importance of the neatk the ther-

faa, he chofe to vary th€f fubftance prefented to the inftru- !"f«°P^! cp°l«^

1 /• r r I f-»- f It by radiation,

ment, as well as to remove all fufpicion or the action of cold No current of air

currents of air. He therefore laid the thermofcope on one could here

fide, and placed underneath one of its balls a folid cake of ice, •'

at the diftance of fix inches. The refult of this experiment

was the fame as of the other, and the bubble was moved one

inch in the tube. Ice-cold water produced the fame effe6t as

ice itfelf.

Exp, 20. Whether this effect of cold bodies be governed by lExp. 26. Metal
the fame laws as thofe obferved by varying the nature of the fmoke cooird"the
furface in heated bodies, or by any other, now remained toinftrumentmore,
be afcertained. It was before found that metal blackened J;^ "^^^^°"'

than a clear lur-

over a candle, did emit much more of calorific rays than the face at fame tern-
fame metal when naked. The fame experiment was now perature.
made with cold bodies. One of the cylinders had its end
blackened, and the other cylinder was left bright and naked, *

Both were filled with ice and falt> and at the fame inftant
they were fufFered to a6t from equal diftanCes on the thermo-
fcope. The bubble moved towards the blackened body ; not
indeed fo much as when the bodies were heated in the fornner
experiments, becaufe the temperature was not here fo far
diftant from the common temperature of furrounding bodies
as in that experiment ; but on feveral repetitions of the ex- *

perinient with thefe cold bodies, the effe6l was conllantly the
fame. It was found that the precipitation of ice out of the Ice radiates more
furrounding air tended fpeedily to raife the temperature, an^^ '^"a" " etal.
alfo that the clean furface, vthen covered with ice, had a
greater frigorific efie€l than when the metal was naked i

Exp. 21. The radiation of heat from animal fubftances ap- Exp. ai. GoM-
pearing, from fome fafts, to be confiderable, a piece of gold- ^f^'^^'"'^ ^|" ^*'

• " . . . ' '^ diates 25 times

beater's Ikin was applied wet to one of the vefiels, and re- more than meral,

mained firmly adherent when dry. This, when filled with hot Hot water mthe
water at 180^, and prefented to the thermofcope in oppofition

02 to

\g() ON THE NATCTJIE OF HEAT.'

to the other veflel clean and bright, and alfo filled with the
fame fluid at the fame heat, was found to be much more calo-
rific. The bubble which moved from the coated body, did
■not return to its ftation until this body was removed to a dif-
tance five times as great as that of the other. Whence our
author concludes, that it emitted twenty-five times the quan-
tity of calorific rays.
Exp.aa. Simi- Exp. 22. The velfels ufed in the lafl: experiment were
ice-coM water. ^'"P^"^^ ^"^ refilled with ice and water. They were then
The gold -beat- prefented at equal dillances from the refpeftive balls ; and the

duce?more°cold^^^^ ^^ ^^^ ^^^^ ^'^^^^^ ^^^ covered with gold-beater's Ikin,
by radiation. was much more confiderable in producing cold. r

The radiation of cold bodies appearing to the Count thus to
be proved beyond all doubt, he was defirous of afcertaining
whether the frigorific rays pofiefs an equal power of aff'efling
the temperature of bodies as the calorific rays do ; the tem-
peratures of the radiant bodies being at the fame difiance each
way from the body to be atled upon.
£xp. aj. A hot Exp. 23. With this intention, one of the vefl!els filled with
Ttirm'nf PO""^e^ ^ce and water, was prefented to a ball of the infiru-
from the com- ment, and the other veflel filled with water at 1 J 2°, was

mon tejnpera- prefented at an equal dillance on the oppofite fide of the fame

tUre, affedt the , ,, , ^ _ , , . ^

thcrmofcope ball ; the temperature ot the room and mltrument bejng 72 ,

equally. or 40° diftant from each of the temperatures of the veffels,

and the other ball of the infi:rument being defended from all

radiation by fcreens. The bubble remained motionlefs ; fa

that the oppofite aftions were in fa6l equal. And when either

veffel was drawn farther off', the efFe6l of that veflel became

lefs, and the bubble moved ; that is to fay, towards the ball if

the cold veflTel were ne^irefl:, or from the ball if the hotter ;

' and thefe efleds were equal in quantity as well as in celerity

of motion.

Why the cool- The Count again repeats his conclufion from thefe expe-

ingbyrarfiatioiiriinents lately exhibited to Profeifor Pidet, M. de Saufliire,

has been lels no- jT.,r,,. ^ ,, ,., ,,

t]cea. and M. benebier at Geneva, that the rays which generate cold

are ju ft as real and juft as intenfe as thofe which generate
heat ; and he proceeds to account for this refult having been
overlooked, by obferving, that the degrees of cold we are able
to produce, are much lefs diftant trom the ufual temperature
than thofe of heat, which are within our power. Thus a can-
non ball, hvMtcd to i6J degrees, or 70 degrees above blood-
heat.

ON THE NATURE OF HEAT. 197

heat, would radiate quite as much as ice; and a bullet of
freezing mercury would radiate fcarcely more than another of
boiling water: both which hot temperalures are very trifling
in comparifon to the heat in which we are habituated to notice
and obferve this phenomenon.

Exp. 24<. After the proof that cold bodies of the fame kind Exp. 24. The
affect the thermofcope equally, when equally diftant frOm the ^j^j^,^ produce
common temperature, it remained to be determined whether moft heat by ra-
the different modifications of furface have the fame effe^s in ^^^^'^^^ ^^^^"^
the ready propagation of lower temperatures, as they had cold.
(hewn before in higher. To fliew this, it was only required
to oppofe them to each other, as to their a61ion upon the fame
ball, as in the laff experiment. With this view both difcs
were blackened, and, the temperature of the room, being 72^
as before, one of them was charged with ice and water, and
the other with water at 112^. Thefe, at equal diftances from
the ball as before, did not affect the bubble, and therefore their
a6tions were precifely equal.

In the confideration of two kinds of rays, calorific and Do not the fame
frigorific, it did not efcape the attention of our author, ^^'^^^^yHI^^I^- ^^l^ as
hot and cold are terms denoting mere relations; fo that the the temperature
fame body will be either hot or cold accordingly as the com- bodt'sThrhJ?
mon temperature, or temperature of the bodies of com pari- or lower than the
fon, is lower or higher. Queftioning, therefore, as to the »^eceiving body,
difference between calorific and frigorific rays, he demands
whether the fame rays may not be either calorific or frigorific,
accordingly as the body at whofe furface they arrive, is hotter
or colder than that from which they proceed ?

Exp. 25. The whole of the external furface of one of the E*P* ^5* Metal
large cylindrical palfage thermometers, Fig. 1, Plate I. ^^^ goU-ht7ter'&
covered with gold-beater^s fkin, and, along with the ftandard fkin cools fafter«
inflrument of the fame kind, was filled with hot water. The
covered inftrument cooled through the fiandard interval of
ten degrees, namely, from 101 ^ to 9 If, in twenty-feven and
three quarter minutes ; but the naked inflrument employed 45
minutes in paffing through the fame interval.

Exp. 26. Both inflruments were fuffered to remain in the ^fp- ^6. And
cold all night, when the temperature in the naked inflrument ^jga^ ^o^g*^^^
was 50|-^, and that of the covered inftrument 49|° ; the air quickly.
Qf the room being 48^. Both inflruments were then removed
into a warm room, of which the temperature continued ber

tween

1£)S ON THE NATURE OF HEAT.

tween et^ and 65^. The covered inftrument acquired heat
the moft rapidly ; for in a quarter of an hour both flood at
5]l°, and at the end of four hours the naked inftrument
fliewed the temperature 61^^, and the covered 63^^ : whence
the Count obferves, that thofe fubftances which part with
heat the moft readily, have alfo the greateft facility to ac-
quire it.
Rays received as [Iq th^,-, proceeds to realbn on the probability that the tern-
emitted alter peratures of bodies pnay be changed, not only by the rays
the heals of bo- they emit, but by thofe they receive from other bodies ; and
'"* as the cooling of hot bodies is fo much accelerated by covering

their furfaces with fnbftances which affeft the radiation or ab-
Radiat'on does forption, he thinks it hij^hly probable that the air is but little
' «ot heat the air. ^^^^^^ ^^ ^^ .^^ temperature, by thefe rays which pafs
through it ; and he contemplates the eftablifliment of this fup-
pofition, fis promifing to explain various interefting pheno-
St?ady tcrypera-nomena; particularly that of the fteady temperature of living
turc of animals, ^^i^^ij,^ notwithftanding the great quantity of heat generated
in their lungs, and the dilferent temperatures of the fluid
which furroiinds them,
miy be affected for it is evident, the greater power an aninial may pofTeQ
y la lauon. ^^ throwing off heat by radiation, independently of the eft'eft
of the contad of the furrounding air, the lefs will his tem-
perature be affedled by the changes in that fluid, or ihe op- J
Inftancc in ne- preffive heat of the climate. The probability that negroes 1
^^^^' and people of colour, who fupport the heats of tropical cli-

mates much better than white people, ofters itfelf in this
place as the confequence of their colour; a quality which not
only enables them to throw off heat, but even, as the Count
much fufpe^ts to abforb frigorific'rays from fuch bodies as
may emit them.
Exp. 27. Black £jp^ 27. When the flat epds of both the horizontal cylin-
marmembla^nT dricat vefTels were covered with gold-beater's fkin, and one
increafes radia- of them painted black upon the covering with Indian ink,
E°"*ffi ^^^^^ ^^^' ^^ indicated by the thermofcope, emitted more

calorific rays from the included hot water than the other veflel
V did.

and alfo reccp- £jp, 28. When the fame two velfels filled with boiling-hot

???• water, were fet to cool, the blackened veffel cooled through

the ftandard interval of ten degrees in 23f minutes, while

the other, which was not blackened, employed 28 minutes.

4f The

ON THE NATURE OF HEAT. 19.Q

The author again reverts to the application of thefe fa<$ls Effects of the
, , ,. ,-^, , , ., . 1 • 1 r oil on the fkins

to animal bodies. Whether the oily coating which ^^^^g^^ ^f nottentot%,

apply to their (kins in cold climates, may not add to their &c. and of the
comfort by reflefling frigoritic rays; whether the Hottentots, T^^'^"^''^^^.^"!'^'
flill more difguftingly befraeared, may not derive advantages negroes,
fimilar to thofe derived by negroes from their black colour ?
are queftions that promlfe to lead to refults of prai^lical value.
Jie then proceeds to explain more fully the manner in which
^pegroes may be fappofed to refill the adion of a burning fun,
.^n oil exudes from the fliin of thefe people when expofed
naked to the fun; which oil refleds the fun's calorific rays.
Heat more intenfe produces fweat, which not only aids the
former procefs, but generates cold by evaporation. But when
the fun is fet, the oil retires from the furface, and the Ikin
becomes well adapted to admit frigoritic rays from the neigh-
bouring bodies.

Exp. 29. The thermofcope was perceptibly afiedled by the Exp. 29. Veffel

radiation of cold bodies: It was defirable to know whether °^ '^f'^ "J^f.

rapidly cooled by

..^his efFedl would be (hewn in a grolTer way, by accelerating radiation from
the cooling of a hot body. For this purpofe, two conical '^'^'
veflels of ihin flieet brafs, each four inches diameter at the
bafe, and four inches high, ending above in a cylindrical
peck, were feparately enclofed in a cylinder of thin pafle-
board covered with gilt paper, and then the veifels were
covered up with rabbit-flvins having the hair on them, in luch
a manner that in> part of thefe veffels, except their flat bot-
toms, was expoled naked to the air. The bottoms were co-

1^, yered with gold-beater's Oiin painted black with Indian ink,
in order to render them as fenfible as poffible to calorific

r .^nd frigorific rays.

The two veifels thus prepared were fufpended, with their
bottoms downwards from the arms of a fiand, and under each
was placed a pewter platter blackened on the infide by fmoke
from a candle. The platters ihemfeives were fupported on
iliallow earthen difties which refted upon wooden ftands; each
pewter platter having a perforated cover of tiiick paper, in the
center of which was a hole fix inches in diameter. The diftance
from the floor of the room to the fmoked furface of each platter
was 40 inches, and the interval between the furface of each
conical velTel and its correfpondent platter immediately beneath,
was four inches. One of the platters remained at the tempera-
ture

jBSOO ON THE NATURE OF HEAT'.

ture of the room, but the other was kept conftantly ice cold
by means of pounded ice and water contained in the dilh
beneath it.

The two conical vefTels were now filled with boiling hot

water, and every precaution was taken to prevent agitation in

the air; the only means by which an afcent of cold fluid could

be fufpected. The refult of the experiment was, that the

vefTel fufpended over the ice-cold platter cooled from 509 to

that of 40*^ ai>ove the temperature of the room, in 33 minutes

and 42 feconds; whereas the other veflTel required 39 minutes

and 15 feconds to cool through the fame interval.

^xp. 30. Repc- Exp. 30. Upon repeating this experiment the next day,

the times were 33 minutes 13 feconds and 39 minutes 30

feconds.

Velocity of cool- As the cooling of thefe veflTels is a complicated procefs which

b^th^radiatki '"^^^^^^^5 the confideration of the heat that palfed through the

from ice, in the covered fides, in thefe different times ; the Count enters into

ratio of 5^0 4. ^ procefs of computation, founded on the principles made ufe

of at page 61, by which he determines that the velocity with

which the heat pafTed through the bottom of the vetfel expofed

to the ice, was to that with which it pafied through the bottom

of the other veffel as five to fpur nearly.

Exp. 31. Pro- jE'jrp. 31. By the manner of defending the two conical vefiels

heat abf^rbed b ^^^'^ ^^^ ^ circular band or hoop of the fine port paper which

the air when a projeded half an inch below its bafe. It is evident that the air in

current was al- this fpace could not pafs upwards, as it became heated by con,

lowed to take ' t r > j

place. It was ^^^> and confequenliy, that very little of the cooling efFcdl could

then one twenty- i^ave been produced by the contact of an afccnding current. To

whole lofs. afcertain what thisefFed might have been, the two velfels were

fufpended as before; but one of them had its bafe inclined in

an angle of 43®, while the other bafe continued horizontal. In

this fituatron they were filled with boiling water, and fuf-

fered 10 cool without the platter and fiands beneath them.

Two effe6ls would follow from thefe arrangements : the veffel,

which in the other experiment had been placed over a plalter

at the temperature of the room, would now cool a very little

fafier by the abfence of that platter, which no doubt mufi have

liad its temperature a little raifed ; and the inclined veflel in

the prefent experiment would be cooled fomewhat more fpee-

dily, by the fucceffive contact of the afcending current of air

which was at liberty to rife.- This velTel was found to cpol

through the ftandard interval of 10^ in 37^ minutes, and the

horizontaj

• N TME iL ATVRE 0¥ HEAT. 2QV

feorizontal veflel employed 38|- minutes. By referring tbefe
fa6ls to computation, the Count finds that the heat loft by
adual communication to the air, is nearly ^y part of the whole
lofs.

Exp. 32. The counter radiation by the platter, v;hich was Exp. 32. Veb-
ftated under the laft experiment as impeding the coolincr pr«- retarded "bVthe
cefs, affords the important profpecl of explaining the effetl of vicinity of other
clothing, and therefore deferved to be more fully examined. ' '^f' ^"^^
The experiments 29 and 30 were therefore repeated, with tlie
diftance of three inches only between the bottom of each velTel
and its correfponding platter. The times of cooling through
iO^, were now 33| minutes and 40| minutes.

Exp. 33. And when the diftance was diminifhed to two Exp. 33. Repe-
ijiches, the times proved 32y minutes and 42|: minutes.
. Thefe experiments fhew that the vicinity of a cold body, The vicinity of
of which the low temperature is not kept up by artificial 5^J"^„ fu"cefl
means, retards the cooling of a hot body. And from this fion will confti-
fea the Count concludes, that if the hot body had been a '"^^ — ^^^^^°S '
•globe fufpended in the center of another larger thin hollow
i'phere, of the fame temperature, at the commencement, as
-the air and walls oF the roora^, the cooling would have been '
more flow than if the external globe had not been prefent ;
and alfo, if the external globe itfelf were included in another
globe of the fame defcription, the retardation would have
been ftili more confiderable. And by extending this fuppofed
experiment to a number of thin concentric hollow fpheres, we
may conceive a great retardation to follow, and fliall become
acquainted with the nature of the eff'eds which take place
when a hot body is furrounded by proper clothing.

. If the fpheres were metallic, the cooling would be flower more effeftuallf
if the furfaces were polilhed than if unpoliflied or blackened ;poHfhed^"^ ^
"whence it is highly probable, that the warmth of any clothing
depends very much upon the polifli of its furface.

The microfcope (hews that thofe fubftances which fuppIyFurs, feathers,
us with the warmeft coverings, fuch as furs, feathers, fJlks,J^^ ^* ^y^\
and the like, have their furfaces highly poliflied; and the
finer the fibres, or the greater number of interpofed poliflied
furfaces, the warmer is the clothing.

^ In the former experiments of Count Rumford, he confidered Clothing defends
I the warmth of clothing as prin^-ipally depending on the ob-^JJj^gfl^^J^g/jj
ilacles it oppofes to the motipn of the furrounding cold air ; preventing cir-

V culation of the
air.

202

ON THE NATURE OF HEAT,

but, by a patient and careful examination of the fubjefl, he
is convinced t}>at the efficacy of radiation is much greater than
he had fuppofed ; from the refalt of the experiment No, 31,
it appears that a very fraall part of the heat of a body cooled
in tl)e air, is in fadt communicated to that fluid; much the
greateft portion being communicated to furrounding bodies at
a diftance; and, in one of his former experiments, a hot body
was cooled, though it was placed in a torricellian vacuum.
Air heated only He confiders the heat which air receives by coming in con-
st Its furface fa6l with a hot body, to be communicated by radiation, in the
and by radiation. ....,,,,. ,.r

lame manner as it is received by other bodies at a greater diU

tance ; and he apprehends that the contiguous particle receives
the heat in preference for no other reafon than becaufe it is at
the furface of the fluid, this being the place where refledlion,
Tefradion, and increafe of temperature, take place ; and,
from thefe confiderations, he explains what has been called
the non-conduding power of tranfparent fluids.
Analogy hz- By extending the analogy of tho(e fadls which we know

tween light and concerning the effed of polifaed furfaces on light, to the ra-
diations of heat alfo, the preceding fads are eafily explained.
The frigorific rays are refleded externally, and a large por-
tion of the calorific rays, which would have itfued forth through
a rough furface, are, in the other cafe, turned inwards by
refledion,
A drop of water The poliflied furface of a drop of water, which rolls about
refifts the heat at a diftance from the face of a piece of red-hot iron, enables
by Us'polilhr* '^ ^^ refled the calorific rays ; the water acquires little heat,
and evaporates flowly.

With a lefs heat the water enters the pores of the oxide
upon the metal, lofes its polifh, acquires heat very rapidly,
and is foon evaporated.
It retains its po- If the metal be lefs oxidable, as, for example, a filver-
lifh longer in fpoon, the drop of water will fupport or refift a lower heat.
flfts^more. ^ ' I" f^^l it does not fo foon lofe its poiifti ; but~at a flill lower
heat, that is to fay, a little above boiling-water, a drop of
water is inftantaneoufly evaporated.
Exp. 34< Water Exp. 34. A clean poliftied fpoon, rendered black by hold-
rolling in a fpoon i,-jg j^ over the flame of a wax pandle, will receive a large
fniok-e, cannot ^''^^P ^^ water, which will roll about without wetting the
^e maic to boil, blackened furface. This drop cannot be made to boil by-
holding the fpoon over the flame of a candle. When the

fpoon

ON FULMINATING SILVER. 203

fpoon IS too hot to be held by Its handle, the drop of water
poured into the palm of the hand is warm, but by no means
fcalding hot.

Exp. 35. If a lar^e drop of water be formed at the end ofExp. 35. Drop
3 fmall fplinter of light wood, and the drop be thruft quickly J^ theTameVf a
into the center of the flame of a newly fnufFed candle, it will candle, is not
remain for a confiderable time in the center of the flame, ^^^^'^^
without being apparently aflfeifted by the heat; and if it be
taken out of the flame and put upon the hand, it will not be
found to be fcalding hot. If it be held for forae time in the
flame, it will be gradually dirainifhed by evaporation ; but it
does not appear that the heat is communicated by the flame,
but by the wood to which it adheres, which is foon heated,
and at laft fet on fire.

The remainder of the Count's memoir confifts of theoretical Why the thco-
remarks and inferences, occupying 29 pages of the Tranfac-''"'*^^' remarks
tions, I have endeavoured faithfully to defcribe the facts in abridged,
the way of abridgement, but cannot with the fame facility
do juftice to thefe argumentative refults. I (ball therefore,
for the prefent, conclude my account of his paper ; but may «

not perhaps wholly overlook his theories upon fome future
occafion.

XIII.

Letter from Pmfejfor Veau-de-Launay to J. C. Dela-
METHERiE, Oil fulminating Silver*,

jl\S it is at all times ufeful to fi:ate fads, whatever may be Accident with
the refults, I think it right to inform you of an accident which ^"^"^inating
occurred m my laboratory.

I had employed one of my pupils, a very good operator, to
prepare a fmall quantity of fulminating filver, which he executed
with (kill.

The quantity obtained was about five grains, or a quarter of
a gramme : it was depofited in a cryfial capfule about two lines
in thicknefs. He had taken a fmall quantity, about half a
grain, which was feparated with a card, and then dried, and

- fFrom Jojurnal de Phyfique, &c. Fioreal, An. XIL

afterwards

QO^ ON EVAPORATING FUKVACES.

afterwards detonated by flight fridion. Next day, that is to
fay twenty-four hours after the preparation, this young perfon
was defirous of taking an equal quantity from the capfiiie to re-
peat the experiment, but he had fcarcely touched the preparation
with the corner of a card when a violent detonation andexplo-
fion took place in the capfule which was (battered into a thou-
fand pieces. His face was covered with the vaporifed prepa-
ration, which was almoft black, and adhered ftrongly to the flvin r
his eyes experienced a ftrong fliock, which produced extreme
pain ; the opaque cornea became red and inflamed. Happily
his fear was the greateft evil : by walhing and bathing his eyes
and face frequently with cold water, the efTeifls of the detona-
tion were foon diffipated.

Fortunately, none of the fragments of the glafs had touched
his eyes or his face ; they were thrown nearly in a horizontal di-
redion, to a confiderable diftance: Some were thrown upwards
of twelve feet.
\ As the effedls of this preparation may have more calamitous

confequences. I think it ufeful to be guarded againft the dan-,
gers which it may occafion.

XIV.

Pyrotechnic ObferrationSt with their application to evaporating
Furnaces *, By Cit. C u r a u d a u , Carre/ponding Member of
the Apothecaries Society of Paris, and Refident Jjfociate at the
Atheneum of Arts,

&INCE I publiiTied ray obfervations on the caufes of the

imperfections of evaporating furnaces, I have had occafion to

make others on the fame fubje6^, the application of which may

add to the advantages in their conftrudion which I have made

known.

Plfadvantagcs in I" ^y ^^^ memoir, I proved that the bottom of the copper

the conftruftion in the evaporating furnaces, not only obftru6ls the elevation of

furnlces'^&c! ^^® temperature, but alfo diminithes the adivity of the fire, and

is rather favourable to the gazification of the combuflible body,

than to its oxigenation : I cited the lamp of Argand with its

* From Annales dc Chimin, No. 149, Floreal, An. XII.

glafs

ON EVAPORATING FURNACES. ^Q'5

glafs Chimney, as an example of the neceffity of ralfing the

temperature round the combufiible, whenever a compleat and

powerful combuftion is required. At prefent, I (hall take the

enameiler's lamp as an example In fupport of my new obferva-

tions ; I may fay that I am indebted to the examination of its

efFeds, for thofe which it has led me to make. In fact, if the EfFefts of the

jet of the flame of an enaraeller's lamp be examined, it will be In'thTfilimt'^ f

found that the intenfity of its adion depends on the current of Argand'slampj

air which is dire6led on the flame of the wick ; it will alfo be

feen, that it is only at the extremity of its jet that the greatefl

energy of the calorific rays exifts, and that its intenfity is fuch

that, by means of this lamp, effeds may be produced, which

are, comparatively, as powerful as thofe obtained in our bed

furnaces.

This mode of action of the caloric proves, therefore, that its
efFeds may be augmented, by augmenting the rapadity of its
current, and by direding it Ikilfully upon the body to be heated.;
Thefe are the conditions which I have endeavoured to unite in
my new contlrudion, and which, agreeably to the application
1 have made of them, are employed to (upport an opinion which
required an experiment on a large fcale to efcape being placed
in the clafs of hypothefes.

Having been lately confulted upon the conftru6tion of a applied to works
brewer's furnace, I took the opportunity to ftiow the great ad-°"^ ^^""^^ ^^^^^*
vantages of the alterations which my obfervations appeared to
me to render necefTary, and to induce the proprietor to conftru6t
his furnace according to the plan I fent him.

The following is the refult of the experiments which were Comparlfon of
made to afcertain tbe advantages pofTeffed by the new furnace ^^^° ^"rnaces.
over that which it replaced, ' . ,

i iThe old furnafce required 2^ hours to raife the temperature
of 2300 litres of well- water to 50*^ of Reaumur, and confumed
in the operation, which was repeated daily, 625 kilogrammes
of new dry wood.

The prefent furnace, on the contrary, confumes only 450
kilogrammes of wood in the fame operation, and is only one
hour in raifing the temperature of 2500 litres of well-water
to 50*^ : Whence it refults, tliat this new conftrudion evidently
makes a faving of fV '" time and nearjy one third in the com-
builible.

Such

20(jp ON EVAPORATING FCRNACES.

Such advantages appeared to me to be of fufficient importance
todeferve to be known, and to make it dcfirable that advan-
tage may be taken of a new procefs which will have great
influence on the economy of the fuel neceffary in manufac-
tures.

Defcription of the Furnace. Plate

Defcriptlon of A. Opening of the fire-place: it is 16 inches wide and 13
the new furnace, , . ,
high.

B. This part of the furnace refembles a vault; It is Slf
inches in height, 31 f in width, and 5 feet in depth. To add
to the effedt produced by the heat, I give the middle of the
fire place a depth of 2 inches more that at its fides, which niaken
it preceptibly concave.

C. An opening made in the middle of the vault, and which
is intended to increafe the rapidity and the action of the calo-
rific rays; it is 5 inches high, and is equal in thicknefs to the
vault. In its lower part, this opening is 23f inches long, and
I?! wide; and, in its upper part, is 191 long, and 13f wide,
which gives each extremity of the opening the form of a fphe-
roid whofe longed axis is in the diredtlon of the length of the
vault.

D. The difiance of the copper from the orifice for the heat
is 5 inches in the middle, and is reduced to 4, at the angle
E, which gives the advantage of concentrating the calorific
rays, in proportion as they lofe their intenfity by their ex-
panfion.

From the angle E to that at F, there is a di fiance of 15
inches: there-entering angle of F is 2^ inches from the cop-
per, and its faliant angle only one inch.

G and H are angles fimilar to that at F, but which are 1 1
inches diftant from each other : thefe angles may be multiplied
according to the height of the copper. The advantages which
they give confift in making the calorific ftreara undergo feveral
breaks, which increafes their power at the place of their
deviation.

I is an opening communicating with the chimney : it is 27
inches wide and 5 inches high. At the angle H, half the
circumference of the furnace fliould be clofed by a row of
bricks, for the purpofe of forcing the heat to dire^ itfelf from

the

ACCOUNT OF A CURIOL'S PHENOMENON, ' 20T

tlie fide oppofite to the chimney; immediately above this
courfe o( bricks, thofe which Cucceed muft be removed four
inches from the copper, and continue i^o to the height of four
inches; afterwards each courfe of bricks muft be brought
nearer, fo that this refer voir of heat may be clofed at the
height of five inches, which muft be done round all the cir-
cumference of the copper.

K is the opening of the chimney : it muft be three deci-
metres fquare through all its height, and at leaft four metres
high.

' L is a blower of hammered iron ; it is one metre above the
copper, and ferves to open or clofe the chimney at pleafure.
' The proportions laid down in this plan are intended for a
copper four feet three inches wide in its lower part, anti
forty inches deep.

XV.

Jn Account of a cunous Phenomenon obferved on the Glaciers of
Chatnouny ; together with fome eccnfional Obfervations con-
cerning the Propagation of IJeat in Fluids. By Benjamin
Count of Romford, V. P. R, S. Foreign AJfociate of the
National Injiitute of France^ Sfc. SfC. *

In an excurfion which I made the laft fummer, in the month Cyllndncal pit
of Auguft, to the Glaciers of Chamouny, in company with ('"^ "^^^^ °''.^'^*
ProfeflTor Pictet of Geneva, I had an opportunity of obferving, j^g water.
on wiiat is called the Sea of Ice, (Mer de Glace,) a phenome-
ncMi very common, as I was told, in thofe high and cold regions,
but which was perfc ftly new to me, and engaged all my atten-
tion. At the furface of a folid mafs of ice, of vaft thicknefs
and extent, we difcovered a pit, perfedly cylindrical, about
feven inches In diameter, and more than four feet deep; quite
full of water. On examining it on the Infide, with a pole, I
found that its fides were polillied ; and that its bottom was he-
mifpherical, and well defined.

This pit was not quite perpendicular to the plane of the
borizon, but inclined a little towards the fouth, as it de-

\

PhiL Tranf 1804, p. 23.

fcended ;

20S AC60CNT OF A CURIOUS PHENOMKNOlf.

fcended ; and, in confequence of this inclination. Its moutM

or opening, at the furface of the ice, was not circular, but

elliptical.

They are fre- From our guides I learnt, th^t thefe cylindrical holes are fre-

quen y oun . qjjgj^^|^, found on the level paf ts of the ice j that they are formed

during the fummer, increafing gradually in depth, as long as

the hot weather continues; but that they are frozen up, and

djfappear, on the return of winter.

Inference againft I would alk thofe who maintain that water is a cOndu(5lor

the conducing ^f ^g^t, how thefe pits are formed? On a fuppofition that
power or water. . . . . , .

there is no direct communication of heat between neighbour-
ing particles of that fluid, which happen to be at different
degrees of temperature, the phenomenon may eafily be ex-
plained ; but it appears to me to be inexplicable on any other
fuppoiition.

The quiefcent mafs of water, by which the pit remains con-
flantly filled, muftneceflarily be at the temperature of freezing;
for it is fiirrounded on every lide by ice : but the pit goes on to
increafe in depth, during the whole fummer. From whence
comes the heat that melts the ice continually at the bottom of
the pit? and how does it happen, that this heat a<5ts on the
hottom of the pit only, and not on its fides ?
Solution of the Thefe curious phenomena may, I think, be explained in the

efFeft by the following maimer : The warm vvinds which, in fummer, blow
greater denfity of ... _ , . , ... . . _ , ,

water above zero, over the iurtaceot this column of ice-cold water, mult undoubt-
edly communicate fome fmall degree of heat to thofe particles
of the tluid with which this warm air comes into immediate
contact ; and the particles of the water at the furface fo heated,
being rendered fpeciiically heavier than they were before, by
this fmall increafe of temperature, fink flowly to the bottom of
the pit ; where they come into contact with the ice> and commu*
iiicate to it the heat by which the depth of the pit is continually
increafed.

-"This operation is exadly fimilar to that which took place in

one of my experiments, (See my Ellay on the Propagation of

heat in Fluids, Experiment 17,) therefults of which, no perfon,

to my knowledge, has yet explained.

Conftanttem- There is another very curious natural phenomenon, which I

peratare of wa- couid wifli to fee explained in a fatisfadory manner, by thofe

of deep lakes, who ftill refufe their atfent to the opinions I have been led to

offered in fup- adopt, refpe6ting the manner in which^ beat is propagated

port of the non- -

ACCOUNT OF A CURIOUS PHENOMENON, 209

in fluids. The water at the bottoms of all deep lakes is con-condufting pro-
ftantly at the fame temperature, (that of 41** Fahrenheit,) P^^^^^^"^'^^-
fummer and winter, without any fentible variation. This
fa6t alone appears to me to be quite fufficient to prove, that if
there be any immediate communication of heat betvi^een neigh-
bouring particles or molecules of water, de procht en proche, or
from one of them to the other, that comnfHiinication mufl be fo
extremely flow^, that we m^y with fafety confider it as having
noexiftence; and it is with this limitation that I beg to be
underftood, when I fpeak of fluids as being non-condu6lors of
heat.

In treating of the propagation of heat in fl uids, I have hitherto
confined myfelf to the inveftigation of the (iraple matter of fa6t,
without venturing to offer any conjectures relative to the caufes
of the phenomena obferved. But the refults of recent experi-
ments on the calorific and frigorific radiations of hot and of cold
bodies, (an account of which I ftiall have the honour of laying
before the Royal Society in a (liort time,) have given me fome
new light refpedling the nature of heat, and the mode of its com- -
muhication; and I have hopes of being able to (how why all
changes of temperature, in tranfparent liquids, muft necelTarily
take place at their furfaces.

I have feen with real pleafure, that feveral ingenious gen- Notice of expe-
ileraen, in London, and in Edinburgh, have undertaken the "^^"^l^sajnft
inveftigation of the phenomena of the propagation of heat in
fluids ; and that they have made a number of new and inge-
nious experiments, with a view to the farther elucidation of that
moft interelling fubjed. If I have hitherto abftained from
taking public notice of their obfervations on the opinion I have
advanced on that fubjed, in my different publications, it was
not from any want of refped for thofe gentlemen that I re- *
mained filent, butbecaufe I ftill found it to be quite irapoffible
to explain the refults of my own experiments, on any other
principles than thofe which, on the moft mature and difpaf-
fionate deliberation, I had been induced to adopt; and becaufe
my own experiments appeared to me to be quite as conclufive
(to fay no more of them) as thofe which were oppofed to them ;
and, laftly, becaufe I confiJered the principal point in difpute,
relative to the paffage of heat in fluids, as being fo clearly
eftabliftied by the circumftances attending feveral great opera- '

tions of nature, that this evidence did not appear lo me to be m

Vol. IX. — November, 1804-. P dang^

5^]0 ACCOUNT OF A CURIOUS PHENOMENON.

danger of being invalidated by conclufions drawn from partial

and imperfe6l experiments, and particularly from fuch as are

allowed on all hands to be extremely delicate.

Heat of the fides In all our attempts to caufe heat to defcend in liquids, the

of the veflel, ^^^^ unavoidably communicated to the fides of the containing

and defcending -^ i r « i r w

current in a vef- vetTel, muft occafion great uncertainty with refpect to the remits
£el of ice. ^f tj^e experiment ; and, when that veffel is conftru6led of ice,

the flowing down of the water refulting from the thawing of
that ice, will caufe motions in the liquid, and confequently in-
accuracies of ftill greater moment, as I have found from my
own experience; and, when thermometers immerfed in a liquid,
atafmallditlance below its furface, acquire heat, inconfequence
of a hot body being applied to the furface of the liquid, that
event is no decifive proof that the heat acquired by the thermo-
meter is communicated by the fluid, from above, downwards,
from molecule to molecule, de proche en proche; io far from
being fo, it is not even a proof that it is from the fluid that the
thermometer receives the heat which it acquires; for it is poffi-
ble, for aught we know to the contrary, that it may be occa-
fioned by the radiation of the hot body placed at the furface of
the fluid.
Reference to the In the experiments of which I have given an account, in my

experiments of -gihy on the Propagation of Heat in Fluids, great mafles,
boiling water •' , . . , r i i- i , . i

landing over many pounds m weight, ot boiling hot water, were made to

ice. repofe for a long time (three hours) on a cake of ice, without

melting but a very fmall portion of it; and, on repeating
the experiment with an equal quantity of very cold water,
(namely, at the temperature of 41® Fahrenheit,) nearly twice
as much ice was melted in the fame time. In ihefe experi-
ments, the caufes of -uncertainly above mentioned did not
exift : and the refults of them were certainly moft flriking.

The conclufions which naturally flow from thofe refults, have
always appeared to me to be fo perfeflly evident and indifputa-
ble, as to fland in no need, either of elucidation, or of farther
proof.

If water be a conductor of heat, how did it happen that the
heat in the boiling water did not, in three hours, find its way
downwards, to the cake of ice, on which i,t repofed, and from
which it was feparated only by a ftratum of cold water, half an
inch in thicknefs ?

I vviOa

ACCOUNT OF A CURIOUS PHENOMENON. 211

I wifbthat gentlemen who refufe their aOent to the opinions Recapitulatory
I have advanced rerpe6ling the caufes of this curious pheno- ^^
menon, would give a better explanation of it than that which I ^
have ventured to offer. I could likewife with that they would
inform us how it happens, that the water at the bottoms of all
deep lakes remains <ionftantly at the fame temperature : and,
above all^ how the cylindrical pits, above defcribed, are formed
in the immenfe maffes of folid and compact ice which compofe
the Glaciers of Chamouny !

A remark, which furprifed me not a little, has been madeby Notice of one re-
a gentleman of Edinburgh, (Dr. Thompfon,) on ^^^^ ^^P^^i- ^^^^^^yj^^'
ments I contrived, to render vifible the currents into which
liquids are thrown on a fudden application of heat, or of cold.
He conceives, that the motions obferved in my experiments,
among the fmall pieces of amber which were fufpended in a
weak folution of potafh in water, were no proof of currents
exifting in that liquid; as they might, in his opinion, have been
occafioned by a change of fpecific gravity in the amber, or by
air attached to it. I am forry that fo mean an opinion of ray
accuracy as an obferver (hould have been entertained, as to
imagine that I could have been fo eafily deceived. For nothing
furely is eafier, than to diftinguifli the motion of a folid fuf-
pended in a liquid of the fame fpecific gravity, which is
carried along by a current in the liquid, from that of a body
which defcends, or afcends, in the liquid, in confequence of
its relative weight, or levity. In the one cafe, the motion is
uniform ; in the other, it is accelerated. In a current, the body
may be carried forward in all directions, and even in curved
lines ; bat, when it falls in a quiefcent fluid, by the aftion of
gravity, or rifes, in confequence of its being fpecifically
lighter than the fluid, it muft neceflarily move in a vertical
direction.

The fa6l is, that I very often obferved, in the courfe of
my numerous experiments, the motions of fmall particles of
matter, of different kinds, in water, which Dr. Thompfon
defcribes; but, fo far from inferring /rowz ^/jem the exiftence
of currents in that fluid, their caufe was fo perfedly evident,
that I did not even think it neceflary to make any mention of
them.

I cannot conclude this Paper, without requefting that the
Hoyal Society would excufe the liberty I haye taken in troubling

P 2 * them

2l4 FERPETVAL MOTION, AND JOINTED PARALLEL RULE.

them with thefe remarks. Very defirous of avoiding every fpe-
cie^ of altercation, I have hitherto cautioufly abftained from
•ngaging in literary difputes; and I ftiall moil certainly endea-
vour to avoid them in future.

I am refponfible to the public for the accuracy of the accounts
^hich I have publiQied of my experiments j but it cannot rea-
fonably be expeded, that I fliould anfwer all the obje6lions that
may be made to the conclufions which I have drawn from them.
It will however, at all limes, afford me real fatisfaction to fee
my opinions examined, and my miftakes correded; for ray firlt
and mod earned with is, to contribute to tl?e advancement of
ufeful knowledge. ,

XVI.

Account of two Sketches ; viz. one for a perpetual Motion, and
the other of a Jointed Parallel Rule, xvhich has no fide Deviation,
In a Letter from R. B,

To Mr. NICHOLSON.
SIR,

I

Perpetual mo- JL was much gratified feveral years ago by fome effays with
in^e PhUofo- ^^^^^^ T^^ obliged your readers upon the perpetual motion. In
phical Journal, the firft volume, p. 375, of your quarto feries, I find an account of
feveral fchemes (neceflarily abortive) for producing perpetual
motions by the action of gravity, and in your third volume, I
find an account of various methods of keeping up the motion
of a machine by means of the changes which take place in the
barometer and thermometer, I have ventured to fend you the
iketch of a project for a perpetual motion of the latter kind,
which has long remained among my memorandums. You will
fee that it is not of the clafs of perpetual motions properly
fpeaking, but merely the application of fome exifting intermit-
tent motions in nature to the purpofe of maintaining the rotation
of machinery. If you (liould heiitate about inferting this, I
fchink the other (ketch which accompanies it of an ufeful in-
ftrument, cannot fail to meet your approbation.
Defcnptionof a Fig. I, Plate XII. A reprefcnts the marine barometer of
wheel kept in H^Hey, but varied by the addition of a veifel B at the open

motion by the ..,, i n-j r rr .

marine baromc- end, in which the water oi Other fluid, expoles a furface nearly
fier. equal

PERPETUAL MOTION, AND JOINTfiD PARALLEL RULE. 213

equal to that in the clofed veflel A. Thefe two vefTels are
conneded by a long horizontal tube G. It is evident that any
change, either in the prefTure of the external air or the elafticity
bf the internal air, will caufe the fluid to run along the tube,
and add to the weight of A or of B according to circumftances.
The heavier veflel will preponderate ; but it will be prevented
from defcending too far by a flop or bearing to which it will
arrive. Any change in the inclination of G will move the at-
tached lever C D ; by means of which, one of the two hori-
zontal racks will be made to pulh round that ratchett wheel into
which its teeth fall, at the fame time that the other rack will be
drawn backwards upon its wheel. The oppofile adion will
drive forward the other wheel ; and as both thefe wheels are
fixed on the fame axis, the fyllem will be driven the fame
way by every change of denfity or weight in the air that takes
place.

The other iiiHrument, Fig, 3, is a parallel rule which is Account of a

franied without any Hiding work, and opens to a much greater "^^ ^^"^^

extent than ufual, without any fide deviation. I do not know

the inventor; but it was communicated to me by a private

hand. The jointed parts are reprefented in Fig. 2, and the

dimenfions are exprefled by the fmall numerals. From the

joint D to the joint E upon the bar, C E, the difiance, is =

1 ; from the joint E to the joint A, = 2 ; from the joint A

to the joint B, = 3 ; and from the joint B lo the joint D, =

,,4. ; which is alfo equal to the part D C of the Bar E C. Now

ft is found, and I muft leave the mathematical proof to your

readers, that the point C moves by the opening from B (upon

which it lies when (hut) in a firait line, very nearly at right

angles with B A. From this property it is eafily feen, that

two parallel rules, having the fyftem of four bars fixed to

each, and conne6led as in the figure, will be moveable without

fide deviation, and will preferve their paraHelifm in all

, fitualions.

I am Sir,

Your obliged humble fervant,

R. B.

Fankiliar

214 HORSK-POWERS OP A STEAM-EVCrNE.

XVII.

Familiar Account of the Method of ejlimating the Value qf a
Steam-Engine in Horfe-Povcers as they are called. By a CorrC"
fpondent.

To Mr. NICHOLSON.
SIR,

Introduaory l\s your excellent Journal is the repofitory for ufeful informa-
letter. tion, whether fcientific oVpra6lical,I have thought I (hould oblige

many manufacturers and others of your readers, by fending you a
very clear report about horfe-powers, which a friend of mine
has communicated to me, and was received by him from an
eminent character in anfwer to an enquiry profeffionally made.
It clearly appears from this paper, that the calculation by
horfe-powers muft be fallacious, unlefs engineers could agree as
to the quantity of work they would arbitrarily, in the firft
inftance, afcribe to one horfe; and then theexpreffion would be
nugatory. And not only fo, but it would not then be true that
the value of a fleam-engine in work, however clearly expretT-
ed in quantity per day, would be fairly fhewn, unlefs the
•wages or food of the working being were taken into the ac-
count. Coals may be fliled the food of a fteam-engine, and no-
thing is more evident than that, if two engines raife equal quanti-
ties of water j5er hour, but confume different quantities of coal,
they will not be equally beneficial to the proprietors. I would
therefore propofe, that the eftimate fliould be made by attend-
ing to thefe two particulars only, and faying nothing about
hortes, at leaft in fpecific arguments intended to have legal
efFecls : And, as a fupplement to the fa6ls and obfervations
contained in the report, I will add, that one of the beft en-
gines of Boulton and Watt, has been known to raife between
28 and 30 millions of pounds of water to the height of one
foot with one bulhel of good coals, which appears to be an
outfide meafure ; and that, though there are fubfequent im-
provements both in the con(lru6lion of furnaces and the work-
ing gear, yet there are Ibme among late engines which fall
fliortof 20 millions.

I am. Sir,

Your conftant reader,

E.T.

Report

HORSE-POWERS OF A STEAM-ENGINE. 215

Report concerning the Power of a Steam-Engine ereBed bi/ Cori"
traa at * ^**.

IT is required to determine whether the fteam-engine ere6led Steam engine aC
g^t ♦ * ♦ * lyy j^r. — ^, be equal to the power of fixteen *****
horfes. The fame has a cylinder of 21| inches diameter, and
gives 23 doable ftrokes per minute, of four feet each.

In anfwer to this quefiion it muft be previoufly remarked, Reafon why

that fleam-eniiines havins: ori<rinally been recommended and f ^^"™, ^"S'n«

" o o y ^ have been com*

fubflituted inftead of horfes, the method of computing by the pared with

number of thofe animals intended to be fupplied by means of ^°'^^"'
this invention, has been generally applied, though it is much
lefs certain and accurate than other methods well known to
mechanical men. The uncertainty of calculating by horfe-Itlsanuncertaijj
powers arifes from various caufes ; fuch as the great differ.-"^
ences of ability between the flrong and heavy horfes ufed in Lon-
don, and thofe of not half the flrength ufed in various parts of
the country ; the greater or lefs degree of fpeed during work ;
the quantity of re-aftion agalnfl: which they are urged to pull;
the (horter or longer time of work ; their food, fiabling, &c.
&c. And this uncertainty, as may eafily be conceived, is (o
great, that the words horfe^poiver cannot pradically be ap-
plied, otherwife than to denote a certain quantity of mechanic
effed agreed upon and underftood between engineers, and
muft not be underftood to denote any elementary meafure, ^
capable of being worked out or inferred within any reafonable
or ufeful limits, from the real power of the horfe hlmfelC

It therefore follows of neceffity, that the engine muft be Words horfe-
iexamined by firft ftating its mechanic effea; that is to %, Jo^e^an'^arbicrarr
how many pounds weight it is capable of raiting through a quantity of
given fpace in a given time, that is to fay, through the height ^^^^'
of one foot during one minute, and then dividing this fum by
the like effeQ producible by one horfe, according to the ftate-
ments and pradice of engineers of the firft reputation. I con-
fine myfelf to MelT. Boulton and Watt, Dr. Defaguliers and
Mr. Smeaton,

The pradice of MelT. Boulton and Watt is, to con fider a Quantities of

horfe as capable of raifing a certain weight, which is ftated to ^^"^^ P^*^ ^°^^^»
. r^ 1 • 1 • r X 1 • 1 • . by Boulton and

be ot 32000 pounds avoirdupois, one toot high m one minute, -vvatt, Defagu-

Pefaguliers' refults brought to the fame form, give 27500 lie« and Smca*

' , tO£U

pounds i

2l6f HORSE-POWERS OF A ST^AM ENGINE.

poimds; and Smeaton's 229] & pounds, under the fame clr-
curaftances. The lowed of thefe performances are more than
equal to the average power of a horfe employed in hufbandry
for eight hours per day.
A fteam engine If the diameter of the cylinder be multiplied by ilfelf (2l|
compute . x2l|), the produ6l will give 446;^ round inches for the whole

furface : and Smeaton reckons the eflf;^6live or working pref*
fure per round inch on the atmofpheric engine, at feven
pounds avoirdupois. It is ufual to reckon the^ working pref*
fure on a clofe engine (like that in queftion), at 10 pounds
the round inch ; but I (hall firft take the feven pounds as
being againft the builder: So that, by multiplying the round
inches 446^: by 7, we have 3l23| pounds for the weight
raifed. But the ftrokes are 23 of four feet double per minute,
that is to fay, 184 feet. JVluUiply the weight 3I'23|: by the
height 184, and the produ6l 574760 will be-the mechanic
efFecl of the engine, or the number of pounds it will raife one
foot high in one minute. Laftly, Divide this by Boulton and
Watt*s horfe-power (5|*^|o), and the quotient 17 ^, or
Very nearly 18, will exprefs the power of the engine in
horfes.

If we follow Defaguliers, the engine will prove equal to 21
horfes.

And, according to Smeaton, its power will bfe equal to 25
horfes.

If we had taken the prefiure at 10 pounds per round
inch,' the powers would have proved much greater, as
below.
Steam engine I" *-^^ above calculations the horfes are fuppofed to be

can work ticble fairlv worked, and the engine is fuppofed to be flopped as
^^'^* foon as the horfes leave off. But an engine can work the

whole 24 hours ; and Smeaton, conHdering that three fetts of
horfes muft be kept to work conftantly for the fame time,
reckoned a fleam engine to be equivalent to three times as
many horfes as could equal its rate of working. The follow-
ing table will (hew the powers of this engine, according to all
thefe feveral methods :

7lb.

ATMOSPHERICAL OXtGEN.

fill

Powei'in Horfes ac-
coiding to Boulton
and Watt.

Ditto ac-
cording
Defagu-
liers.

Ditto ac-
cording
to Smea-
ton.

24 hours worV
according to
Smeaton in
horfes.

71b. prelVure
per round
inch. ,

or 18 very nearly

21

25

75

lOlb. preffure |

per round | 25

inch. , i

30

1

1 35|

107

XVIII.

Experiments proving the Necejfity of atmojpherical Oxigtn in the
Procefs of Vegetation. In a Letter from Mr. John Gough.

To Mr. NICHOLSON.

SIR,

JLJR, Prieftley and M. Ingenhoufz have made many experi- Rcfleftionson

ments with plants, confined in azote; from which philofophers ^^"^"^^ '7'^"

have inferred, that vegetables differ from animals in not requir- kind.

ing the prefence and fupport ©f atmofpherical oxigen. One

circumftance however occurs in all thefe experiments, if my

memory be correal, which renders the conclufion doubtful:

the plants, ufed in them were in conta6t with the water that

confined the azote in the inverted jars, through the medium of -

which they had evidently the fame indirect communication

with the atmofphere that fifties are known to require.

With a view to throw fome additional light upon this dif- Experiments o«
putable point in the ,iFegetabIe economy, I determined to fur- J"^cculentvcgc-
round certain fucculent plants entirely with azote; which pof-
fefs the Angular property of vegetating when fufpended by the
roots in dry air. My method of performing this confifts in fix-
ing the fubje€l of the experiment by means of a thread, to a
fmall perforated board, landing on a pillar, which was fur-
•ifhed with a foot of lead. The plant being thus fecured, was
introduced through water into a glafs jar of azote; where it
was wholly furrounded by the gas.

Exp. 1, The firft experiment, I made in this manner, was Experiment with
tried in June 1 800. A plant of fedum acre was furrounded by ^^^""^^^^^ ^°'"*
aeote when it was ready to expand its flowers, and another
was placed befide it, under a fimilar jar 5 which contained
3 common

to flower.

218 ATMOSPHERICAL OXIQEN'.

common air. The latter fpecirnen flowered very well j but
the former died away without opening one of its bloflbms.
With the fame Exp. 2. The event was the fame when I made ufe of a
la flower. branch of this fedum already in flower; for the plant withered

and did not flied its petals; which is contrary to the ufual ha^
bits of this vegetable, when it is left to the impulfes of nature
unthwarted by art.
With barren Exp, 3. Several plants of fedum acre were alfo confined in

fame and fem- J^^^ ^^^^^ ^''^-^ azote laft fpring, before the flower buds were
pervivum tedo- formed upon them: not one of thefe attempted to vegetate;
'""^' on the contrary they all withered in the courfe of four or five

weeks. This was not the cafe with other fpecimens, which
were placed befide them upon fimilar flands, under jars con-
taining common air and (landing in water; for they remained
green and vigorous, after the former were dead; they had
moreover produced a number of purple filaments fpringing
from the Jlalk; which is conftantly done by the fedum acre,
when fufpended by the roots. It is proper to remark, that the
air of the latter fet was frequently changed, with a view to keep
it near the ftandard of the atmofphere. The fempervivwn tec*
torum did not oflfer to vegetate when treated in the fame nian^
ner by being confined in azote; but it appeared to be more te-
nacious of life under this kind of treatment, than the fedum
acre,
lofcrence from ^^^^ preceding experiments induced me to conclude, at the
thefe experi- time of making them, that the welfare of fucculent plants re-
^^^ ' quires them to be expofed to the atmofphere, and that they

cannot grow when furrounded by azote, nor even prefervethe
vegetative principle in it, for an indefinite length of time.
Seeds and bulbs ^ hdive fliewn in the fourth volume of the Manchefter Me-
in the fame pre- moirs, that feeds and bulbs are not lefs indebted for their prof-
perity to the agency of oxigen, than fucculent plants appear
to be from the prefent letter. Thus it is manifeft that the far-
ther we carry our refearches into the nature of organized bodies,
the greater is the number of them ; which are found to be in-
capable of performing their natural funflions, when deprived
of refpirable air; but as the truth of this maxim remains to be
extended experimentally to vegetables of a lefs humid confli-
tution, than the fedums, the following fa<5l may be related
with propriety.
Experiment ,£^J3. -t. A diminutive plant of cerajilum vulgalum was placed

made with Qtt the 18th of February, 180k upon a ftand covered with a

ATMOSPHERICAL OXIGETT, 219

flice of wet fponge; it was then put under an inverted jar,
containing common air, and (landing in water. Tins plant
encreafed conliderably in bulk in the courfe of 20 days; be-
fides which it had taken root in the fponge; it was therefore
transferred into a jar filled with azote; but this change of cir-
cumftances put a flop to vegetation; for the herb made no fur-
ther advances, but withered away.

Exp. 5. In order to diverfify thefe experiments as much as with plants in
poflible, I took a number of phials, having narrow necks, and ^^'^^ deprived
filled them with water, which was either procured from fnow,
or deprived of air by boiling. Proper plants being then placed
in the bottles, they were introduced quickly through water
into jars filled with azote; under which circumflances, all my
fpecimens died away fooner or later without making one effort
to vegetate. The herbs ufed on thefe occafions were the com-
mon garden fpear-mint and the draco-cephalum Moldavicum;
both of which vegetate freely in bottles of water ex})ofed to
the atmofphere. I alfo treated in the fame manner, a branch
of Lyfimachia vulgaris, which was ready to flower; it de-
clined gradually for a month, but never opened one blofTom;
though it is an aquatic plant and flowers very well in jars of
water. It may here be remarked once for all, that vegetables
die very flowly in azote, provided they are fupplied with water
deprived of air; but if my experiments may be relied on, all
their natural fiinflions ceafe in thefe circumflances, as foon as
they are removed from the atmofphere.

Exp. 6. The lofs of energy experienced by plants confined Plaats^iem
^ ... . , . . T r -^ . . . aaote for want o#

in mephitic air, does not appear toarile from an injurious qua- (j^ej^ prope»

lity of the gas, but from the want of the falutary ftimulusofftimulus.
oxigen; for a flip of fpear-mint, which had remained twelve
days in a glafs of azote, recovered upon being reflored to the
air, with the lofs of its loweft leaves only ; and an ofT-fet of
fempervivum vegetated freely after being removed from a jar
of the fame gas, in which I had kept it, from the 2nd of April
to the 2nd of May, flanding in a bottle of fnow water. Thefe
fa6ts feem to argue, that vegetables, treated in the manner de-
fcribed as above, fuffer a fpecies of torpidity, from which
they may be recalled by the prefence of atmofpherical air, pro-
vided the re-admifiion of this necefTary agent be not delayed
too long; in which cafe, the plant perifhes, in confequence of

lh«

4

220 ATMOSFHKRICAL OXIGEN.

t}^ continued ina6tivity of its organs, and tlie fermentation of
rts juices; which is occafioned by the fufpenfton of all its
funftions.
Succulent plants This fluid (o necefTary to the procefs of vegetation, is evi-
*hf Itmof herT ^^^^^^ abforbed from the atmofphere by fucculent plant?, bulbs,
but dty ones and a variety of feeds, when properly moiflened; for they will
feooi water. all vegetate freely in open fituations; bjut the following ex-
periment feeras to prove that trees, flirubs and the lefs juicy
herbs derive air from water, as fi flies do.

Exp. 7. I introduced the lower extremities of di-fferent
plants, or more properly of the branches of different plants,
into phials filled with water, and after luting the necks with
wax, I funk the bottles in pots of water, fo as to leave th^;;
foliage of the plants expofed to the fun and furrounded by thei
atmofphere. The evaporation caufed by the adlion of the
light drew the water out of the bottles, and the air defcendin^
at the fame time through the fubftance of the plants preventer
a vacuum being formed in, thefe plofe veflTels.. This facl liadP
nearly perfuaded me, that vegetables pofTefs a faculty analogous
to refpiration; but when I repeated the experiment with phiy
^ als perforated in the bottom, they remained full of water. This
eircumdance (liews the refpiration in quefiion to be merely ac-
cidental and to be occationed by the necks of the bottles being
luted; on the other hand it is highly probable, that air enters
the veffels of vegetables in conjun«5lion with water. Here it
Is decompound, in confequence of the ftimulus given to the
vegetative principle by its prefence ; the azote is afterwards
affimulaied into the fubftance of the })lant, while the oxigen is
rejefled either wholly or in part. This gas, after its expUlfion
flows into the mephitic air, contained in the jars, the volume
©f which is thereby augmented, and its quality improved ; but
I will not venture to fay, that the two gafes form a new che-
mical compound on thefe occaiions.
Exception to the ^^'P' ^- ^ ^^ acquainted with a Tingle exception to the ge-
genaral rule that neral rule that air is requifite in the procefs of vegetation. For
grants require ^,[^qy^ plants have withered in azote they become mouldy; that
is, in the language of botany, they are covered with the mu-
cor mucedo. The worms which inhabit the decayed livers of
fliecp, &c. furniHi us with a parallel inftance in the animal-
kingdom; and the inveftigation of thefe fingular anoraali^J
forms a difficult problem in the natural hiftory of organized
bodies..

The

t SCIENTIFIC NEWS. <^|

The (entiuients contained in this letter, are oppolite to the The effay c«i«
common notions relative to the nature of vegetation, and fo^^ ^ *
manifeft a departure from eftaWiflied opinions may be thought
to require an apology. The juftification of my conduct how-
ever appears in the body of the efTay. The experiments are
related with an attention to circumftances; which will enable
alinoft any perfon to repeat them; and Ihould fome philofo-
pher undertake to do it, his labours will either eftablifli my
opinions, or confirm the contrary doctrine, by the refutation of
them. There is one omitlion in the detail of tbefe experi-
ments; I have neglefted to remark, that the term azote figni*
fies nothing more than common air deprived of oxigen by the
fulphuret of potaih or the martial pafte of fulphur, but mor«
frequently by the former. The determination of the queflion
is of fome moment, not only to natural hiftory, but perhaps to
agriculture alfo ; and I could wifli it to be refumed by a philo-
fopher, whofe advantages are fuperior to my contra6led powers
of obfervation and imperfect apparatus. Should any man •of
fcience undertake the talk, I would recommend the fedum acre
to his notice; becaufe the filaments which fpring fr>om the
ilalk of this plant in common air afford a criterion whereby the
progrefs of fimilar fpecimens confined "in azote may be ob-
ferved and afcertained,

JOHN GOUGH.

'^Middlejhaiv,
Oclober 24^, 1804.

I

SCIENTIFIC NEWS, ACCOUNT OF BOOKS, 8^c.
Frothing of Oil by EkStricity,

1 HE anonymous author of, fome eledlrical experiments com-
^nunicated to Van Mons the following fact, from whofe Journal
I tranflate it. He wa« making an experiment to afcertain tho
conducting quality of oil, for which purpofe he had filled one
third part of the length of a tube with the oil of Colfa, The
lube was three feet long and half an inch in diameter, having
its elofed end drawn out; The open extremity was fecnred by
• cork, through which a needle was ihruft; and over the cork

was a coaling of wax. tx) prevent the oil from tranfuding. The

tube

222 JtCCOUNT bJ" flOOkS.

tube being then placed on two infulating fupports, and the
needle turned towards the part moll remote from the machine,
the tube was flightly inclined, in order that the oil might run
down to that part of its capacity which was neareft the prime
condudtor. He then put the machine in aflion, and with great
forprife obferved the oil gradually to enter into a ftate of ebul-
lition ; beginning at the furface and fpeedily acquiring a ftate
of eflfervefcence perfe6lly refembling that of fparkling Cham-
paigne. Upon opening the tube, a gas efcaped with violence,
which the author did not colled, but which well deferves to be
examined. This aftive electrician intends to fubjeCl the differ'
ent vegetable and mineral acids to the adion of eleClricity by
the fame procefs.

Native Magnefia,
GIOBERT has found that a white earth conlidered as pure <
alumine and employed at Turin in the fabrication of porcelain,
contains 0,80 of magnefia. Van Mons.

Gray^s Experl- Tlie Experienced Mill'ivright; or a Treatife on the ConJiru6tion of
cnced Mill- y?;;w<? of the mojl ufcful Machines, with the lateji Improvements,

To which is prefixed a Jkort Account of the general Principles
of Mechanics and of the Mechanical Powers, lllujlratedwith
fortj/ Engravings. ^3/ Andrew Gray ^ Millwright, very large
quarto i 73 Pages of Letter Prefs, of the fame Size as the
Engravings,

THE author is a pradical mechanic, who has been up«<
wards of forty years employed in ereding different kinds ol
machinery; and the greatefl part of the Defcriptions in thii
Work are of Machines which he has either planned or fuper^
intended their conflru6tion. Thefe Drawings being accuratelj
made to fcale, are not, as he remarks, (o be confidered as me-
chanical fpeculations, always doubtful till fubjeded to aftuj
experiment, but as cafes of pradical knowledge, the effeds c
which have been fully tried and long approved ; moft of thet
being fliil employed for the purpofes of their original fabrications
. Previous to his Account of the Machines, this author give
a popular Treatife on Mechanics, in fix different chapters, bcii
ginning with General Principles and Definitions, which are fol

lowec

ACCOUNt OF BOOKS. 223

lowed by Explanations of Simple Engines, called the Mecha-
nical Powers. Thefe are fucceeded by an Account of the
Effeds of Fridion, and the bell Method of applying thofc
Mechanical Powers?. Pradical Diredions for deiigning and
conftru61ing the Parts of Machines are in the next place given ;
and laftly, the author treats on the Strength of Machines, the
relative Velocity of their Parts and the leading Do6lrines which
are. neceffary to be attended to in (heere»5ling of Water-Mills,
The Machines of which Meafured Plans, Elevations and
Sedions are given, are; A confiderabfe number of Thraftiing
Machines, to be drawn eitiier by Water or by Horfes, with
the Elevation of a Wind-mill to turn Machinery of this De-
fcription; one Snuff Mill; two Sheeling Mills; feveral Corn,
Barley, Malt, and Flour Mills; one Oil Mill; one Flax Mill;
one Paper Mill; one Saw Mill; one Fulling Mill; Bleaching
Machines, Beetlilig Machines, and various Pumps.

Thefe Drawings and Defcriptions will no doubt prove of
high value to the man of butinefs; though it is perhaps to be
regretted that the fame attention to junior ftudents which is
difplayed in the introdudory treatife, is not as fully ftiewn by
explaining the relative operations and eflefts of the parts of
thefe machines in the defcriptions which accompany the draw-
ings.

Pradical Ohfervatiom concerning Sea Bathing; to zvhich are

added, Remarks on the Ufe of the Warm Bath, % A. P.

Buchan, M. D. of the Royal College of Phj/Jicians, London,

Croxvn 8vo, 207 Pages.

IN the early tlages of human fociety, when the occupa- Buchan on fea
tions of man led him to ftrong exercife in the open air, it is * "^*
probable that his health may have been chiefly impaired by the
fortuitous occurrences of his mode of life, and the dire6l wear
of his organs engaged in the grofs and adive labours of his life.
It is probable that he may have felt little of thofe difeafes
which the claffification and habits of a refined and luxurious
fociety have introduced. Neither mental fatigue, nor the
anxious and incelTant labour of crowded cities could have
operated upon his powers, nor was he fubjeded to the miferies
of indolence, repletion, and the hftlefs want of motive which
benumb the faculties of the rich, Thefe are the prices which

bjr

■

Buehan on fca by oUF numerous miftakes we are corapelled io pay for the fu^

^* perior enjoyraerits which an enlightened ftate of fociety can

rafibrd to thofe only who poflTefs- the virlue, the condtift, and

the good fortune to know and to acquire them. Among the

moft oppreffive of thefe confequence^^ no doubt, is the lofs of

•hcaUh ; and. while we make facrlfices to what we imagine tP

be our welfare, it. becomes us occ^fionally. to interrupt our

ufual train of habits, to unbend the mind, give repofe to the

^ fyftem, and recover, by an oecafional change of our ocCtfpa-

' tiouSs,. that vigour which famanefs of purfuits,^pd cqnfiriejnent

Xeldom fail to impair. . , . "

Goe.of the mcu^ns at prefwt much-reforted to i.^, io tepair
to the lea^Goaft ; paflly with a view tQ enjoy a fcene which,'
by its imprefliye magnitude and the numerous changes it un-
dergoes, cannot but be highly interefting; but principany with
;^> the intention of bathing in the fpa. Bathings is certainly of the

greateft benefit m many cafes, and, tike every other pra^ice
capable of flrongly affeding the human frame, it muft alfo, ift
other cafes be capable of operating to theinjury of the health.
We have no,dire<f^ general treat ife on this fubje^; and to give
the requifite information to individuals by which they may fafely
and judicioudy regulate themfelves requires fomewhat moj-e
than mere medical fkill. The prefent work abounds with In-
terefting fa6ts and ctear dedufitions, and* is written with that
candid fpicit of philofophical remark which fhewsan jnlimate
acquaintance with; the moral as well as the phyncal conditions
of our exigence, and the accidents to whicb we are expofed.
I am much miftakCn*if" any one who begins to read this work
* .vvill be difpoted to quit it without perufing the whole; and
' " " there. are few who can haveXo exteniively coniidered the fiib-
jedt, ,or wh-Qare^fo little comcerned in its difcuffion as not te
tderive. advantage from tfae many points of information it tan>-

1i^

''/n7j}^\,7£>w7ua.VolM.-P7 JX./f. 124-

'^/.(;t6r.

Drawn by Blunt.

End raved bv^Uto

Fh£lM.Joumai.YolJX.riX.p. 22/1.

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——■»——— ^f»

J OUR N A L

OF

NATURAL PHILOSOPHY, CHEMISTRY,

THE ARTS.

DECEMBER, 180+.

ARTICLE I.

Ddfcription of a Tubular Pendulum; having all the Properties of
the Gridiron ; but being more compact as ivell as morejieady in,
its Motions, In a Letter front Mj-.EdwardTroughton,
the Inventor,

To Mr. NICHOLSON.
Dear Sir,

lliVER fince the commencement of your Journal, I have Advantages of
often thought of regiftering therein, the improvements which p^Jj^g^^^^^J^"
I frequently make in aflronomical and other inftruments. No philofophical
man perhaps had ever a greater antipathy to writing than my- 'P***"^^**
felf, and drawn as I am into the vertex of butinefs, and
working with my own hands from nin<; to twelve hours in a
day, leaves me but little time for literary purfuilsj yet in one
who values himfelf on account of the originality of his ideas,
it muft feem flothful not to commit them to the prefs, which
until that is done, are like flowers or fruit growing fencelefs
by the way fide, which every one that pafles by may gather. ,

I always confidered the pendulum of a clock more fui table Pendulums for

io our ftile of workmanftiip and habits of thinklncf, than to *'*'',^^,^ ^/^. PJ*'^^"

. ^ ^' cularly fuited to

tliofe of any other defcription of artJits; and agreeable to this mathematical
idea, I have made pendulunjs near twenty years, and 1 own ^°'^*''"^"'
Vol. IX. — December, 1804-. Q the

225

KEW PENDULUM.

Tubular pendu.
lum.

Itiftson the

principle of the
gridiron.

Defcription of
the tubular
pendulum by
the drawing.

the fubjed is tlill agreeable to me, being yet unincumbered
with patents, the reafon of which no doubt fs, that the few
wanted holds out no profpecl of gain.

Under thefe circumftances, I offer you the following de-
fcription of my tubular pendulum, which I contrived about (he
middle of laft July, and which I have juft brought into a6lion.
The honourable mention which you made of my mercurial pen-
dulum (Phil. Journal for May 1797) the excellent papers which
you have ai different times given to the public on this fubje61,
and its importance to practical fcience, efpecially aflronomy,
leave me no room to doubt but this communication will be
agreeable to you.

It may here be proper to remark that the nature of this pen-
dulum is by no means new; it is of the gridiron kind, and al-
though extremely unlike it in outward appearance, is only a
new fpecies of that genus. Without further introdu6tion, I
^will now proceed to give a brief defcription, with reference
to the accompanying (ketches, and then conclude with a few
general remarks.

Fig. 1. and 2, Plate XIII. drawn to a fcale of one eighth of
the real dimenfjons, exhibit the fliape of the whole inftrument,
in which the parts of aftion being completely concealed from
view, it appears, excepting the ufual fufpenfion fpring, to h^
made of folid brafs. The firfl: of thefe figures gives a front
view, the latter fhevvs it as feen edge wife. This figure of the
bob is ufed more on account of its being eafy to make, and
fightly, than from any other connderations; it is made of one
piece of brafs, about 7 inches diameter, 2,5 thick at the centre,
pnd weighs about 15 pounds avoirdupoife: the front and back
furfaces are fpherical, with a thick edge or cylindrical part be-
tween them. The apparent rod is a tube of brafs, fliewn in
both figures to reach from the bob nearly to the top; this con-
tains another tube and five wires in its belly, fo difpofed as to
produce altogether (like the nine-bar gridiron of Harrifon)
three expanfions of fieel downwards, and two of brafs up-
wards; whofe lengths being inverfely proportioned to their
dilatation, when properly combined, dellroy the whole ef-
fe6t that either metal would have fingly. The fmall vifible
part of the rod near the top, is a brafs tube, whofe ufe is to
cover the upper end of the middle wire, which is here fingle,
and otherwife unfupported.

5 Reckoning

NEW PENDULUM. 227

Reckoning from the top the firft aaion is downwards, and Defcrlptlon of
confifts of the fpring, a fliort wire 0,2 diameter, and a Jong pg^^j^i^j^ by
wire 0,1 diameter; thefe all of fteel firmly connc6led, reach the drawing*
down within an inch of the centre of the bob, and occupy the
middle line of the whole apparatus. To the lower end of the
middle branch, is fatlened the lower end of the interior brafs
tube, 0,6 in diameter, which terminates a little ftiort of the top
of the exterior tube, and produces the firft dilatation upwards.
From the top of the interior tube depend two wires 0,1 dia-
meter, whofe fituation is in a line at right-angles to the fwing
of the pendulum, and reach fomewhal lower than the attached
tube itfelf, which they pafs through without touching, and ef-
fect the fecond expanfion downwards. The fecond action up-
wards is gained by (he exterior tube, whofe internal diameter
juft allows the interior tube to pafs freely through it: its bot-
tom is conneded with the lower ends of the laft deicribed wires*
To complete tiie correction, a fecond pair of wires of the fame
diameter as the former, and occupying a pofition at right angles
to them, ad downwards, reaching a little below the exterior
tube, having alfo palTed through the interior one without
touching either. The lower ends of thefe wires are fattened
to a fiiort cylindrical piece of brafs, of the fame diameter as the
exterior tube, to which the bob is fufpended by its centre.

Fig. 3. is a full fize fedion of the rod, in which the three
concentric circles are defigned to reprefent the two tubes, and
the rectangular pofition of the two pair of wires round the raid- •
die one, are fiiewn by the five fmall circles. By copying this
arrangement, from the elegant conftru6lion of your own half
feconds pendulum (Philf. Journal for Auguft, 1799} I avoided
much trouble, which muft have occurred to me, unlefs indeed,
I had been impelled on the fame idea, by the difficulty of con-
triving the five wires to adl all in a row, with fufficient free-
dom and in fo fmall a fpace. Fig. 4. explains the part which
clofes the upper end of the interior tube: the two fmall cir-
cles are the two wires which depend from it, and the three
large circles ftievv the holes in it, through which the middle
and other pair of wires pafs.

Fig. 5. is defigned to explain the part which flops up the
bottom of the interior tube, the fmall circle in the centre is
where the middle wire is fattened to it, the others the holes for
-|iie other four wires to pafs through. Fig, 6. is the part which.

Q2 . clofes

228

NEW PENDULUM.

Dcfcription of
the tubular
pendulum by
the drawing.

Difficulty of
preventing flex
ure and darting
motion in the
gridiron^

clofes the upper end of the external tube, the, large circle in
the centre is the place where the brafs covering for the upper
part of the middle wire is inferted, and the two fmall circles
denote the faftening for the wires of ihe laft expanfion. Fig. 7
reprefents the bottom of the exterior tube, in which the fmall
circles (hew the faftening places for the wires of the fecond
expanfion, and the larger ones the holes for the other pair of
wires to pafs through. Fig. 8. is a cylindrical piece of brafs,
which fliews how the lower ends of the wires of the laft ex-
panfion are faftened to it, and the hole in the middle is that
whereby it is pinned to the centre of the bob. The faftening
of the upper ends of the two pair of wires is done by fcrew-
ing them into the pieces which ftop up the ends of the tubes,
but at the lower ends, they are all fixed as reprefented in Fig. 8.
I have only to add to this defcription, that the pieces repre-
fented by Fig, 7 and 8, have each a jointed motion, by means
of which the fellow wires of each pair would be equally
ftretched, although they were not exactly of the fame length.

In the apparatus thus conne(5ted, the middle wire will be
flretched by the weight of the whole; the interior tube will
fupport at its top the whole except the middle wire: the
fecond pair of wires will be ftretched by all except the mid-
dle wire and interior tube; the exterior tube fupports at its top
the weight of the fecond pair of wires and the bob, and the
fecond pair of wires are ftretched by the weight of the bob
only,

Thefirft pendulum which I made of the tubular kind, had
only three fteel wires, and one tube above the bob; that is two
expanfions down and one up; and the quantity which one
of brafs falls fliort to corredl two of fteel, was compenfated for,
by extending tbofe branches of the rod below the bob, and bring-
ing up an external tiibe to which the bob was affixed. There
is an aukwardnefs in this conftruclion, owing to the rod reach-
ing about 13 inches below the lower edge of the bob, other-
wife, it is not inferior to the one firft dc fcribed.

The principles of the gridiron pendulum, I believe, have
'never been queftioned, indeed they cannot be; the difficulty
of conftrufting it ftrong enough to prevent lateral flexure
in the lifting bars, and confequent friction in the holes of the
different crolfing pieces neceftary to bind it together, which
occafion it to act by ftarts, has been the only obftacle to pre-
vent its gen«ral application to the beft clocks.

To

NEW PENDULUM. 229

To remedy this evil I contrived the one here treated of, and —is prevented
m my own judgment, have fucc^eded as near perfection as^^i^gg;
any effort of mine ever did. The tubes are drawn flraight
and regular in an engine, in the manner that wire is done :
and their ftrength alTure fuccefs, preventing the poffibility of
any fenfible bending, while the freedom of a6lion prevents any
irregular motion whatever.

I have no farther quarreled with my own conftru6iion of the Troughton's
mercurial pendulum, the principles of which are faultlefs, and JJ,^iy^^"j perf^£l
form elegant; than that it is quite unfit for carriage, and an but not porttble.
article too hazardous for me to deal in ; but after all, candour
obliges me to give the preference to the original one of Gra-
ham, which on account of fome fenfelefs criticifms about one
part taking heat fooner than another, evaporation of the mer-
cury, &c. was too haftily laid afide, Graham undoubtedly Graham's pen-
made his pendulum before (he expanfions of either brafs or ^"'""^ ^PP'^°^^'^-
mercury were accurately known; but an ingenious friend of
mine, has from the beft experiments, computed the different
parts to mathematical precifion, and introduced it a fecond
time to the world ; and already, tj^ere are not wanting proofs
of its pradical excellence.

Smeaton's pendulum with tubular bob is a good one, but Smeaton's
on account of the glafs rod, like my mercurial one, is totally goo^i ^^^"ot
unfit for tranfportation, and like Graham's, is unfightly; while
all three labour under the unavoidable difadvantage of not
being applicable to the pyrometer in their compound and pen-
dant fiate.

I am about to conftru6l a pyrometer fit to try the tubular
pendulum in its finifhed flate; a pin fixed in the centre of of-
cillation, (liall be contrived to ad on a nice fpirit level, and '

ftiew the expanfion, if any, in angular meafure : by which I
fliall be enabled to adjuftit; for I have no idea of adjufting
one by the going of a clock, that complicated apparatus will
always, I fear, have too many errors of its own, to be ufed as
a criterion of the merits of this more perfe<fl inftrument,

I will here fubjoin the lengths of the different parts of tu- Dimcnfions ani

bular pendulums in inches; alfo, the expanfions of brafs and i""®""^^ °^/*y**

^ 1 ftruCtion of the

fteel from which I computed them. The length of the inte- tubular pcndu-

rior tube is 31,9, and that of the exterior one 32,8, to which ^**'"*

muft be added 0,4- the quantity which in this pendulum, the ;

centre of orcillation is higher than the centre of the bob; thefe

all

gSO NEW PENDULUM.

all of brafs. The parts which are of fteel are the middle wire,
including 0,6 the length of the fufpenfion fpring, is 39,3, firft
Expanfionsof P^i*" of wires 32,5, and the fecond pair 33,2. From experi-
briis and ftecU ments which I tried in the year 1794, I found my brafs to ex-
pand with 60* of heat 0,000640 on an inch, and my fteel
0,0003966. Smeaton obtained under tlie fame circumftances
0,0006444 for brafs, and 0,0003833 for fteel. Roy found
brafs to expand 0,0006316 and fteel 0,0003816.

The above lengths computed from ray expanfions will I think
be found very corre6l; if they are tried by Smealon's, the pen-
dulum will feem to err in excefs, or gain with heat, about 0'',9
a day with 60® of Fahrenheit; if Roy\s be ufed, it will err
jilfo in excefs, under the fame circumftances fomething more
than one fecond. The above ftatement ftiews with what care
experiments of this kind ought to be condu(5^ed. All the di-
menfions are given in inches and decimals.

If my pyroraetrical experiments turn out fuccefsful, they
v|nay likely be the fubjed of another communication; and I
, will referve till then my reafons for giving the preference to
my own expanfions in the conftnidion of the inftrument here
defcribed ; for this letter, being twice as long as I firft intended,
iliall now be concluded by,
Dear Sir,

Your obliged and obedient Servant,
EDWARD TROUGHTON,
November 3, 1804.

II.

Jietter from W . Jess.op, Fftj. on (in Improvement in the Procefs
of hlajiing Rocks zvit/i Gun-powder.

To Mr. NICHOLSON.
SIR.

If I am communicating to you what you already know, you
will accept as an apology for it that it is not generally knowii,
and will be interefting to all who are concerned in mining or
blafting rocks with gunpowder.
Vfual procefs of The uAial procefs, after drilling a hole and charging it with
boring and powder, is to introduce a wire or fmall iron rod, to preferve a

BLASTING OP ROCKS, - ^3^ .

communication with the fuze, and then to ram up the re-
mainder of the hole with ftone pulverized by the operation of
ramraing it; after which the wire is withdrawn and the prim-
ing introduced.

This is a tedious operation, often attended with danger, and >s tedious, dan-
frequently the labour and powder is loft by the priming hole fgr^in.^ ""'
being obflruded in ftriking out the wire with a hammer.

I had been informed that inftead of this tedious operation} Loofc fand pro-
the blafting had been effeaed by introducing a ftraw filled with P^^*^^ .'"*"<! °^
fine powder, and then filling the hole with loofe fand,

I hardly could believe this, conceiving that the part where
there would be the leaft refillence would firfl yield to the ex-
plofion, and therefore that the loofe fand mufl of courfe be
blown out.

But in the month of Augufl laft I tried the experiment in Succefs of the
fome very hard rock at Fortwilliam and it completely fuc- experiment,
ceeded: I fince then have tried it on the lime rocks at Briflol
with the fame effe^.

A kw days (ince, wifliing to know how fmall a quantity of Oak 20 inches
fand would produce the efFea, I caufed a hole of l| inch in f^^^^J^ f^^^^
diameter and 12 inches deep, to be bored in a knotty piece of charge of 3
oak of about 20 inches in diameter and charged it with three *"^^*^ ^*"***
inches of powder, and upon that four inches of fand, intend-
ing (as I fuppofed that mufl be blown out) to repeat the quan-
tity of fand inch by inch to the quantity that would be, fuffi-
cient, but to my great furprize, it fplit the piece with great
violence into fix pieces,

I then repeated it on a fimilar log of oak, with a charge of The fame
two inches of powder, and three inches of fand; it fplit the *=^^^^^^^'^ ^'^^^
piece in two, and fent half of it into the air to the diftance of
forty yards.

I think it may puzzle a philofopher to account for this: I Conjeaure as to
bave fuppofed that the fand in contadl with the powder, firft
moving, the particles wedge each other fall: before the motion
has time to be communicated to the whole.

I have reafon for thinking that a much lelTer quantity of Lefs powder
powder will produce the efFed in this way than by the common ^'^^ f^ohMy
method; for as it lies loofe in its chamber and makes itfelf this way.
more room by a little yielding of the fand, the whole will take
fire, and efpecially if when half the charge is put in, the ftraw
be introduced and then the other half charge, fo that it may
take fire in the middle of the charge.

That

232 MUCILAGINOUS MATTER.

The fand ap- That the fand will yield a little, I think I may infer from

little. having charged a lube of tin 14 inches in length and 1| diam-

eter, with three inches of powder; on exploding it immcrfed
in water, I found /ire inches of the tube abruptly cut off, while
the remainder, was uninjured, but I do not confider this in-
ference as decifive.

For want of time I was prevented from trying how much lefi
than three inches of fand would have been fufficient.

I am. Sir,

Your moft obedient,

W. JESSOP.
London Coffee Houfe,
Nov. 8, 1804.

A charge of P. S, Might not this be ufeful on the evacuation of a fort,

fand would pro- in deftroying cannon, inflead of the ineffe£tual mode by fpik-
bably deilroy . ^
ardUcry. »"g ?

111.

On the Mucilaginous Matter of certain Vegetables, and their life
as a Suhjiitute for Gum Arabic: by Mr. Thomas Willis ;
being a Continuation of Experiments made upon the Suhjedt by
him, in Addition to thofe for77ierlTt/ puhlijhed in the Tranfu6tions
of the Society of Arts.*

Letter to CUkKLES TAYLOR, Efq.
SIR,

MucHaglnous i HAVE taken the liberty of prefenting to the Society for
powders from the Encouragement of Arts, 8z,c. fpecimens of the powder of
vernal fquills, of white lily-roots, and of falop, for their con-
fideration and trial. I believe the bulbs of the vernal fquill
will be found to be equally ufeful as thofe of the hyacinthus
non-fcriptus; and the ftrong mucilage from the white lily-root
and the falop much more fo.

As gum-arabic has been at times, during the laft war, above
30/. per cwt. the multiplication of diflerentfubflances that will
anfwer the fame purpofe, will afTuredly be an obje6l of a very
interefting nature to manufacturers in time of war.

* Extraaed from their Tranfaaions, Vol. XXI. The former
experiments are in our Journal, VII, 30.

I have

MUCILAGINOUS MATTER. 233

I have fent all the powder of white lily-root I had left; but
am at the prefent time drying fome taken from the garden two
or three days ago. As foon as it is powdered, I will fend yoii
a large quantity of it.

I^jm, Sir,

Your moft obedient Servant,
THOxMAS WILLIS.
March St, 1803.

SIR,

FROM the candour and approbation my paper on the ufe
of the hyacinthus non-fcriptus, as a fubftitute for gum-arabic,
in.>fome trials in calico-printing, met with from the Society for .
the Encouragement of Arts, &c. I refolved to purfue the fub-
je6l further; and now offer the following obfervations for your
confideration, in hope that trials may be made, that will be
found to be of general benefit.

Having frequently obferved, in old gardens, that the vernal Root of the

fquill grew very prolific, I conceived the root of them might ^^'■".^'^?"^"^«^y

, raucilxginous*

be equally as mucilaginous as (he roots of the blue bells. I pro-
cured three pounds f\% ounces of them on the 8th of July,
1802, and diced and dried them. They produced one pound
one ounce of powder, one drachm of which was difiblved in
four ounces of water, by letting the mixture boil a minute or
two. When the liquor was cold, there was a mucilage full as
flrong as one made with a drachm of the powder of blue bells,
in the fame proportion of water; from which circumftance, I
fliould think the vernal fquill will anfwer the fame purpofes as
tlie hyacinthus non-fcriptus. If it fliould, it is a root that may
be very eafily and plentifully propagated, and whenever gum-
arabic is dear, may be found ufeful. It is to be remarked,
that I found no pungency in the powder of the vernal fquill.
I have frequently eaten of it, and the tafte is rather agreeable.

On the I8th of Auguft, 1802, I colleaed four pounds of White lily root
the white lily root, which yielded, when dried, rather more Jag°nou7. "^"*^*"
than one pound of powderc A drachm of it was diflblved in
four ounces of water, by gently boiling it a minute or two;
the mucilage was much flronger than that made with the ver-
bal fquill, but fomewhat darker coloured. This root may

poflibly

234* MUCILAGINOUS MATTER.

podibly anfwer the fame purpofes better than Ihofe above men-
tioned. The powder of the lily-root leaves a bitternefs on the
tongue.
Gum obtained Twelve ounces of the fre(h roots of the white lily being
tvaporatijn.^" bruifed and preflfed, yielded by evjaporation one ounce and one
quarter of brown gum.

There being a fmall quantity of it, I made no trial with it;
but very probably the exprefled juice might be ufed by the
calico-printers with advantage. Thcfe roots can be procured
at all times, and propagated to any extent ; but it muft be ob-
ferved, that thefe bulbous roots are ftronger when they are
without flems, or only beginning to ftioot out leaves; and the
prefent time is as proper as any that can be for procuring them.
Conofrcy root. I tried comfrey-root ; but the dark colour of the cuticle of

the root afFedled the folulion, by making it of a dark dirty
brown.

I do not pretend to claim any merit in making the above
experiments. Every one who is acquainted with thefe roots*
well knows that they are all mucilaginous. My defign is only
your patronage, to render them ufeful in (he arts, that their
virtues and etfects might not lay dormant, but be rendered
ferviceable to trade,
powder of After making the above trials, the powder of falop-root

fjbp r^ot affords ^jjj. ufg^] by ditTolving one drachm of it in four ounces of
very lirong . -' " • , t t .

mucilagtj pro- water, in the manner above mentioned. It produced a very

bably cheaper ft,ong mucilage, and, when cold, was a perfed jelly, and
than gum-.arabic. , , , . , ... , r i ,• r .i

much clearer than either of the other loiutions. 1 am greatly

of opinion, that the powder of this root will not only anfwer
all the purpofes of gum-arabic, but will be found full as cheap,
if not cheaper, in proportion to itsftrength, than gum-arabic;
but this is fubmitted to your confideration and triaL

I have fent fome fpeciraens of the Powder of the Vernal
Squill, of While Lily Root, and aifo of the Salop Powder,,
in order that they maybe tried by your dirediion; and if they
fliouldbe found of benefit to commercei nothing would give
me greater pleafure, than to find my flender abilities have
been of utility to my country, and h(;noured with the appro-
bation of the Society.

I am. Sir,

youjr obedient fervant,

THOMAS WILLIS.

J^arch22, 1803,

Examination

HORIZONTAL iMOON,

IV.

235

Examination of Mr. Ezektel Walker's Experiments and Theory of
the Enlargement of the Horizontal Moon. In a Letter from
C. L.

To Mr. NICHOLSON.
SIR,

A OUR correfpondent Mr. Ezekiel Walker, has favoured the Affertion of
world with a new attempt to account for the apparent enlarge- ^li^^^^^
mentof the horizontal moon*, in which, afier indulging his images vaiy
wit, andexpreffing his aftoniaimcnt at-the expence of thofe ^^^^ ^^« P»P'^'»
who have laboured on the fame fubje6l, he proceeds to aHlire
us that the piStures on the retina are not permanent but vary as the
dimenfions of the pupil vary.

That you, Mr. Nicholfon, who are in fome refpeft account-
able to the world for what you admit into your Journal, and
who poflefs a jufl: celebrity for the manner in which you have
executed the (a{k, — that you thould have omitted to favour the
writer and your readers fo far as to rejed his paper, is to me
no olherwife to be explained than by referring it to your im-
partiality ; which may have induced you to leave the refutation
of aiiedged fads to your correfpondents rather than enter into
a difcudion refpe6ling them yourfelf.

I cannot for a moment fuppofe you to have had a doubt con- Confequences

cerning this imaginary novelty in optics. If Mr. Walker's 5j5[7^^^^°Ji°''

pofition were true, the magnifying powers of the fame tele- founded.

Ibope would vary with its aperture; a well illuminated theatre

or room would become contra6led in its apparent dimenfions;

the paper at which I now look would fuddenly become larger

when I cover the candle with my hand ; and in a word we

fliould have no certainty if the magnitudes of things were to

appear different with every change of the pupil.

None of thefe things do in fadt happen, and it feems almoin Experiments of

' . Mr. "Walker

trifling to infift upon them. Still IqU is it neceffary to have repeated.

recourfe to lines and figures; but for the fake of your lefs
inftrucled readers I will meet Mr. Walker by corre6t experi-
ments of the fame defcription as his own,

* Philof. Journal, IX. 164.

JExp.

236

HORIZONTAL MOON,

The image Exp. 1. I took a clear double convex lens fupported on %

StbrlaV'"'^^"^* and placed the fame oppofile an Argand's lamp; fo
aperture is the that a good image of the flame was formed upon a paper fixed
iamt as againft the wall of the room. From the flame to the lens the

diftance was 49|- inches and from the lens to the image it was
88 inches. The horizontal breadth of the image was repeat-
edly meafured = 1.58 inches and to a greater degree of pre-
cifion than one hundredth of an inch,
with a con- ^^P* 2. The lamp and lens were fuffered to remain unaltered

Crafted aperture, j'n the fituations they poflefled in the former experiment; but
a fcreen was placed clofe to the lens, having a circular hole
of one inch diameter concentric with the lens iifelf. The
image was then fainter but very diftinct, and meafured exa6tly,
the fame as before.

In both thefe experiments the papers on the wall were fe-
veral times changed to prevent any deception from the appear-
ance of former meafures; and the nieafures were taken along
the fame horizontal line by the help of a line on the wall.

Hence it was feen that a diminution of the pupil or aperture,

to admit lefs than one thirty-eighth part of the light, made no

difference in the image.

The experiments Exp. 3. I took a good achromatic objed glafs of Dollond,

repeated with anj^^^j^^ ^^ aperture of 1.9 inch and placed it at the diftance of

achromatic lens. !. , , , . , . ,

52| inches from the lamp; when it gave a good image on the

wall at the diftance of 70| inches from the lens. The hori-
zontal breadth of the image was 1.2 inches.

Exp, 4-. When the experiment was repeated with no other
change than that a fcreen with a central hole of 0.3 inches
was placed before the lens, the image proved 1 .2 inches as be-
fore.

The two laft experiments were made with the fame care

and precautions as the former. They (hew that no diminution

of the image takes place when the pupil isdiminithed toadmit

lefs than one fortieth part of the light.

Probability that I may not conclude. Sir, without making fome obfervations

Mr. W. was ^^ j|jg (\\reQ, con trad id ion of my experimental refults to thofe

deceived, and ,-rT n . i,^ t r ■, , ■ • • i

how. ot Mr. Walker s. May 1 alcribe to him any thmg more than

inaccuracy.? Afluredly I do not. Neverthelefs, if he raea-,
fured fo uncertain a thing as the length of the flame of a candle
without being afliired by repeated experiments that its perma-
nency was entitled to fome confidence -, if he held his fcreen

nearer

HORIZONTAL MOON. 237

nearer to his lens when the h'ght was rendered fainter by h«
card; if he miftook the greater vifibility oi' the fmaller image
for a proof that it was in the focus of the lens; in a word, iif
he did not paufe and examine former fads before he adopted a
conclufion fo repugnant to many of them, I would fubmit to
yourfelf and readers whether he has aded confiftently with the
rules of philofophical inveftigation, or has any reafon to prize
his own foiution beyond that which is founded on the rules of
linear perfpeclive*.

I am. Sir,

Your humble fervant,

C. L.

V.

Tfie Method of preparing Chinefc Sni^, By Michael de

GuUBBENS.f

In the ads of the Swedifli Academy, for 1764., page 38, Ekeberg*s ac-
we find a defcription of the preparation of Chinefe S(y, b. enoneous."^^
the late Captain Ekeberg ; but as this defcription is not only
incomplete but even deficient in accuracy, fo as not to produce
the true Chinefe compound, I am well convinced that Mr.
Ekeberg muft have been unacquainted with the a6lual procefs.
It is moft likely that he depended upon information given him
by the Chinefe who are not always to be trufted; a fa6l of
which I have had fufficlent reafons to be convinced, during

* Mr. W. having foppofed that the want of land obje6ls muft
take away the notion of diftance at fea, reminds me of an incident
concerning the Panorama of Black-Friar's Bridge. Thispiflure
was exhibited with indications of a confiderable wind with waves
on the river, at the fame time that the buildings on the London fide
were feen reflected in the water. I took notice cf this inconfiftency,
and the ingenious author replied that the water had been atfiift
painted as if fmooth ; but it was found neceffary to put in the waves
in order to give diftance by their regular diminution in perfpeflive,
and that the rcfleilions were kept In from a notion that they would
rather add to the eifeft than offend by their want of perfeiSl truth.

f Extraftcd from the Memoirs of the Academy of Sciences of
Stockholm for 1803, by M. Linborn, and inferted in the Annales "* '*

-de Chimie, Vol. L, from which the prefent tranflation is made.

my

1>38

Ingredients of

Procefs.
^ericots arc
koiled in water.

■<*-then mixe^
with wheat
flour.

—and thinly
fpread out in a
veflel covered
up.

A peculiar
mouidtnefs Is
fufFered to come
on by admitting
the air :

Chinese soV.

nay five years refidence in (heir country, in my attempts (o aC»
certain correctly the manner of treating a fpecies of filk-worm
(irhich affords its thread five or fix times in tlie year, as well as
their methods of dying cotton and filk and feveral other branches
of domeftic oiconomy.

Having fi nee received for a confiderable remuneration true
notions concerning thefe objeds, I faw how far the former re-
citals had differed from the truth. The fame thing happened
in my attempts to difcover the preparation of foy; but as I at
laft became perfe6lly acquainted with it, I think it proper to
communicate the fame to the academy.

Soy is prepared with a fpecies of haricots (which are white
and fmaller than thofe of Turkey) wheat flour, common fait,
and water. The following are the proportions; 50 pounds of
haricots, 50 pounds of fait, 60 pounds of wheat flour, and
250 pounds of water.

After having well waffled the haricots, they are boiled in
well-water in an open veffel for fome hours, or until they have
become fo foft as to be worked between the fingers. During
the boiling they muff be kept covered with water to prevent
their burning, and care muff be taken not to boil them too
much, becaufe in that cafe too much of their fubftance would
remain in the water of deco6lion. The haricots being thus
boiled, are taken out, and put into large (hallow wooden vef-
feis, which in China are made of thin ffaves of bamboo, two
inches and a half in depth, and five feet in diameter. In thefe
they are fpread out to the depth of two inches, and when they
are cold enough to be worked with the hand, the wheat flour
is gradually thrown in and well mixed with the haricots, until
the whole of the before-mentioned quantity has been ufed.
When the mafs becomes too dry, fo that the flour does not
mix well with the haricots, a little of the hot water of deco6tion
is added.

The whole being well mixed, the mafs is then fpread abroad
in the veflels before-mentioned, taking care that its depth ftiall
not be more than an inch or an inch and a half; and the mafs
is then covered by a lid which fits exa6lly. When the mafs
begins to become mouldy and heat is difengaged, which hap-
pens after two or three days, the cover is then raifed by put-
ting two fficks beneath it, in order that the air may have free
accefs. During this time a rancid odour exhales, and if the

CHtNESE St>y^ 23i^

mafs becomes green, it is a fign that the wliole goes on pro-
perly ; but if it begins to be black, which mull be carefully
noticed, the lid muft be elevated ftill more, in order that the
mafs may have more air. If it once becomes black, the whole
is fpoiled.

As foon as all the furface is covered with green mouldinefs, '^1^1^°^^^'''^
which ufually happens in eight or ten days, the cover is taken
off, and the compound is expofed to the fun, and the ajr for
feveral days. Wiien it has become as hard as a flone, it is cut
into fmall fragments, which are thrown into an earthen vefTel, ^Ud mixed with
upon which the 250lbs. of water, having the 50lbs. of fait fait water ;
firft diflblved in it are poured. The whole is then well ftirred
together, and notice is taken of the height at which the water
ftands. If it be not convenient to put all the mixture into one
velTel, a number may be ufed, taking care that the materials

be proportionally diftributed in each. The vefiel thus filled is ^nd in a veffel
1 1 • I r . • n- » 11 placed in the

placed in the lun, and its contents (tirred up regularly every fu„and daily

morning and evening, and a cover is put on at night to defend agitated

it from the cold, as well as to prevent any rain from finding

entrance either by day or night. The hotter the fun the fooner

will the foy be completed. The procefs is feldom undertaken for two or three

but in the fummer, notwithflanding which it lads two or three "^^"'^^s.

months.

As the mafs diminiflies by evaporation, well-water is added; When the fluid
and this digefiion is continued till the fait water has entirely fmooth^amT
dilTolved the flour and the haricots. The veflel is flill left for homogeneous
fome days in the fun, in order to compleat the folution ftill more
efFe6iually, as the good quality of the foy depends upon this
circumftance; and the daily ftirring or agitation is continued to
the very lafi.

When at length the mafs has become very fucculent and it Is ftrained by
oily, the whole, as well the thick as the mort^ fluid portions, P'"''^"'^^ ^"'^ ^*
is poured into bags, through which the foy is pretTed, and is
then clear and ready for ufe. It is not afterwards boiled, as
Mr. Ekeberg pretends. It is to be kept in bottles well corked.
The Chinefe who deal in this article keep it in large pitchers
well clofed. Before it is lirained in the prefs the foy is of a
deep brown colour, but it afterwards becomes black.

The Chinefe alfo prepare two kinds of foy from the dregs Inferier foy firom
which remain. The firft time they ad4 l.>0!bs. of water and ^^^^ *^*^*

A^Qlbs.

240 CltTNESE 80V.

5dlbs. of fait, and after having preflTed the mafs, they again add
lOOlbs. of water and 20lbs. of fait, always proceeding as be*
fore defcribed.

The two lafl kinds of foy are not ftrong, but very fait, more
efpecially the latter, which is alfo lighter coloured. Thefe two
kinds are the mod common in China, and are ufed both by
natives and Europeans. The differences of price are as 8.4.1.
ThlBprocefs has In this manner I prepared in 1759, at my refnlence in Can-
terifier" ton, the whole of the foy I made ufe of, and I alfo brought

feveral bottles with me to Sweden. It was fucculent, oily,
moderately fait, and very different from what is commonly fold
in Europe. With regard to its taffe, it might be put in com-
petition with that of Japan, which is generally confidered as
the beft.
by the writer This defcription is more particularly to be depended upon,

'^^'^ ^ ' as I always made the preparation myfeif; and I can venture to

affert that this procefs is the only one for obtaining foy of the
beft quality.
Soy contains no Mr. Ekeberg affirms that the foy Is boiled with the addition
ipice or ugju-, Qf f^gar, ginger and other fplces; but this is without founda-
China for three tion, and cannot be true, for a lb. Chlnefe of foy cofls no more
half-pence a ^^^^^ ^^^Q candareens of Chinefe money *. This was the conv
mon price during my whole refidenceat China, and is too low
to admit of thefe ingredients in the preparation. It is alfo the
fa6i that foy has no indication either of fugar or fpice in its
tafte; its principal character is faline.

VI.

On the Laws of Galvanifm. la Letters from C. Wilkinson
and Thomas Harrison, Efqrs.

Windermere Lake, Wejlmoreland, Nov, 8.
Dear Sir,

Some account 1 TAKE the opportunity of a few days relaxation in this ro-
of Mr. Cough, p^g^^^^j^ an^j pi61urefque fituation, to trouble you with feme

* The Chinefe pound or tael is, I think, about 20 ounces, and
the candareen is a little more than three farthings, that is to fay, it
is one tenth part of the mace which is valued at eight-pence. N.

galvanic

LAWS OF GALVANISM, 241

galvanic obfervations, which principally originate from a very
pleafureabie converfation I have lately had with my friend
Mr. J. Gough, of Kendal. To you. Sir, this gentleman, as
a philofopher and mathematician, is well known. Although
deprived of fight in very early infancy, it is amazing to ob*
ferve the rapidity with which he proceeds in geometrical in«
veftigalions. Independent of this very ftriking acquifition,
he is the beft botanift and natural hiftorian this country pof-
fefles. To thefe branches of knowledge he adds very con-
fiderable claffical knowledge ; and in his pneumatic enquiries
he places no dependance upon any of the gafes which he does
not prepare himfelf. To converfe with fuch a perfon is to be
improved. To fome ledlures I delivered on galvanifm a few
days ago, at Kendal, I was honoured with his attendance;
and in tonfequence of the law I was attempting to explain,
relative to the powers of galvanifm on metallic bodies, I was
favoured, the fubfequent day, with the following letter from
a very intelligent and well-informed profeffional gentleman at
Kendal, Mr. Harrifon, brother-in-law to Mr. Gough ; the
particulars of which I dare fay you will find fufficiently in- ^

terefting to merit infertion in your valuable Journal.

To C. WILKINSON.

Dear Sir, Kendal, Nov, 5, 1804.

I MENTIONED to you yeflerday my doubts refpedting the inyeftjgatlon of

law of galvanifm, which you have laid down in Nicholfon's^!.P°^"°^ .

, „ ,, , ^ , ^ , .... different piles m

Journal for March 1, 1804 ; where you lay, that the ignitmg burning wire.

powers in batteries of the fame total furface, are as the fquares
of the furfaces of the elementary plates, fingly taken in each :
This, if I miftake not, you repeated in your lecture oflaft night ;
at which time I exprefled ray doubts to Mr. Gough, and we
afterwards examined the data given in the paper before-men-
tioned ; on which we made the following calculations, and
found that your conclufion was ftridly true according to your
data, but that the forces of different batteries expofing un-
equal furfaces, will be in the ratio compounded of the number
of plates in each battery, and the fixth power of the fides of
the elementary plates fingly taken in each. The data yoa
have given are the following : IQO plates of four in, fq. ig-
VoL. IX, — December, 1804-. R nit«d

O^^ lAWS OF GALVANISM

Inveftigatlon of nited half an inch of wire; 400 plates ignited two inches}
Afferent" iks in ?"^ ^^ P^^*®^ ^^ eight inch. fq. ignited 16 inches of the fame
burning wire. Wire.

Now in order to accommodate thefe numbers to algebraic
palculation, we will fuppofe a comparifon of three batteries,
two of which are compofed of plates of equal diameters, but
differing in number ; the third Qiall alfo differ from the firft
jind fecond in the magnitude of its plates, and agree with the
fecond in the number of them.

Let n be the number of plates in the firft, m the number in
the fecond and third batteries; w and y the diameters of the
two fets of plates. Then, if the power of any fingle plate
bear any conftant ratio to its furface, it will alfo have a con-
ftant ratio to fome power of its diameter, becaufe the furface
is as the fquare of the diameter in fimilar figures : let p be that
power ; let I, k, and z exprefs the lengthy of wire which are
ignited by the 1ft, 2d, and 3d batteries: then from the firft
datum, 71 : f?i :: I : k, becaufe the effedl is as the number of
equal plates, according to experiment. Again, feeing that w
js the diameter of the plates in the firft and fecond batteries,
and 1/ the diameter of thofe compofing the third, and p ex-
preffes the power determining the law of force for plates of
different diameters, the force of a plate in the firft and fecond
batteries, will be to the force of a plate in the third, as
stP : j/P, and as the number of plates in the fecond and third is

Plate. Plates,
equal, we fhall have ?nw^ : my^ :: k : z, becaufe as 1 :m :i

Plate. Plates.
lyP : k, and as 1 : m ii y^ : z, then as io^ : y^ :: k '. z, but as

Ik: kz :: I: z =z

.^'U^' gi

?i : ?n :: I : k; therefore nm^ ; viy^

To apply this general theorem in order to determine the
value of p in all cafes, we will begin with your own experi-
ment made with equal furfaces on different numbers.

Since 100 plates, of four inches, ignite half an inch of
wire, and 50 plates, of eight inches fq. ignite 16 inches, we
have n= \00, ?n = 50, w = 4-, yz=3, 1 = 1^, z= 16; there-
fore 100 X 4P : 50 X 8> : : 1 : 16 ; but fince 8 = 2x4, 8^=

!''X 4P, therefore 2 : 2?

16, and 16 =^=: 2^-

but

1<AWS OF GALVANISM, 2431

but 16 =: 2'* J hence 2* = 2^— * ; therefore p = 6 ; hence
the force of plates are as the 6th power of their diameters.

When the furfaces are equal, the igniting force is as the 4th
power of the (ides of the individual plates; for in this cafe we
have n zv'^ z=:my^, and n : m : : y^ : rv^ ; therefore the theo-
rem WW;* : my^ : : i : Zt becomes t/"^ iv^ : tp''' y^ : : I : z ; that
is, w^ : y^ : : I : z, which is the law in your particular cafe.

This theorem will be found ufeful in eftiraating the force of
batteries in general ; as an example of which we fhall calcu-
late, by means of it, the force of your intended battery, con-
lifting of 50 plates, each 24 inches diameter. In order to de-
termine the quantity of wire that will be ignited by fuch a
battery, we have w =: 100, m = 50, w = 4, y = 24, or fix
times tv, / = { ; therefore 100 x 4<^ : 50 x 6^ w^ : : I : z;

6^
that is, 2 : 6^ : ; f : z, and z = --- = 36^ x 9 incites, or

4

972 {eet.

I am. Dear Sir,

Your's refpedfullj,

THOMAS HARRISON.

Stramongate, Kendal.

YOU will obferve, Mr. Editor, from the above theorem. Experiments on
that my ftatement of the powers of two different galvanic the decompofi-
arrangements, equal in their metallic furfaces, being as the
fquares of the furface of two individual plates, or, which is
tlie fame, as the 4th power of the diameter of each plate, is
corre6t only where the metallic furfaces are equal ; when they
sye not equal, then the powers are as the 6th power of the
' diameters, or as the cubes of their refpedtive furfaces.
. In a fhort time you will have the pleafure of a paper from
Mr. Gough, relative to the decompofition of water by gal-
vanifm: With this view we tried together the following ex-
periments, the refults of which tend to favour the explanation
I have attempted in the Elements I fometime fince publifhed*

For this purpofe I employed 270 plates, contaiainga fur-
face of €720 fquare inches, and connected with the pofilive
and negative fides by wires of platinum. Thefe platinum wires
were inferted in a difti of water at eight inches from each
other; the pofitive wire difengagedpxigen gas, the negative

R2 wire

244? LAWS OF GALVANISM.

Wire hidrogen gas. The decompofition took place very
flowly ; in proportion as the wires were approximated, the
decompotition increafed in the fame ratio.

The platinum wires were then inferted into a capillary tube
whofe bore is about -^-^ of an inch, filled with water; no fen-
fible effedl was produced till the wires were placed at the dif-
tance of half an inch, and then only a folitary bubble became
difengaged from the negative wire, never completely detached,
but hovering round the extremity, not being fet at liberty by
the evolution of another particle.

When the platinum wires were inferted in a tube whofe
bore is -J of an inch, at the diftance of fix inches a flight de-
compofition was obferved, and which neceflarily increafed in
proportion as the wires approached each other.

When the platinum wires were inferted in different glafles
of water, and the extremities of a frog deprived of its inte-
gument conftituted the connedling medium between the two
glaHes, or a wet piece of cloth, at the difiance of three inches
a flight decompofition was obferved.

When two wires are conne6ted with the diflx-rent ends of a
galvanic battery, the wires immediately participate, as to
their eledrical intenfity, with the refpedive plates with which
they are in conla6t.
Inveftlgatlon of Let us fuppofe P the wire from the pofitive end of the bat-
compoTtloltV ^^^y* ^"^ ^ *^^^ negative. PL AT], Fig. 2. Let us fup-
watcr by gal- pofe that the galvanic arrangement is fuch, that, when the
vanifm. wires are placed at the diftance o, a, the decompofition

commences. If the wires be placed at b and b, the decom-
pofition is confiderably increafed ; and this increafe will go
on, till the maximum will be at d, d, when the wires are
infinitely near each other without being in contact.

The pofitive wire, according to its eleftrical intenfity, pro-
duces a correfponding fiate in all fluids with which it is in
contaft, proportionate to their capacities ; fo alfo the negative
wire ; and it is evident from the principle of eledrical charges,
that the influence of each muft extend to equal diflances ; it
will therefore follow, that when at a, c, fuppofing thefe
points the apices of two equal cones, the areas of their
refpedive bafes will be the leaft poflible, and confequently,
in their concourfe at ?, will only influence a fingle particle of
water. When the wires are placed at b, b, then ci will ex-

prefs

LAWS OF GALVANISM. 245

jircfs the radius of the circular bafc (riippofing hc^^a z), and Inveftlgatlon of

r I . .. V . r L- in J . ,, ^the laws of de-

conlequently a greater proportion of water lubjeaed to the compofition of

influence; and therefore evidently when at d^ d, or infinitely water by gal-
near, the maximum of decompofing efre6ls muft take place. ^'*"' "^*
This we obferve is confonant to experiments.

If a particle of water confifts of a particle of oxigen and of
bidrogen in a ftate of chemical union, and if an agent be em-
ployed fufhciently fubtle to penetrate the conftituent particle
of water, a feparation will take place. Thus caloric will de-
ftroy the aggregation of the conftiluent particles of many fub*-
fiances, without producing any decompotition; in this cafe it
only afls by penetrating the interftices formed by the confti-
tuent particles, without pervading the fubflance of the con-
ftituent particle itfelf. Thus the portions of water, although
participating of the refpeflive electrical intenfities of the two
wires, as yet undergo no decompofition ; as yet it has not
conip4eteIy pervaded the j)article of water. When a particle
of water is influenced on one fide by the pofitive wire, and
on its other fide by the negative, then the particle of water
becomes a fmall Leyden phial ; and if the energy of the ap-
paratus fliould be adequate to overcome the refiftance be-
tween the two fides of the particle of water, a feparation is
produced, and the water becomes refolved into oxigen and
bidrogen.

This deftrudion of the water will take place at z, the ini-
termediate diftance between a, a; becaufe, when thus re*
molely fituated, only a fingle particle of water becomes thus
operated upon ; when at b, b, a greater number of particles
of water become thus influenced, and confequently the de-
compofition is more rapid.

If water placed in a capillary fUbe be employed, it is evi-
dent, however near the platinum wires are approximated,
the areas of the bafes of the refpedive cones will be not at all
increafed, and, confequently, the maximum of its power will
be confined comparatively to a folitary particle of water.
The inftant a particle of water becomes thus feparated into
its elementary portions, it might be expe£led that thefe por-
tions would be evolved at i, as being the point of concourfe
between the pofitive and negative ftates ; but in this form
they are not in the gafeous ftate ; they require caloric, &c. ;
and ihat they do not very readily acquire this other principle

neteflary

^4(J LAWS OF GALVANISM.

necefTary to conftitute them gafes, is evident from the oxigen,
if' an oxidable metal be employed at the poiitive end, enters
ing into combination with the metal, inftead of being difen-
gaged in an aeriform ftate.

Water is a conductor of ele6lricity ; its capacity for this
principle being in proportion to its condufling powers. When
converted into vapour, its conducing powers are increafed,
and fo alfo in the fame proportion its capacity, as is evident
from water, when undergoing this change, abftrading elec-
tricity from furrounding bodies.

When a particle of water is refolved into its elementary
portions, a change takes place in their capacities for eleflri-
city, caloric, &c. at the very nafcent inftant. Oxigen we
know, from other experiments, has its capacity for eledricity
increafed, and muft acquire this principle before it can afTume
a gafeous form. This acquifition/ will be effected with the
greateft readinefs in the dire6tion towards the pofitive wire ;
while the hydrogen particle having its capacity diminiflied,
will be fimilarly determined towards the negative wire.

For a future Journal I will trouble you with fome experi-
ments relative to this change of capacity. I am anxious firft
to perufe Mr. Gough's intended paper, from whofe philofo-
phical abilities much may be expeded.

Having extended this paper to a greater length than I at

firft expeded, I ftiall defer, till another opportunity, a reply

to Mr. Cuthbertfon's obfervations, and flatter myfelf 1 fhalf

be enabled to clearly point out the error into which Mr. C.

has fallen.

Cure of rheu- Although your Journal may not be deemed the proper me-

matifmand djum for any medical communications, as I have lately wit-

palfy by galvan- , ■' . .

ifm. nefled the very powerful efFedts of galvanifm m rheumatic and

paralytic afFe6tions. Whatever may prove of benefit to man-
kind will, I am perfuaded, be readily admitted into your
valuable Work.

I am. Dear Sir,

Your's, with the greateft refped,

C. WILKINSON,

Surgeon, 19, Soho Square,

London.

Remark

CONTACT OF ELEM. PARTICLES, 247

VIL

B^mark upon an Ajfertion (t/' Lavoisier, ivhich has been re^
peated by eminent Chevdfis. ByV. Prevost, Profejfor at
Geneva, and Correjpondent with the National Jnjiitute of
France, *

" T

' J-T is a conftant phenomenon in nature that when Affertlon of La-

any body whatever is heated ..... its dimenfions become ]^°'^*^'i» J.^^^
■' ■' lince bodies are

increafed in every diredion If after having heated contraftible by

a folid body to a certain point, and by that means feparated '^f^* ^^^^^ P^*"*
•• ' tides me not xvk

its particles more and more, it be then fuffered to cool, thefe contaft.

^particles will approach each other, according to the fame gra-
dation by which they were before feparated ; the body will
pafs through the fame dimenfions it before poflTefTed ; and if it
be reduced to the fame temperature as at the beginning of the
experiment; it will refume its original volume. Bat as we
are very far from being able to produce an abfolute fiate of
cold ; but on the contrary, as there is no degree of refrigera-
tion which we cannot fuppofe to be capable of being further
augmented, it muft follow that we have not yet fucceeded in .
bringing the particles of any body as clofely together as is
poffible, and confequently that the particles of no body in nature
can be in a fiate of contact; a very finguiar conclufion, but to
ivhich neverthelefs it is impoffible to refufe our aflent." —
Elementary Treatife of Chemijlry, hy Lavoifier, Vol. I. at the
commencement.

The fame aflfertion is repeated feveral pages further, where The fame aflcr-
zn example is taken of a veflel filled with fmall leaden fhot. ^'°" repeated,
*' The balls touch each other," fays our author, *' whereas
the particles of bodies do not touch, but are always kept at a
fmall diftance from each other by the effort of caloric."

The authority which this celebrated chemift enjoys in the
learned world, is probably the only caufe why this conclufion
has been adopted. It is at leafl: certain that it is not legiti-
mate, though it has been fo often repeated ; and more parti-
cularly in a late work, no lefs remarkable for the depth of
feafoning and extent of knowledge which it difplays. Ber-

Annales de Chimiej Vol. L. p. $8.

thollet.

24S

>y Bcrthollet.

CONTACT OF ELEl

PARTICLES.

Apology for
Berthollety

thollet, in his Ejfai de Static Chimiquc, Tom. I. p. 24, parag.
2, * has thefe words ; ♦' Cohefion is the effed of that affinity
which the particles exercife on each other, and keeps them at
a diftance, determined by the equilibrium of this force with
thofe which are oppofed to it ; for the property poflefled by
the moft compaft bodies of undergoing a diminution of volume
by reducing their temperature, proves that there is no irnme-
diate conta6l between their parts."

After all, it is not furprifing that an author, who has un-
dertaken and fuccefsfully executed a work of fuch immenlity
with regard to chemiftry, fhould refer to one of his mod cele-
brated predeceflbrs for the folidity of an argument which re-
lates to the principles of natural philofphy ; and this condud
is fo much the more natural, as the argument never having
been contefted, though frequently quoted, a confiderable
prefumption arifes in its favour, to difpenfe with any careful
examination in cafes where it is not intended to be farther
applied. Now it does not appear that any farther ufe is
made of the propolition throughout the great work to which
our attention is now dire6led. I therefore confider the paf-
fage here extrafted, rather as the occafional mention of a
fmgular paradox, than as a thefis which the author was de-
firous of eftabliftiing.
whofc authority lyCt this be as it may, it will notwithftanding follow, that
may neverthc- ^\^Q mere incidental mention of an aflertion by an author fo
WiAingthV ^'juftly refpedled, will be confidered as a proof of its truth.;
error, jind that the numerous difciples of this great mafter will re-

peat it with confidence. It is therefore defirable that its want
of foundation ftiould be iniifted onf and that it (liould be di-
re6lly refuted in a Journal of extenfive circulation ; more
particularly amongft ihofe who are moft likdy to be mifled
by fuch an error.
The author docs Before we proceed, it will be proper to make an eflential
not dtfcufs the ^jftinction. The afifertion is as follows : Tfie particles of bo-
felf ^ but^onlUn- <^^^* ^^ "^' ^oMc/t each other ; or in other terms, there is no
fifts that expan- immediate contatl between the eleintntary parts of bodies. Now,
^' aaion "^rovc ^° ^P®^^ ^'^^ propriety, I do not at all ii^tend to deny thiiS
nothing. affertion, neitbier do I propofe tp eft^blifti it, 411 th?it |

intend to do is, to fliew that it is not legitimately concluded

* See Lambert's Tvanflation, Vpl, I, p. 2. ^v

from

CONTACT OP ELEM. PARTICLES. 249

from the principle whence it has been deduced ; namely,
the diminution of volume which accompanies depreffions of
temperature. Now I fay that this diminution does not at all
prove that the elements of bodies have no immediate conta6t,
and confequently that this laft aiTertion is fo far gratuitous.
And this is the whole of what I defign to prove.

If it be true that there are numerous conceptions and ex- We can eafily

amples which are evident and eafy to be given, of bodies ^'""'y! expan-
ri- ^ ,., . . 1 r . . . r • r "on Without cef-

fubjett to dilation and condenfation without Iheir parts ceafmg fation of con-
to be in immediate contact, it mufl neceflarily be concluded/^^*
that dilation and condenfation can afford no proof in this re-
fpe6t. For why (hould we refufe to admit fome of thefe con-
ceptions, or to apply fome of thefe examples to the cafe of
the elements ?

1. Conceive the particles to be elongated and united by i. Inftance: the

their extremities, like the legs of a pair of compaffes; and '^^^ °^ '^°'"P^^"

. . . n^^y open and

they may turn with regard to this point of union, as a centre, ihut.

and produce condenfations and dilations of the whole apparent

mafs of the body fucceffively.

2. A dry fponge, or fruit, or mucofity, being plunged in 2. Sponge, &c.
water, will dilate without any ceffation of the fenfible con-"^^^']^ *^°'^-
taQ; and on the contrary, the fame bodies, when wetted, larged,

if expofed to become dry, will undergo condenfation.

3. The example of the dilatation of ice and fome metals by 3. Expanfion in
cryflallization, an example formally remarked, lludied, and"^^*'**

well explained, particularly by the latter of the two learned
chemifts I have cited, muft (liew the falfity of the affertion
which I refute.

Upon reading the work of Berthollet, and taking notes of
fuch things as I was defirous of retaining, or concerning which
I faw reafon to doubt, I wrote what is here tranfcribed, i, e.
the fummary indication of the three conceptions, or examples,
proper to elucidate this fubjeft.

I had no intention of fubmitting my remark to its natural Similar remarks
judges, when five or fix weeks afterwards, being employed ^^ ^^^^Sc
in* a very different occupation, I found in the papers of a
learned * philofopher, which were entrufted to me at his

death,

* George Louis Lefage, Correfpondent of the Academy of Sci-
,-^nces of Paris, afterwards CorreJ^ ondent of the National Inftitute,
•r Member

55^ "CONTACT 6f ELEM. P ARTtCLESfi

"death, a card which contained the fame remark, but in a
more abridged form, and by fimple indication. As it offers
a variety of examples and conceptions of the fame nature as
thofe which I have given, though neverthelefs different, I
fhall here give them verbatim :

Note ofG.L* Lefage,

" Methods of (hewing that this confequence does not

follow :
Expanfionand *t i, pour fingers of one hand introduced more or lefs be^
i^'of theh'ands-^^^^" ^^® ^^^^ intervals of the fingers of the other hand,
a. Combs, &c. " 2, The fame with a couple of bruthes, or cards, or

combs.

3. Cotton, &c. '* 3. Carded cotton, or hair, and foap lather.

4. Snow. " 4. Snow.

5. Ofcillation. " 5. Agitation or ofcillation, which renders the fame par-

ticles alternately contiguous and feparate more than a thoufand
times per minute.''

Condufion*

The perufal of this note determined me to publifli mine;
not only becaufe I found niyfelf authorized by this coinci-
dence, but alfo to render a firft homage to the memory of a
philofopher no lefs modeft than ingenious, and to begin in
fome rerpe6l to execute his will, by publifiiing at leaft one of
his notes without making any change. The laft conception
offered in this lafl: Qiort note, will probably induce fome phi-
lofophers to refiedl again upon this fubje6^, and may perhaps
lead them towards the opinions of the writer.

Member of the Royal Society of London, and of feveral other
learned Societies, died at Geneva, the 28th Brumaire, in the year
XII. (Nov. 19, 1803). His principal writings have not yet been
publifhed. I fhall foon give a fhort notice, as well as fome details
of his literary life, proper to facilitate the perufal of his works, and
eftabliih tbfiir originality. P.

Accouj\t

CHAMOY LEATHER.

VIII.

mi

Account of a Memoir on clmmoying of Leather.
By M. Seguin, *

SEGUIN, who has already publldied feveral interefl-

ing works on the arts, relating to the preparation of fkins,

has lately, read to the Inftitute a firft memoir on chamoying,

from which we fliall give an extra6l.

The author ftates, that the art of chamoylng confifts in dif- Mechanical
^ , A . • 1 •! • • ,• xi -.1 operations of

pofing the Ikms to receive the oil ; m impregnating them with chamoying.

it by different operations, of which he probably referves the
details for a fecond memoir ; in then canting them to undergo
a fpecies of fermentation; in expofing them to the air; and^
laftly, in taking from them, by means of potafli, the excefs
of oil which is ufelefs to them.

He afterwards palTes to the chemical examination of a cha-
moyed (kin.

' He found that this fkin did not undergo any alteration by Chemical exa-
a long boiling in water; but that, if any acid wTiatever i'"* ^'"y'.^^J^^^^^
added (M. Seguin made ufe of fulphuric acid), the fldn dif-
appeared entirely ; that a certain quantity of a concrete oil
fwam on. the furface of the liquid ; that the liquor contained
gelatine; and that, by its evaporation, it depofited cryftals
of fulphate of potath. He alfo afcertained, that on pouring Gelatine poure4
gelatine into a foiution of foap, an infoluble precipitate is ob- X^^^ilxllV^
tained, which, treated with an acid, comports itfelf exa6lly precipitate which
like a chamoyed (kin. refembles a cha-

r^. /- /, . . /• 1 ,• , 1 • 1 .1 r moved fkin in

Thefe refults, and the confiderations to which the expofi- jtj chemical pro-

tion of the principal operations of chamoying have given rife, perties.
induced M. Seguin to conclude that the Ikins, in the fermen- Theory of the
tation which they undergo, yield a part of their oxigen to the °P^"'^'°°*
oil; that the potafli employed to cleanfe them, forms a foap
with the oxigenated oil ; that one part of this foap, by com-
bining with the difoxigenated tkin, produces the infoluble
fubitance which makes the (kin chamoyed; and, that the other
part ferves to conftitiite that greafe which remains in the
leather.

* From Bulletin des Sciencef, Tom. III. p. 20^.

This

252 LIQUOR tOR RENDERING STUFFS WATER-PROOF.

Tills worl; is the more interefting, becaufe hitherto no one
has confidered chamoying in a chemical view, and becaufe
the analyfis to which M. Seguin has fubmitted his refults,
renders it fufceptible of acquiring that perfe(5iion which the
difcoveries of this chemift have already given to the art of the
tanner.

IX.

Analyfis and Decompofition of a Liquor employed to render Stuffs
impermeable to Water, By M. Vauq.uelin. *

J.T Is known that, for fome years, difFerent perfons have
been fuccefsfully employed in rendering (luffs impermeable to
water, an objeft of great importance in the clolhing of foldiers
and failors.

The inventors of this procefs have hitherto kept the means
they make ufe of fecret : there was only reafon to fuppofe
that fome fat oil was the bafis of their receipts, but experi-
ment has not yet developed it.

A bottle of tliis preparation, of which the efficacy was known,
liaving accidentally come into my hands, gave me a defire to
inveftigate its compofition ; but before ftating the plan which
I followed with this view, I fliall defcribe its phyfical pro-
perties.
Phyfical charac- It is a white liquor, milky and opake, of a bitter tafte, and
ters of a liquor fuelling like foap ; on its (urface there is a fpecies of cream
ftuffs impermc- refembling that of milk, and it ftrongly reddens the tindure
able to water, ©f turnfole. From thefe properties I thought it was fimply a
folution of foap, of which it ftill retained the fmell and tafte,
which had been decompofed by an acid ; but fubfequent
experiments foon convinced me that there was fomething
more in it.
Chemical exa- Fi'^'fi Experiment. — To find whether I could feparate the
mination. white matter which rendered the liquid turbid, by filtration,

A turbid part Is I P^^ ^ certain quantity of it on bibulous paper : it pafled tur-
feparated by re- bid and milky for a long time, but, by returning it feveral
peated filtiation. ^.^^^ ^^ ^j^^ ^^^^ gj^^j.^ j fucceeded in obtaining it as clear

• From Bulletin des Sciences, Tom. III. p. 210i .

LIQUOHf FOR RENDERIWG STUFFS WATER-PROOF, 253

ax water; and I afterwards examined the liquor, and the
matter which remained on the filter, feparately.

Second Experiment. — If my conje6^ure was well founded,
I fhould only find in this liquor the bafe of a foap united to an
acid, of which there was a fuperabundance. My firft care Contains ful-
was to fatisfy myfelf of the nature of this acid, and that which P^""*^ ^'^''^^
its tafte had already indicated to me, was confirmed by mu-
riate of barytes producing in it an abundant precipitate, in-
foluble in nitric acid : thus I was convinced that the liquor
contained fulphuric acid; but, on the other hand, ammonia Ammonia formi
having produced in this liquor a white, flocculent, I'l^mi- ^^J^^j'^J^jP"^*?*'
tranfparent precipitate, I faw that it contained fomething
more than the fait refuhing from the decompolition of foap.

Third Experiment. — I then precipitated a certain quantity
of this liquor; I waftied the precipitate and dried it : as it
had all tlie phyfical chara6^ers of alumine, I combined it with
fulphuric acid ; I added to it a little fulphate of potalh, and,
by a flow evaporation, obtained fome very fine alum. We Contains alu-
bave therefore already found in this liquor alumine and ful-f^'"^' probably
phuric acid, doubtlefs combined in the ftate of alum. alumj

Fourth Experiment, — It was now requifite to know whether
the liquor from which I had feparated the alumine, did not
ftill contain fome other fubftance, and I therefore fubmitted
it to fome trials by the re-agents, among which the oxigen-
aled muriatic acid and theinfufion of nut-galls enabled me
to difcover a new body : the firft rendered the liquor turbid, and alfo an ani-
and foon afterwards produced white flakes in it j the fecond ™^"^tt">
produced yellowifli-white flakes, in much greater abundance
than thofe arifing from the effe(5t of the muriatic acid ; whence
I fufpefled that, befides the matters mentioned above, this
liquor contained an animal inatter, and more particularly ge-
latine.

Fifth Experiment. — To be better fatisfied of the nature of
this fubftance, I evaporated the liquor to drynefs, by means
of a gentle heat; I obtained a yellowifti fait, of a bitter tafte,
which, by being re-diflblved in water, left a voluminous
yellow matter, in the form of flakes, very glutinous, and ac-
quiring, by drying, a fort of elafticity. This fubflance,
placed on burning coals, fwells and exhales white fume^,
which have the odour of ammonia and fetid oil, fuch as are
generally given by animal matters.

I no

^54* LIQUOR FOR KENDERING STUFFS WATER-PROOF.

which is gela- I no longer doubted that a certain quantity of animal ge*
latlne had been put into this compofition, with ihe intention
of giving greater vifcoftty to the liquor, and enabling it to
fupport, for a longer time and more effe6tively, the parts of
the oil in fufpention. It is probably by heat and by a com^
niencement of decompofition, that the animal gelatine had be*
come infoluble in water; but I perceived that the liquor con-
taining the faltalfo held fome of it in folution, for the muri-
atic acid and infufion of galls ftill formed precipitates in it,
. only lefs abundant than the firti time.

Ijramination of Sixth Experiment. — In this experiment I endeavoured to
aL^' ^ ' ^^^^^ ^^® nature of the fat fubftance retained in the filter, and
of which I have fpoken above: my intention was principally
to difcover whether it held fome other fubftance in combi-
nation.

For this purpofe I burned it with the filter in a platina cru-
cible; it exhaled a vapour fjmilar to that of tallow or the oilsj
it left fome adics, of which the filter had furniflied a part : I
found a fmall quantity of alumine in them, which could only
proce<^d from the oil, for the bibulous paper did not contain
an atom. I am alfo of opinion, that, in addition to the alu-
mine, this oil contained a fmall quantity of animal matter,
but I cannot pofitively aflert it.
which retained Thus, notwithftanding the excefs of acid which exifted in
fome alumine in ihe liquor, the oil in precipitating carried with it, and re-
tained in combination, fome alumine, and probably fome ani-
mal gelatine.
It 13 a combina- Hence the fubftance which, by uniting with fluffs, ren-
tion of oil, alu- ^^j.^ them impermeable to water, is not the oil alone, but a
mme, and am- -i-rin i, ? i ^ , ^

mal gelatine J combination ot this fubltance with the alumme, and probably

with the animal gelatine, which renders this property more

durable,
and yields a little Seventh Experiment. — The liquor which I bad fucceflively
^°<*^^^^^"^P^^^^ deprived of the oil, the alumine, and, in part, of the animal

matter, by the different procetTes mentioned above, ^ave me,

by a flow evaporation, cryftals of a fait compofed of foda and

fulphate of potafli.
Another ana- Eighth Experiment. — I made a better analyfis of this liquor

^^^* by another procefs, which I (hall detail very briefly.

I precipitated the alumine and the oil by lime-wafer ; I

collc6led, waftied, and calcined the precipitate : that wbich

remained in the crucible was alumine and lime.

4 The

CASES ACfiORPED BY CHARCOAt* 2^53

The liquor, from which thefe matters had been feparated^
evaporated to a certain degree, yielded fulphate of lime, ^
certain quantity of animal matter, become infoluble by the
deficcation of the liquor, and, finally, fulphale of foda and
potafli, containing alfo animal gelatine, foluble in water.

The following is the manner in which I conceive this liquor Manner of pre-
was prepared, with the exception of the proportions : Soap and P^""S tlie U-
glue, or any other gelatine, was difTolved in water ; a folu-
tion of alum was mixed with the folution of thefe fubftances,
which, by its decompofition, formed in the mixture a floccu-
lent precipitate, compofed of oil, alumine, and animal mat-
ter; afterwards fome dilute fulphuric acid was added, to
reditfolve the alumine in part, to render the precipitate
lighter, and to prevent it from falling: but the alumine
being once combined with the oil and animal matter, will
not diflblve again entirely in the fulphuric acid, which is the
reafon why the oil continues to be very opake, and neither
rifes nor precipitates : it will be undertiood, that too much
jfilphuric acid is not to be added. I do not know if this is
precifely the manner in which it is made; I only know, that
by following this procefs, I fucceeded in compofing a liquor
exaflly refembling it, and which poflelTed the fame pro-
perties.

New E^ri??ients on Abforption hy Charcoal, made by Means of
a new Machine. By C h. Morozzo.*

1. In the fecond memoir which I publilhed on charcoal, iii.Firft notice of
1783,t I mentioned my intention of employing its property of ^^® invention,
^ibforbing the gafes, to form a good eudiometer. I immedi-
ately fet about the conftrudion of an inftrument with which I
made fome experiments; but the agitation of the times obliged
me to abandon my purfuits: a philofopher, however, to whom
I had thown this inftrument, took the libert/'l>f publithing it,
notwithftanding its imperfedions, and without naming the

• From the Journal de Phyfique, Floreal, An. XII.
f Journal de Phyfique, p. 376.

author.

2^Q GASES ABSORBED BY CHARCOAL.

author *. Let us pafs over thefe unpleafant events, as well as
the alterations and corredions which I made to bring the in-
ftrument to its prefent ftate: the defcription which follows, and
the figure will be fufficient to fliow what it now is.

Defcription of the Injirument, (Plate XIV.)
Defcription of ^^* A B is a tube of clear glafs, three lines and a half in
the iallrumcnt. diameter and eighteen inches high : to this tube a ftop-cock C
is fixed, to ftiut the communication, by means of the key D,
fo that the tube may be filled with water or mercury, and the
gas to be examined may be afterwards pafled in. To this (lop-
cock C a large one E is foldered, an inch and a half in dia-
meter, and almoft three inches long. The handle F F ferves
to turn the key of the flop-cock E ; this key has a hole, one
inch and three lines in depth, and feven lines in diameter,
(Fii^. 2.) in which the charcoal is placed. This key isperfe^ly
tight, and, when turned, communicates with the cock C, Fig,
3, not permitting the palTage of any air whatever. The large
llop-cock is enclofed in a wooden frame, and well fecured by
means of the nut H, which confines the lower end of the flop-
cock E behind the board; the lower extremity of the tube dips
into a velfcl of mercury II; the board M M keeps the inflru-
ment perpendicular; N N are pads which ferve to raife the cup
filled with mercury; O O is a fcale mounted on a flip of wood,
which is graduated to inches and lines. The endlefs fcrcw P
ferves to raife or lower this fcale, to bring it to the level of the
mercury in the cup.

III. After having ufed the inftrument for fome time, it is
neceflary to unfcrew the keys to clean them, for, by ufe, dufl,
charcoal, or alhes will get in, which deranges the inflrument,
and fuflers air to pafs.

IV. From feveral experinvents, I found that the flop-cock
D C, which is attached to the cryflal tube fliould be of fleel,
for on examining the refidual air, or filling the tube with mer-
cury to examine any gas, the mercury will at length attack the
copper.

* The author does not name the perfon here alhided to ; and in
a note he gives a defcription of this firft imperfcft inftrument, re-
ferring to the figure fo publiflied. This ts omitted, becaufe of little
■utility and not intelligible without that figure, N.

V. I

GASES ABSORBED BV CHARCOAL. 257

V. I alfo think it right to propofe a fmall alteration: it is Propofed im-
that the extremity of the tube which is plunged into the bowl ^"^^

oF mercury, fliould be a litlle more bent, that the refidual gas
may be transferred with greater eafe; this flight variation^
however, is not at all injurious to the inftrument, becaufe the
heights are raeafured by that of the mercury, the level of which
is indicated by the fcale prepared for that purpofe; its greateft
inconvenience will be to make a larger and more cylindrical
bowl neceflary,

VI. This machine was made by J. B. Piana, a very fKilful ^Accuracy of th«

^ o > . . , r , I - inftrument.

mechanic; he conitructed it with fuch accuracy, that it pre-

ferved the mod perfe6t vacuum for eight days, which is what

I am unacquainted with in pneumatic machines. ,

Manner of vfmg the Inftrument *

VII. Suppofe I am defirous of examining the abforption Method of
effeded in atmofpheric air by charcoal. The tube A B is filled ^ ^"^ *^*
with the atmofperic air of the place in which the machine is:

the Hop-cock D is open, the upper one is clofed : I place the
cup of mercury under the tube, into which I infert a fmall
glafs fyphon, to caufe the air to take the level of the mercury*
If I make ufe of a gas, I pump out the internal gas of the tube
with a glafs fyringe, to bring the level within the tube to that
of the exterior mercury in the bowl. Afterwards, by means
of the fcrevv P, I move the fcale till its zero is alfo at the
level of the mercury.

I make a piece of charcoal, weighing, half a dram or thirty-
fix grains, red-hot, and with tongs place it in the cavity G of
the large ftop-cock; I then turn Ihe handle F F, and in a few
minutes the mercury will be feen to afcend more or lefs in the
tube, according as the air is more or leCs pure.

If it is wiihed to examine other gafes, or atmofpheric air
brought from another place, then clofe the key D, and fill the
tube A B with water; afterwards difplace the water with the
gas, in the common way by means of a transferrer; bring it
to the mercury, and, by means of bibulous paper, abforb the
water perfedly ; then wipe the outfide of the tube carefully
with warm flannel, and leave the inftrument at reft for two
hours : or otherwife make ufe of a mercurial apparatus, which —

is preferable.

Vol. IX. — December, 1804. S Incon-

258 CASES ABSORfifcD BV CHAKCOAL. '

Inconveniences of the Injlrument.

Inconveniences. VIII. Nothing is more certain than the propei fy pofTefled
by charcoal of abforbing a more or lefs confiderable quantity
of gas, and of atraofpheric air ; the experiments which I have
publiflied are a complete demonftration of it; but I then made
ufeof white glafs tubes, hermetically fealed at the upper ex-
tremity, and paiTed the charcoal under the mercury, by which
its interftices were filled with that fluid. At prefent, on en*
deavouring to make comparative experiments with my new
machine, which I was defirous fliould be a perfe6l eudiometer,
1 found that the cavity G, in which I placed the charcoal, and
Ihe fmall fpace between the two keys of the (lop-cock, con-
tained air ; that by the heat of the charcoal this air was di-
lated, and partly expelled, and that confequently, on opening
the key of the (lop-cock, a fmall abforption was occalioned
"by the vacuum thus made, and the mercury then rofe. To
Convince myfelf, and to difcover at what quantity this abforp-
tion might be calculated, the apparatus being arranged as for
Other experiments, inftead of charcoal I introduced a piece of
fed-hot pumice-ilone (I gave the preference to this fubdance,
becaufe I was certain that it had not the property of abforbing
the air, and alfo that it would not take a greater heat than
charcoal) ; on turning the key an abforption of an inch took
place, and from feveral experiments, I am convinced that this
quantity is uniform within half a line.

Congestion of the I?)Jiru?nent.

Correflion of IX, From the experiment made with the pumice-ftone, it is

the inftrument. obvious that if an inch is deduded from the total abforption,

the real abforption produced by the charcoal will be obtained.

Befides, in comparative experiments this imperfe6lion caufes

no error; becaufe as they are all condu6led in equal circum-

' fiances, the variations produced, either by the different gafes,

or by the different quality of the charcoal made ufe of, will be

always proportional,

X. With this iuftrumept I made feveral experiments whicb
I (liall now rela.te*
Or(J«T of the ex- XI. I began by examining the a6lIon of charcoal when cold,
Venmcat*. ^^^ afterwards at a low heat ; I then examined the abforption

by

GASES ABSORBED BY CHARCdAlv 259

by charcoal expofed, for a greater or lefs length of time, to the
light of the fun j this enablecl me to afcertain the quantity of
ligiit and caloric which enter into the charcoal.

XII. TThe experiments on atmofpheric air, which is more or
lefs abforbed according to its purity, follow next.

XIII. After thefe are the experiments on different gafes,

XIV. Oxigen gas gave me very fmgular refults, diame-
trically oppofite to thofe I had obtained in tubes hermetically
fealed, and when I pafled the charcoal through the mercury,
which deranged me greatly in the confequences I deduced
from it,

XV". After this article will follow fome confiderations on
the quality of the charcoals madeufe of, which prove that their
property of abforbing is different according to their different
qualities.

XVI. I afterwards ihow that my Inftrument may beufed in
many cafes, if inftead of mercury, coloured water is employed,
but with requifite modifications.

XVII. The charcoals which had been employed in the ex-
periments all acquired a greater weight : I endeavoured to
extra6t the air which they had abforbed.

XVIII. I alfo mention the trials which may be made by
faturating the charcoal with different fubflances, having only
made four experiments.

XIX. I then proceed to the conclufion, in which I endea-
vour to give the explanation of thefe experiments. The opi-
nion which I had adopted in the fecond memoir, receives ad-
ditional confirmation from it ; but the refults of the experi-
ments I made on oxigen gas havihg changed the ideas I had
formed, I am not willing to hazard an explanation at prefent.
Philofophers will therefore be contented with having newfaCls
and new experiments.

The experiments which I detail were repeated feveral times,
and their accuracy may be depended on, as I can affure my
readers, that I have always confidered truth as the brightefl
ornament of a philofopher.

Experiments ffiade with my new Inftrument.
Ifl, The charcoal which I generally employed was that of Experiment!

beech-wood ; the weight of the pieces half a dram, that is to ^^^^ ^^"^ "*^^
g- .1 ' , r ■ inftruaicnfc.

lay, thirty-Iix grams.

S 2 2d. The

2^

On charcoal
heated without
the contaft of
lire.

and cxpofed to
the folar light.

GASES ABSORBED BY CHARCOAL.

2d. The tube of my glafs was eighteen inches long, from the
bottom of the key to the furface of the mercury, the level of
which is indicated by the moveable fcale. The diameter of
the tube is three lines and a half: it contains one ounce and
feven drams — five grains of water, or a volume of atmof-
pheric air of four grains and a half at a temperature of -{-10^,

3d. Being defirous of throwing a light upon the property
polfefled by charcoal of abforbing a part of the atmofpheric
air, as well as of feveral gafes, by means of my new inftru-
ment, I made a great number of experiments, which I Ihall
now defcribe.

4th. Charcoal, when cold, has the property of abforbing
fome fmall portions of atmofpheric air, and this abforption, al-
though very flow, is not complete in lefs than twenty-four
hours.

5th. Wifliing to try whether charcoal to which heat had
been communicated without direft expofure to fire, would (how.
any abforbent power, I placed a piece in a fmall matrafs,
which I immerfed in boiling water for an hour; having after-
wards put the charcoal into the machine, I obtained an ab-
forption of about three inches.

6th. I boiled oil, in which I left the matrafs for an hour ;
an experiment with this charcoal gave an abforption of three
inches two lines.

7th A fmall matrafs containing a piece of charcoal was im-
merfed for an hour in boiling alkaline lixivium : it gave an
abforption of three inches three lines nearly.

Thefe three experiments ftiow that heat communicated to
charcoal, even without the conta6l of fire, gives it the pro-
perty of abforbing a larger portion of air.

8th. The preceding experiments induced me to examine
whether the light of the fun would communicate the fame
property to charcoal, I therefore expofed different pieces to
this light, in a white porcelain bowl, and the abforptions were
proportionate to the times which the pieces were expofed to
the light of the fun *.

* At the inftant of putting a piece of charcoal into the machine,
1 placed another which had been expofed with the reft to the fun for
three hours, on the bulb of a thermometer j it only raifed one de-
gree and a half of Reaumur's fcale : the heat therefore was not
very confiderable, .

After

GASES ABSORBED BY CHARCOAL. 2^1

After two hours the charcoal abforbed one inch two lines.
After three hours, one inch eight lines.
After five hours, two inches.
After feven hours, three inches nearly.
It is difficult to obtain very precife refults, becaufe the heat The light unltee
of the fun is greatly varied, according to the wind ; but in ^^ j '^ ^^'
this cafe it is light as light which unites with the charcoal, for
in very cold days when the thermometer in the (hade was at —
6^, I flill obtained an abforption *.

9th. Being defirous of afcertaining whether this abforbent
property belonged to charcoal exclufively, I tried fevera! other
bodies, which there was reafon to believe contained a great
deal of the matter of fire.

10th. I took a fmall cylinder of loaf fugar, cold; it did not Experiments •n
produce the fmalleft apforption. ^°*^ ^^^"*

A fimilar piece, which I had heated in a matrafs with boil-
ing water, gave an abforption of between two and three lines.
A piece of fugar which had been expofed to the fun for two
hours alfogave an abforption of between two and three lines.

11th. I then proceeded to the examination of fulphur and on fulphur,
fealing wax.

A cylinder of fulphur of the fame weight gave no abforp^
tion when cold.

A iimilar cylinder, which had been expofed four hours to the
light of the fun, gave an abforption of about three lines.

A piece of cold fealing wax did not give the leaft abforption, and on fealing-
and a fimilar piece which had been two hours in the fun, gave^^**
an abforption of about two lines.

12th, All thefe fmall abforptions which were obferved as
well in the fugar as in the fulphur and fealing wax, were only
owing to the flight heat of thefe bodies, which produces a di-
latation in the air of the cavity, and a difplacing of that por^
tion of the air which is filled by the folid body ; for a piece of
pumice ftone, of cork, or of any other body, produces the

* It would be intereftlng to examine the abforptions which might
be produced by different pieces of charcoal which had been in the
light of the fun tranfniltted through coloured glafTes, or by making
the different coloured rays fall on the charcoal by means of aprifm,
and to obferve whether the piece expofed to the red ray would abforb
more or lefs than that which had received the violet ray, and fo of
the others,

fame

262 GASES ABSORBED BY CHARCOAL.

Charcoal alone fame effea. It is therefore in charcoal alone that this abforb-
abfoJbent°pro-" ®"^ property refides, and it is developed to the higheft degree
petty. by heat and light.

Experiments on Ahnoffyheric Air.
Experiments on 13th, I then proceeded to examine the effecSls of incandef-
^ ^ "^* cent charcoal on atmofpheric air, in my inftrument, and I re-
peated the experiments feveral times : the air of my garden
was conftantly lefs abforbed than that of ray bed-room, an hour
after the windows had been opened, and this was lefs abforbed
than that of my bed-room in the morning before opening the
windows : the abforptions were.

The air of the garden, feven inches fix lines.

The air of the room after the window had been open, eight
inches one line.

The air of the room, in which it had not been renovated,
eight inches fix lines.
Former experi- 14th. In the experiments which I made in the year 1783,
°*^"^'» vvith tubes twelve inches in height, and one inch in diameter,

I pafled the charcoal through the mercury ; the abforption of
the atmofpheric air was then always about three inches and
fix lines, that is to fay, a little more than one fourth ; in this
cafe it is uniformly greater and about one third. Probably the
mercury filled many of the interftices of the charcoal when it
was pafled through it, which might prevent this greater ab-
forption.
JUraf a privy. 1 5th. I afterwards examined the air of a privy, which was
taken into the fyringe feven toifes above the fewer.

The abforption was eight inches, that is to fay, nearly equal
to that of my room. This did not furprize me, becaufe in
thofe compofitions which contain azote, this gas is not mnch
abforbed, as we (hall prefently fee : befides, Mr. White with
an eudiometer of nitrous gas alfo found that the air of a privy
gave him an abfoption equal to that of common air*.

Experiments on the Gafes.
Experiments on \6ih. After having examined the atmofpheric air, I pro-
ceeded to the examination of carbonic acid gas ; I filled the

• See Journal de Phyfique, Tom XVIII. p. 145, and the reflec-
tions of Guyton Morveau in his excellent treatife on the means of
difinfefting the aii*.

tube

GASES ABSORBED BY CHARCOAL. 2^3

tube with this gas, which I had extraded from powdered mar- Carbonic acid
ble by vitriolic acid. I placed the incandefcent charcoal in the sa^«
machine which effe6led an abforption of lixteen inches fix lines,
that is to fay, of eleven twelfths of the capacity. This ex-
periment correfponds exactly with that which I made with the
tube of twelve inches in height, and one inch in diameter, and
in which the charcoal was palfed through the mercury : the
abforption in that cafe was eleven inches.

17th. I afterwards examined the effed produced on the fame
gas by a piece of charcoal which bad remained five hours in
the folar light. Itcaufed an abforption of ten inches and three-
lines, which furprized me greatly.

18th. But to afcertain whether charcoal has any peculiar
affinity with carbonic acid gas I tried this gas by placing a
piece of cold charcoal in the macliine, and the abforption was
nine inches fix lines.

1 9th. To difcover the efFe6t of carbonic acid gas when mixed A mixture of
with atmofpheric air, 1 filled the tube, which is eighteen inches ^^^^ and^^atmof-
high, with nine inches of carbonic acid gas, and nine inches pheric air.
of the air of my room with the windows open : the charcoal
effeded an abforption of twelve inches and three lines.

On analyfing this experiment, it agrees perfectly with thofe
related above, for

The abforption of the air of my room was 8 inches 1 line.

■ of the carbonic acid gas 16 6

Total 21. 7

The half of this is twelve inches three lines and a half,
within half a line of the abforption obtained.

20th. I afterwards tried the adion of charcoal in hidrogen Hidrogen gas.
gas, obtained from iron by fulphuric acid, and the abfoption
was three inches and one line : it was accompliftied in five or /

fix minutes, and flopped at that height ; the effed obferved
in my machine did not furprize me, for I had noticed in my
firft memoir, that of all the aeriform fluids, hidrogen gas was
abforbed the leaft. There is a perfed correfpondence betw^een
this experiment, and that which I made in the year 1783, in
cryftal tubes of one inch in diameter and twelve in height : the
abforption was then two inches and one line, that is to fay, one
iixth of the height ; in my new machine, the tube of which is
eighteen inches long, the abforption was three inches and one
line, which is alfo the fixth of the capacity.

21ft. On

264? GASES ABSORBED BY CHARCOAL.

21ft. On trying the fame hidrogen gas with a piece of char»
coal which had been kept about four hours in the bright folar
light, I had only an abforption of fix lines.
Azote gas. 22d. I next proceeded to the examination of azote gas. I

began by examining that obtained from atmofpheric air, in
which a candle was extinguilhed.
The abforption was fix inches.

23d. I examined that obtained by the combuftion of fulphur,
and had an abforption of feven inches and three lines : it is to
be obferved that this gas always contains fulpbureous acid, and
for that reafon more of it was abforbed.

A fecond experiment with the charcoal g^ve me feven inches
and two lines.

I afterwards tried the azote gas obtained from atmofpheric
air in which I had extinguithed a large piece of charcoal under
a bell : the abforption was feven inches fix lines ; but this gas
always contains a little carbonic acid, and confequently there is
a larger abforption,

24"th. To be fure of having the pureft azote gas without
mixture, I took the gas obtained by decompofing nitrous acid
by means of hidrogen gas, which laft gas had been obtained
from the decompofition of water by iron.

The abforption was only fix inches and one line.
We have not yet very correal ideas with refpe(5l to azote :
it appeared to me, however, in feveral of the experiments
which I made with atmofpheric air, that when it is united
with aqueous vapour, more of it is abforbed than when in a
dry ftate. Befides it is evident that the azote gas is not much
abforbed, which correfponds with my firfl: experiments.

(The Condiifion in our next.)

xr.

On the Commerce of Hens Eggs, and on their Prefervation. Bj/
M. Parmentier *.

The bulk of -^ HERE are very confiderable differences ifi the eggs of
the v^^g does hens in refpefl to fize. Some are as large as the eggs of ducks,
much ^n^the** while Others refemble thofe of pigeons. M. Parmentier, from

on the breed * ¥^o^ Bulletin des Sciences, Tom. III. p. 214.

pf the hcut • obfervations

EGGS OF I^ENS. 2^5

obfervatlons on a great number of hens of different breeds,
which he reared in the fame place, has found that the bulk of
the eggs depends much more on the breed of the hen than on
the quantity of nourifliment. Thofe breeds which give the
largefl: eggs are not however to be preferred on that account,
becaufe with them as much may be loft in the quantity of eggs
as is gained by their fize. Of all the breeds known in France
the author gives the preference, with refpe6l to the produce of
eggs, to that which is called the common hen, and which is
only common becaufe its merit h known. Thofe which have
black legs are in greater efteem than thofe with yellow ones.

From comparative experiments continued for a year, M.
Parmentier found that though the eggs of this breed were not
fo large as fome others, yet every thing befides being ec^ual
they produced at lead one half more.

Next to this breed of hens comes the crefted hen and the Superior brecdi.
large Flemidi hen. The one is more delicate eating, becaufe
laying lefs than the common hen, it grows fatter; the other,
without being more produdive, is preferable for raifing chick-
ens. The ftlkj/ hen (poule defoie) fo beautiful in its form and
in the finenefs of its plumage, fo careful in laying, foadiduous
in fetting, fo tender of its chicks, might be recommended, but
unfortunately two of its eggs are not worth one common egg.
This circumftance places it among thofe which muft be left for
the curious.

After the choice of the breeds, care muftbe taken that the Management of
hens are neither fed loo abundantly nor too fparingly ; that they ^^^ ^^"**
do not wet their feet, that they are fufficiently clofe in the rooft
to heat and eledrify each other; and, that they meet with a
little warm dung in the day time.

When the only obje6l in keeping hens is to procure eggs^
and thus turn to profit the grain which remains among thechatF
and in the dung-hills, it is wholly ufelefs to keep cocks at the
fame time, becaufe experience has fliown that hens deprived
of the male do not lay lefs than thofe which have it. The
faving by this is not the only nor the greateft advantage. The
unfecundated eggs keep much better than thofe which are fe- Unfecundated
cundated. It has been found by experiment that they can fup- ^68^ 'fail Uabje
port a heat of 32*^ (87® F.) for thirty or forty days without experi- ° ^
encing any change. It is therefore evident that the evapora-
tion of the liquors is not, as Reaumur thought, the immediate

caufe

266 EGGS OF HENS.

caufe of the putrid change in eggs, and that to prefer ve them,
it is not fufficient to cover them with greafe or oil, as this
learned man recommends, fince in the experiment mentioned
above the unfecundated eggs did not fpoil, though they loft
confiderably by evaporation. The fecundation, by the prin-
ciple of life which it communicates to the germ, expofes the
eggs to many accidents which do not take place with thofe in
which the male has had no (liare.
Caufes of the M. Parmentier particularizes fome of thefe accidents. Some
fpoilingof eggs, of them arife from the commencement of the developeraent of
the germ. Sometimes it is enough if feveral hens lay iheir
eggs in the fame neilj for the egg which is fiift laid in it, par-
taking in fuccedion, and for fome hours, of the heat of the
hens which follow each other, undergoes a fpecies of incuba-
tion which excites the vitality of the germ, and this egg be-
comes changed, though it is but recently laid. It is thus that
eggs of the fame age appear frequently todiflfer in their frefli-
nefs. At other times the change in the egg may arife from
the fecundating germ being killed, either by thunder, or in
the conveyance, by the jolting of the carriage or the rolling of
the vefle!, or by the lapfe of time. When the germ is once
dead it corrupts, and communicates the corruption to that
Utility of im- vvhich furrounds it. This theory appears to explain one me-
merfing the eggs (^Qfj T made ufe of fucccfs fully for prefervins: CiTSS even when
for a {hort time „ i . , -. rn ■ i • .. r , rr

in boiling water, ^^^i*"^^^®" ' it coniilts m plunging them for a couple ol fe-

conds into boiling water. It is knowfi that by this means they
become fufceptible of being prefervcd for feveral months, if
they are afterwards kept in a cool place, or in fait, M. Par-
mentier fufpefls that the utility of this procefs depends on the
deftruclion of the vitality of the germ by the boiling water.
Eggs laid atfca Mariners aflfert that eggs laid at fea keep belter than others,
keep longer than ^j-^y ^qj jj^j^ arife from the hens on board a fliip having no com-
munication with cocks? For the fame reafon the diminiflied
vigour of the cocks in our poultry yards, in autumn, may be
one caufe of the eggs laid in that feafon being more capable^f
being kept than thofe of the firft laying, to which may be added,
that the hens are at that time fed more with grain and lefs with
herbage.
R,cquirjt:?s for From thefe obfervatlons, M. Parmentier thinks that the firil
keeping eggs condition towards obtaining eggs capable of being preferved

ana

HARD AND WHitE COPPER. £§7

and tranfported without fpoiling, is not to keep acock with (he
hens in the poultry yard. It is an error to fuppofe that eggs
not fecundated have a worfe tafte than thofe which are fo.
The author afcertained that the moft delicate palate was inca-
pable of difcovering any difference. Afterwards it is only re-
quifiteto (belter the egg9»from humidity, light, heat, and frod.
The method which fucceeded bed with the author was to pro-
cure balkets made of llraw, in which he placed the eggs with
layers of chaff between them. The ftraw and the chaff are
dry materials, fmooth, very bild conductors of heat, and con-
fequently, very proper to preferve the chara6ler of freflinefs in
the eggs: thcfe balkets were afterwards fufpended in a dry,
dark and airy (ituation.

XII.

Method of giving the Colour , Grain, and Hardnefi of Steel to
Copper. By B. G. Sage*.

.ARGRAFF and Pellctier have publifhed their invefliga-
tions relative to the union of phofphorus with different metallic
fubflances; the French chemifl has brought this procefs to per-
fedion : it was by repeating and varying his experiments that
I difcovered that the readied and moft certain method of phof- The readleftand
phorating copper is to take the copper in the metallic form, toJJ^^j 0^011^1112'
melt it with two parts of animal glafs, and a twelfth part of copper andphaf-
powdered charcoal. But it is effential that the copper fliould^^°'^^^*
offer a large furface; an advantage which is obtained by uiing
chips of this metal, which are to be placed in alternate layers
with the animal glafs mixed with the powdered charcoal, I
expofe the crucible to a fire brilk enough to melt the animal
glafs; it forms phofphorus; the greatefl part of which burns,
while another part combines with the copper, in which it is
fo confolidated that it does not quit it, although it is kept ia
fufion for twenty minutes under the animal glafs which has not
been decompofed.

When the crucible has cooled and is broken, the phofpho- Phofphorated
rated copper is found under the glafs, which has paffed to the ^^P^'^'^'

* From Journal de Phyfique, Meffidor, An. XII.

4 fiale

26S

HARD AND WHITE COPPER^

Its aAion on
poliihed iron.

Is more fuflble
than copper.

Does not quit
the phofphorus
without diffi-
culty.

Refcmblcs fteel
in hardnefS)
grain and colour,
and does not tar-
nifh by expo-
furc to the air.

A fmall quan-
tity of charcoal
to be ufed in its
preplration.

Ked enamel.

Copper and
phofphorus can
only be com-
bined in the dry
way.

ftate of a red enamel, in the form of a grey and brilliant but-
ton : on weighing it, it is found to have acquired one twelfth
by this operation.

If the melted phofphorated copper falls on a plate of poliihed
iron, it fpreads itfelf in the form of plates of various configu-
rations which are iridefcent like the neck of a pigeon.

Phofphorated copper is much more fufible than red copper :
it may be often melted under charcoal powder without lofing
its properties.

The fame phofphorated copper, expofed for a long time
under a muffle, does not feparate from the phofphorus with-
out great difficulty.

The copper thus combined with the phofphorus acquires the
hardnefs of fteel, of which it has the grain and the colour;
like it, it is fufceptible of the moft beautiful polirti; it is turned
eafily in the lathe; it does not change in the air: I have for
fifteen years, kept buttons of poliflied phofphorated copper in
my laboratory, which have not experienced the leaft change.
The copper does not develope any fmell on being rubbed : if
it was dudile it would be of the greateft utility, lince fat bo-
dies do not feem to make any impreffion upon it.

In the phofphoration of copper there is only a part of the
animal glafs decompofed : becaufe a fufficient quantity of char-
coal is not employed to convert all the acid into phofphorus;
but it is necefTary that this fliould be the cafe, that the phof-
phorated copper may feparate and colled with facility.

The deep red enamel which is formed in this experiment
may be advantageoufly employed for porcelain or the enamels,
fince it does not change colour in the fire.

Copper cannot combine with phofphorus except in the dry
way. If a cylinder of phofphorus is put into a folution of ni-
trate of copper diluted with four or five thoufand parts of wa-
ter, at the end of eight days the copper will be found in a me-
tallic form, cryftallized and duflile, forming a cafe for the cy-
linder of phofphorus.

pbjervations

ON MIXED GASES. 269

XIII.

Obfervations on Mr. Gough's tvoo Letters on Mixed Gajcs,^

To Mr. NICHOLSON.
SIR,

iVjiY reply to Mr. Gough's ftri6lures being chargeable, it lntrodu£lIo««
feems, with acrimony and ridicule, and with having but few
arguments, and thofe in appearance negligently conduced,
(though the laft charge requires a whole letter to make it
good) ; I propofe, in what follows, to avoid the two former
of thefe as much as may be, and to be as careful as poflible in
conducting my arguments ; fo, that if they appear to Mr. G.
deftitute of that logical precifion which charaderifes his, he
may afcribe it to ray inability, and not to any want of iacli-
nation.

The accuracy of Mr. G.'s demonftration in the former let- Obfervations on
ter, depends upon that of three phyfical data : IJl, The fpe- J^t'tefo^ mixed
cific gravity of azotic gas ; 2d, The fpecific gravity of oxi- gaffes,
genous gas ; and, Sd, The quantity of oxigen in a given vo-
lume of atmofpheric air. If any one of thefe be wrong, it
may prove fatal to his demon ftration : now it unfortunately
happens that all three are wrong, and that, when corrected,
they prove the very reverfe of his propofition ; namely, that
atmofpherical air is a mechanical mixture of oxigenous and
azotic gafes.

Mr. G.'s data are,

Sp. gravity of azotic gas, .985

oxigenous gas, 1,103

Quant, of oxigen in atmo-

fphere, per cent, in bulk, 22-25-28, uncertain which.
The true, or at leaft the moft approximate numbers, are,
Sp. gravity of azotic gas, - ,966

oxigenous gas, 1 . 1 27

Quant, of oxig. in atmofphere,
j^er cc«^ in bulk, - - 21

Then, per Mr. G.'s theorem, 21 x 1,127 = 23.667
and 79 X .966 = 76.314

99.981
• Seepages 107, 160, of the prefcnt Vol.

The

270 O^ MIXED GASES,

Obfervations on The fum is fo near 100, that Mr. G. will not venture to pre-
Mr. Cough's fume any thing on the difference, further than that the data
gjfg5^ are ftill in a fmall degree incorrc6t, which I believe no body

will difpute with him.

Mr. G. by this time is ready to query, How do you know
your data to be more correct than mine? I will now inform
him.

Dr. Prieftley was perhaps ihe firft to inveftigate the fpecific
gravities of the two gafes in queftion. His method was very
exceptionable; but fuch is generally the cafe in the infancy
of any fcience. (Sec Vol, IL Page 452, abridg. Ed. of his
JS'cit. Philof.) He found azotic gas as much lighter than
common air as oxigenous was heavier, Mr. Kirwan foon
after gave a much nearer approximation; namely, the one
which Mr. G. has adopted. Lavoifier alfo found the fpecific
gravity of feveral gafes. (See Elements of Cheviijiry, Append,
Table 7). His refults nearly agree with Kirwan*s in regard
to oxigen, but differ confiderably in regard to azote. Laftly,
Mr. Davy, when invefHgating the compounds of azote and
oxigen, found it expedient to afcertain with precifion the
fpecific gravity of the two gafes. Having every means of
his predeceffors, and their refults before him, he ought at
leaft to have decided in regard to the difference between
them. Accordingly he finds his refults to agree with Lavoi-
lier's in refpe6l to azote; but he finds the fpecific gravity of
oxigen fomewhat greater than either of them. (See Re-
fearches, pag. 565).

The following table exhibits the refults of all thefe together,
reduced to the ftandard of atmofpheric air.

Specific Gravities of

Azotic Gas. Atmof. Air. Oxigenous Gas.

According to Prieftley, .989 — 1. 000 — 1.01 1

Kirwan, .985 ■— 1. 000 — 1.103

Lavoifier, .966 — 1.000 — 1.102

Davy, .966 — 1.000 — 1.127

As for Mr. G.'s third datum, I think it fcarcely pardonable in
the prefent day, for any one to pretend to difcufs a queftion
concerning the conftitution of the atmofphere, under the un-
certainty whether it contains 22 or 28 per cent, of oxigen.
He ought to be acquainted with the hiitory of eudiometry,

and

ON MIXED GASES. ^71

and to repeat experiments confidered as decifive, erpecially Obfervatlons oa
?s they are of a fimple nature. All the chemifts of Europe j^^[;^^°"^^^*^^
fecm to be agreed, that either 21 or 22 per cent, in bulk, is gafes.
the proper number. My own experience gives 2 J for the
iieareft integer, which agrees with Mr. Davy's in your Journal,
(quarto Series), Vol. V. page 175 : if Mr. G. entertains any
doubt on the fubjeft, I would refer him to that paper, and he
will receive ample fatisfaiflion.

After what has been faid, I think Mr. G. rauft be fatisfied
that he has virtually demonftraled the atmofphere to be a me-
chanical mixture of the two gafes ; If, however, he (till
alledge that I only oppofe one authority to another, and that
his is as good as mine; then I would recommend him to
fatisfy himfelf as follows: mix 21 parts (or a quantity of gas
containing 21) of pure oxigen, and 79 of pure azote, toge-
ther; after this proceed to the analyiis of the gafes, and exa-
mine the differences between the refults, and tliofe done from
the analyiis of 100 parts of atmofpheric air.

I cannot conclude thi>? article without obferving, that Mr. G,
mufl have been totally unacquainted with the opinions of chemi-
cal philofophers on the fubjeft, or he would not have expanded
into the compafs of five or fix pages a fimple argument, which
has often been adverted to by others, and is now wholly
abandoned as untenable. Mr. Davy, in his Refearches,
publifhed in 1800, advocating the notion of almofpherical air
being a chemical compound, produces four evidences, one of
which is flated as follows ; See Page 326.

** 2dly, The difference between the fp.gr. of atmofpheric
air, and a mixture of 27 parts oxigen and 73 nitrogen, as
found by calculation ; a difference apparently owing to ex-
panfion in confequence of combination." In a note he adds,
** The two firft evidences have been often noticed." This
gentleman however foon after, finding that the atmofphere
contained only 21 percent, of oxigen, mufl have feen that this
evidence was not to be admitted. Since that time it has not
been urged by any one to my knowledge.

I come next to Mr. G.'s reply at page 160. This at the
commencement purports to be a defence of the charge, that
my argumenis are but few, and negligently conduced ; at the
conclufion it is afferted to be an anfiuer to all my ohjeSiiom,
and fojnething more. This language may be that of logical

precifion

272 ON MIXED GASES*

Obfervations on precifion with Mr. G. ; but it would have been more intelli*
letter orTmixcd ^'^^^ ^^ "^® '^ ^^ ^^^^ flated the objefts of his reply thus:
gafes, fj?, A refutation of Mr. D.'s arguments in favour of his

fydcm.

2d, An anfvver to his objecStions brought againfl mine.

3d, New objedions to his fyftem.

The firft thing worthy of notice is the objedlion to my ar-
gument for the mutual penetrability of gafes, I have afTumed
one poftulate and taken tzvoj and the latter of them is erro-
neous, namely, that all gafes are porous. It is true, I have
taken two poflulates into the argument, without exprefsly
requiring both ; the former being peculiar to my theory, was
necelTarlly demanded in a formal way ; the latter being the
refult of all experience, and never in any one inftance having
been found to fail, 1 thought it might tacitly be aflumed.,
However, the judgment of philofopliers muft be fufpended on-
this head, as Mr. G. it feems, is about to prove that Jio gas
is porous, and that a cubic foot of one gas cannot be put into a.
"jejjel that is previoiijly occupied by another gas. Mr. G. furely
cannot be ferious in this objedlion ; but merely ufes it to gain
time, and means to turn it off with a laugh, that he has at
leaft produced one folid argument againft my airy hypo-
thefis.

Mr. G. finds it extremely convenient for his purpofe, that
I fliould grant him the following poftulate : " If a particle of
vapour can pafs freely through the air, a fecond can alfo fuc-
ceed it at any given diftance." I certainly cannot concede
fo indefinite a demand ; but it will perhaps be of equal ufe to
him to have the following: If d be the diftance of two par*
tides of vapour of the temperature of 212°, and prefiure 30
' inches ; then, at the temperature oF 60° or upwards, if one

particle of vapour can pafs freely through the air, a fecond
may fucceed it at any diftance greater than 4 d.
i As for the important argument which I confider equivalent

to a demonftration of the nature of vapour, and of its relaiion
\ to gafes, and entirely inimical to the notion of chemical affi-

nity, Mr. G. has not ventured to revive it : Probably he has
fomething in referve on this head. I mean the argument de-
rived from the fad, that a vacuum, or any kind of air of
any denfity whatever, takes up juft the fame quantity of any
\ vapour.

The

\
\

\

ON MIXED CA&SS. 'ZlO

The propofition refpeaing the mechanical aftion of ah" on ^^^^^^^'^"^^^
the furface of water, will be anfwered by Mr. G. when he jg^ter on"mixcd
has proved that air has no pores, or no capacity for the re-gafes.
ception of water. For, nothing can be more clear than that,
whatever may be the preffiire of the atmofphere, and how-
ever few the points of its action, water cannot be forced into
the pores of air, if it have none.

Mr. G. proceeds to (late two new fa6ts, which are faid to
be inexplicable on my principles : I muft undertake the ar-
duous talk. The fads are, 1^, Air containing aqueous va-
pour is fpecifically lighter than air without it, cateris paribus ;
and, 2d, A bottle internally moift, containing air, being heat-
ed, more air is expelled than if the bottle had been dry.
Both granted. — Now for the explication. The fpecific gra->
vity of aqueous vapour has been found by De SaulTure, Watt,
and others, to be about -J or | of that of atmofpheric air in
like circumflances ; by fome experiments of my own I am
induced to think it is nearly .7, that of air being 1. Let the
temperature be 64-**, and the air be filled with vapour as much
as poffible in the temperature, in which cafe -~^ of the elaftic
force will be due to the vapour. (See Manch. Mem, Vol. V,
P. 2, page 559); then, by the theorem fo elaborately exem-
plified in Mr. G.*s former letters, we have — ^ =

49.7

~- zz .994, for the fpecific gravity of common air filled with

^^'apour at 64*^, when that of dry air of the fame temperature
rwould be 1 . Thus it appears that my hypothefis not only ex-
plains the fa<5l of diminifiied fpecific gravity, but accounts for
the quantity of diminution. Can Mr. G. s theory of chemical
folution do this ?

In the fecond cafe we find heat generating vapour, which
increafing in quantity and force with the temperature, diffufes
itfelf through the air in the bottle ; the hand being occafionally
removed from the mouth, fufl^ered the extra-portion of air
and vapour to ftart out ; juft as if there had been a generation
of a like portion of oxigen, or any other permanent gas, in-
ilead of the vapour ; in which cafe a portion of both does
certainly efcape. Mr. G. finds the vapour generated this
way between 59 and 126°, to be rather lefs than -g. of at-
VoL. IX.— December, 1804. T mofpheric

; 2(74 ON MIXED OASES.

-Obfervations on m«fpheric fOTCC ; it QUght to be juft -J by the table above

i^tte^n mixed ^^^^^^^ ^^' ^^^ »t is obvious, that by removing the hand

gafes. occafionally, the full quantity of vapour for any temperature

could never be obtained in this way, no more than pure oxigen

.could be procured in the botlle by a fimilar procefs. The

.grand queftion with Mr. G. however, is. How does vapour

of half an inch force, expand the pores of air fubjedl to 30

inches of preflure ? And his anfwer feems to be, it is impoffible,

according to the axioms of dynamics. This queflion is what

.1 (hall now confider.

Having myfelf iludied the principles of dynamics, as well
as thofe of many other mathematical and phjfical fciences,
under the tuition of Mr. Gough, I feel under ftrong obliga-
- lion to him ; but thefe, he will readily grant, do not bind
me to fubfcribe to his opinions, when I cannot, perceive them
to be well founded. He charges me, in the prefent inftance,
with a miflake in regard to dynamics ; but he has not pointed
out any particular axiom which! have offended : The miftake,
I think, is with him, and fliall endeavour, in what follows,
to point it out.

It is a principle in dynamics, that whenever a fyftem of
bodies ad upon each other, and are in a fiate of equilibrium,
the leajl farce rmprefled upon any one difturbs the equilibrium.
Thus, the ocean and the air, though bound to the earth by-
its fuperior attradion, are neverlhelefs difturbed by the feebler
influence of the moon. Air in a bottle is a fyftem of particles
at equal difiances repelling each other, but in equilibrium by
the gravity of the incumbent atmofphere ; confequently the
kaji force imprefled upon them rauft difturb that equilibrium.
Now, ex hypothefi, air does not repel vapour at a diflance,
but only in conta6t ; therefore vapour can be formed in fuch
a fyftem : when once formed, it meets with no elaflic refift-
ance or repulfion but from particles of its own kind ; there-
fore it is conflantly tending outwards, where the particles of
its own kind are leaft denfe : in its way it infringes upon par-
ticles of air, and exerts fuch force as it is capable of upon
them : a number of particles of air are thus gently propelled
in the diredion of the ftream, and the refl of the fyllem are
obliged to accommodate themfelves in order to preferve ibe
equilibrium : thus the diftaaces of the particles of air are gra-
4 duall/

CONDENSER OF FORCE'S. ^75

dually increafed, and that in proportion to the force which
the vapour exerts. Therefore vapour of the lead poffible force
can, in fuch circuraftances, extend the pores of air. Q, E. D.
I remain your's,

J. DALTON.
Manchefter, Nov. 15, 1804-.

XIV.

Sotm Account (^a Condenfer of Forces, or a Method of ohtaiti*
ing the greateji pojible Efftii from a firfi Mover, of which the
Energy is fuhjed to Increafe or Diminution within certain
Limits; and in general to vary at Pleafare the Rejijiance to
which the Effort of the firft Mover forms an Equilibrium in
<Lny Machine whatever, without changing any Fart of the Con^
Jirudiion. Pj^ R. Prony.*

JL HE problem of mechanics, of which the folution is here Problems la
jgiven, is one of the fmall number of thofe which, leading to"^^^^*"**'*
refults independent of the particular mechanifm of the ma-
chine to which they are applied, prefent, in their folution, a
generality which may be compared with that of the rational
mechanics, or analyfis.

It may be enunciated in the following terms :

*' Any machine being conftru6ted, to find, without making enunciated,
any change in the confl:ru6lion, a means of tranfmitting to it
the adion of the firft mover, by fulfilling the following con-
ditions ; viz.

'* I. That it may be poffible at pleafure, and with greatCondltions*
fpeed and facility, to vary the refiftance (againft which the
effort of the firft mover muft continually make an equilibrium)
in limits of any required extent,

" 2. That the refiftance being once regulated, (hall be ri-
goroufly conftant until the moment when it is thought proper
to increafe or diminith the fame.

'• 3. That in the moft fudden variations of which the effort
of the firft mover may be capable, the variation in velocity of
the machine ftiall never undergo a folution of continuity."

♦ From the Bulletin of the Philomatiuc Society at Paris,
No. 83,

T 2 I ftiaU

27f CONDfiNSER OF FORCES.

Solution cxhi- I (hall here apply the folution which I have dlfcovercd of
bked in an en- ^j^jj problem, to the dynamic effba of wind ; it will be eafy
to make the fame general when the other firft movers are ufed.
Problem in dy- The fe6lion and plan of the machine are exhibited in Plates
pofe aVonftan°^" ■^^* ^^^ XVI. O O reprefents the vertical arbor to which
weighttoava- windmill fails are adapted; eeee is an aflamblage of carpen-
m^ver^'^and ^'^' °^ which one of the radii O e, bears a curved piece h d,
tranfmit the of iron or fteel : Vertical axes of rotation a a a, being placed
force, &c. round the axis O O, alfo divide the circumference in which
Ihey are found into equal parts.

Each of thefe axes carries a curve af, of iron, fteel, or
copper; fo fituated, that when the wind a£ts upon the fails,
the curve b d preffes againft one of the curves af, and caufes
the vertical axis to which this laft curve is fixed, to make a
portion of a revolution.

The curves b d and af muft be fo difpofed, that when b d
ceafes to prefs on one of the curves af, it (hall "at the fame
fj ^}^^^^^ begin to a6l upon the following curve : the number of
axes which are provided with thefe curves, muft be deter-
mined by the particular circumftances of each cafe ; and it
is alfo pradicable to fubrtitute, inftead of b d, a portion of a
toothed wheel having its centre in the axis O O, and to place
portions of pinions inftead of the curves af, but the difpofl-
tions reprefented in the figure are preferable.

Each of the axes aaaa (which are all fitted up alike,
though, for the fake of clearnefs, only one of them has its
apparatus reprefented in the drawing), each of thefe carries
a drum or pulley tt rVy on which is wound a cord that palfes
over a pulley p, and ferves to fupport a weight Q by means
* ^ of the lever F G, upon which this weight may be Aided and
faftened at different difiances from the point of motion G.

The fame axes a a pafs through the pinions q q, to which
they are not fixed ; but thefe pinions carry clicks or ratchetts,
which bear againft the teeth rr; fo that, when the weight Q
tends to rife, the ratchett gives way, and no other effect is
produced on the pinion qq, either by the motion of the axis
or of the drum t trr, excepting that which caufes the afcent
of the weight </.g,. But the infiant that the curve or tooth b d
ceafes to bear againfl: one of the curves af after having
caufed the correfponding weight Q to rife, that weight Q
tends to redefcend, and then the toothed wheel r r acts againft

the

CONDENSER OP FORCES. 217.

the ratchett, fo that Q cannot defcend without turning th^ P'^ '• n ^y-
pinion qq along with the drum ttrr. ,,.,/^°i'''

The pinion 9 </ takes in the wheel ah, from the mot i< > s^

which the ufeful effect of the machine immediately refuitsj i.
that the effect of the defcent of one of the weights Q, is to tr
folicit the wheel A B to motion^ or to continue the motion *^'^*^'^»
in concurrence with all the other weights Q, which defcend
at the fame time. This wheel A B carries beneath it oblique
or bevelled teeth G D, which take in a like wheel C E, and
caufe the buckets at S to rife.

The alternation in the motion of thefe buckets may be ef-
feded by the mechanifm I have defcribed in the firft volume
of the Memoirs of the Inftitute.

From the preceding defcriplion it is feen that the machine,
being fuppofed to ftart from a flate of repofe, the wind will
at firft raife a number of weights Q, fufficient to put the ma-
chine into motion, and will continue to raife new weights
while thofe before raifed are fallen ; fo that the motion once
imprelTed will be continued.

Among the numerous advantages of this new mechanifm we
may remark the following :

1. No violent (hock can take place in any part of the me-
chanifm.

2. The ufeful effed being proportioned to the number of
weights Q, which defcend at the fame time, this effect will
increafe in proportion as the wind becorpes ftronger, and
caufes the fails to turn with more velocity.

3. The weights Q being moveable along the levers F G,
it will always be very eafy to place them in fuch a manner
as to obtain that ratio of the effort of the firft mover to the
refinance, as fliall produce the maximum of effect.

4. From this property it refults, that advantage may be
taken of the weakeft breezes of wind, and to obtain a certain
product in circumftances under which all other windmills are
in a flate of abfolute inaftivity : this advantage is of great
importance, particularly with regard to agriculture : the wind-
mills employed for watering lands are fometimes ina6live for
feveral days, and this inconvenience is more particularly felt
in times of drought. A machine capable of moving with the
(lightefl breeze, rauft therefore offer the moft valuable ad-
vantages.

I Oiall

278 rttvsstc ACID.

I ftall give a more ample account of this apparatus in a
memoir which I (hall prefent to the Inftitute, as foon as the
machine which I am now eredling in the country (hall be
completed, *

XV.

AhJiraSi of a Memoir on the Pojfibiliti/ of obtaining Prufmte of
Potajh free from Iron ; the Unalterahility of the Prtiffic Acid
at high Temperatures s and the true Nature of the Combina^
tions of this Acid with different BafesA Bj/Bvckolz,

Utility and ad- J. HE combination of prufTic acid with falefiable bafes, forms'
fic"4mpoundV ^ ^^^^^ ^^ ^^'^^ ^^ ^^^ greateft utility to the analytical chemift ;
for by means of them he is not only enabled to afcertain
whether a metallic fubftance be prefent in any folution which
forms the fubjefl of his refearch, but alfo what metal is pre^
fent, as well as its refpedive quantity. But in order to be
accurate in this refpedt, the re-agent employed muft itfelf be
free from metallic admixture ; or the quantity and nature of
/ the metal it contains muft at leaft be known. To accomplith

this, chemifts have hitherto laboured in vain. To remedy
thefe defects, Mr. Bucholz has inftituted a number of expe-
riments which led to facts hitherto unknown ; and as they are
highly important, we (hall exhibit the refults of the principal
ones, which are as follows :

* The pra6llcal mechanic may perhaps find if an advantage to be
informed, that the whole effort of a firft mover cannot be tranf-
mitted by this, or any other mefhod of raiting weights, in order to
operate by their fall. If the wind had been employed to raife a
maximum of weight through a given fpace in a given time, this
weight would be lefs than would continue in equilibrio at reil againt^
the fame force, as is well known ; and if this weight be again em-
ployed in like manner to raife another maximum of weight, this
alfo will be lefs than the former, Sec. For this reafon it is that the
fly has been ufed as an equalizer of fteam-engines, in preference to
the older method of raifing water and fuflfering it to defcend on an
overfhot wheel. W.N.

f Abridged from a memoir in Gehlen's new Journal of Chemifr
tfy, yd. I. Part IV. Page 406, by — A.

1. Pjuflip

PltVSSIG ACID,' 2-79"

1. Pruflic acid can only be formed during the carboniza- Pruffic acid is
tion of blood or animal matter, at a red heat: We, therefore, ^°J"jj*g^^°"^y **
need not be afraid of heating the mixture of blood and alkali,

in the preparation of pruffiated alkalies, to incandefcence,

2. The affinity of pruffic acid with alkalies is greater at Its affinity whife
high temperatures, and in the dry way, than at low tempera- ^^.^J^^^^'® "
tures, and in the humid way.

This obfervation diftinguiflies pruffic acid from the reft of All other vege^^j
the fo called animal and vegetable acids, and their co»bina- deitroyed by%-
tions with alkaline bafes ; for all of them are deftroyed at a nition.
red heat. Hence it is obvious,

3. Tiiat in the preparation of pruffiated alkalies, the pre- Water fliould be
fence of water ihould be avoided as much as poffible. avoided.

4. The dire<5l combination of pruffic acid with alkalies, can- P. acid and alk.
not be accompliffied. ^° ''^J^^^^

,5. Pure pruffiated alkalies are decompofable by the affufion P. pruffiated alk»
of water; part of the pruffic acid efcapes, and may eafily he d^<^om^hhk by"
recognifed by the odour of bitter almonds, and frequently alfo
by that of ammonia.

6. The combination of pruffic acid with alkalies can only P. acid does not
' be effected at all temperatures up to a red-heat, by the interpofi- <=o"™b»ne with

tion of a portion of oxide of iron ; and the affinities confifting temp, but by
between the pruffic acid and alkali, are retained with a greater medium of irony
force in the humid way, in the ratio of the ponderable quan-
tity of iron prefent,

7. All the precipitates obtained in chemical analyiis by Common pruf-

means of pruffiated alkalies prepared m the ufual nian-^*^^^^*^®"*^""^^;,
. 1 r • • 1 . 1 "^"^^ metals with

ner, contam more or iels iron, without exception; whereas iron j pure p,

the fame precipitates, produced by the a6lion of abfolutely 8'^^ * different

pure pruffiates, are free from that metal, and of a different

colour than the former.

8. The affinity of oxide of iron to charcoal, is more power- Moft of the
ful than the joint attradlion of pruffic acid and potafli to that ''■°'? prefent re-
metal; hence we always find that the greateft quantity of ^^"^ when*. '
that metal remains behind with the charcoal, in the ufual alk, is made,
procefs for obtaining pruffiate of potafli.

9. The precipitability of the oxides of metals by pruffiated Petals are pre-
alkalies, is in the ratio of their oxidability, or quantity of cip. by p. alk. in
oxigen they contain. ^^^ order of oxi-

Such are the obfervations of this chemift. Other lefs in-
terefting fafls will be omitted in the prefent abftrad.

Experimental

280 FRUSSIC ACID.

Experimental Enquiries concerning the hejl Method of preparing
Prujfiate of Potajh free from Iron.

Preparation of Four oz. dried blood were intimately mixt with a folution
kaU pure*. *' ^^ potalh (containing one ounce of potalh), then evaporated
Low ignition of to dryncfs, ignited to rednefs, till no more flame undulated
poteV,'°aliVfo^ at the furface of the ignited mafs. The ignited raafs was
lution by water, diffufed through fix ounces of water, and the folution filtered.
The filtered fluid was colourlefs, it contained an excefs of
alkali, and emitted a flrong odour of bitter almonds. It
yielded, on being evaporated as expeditioufly as poflible, a
faline mafs, confining of a mixture of pruflSate and fub-car-
bonate of potafli. In order to feparate thefe two falts, one
drachm of the faline raafs was introduced into a vial con*
taining a mixture of half an ounce of highly concentrated
The fait was alcohol and half a drachm of acetic acid, of 1,036 fpec. grav.
tic acid and alco- O" ^g'*^^'"g ^^^ ^^^^ "^ fenfible eflfervefcence took place,
bol. but much pruflic acid was difengaged; a proof the pruflic

acid was retained with a lefs affinity by the alkali than the
carbonic acid. On examining the refidue, which had been
treated with acetic acid and alcohol, it was found to contain
only a fmall portion of prufliated alkali.
Very little pruf- From this experiment we learn, that one part of potafli
fe^arable from cannot be converted into prufljate of potafli, by being heated
the carbonate by to rednefs with four of blood ; and that the quantity of either
thofe agents. ^^.^^ ^^ carbonated alkali, under thefe circumftances, can-
not be feparated from the pruflSated potafli by means of
acetic acid and alcohol.
Lefs orWood In order to learn if a lefs quantity of blood would not be

was then ufed ^^^q advantageous for the produ6lion of pure pruffiate of
in the igmtion. » ^,-,Vii i ri ,r

potafli, four ounces ot dried blood, and two ot carbonate or

potafli, were heated to rednefs in a crucible till no more flame

appeared. On covering the mixture with charcoal powder,

Gr^at evolution and again heating it, a prodigious evolution of ammonia took

ofaqaflttoni*. place; a phenomenon I do not venture to explain. The

mafs, after having been diffufed through water, filtered and

evaporated, yielded a crop of cryfials, confifiing of prufliate

and fub-carbonate of polafli, the former predominating con-

fiderably.

The fubcarbon- On fubjefting this mixture of falts to the joint action of

rot^fepafable^^y ^^^^^^ ^^^^ ^"^ alcohol, it was found. impoffible to feparate

alcohol and the pfuflSate of potafli from the fub-carbonate.

•ceticacid. Being

PRUSSIC ACID. 281j

Being thus perfuaded that a lefs quantity of blood was not Blood and alkali,
more advantageous for forming pure pruffiate of potafli, I !^Jilnenr Lon*I
again mingled two ounces of dried blood with one of carbon- ly ignited for
ate of potafti : this mixture was treated as before, with the ^'^'Kr^"^ °^
exception that the mafs, after the flame had entirely difap-
peared, was ftrongly ignited for three quarters of an hour.
The obtained mafs, after refrigeration, weighed nine drachms.
Digefted cold with four ounces of water, and filtered and
evaporated, it afforded a dark coloured fluid. On dropping The fluid of fo-
into a confiderable quantity of muriatic acid, no blue, but a ^"^^°" ^^.^ ^}^*
white precipitate fell down, which was infoluble in muriatic fome iron,
acid : Acetic acid occafioned no change in this dark-coloured '^oug^i very-
fluid ; and on mingling it with fulphuric acid, and evapo-
rating the mixture to drynefs, and re-diffolving the mafs in • -
water, it yielded a fmall quantity of pruflian blue ; a proof
that iron was prefent in this fluid.

The quantity of iron being very fmall, but the colour of
the fluid very dark when compared with thofe of the former
procefl^es, it was natural to fuppofe, that the colouring-
malter could not be attributed to the minute quantity of iron
prefent, but that perhaps a portion of charcoal was diflTolved
in the fluid : to invefl:igate which the following experiments
were inftituted :

A like quantity and like proportions of blood and carbonate Repetition of the
of potafli, asftatedlaft, were gradually heated to incandef-^XnT/thr'^
cence, and the fire gradually augmented, until the mafs began la^k,
to fu/e on the fides of the crucible. The mafs, after having ,
been diffiifed through water and filtered, yielded a much
darker-coloured fluid, which, when mingled with muriatic
acid, yielded a pearl-coloured precipitate. After being mixt
with muriatic or fulphuric acid, evaporated and rediflblved
in water, it afforded a confiderable quantity of oxide of iron;
a' proof that the union of the pruflic acid with potafli is perraa- The pruflic acid

nent at very high temperatures, but that this combination, ''^."f^"f "'"^^<*

n T n rt- 1 with alk. at very

under fuch circumftances, exerciles a ftrong action upon the high temp, and

oxide of iron contained in the blood. Jf^" '^on

Thefe fads were proved by repeating this experiment,. but Lefs oxide taken

taking care to expofe the mafs to a fomewhat lefs degree ofup by lefs heat.

heat. The fluid now obtained was lefs coloured, and yielded

lefs oxide of iron.

This

282 WiUSWG ACID,

Experiments This being proved, the author varied his experiments, fo

with pure alkali. ^^ j^, ^e thoroughly convinced of the fads. He alfo endea-
voured to afcertain, whether alkalies, freed from carbonic
acid, were better calculated for the produftion of pruffiated
alkali; and, if poffible, to find out the proper proportions of
ingredients for obtaining this fait. With that view, a quan-
tity of folution of potafh, containing one ounce of alkali freed
from carbonic acid, was mixt with three ounces of blood,
and evaporated to drynefs. (It was of a colophony colour,
foluble in water, and emitted, on being heated, a very ftrong
Low heat pro- odour of ammonia). On being transferred into a crucible,
Son 0"?."*' ^""^ gradually heated till no more flame appeared, and diffufed
acid and the aU through four ounces of water, it yielded a limpid fluid, of
^^^* a ftrong alkaline tafte, and odour of bitter almonds. The

ufual experiments proved, that it contained comparatively
little pruffiated alkali, but a large quantity of carbonate of
potafti.
Exp. to deter- Being thus convinced that this experiment proved fruitlefs,
mine the proper- j^ ^g^g deemed neceflary to afcertain the refpedtive quantity
ate and blood re- of oxide of iron contained in the prufliated alkali, that might
qiiifite to pro- jjg produced from a given quantity of blood and carbonate of
^t^ Sec. potafli.

The experi- With that view, four ounces of dried blood were mixt with

ments witli low ^ folution of carbonate of potafli, containing one ounce of
4 oz*. blood and Carbonated alkali : the mixture, after being evaporated to

1 alk. carb. drynefs, was heated till the flame ceafed to appear. It now

weighed 1^ oz. On being elixiviated with eight ounces of
water, it afforded a fluid of a very pale yellowifti brown, or
wine colour : Its tafte was alkaline, mixt with that of bitter
almond' Two drachms of water mixt with 20 drops of a
concen):ated folution of muriate of iron, when decompofed
Produa very by this prufliated alkali, afi'orded four grains of prufliian blue,
liitle. ^f jpt^ f^Qjjj, the adhering oxide of iron by muriatic acid.

2 oz. blood, Two ounces of dried blood and one of carbonate of potafli,
1 carb. alk. treated in a fimilar manner, yielded, by being mingled with
Pr'^dua'notin- » like quantity of muriate of iron, 4f grains of pure pruflTian
creafed. blue.

(The Remainder in our next.)

Obftrvations

SPEAKING TRUMPETS. 2^h

XVI.

Obfervations on the Caufe which augments the Jnteiifity of the
Somdin Speaking Trumpets, ^j^ J. H. Hassenfratz *.

^ALTHOUGH the I'peaking-trumpet is an inftrument which Anriquity of the
has been long known, fince Kircher is of opinion that Alex- ^ *"* ^'^*"^'
ander ufed it to command his army, and Solard made one in
Paris, in I654f, from the defcription which Kircher had given
of that of Alexander, it was not, however, until 1671, when
Morland made known that which he had conftru6led, and in- MorIand*s«
vited men of fcience to determine the figure mofl proper for
this inftrument, that the fpeaking-trumpet was really known
among us, and began to be ufed.

It appears that Morland did not adopt the conical form ter-
minated by a mouth piece, which he gave to the fpeaking trum-
pets of glafs, iron and copper, he made until after a fucceffion
of trials on the beft form to be given to them, lo make them
produce articulate founds.

It alfo appears that it was without knowing it, and by chance, Caflegrain's,
that Caflegrain gave the fpeaking trumpet, which he made in
J 672, the hyperboloidal form firft noticed by Sturm.

Until 1719, when Haflfe publiftied a diflertation on the im- Were at firft
provement of fpeaking trumpets, this inftrument was con- *^""^^ VT
ftruded without principles; for we neither can nor ought to principles,
confider as principle, the harmonic proportion mentioned by
Caflegrain as being neceflary between the length and the width
of the tubes of fpeaking trumpets.

The law of the refledion of found in echoes, led Haffe to Haffe's theory
apply the theory of catoptrics to fpeaking trumpets, and in- "^5^^ ^"^["^"'
duced hira to confider the combination of the ellipfoidal and intenfity of
paraboloidal forms as the moft advantageous for this inftrument : ^^^^'^ ^ ^^^"**
but this union not producing the efte<ft which the profelfor of
Wirtemberg had hoped for, it was abandoned, and in conform-
ity with his opinion, the augmentation in the intenfity of the
found continued to be confidered as (he product of the reflec-.
tion of the fonorous rays in the fpeaking trumpet, and of the
vibration of the fubftance of which it was compofed. It wks
for this reafon that, in the fabrication of thefe inftruraents, the

• From Annales de Chimie, Pralreal, An. XII.

attention

284* SPEAKING TRUMPETS.

attention was direaed to having a hard, elaftlc and thin fub-

ftance, that it might vibrate in unifon with all the tones, and

refledl the fonorous rays which ftruck it in all diredions.

L»rabert*s In 1763, Lambert withdrew from the theory of fpeaklng

vSon injurc«*'""^P®*^' *^® vibration of the materials of which they are com-

the articulation pofed: he (liowed that the vibration of the fides which is cal-

of the founds, ^ulated to augment the intenfity of a long continued found,

would render articulate founds confufed, which muft fucceed

each other rapidly ; that in this cafe therefore it would be ne-

cetTary to fpeak extremely flo'w, and that, even by fpeaking

flowly, it would be impoffible to diftlnguifti the confonants,

which are only momentary modifications of the vowels; that

the latter, pronounced in the trumpet, would be fo fonorous,

that the confonants muft be guefied at, which would be ex-

Speaklng trum- tremely difficult. By fprinkling the exterior furface of a tin

but\te''founa'is O^eaking-trumpet with faw-duft, I fatisfied myfelf that the

equally ftrong furface vibrated in fome circumfiances, but I was equally fa-

when thcvibra- tisfied, on covering the outfide of the trumpet with a foft loofe

iluff to ftop and obftrudl its vibrations, that the intenfity of

the found was no lefs ftrong, in this fecond cafe, and, that

thus the vibration of the fubftance of the trumpet was, at feaft,

ufelefs, if it was not injurious to the diftinclnefs of articulated

founds.

In his memoir, publiflied among thofe of the Academy of
Berlin, for the year 1763, Lambert has attributed all the aug-
mentation of the intenfity which the found experiences by
fpeaking into a trumpet, to the refle61ion of the fonorous rays
on the fmooth and poiiftied furface of the interior of this inftru-
ment; he fays that, of all the forms, that beft calculated to
concentrate the found by retleding it, and the moft eafy to
Proportions of aeon ftrud, is the conic form: he afterwards ftiows that the
conical fpeaking j^f^y^^^ \^ ftrengthened in conical fpeaking trumpets, in the pro-
portion of double the length of the cone which forms the trum-
pet to double the fize of half the angle at the fummit of the
cone, fuppofi ng the length of the cone to be equal to the ra-
dius. If the angle of the cone is made = <p, the found is
ftrengthened in the proportion ^2 : 2 (fin. l^).

Seeking, from thefe formulae, to difcover what would be
the beft proportions to give to conical fpeaking trumpets, he
found that whatever the angle of the fummit of the cone was,
ks bafe muft be equal to the diftance between the fummit of

- the

SPEAKING TRUMPETS. 285

the cone and the mouth of it, and that its length muft be equal
<o the diameter of the mouth, divided by four times the fquare
of the fine of half the angle of the cone : that thus in a trum-
pet of fix feet in length, the angle of the conemufl be 16** 17.
and that fuch a fpeaking-trumpet would make the found 96
times more intenfe.

Lambert therefore, as well as thofe who have preceded hira,
confidered the augmentation of the intenfity of the found in
fpeaking trumpets, as the refult of the adion of the refle<5lion
of the fonorous rays againftlhe interior fides of tlieinftrument.

It would appear that fince Lambert's memoir, fpeaking Thefe Inftni-

trumpets have been made ufe of, without attending to the J^rr^beerdnl

^ caufes which augment the intenfity of the found, and, in fad, ftrufted without

it is feen that in all works in which this inftrument is fpoken of, attending to the

cjufes ol^ the
its effeds are attributed either to reflection alone, or to reflec- jncreafe of

tion combined with the vibration of the fubftance of which it found.

is formed.

If we compare the theory of fpeaking trumpets with that of J^^o^'yoffpeak-
the inftruments which have fome refemblance to it, fuch as ^ther inftru! ''"
trumpets and hunting horns, we muft be attonithed to find thatmcnts.
they are referred to different principles. In the fpeaking trum-
pet, the caufe is attributed to the refledion of the found; in
the other inftruments to the vibration of the air contained in the
tube. Why thefe tvyo caufes, while the efFedsare analogous?
This analogy has led me to inquire if, in reality, the refledion Does refleftion
produced the augmentation of the intenfity of articulation in Jf"" ^'"«
horns and acouftic tubes, as well as in fpeaking-trumpets, as is found ?
generally believed.

On examining the ears of animals, it is feen that the great- Animals do not

eft number have an exterior auricle, which moft of them di- ^^^L^^ ^^^ '^'^'

flection of
red towards tl^e place from which the found proceeds; this found.

auricle being, in many animals, covered inwardly with hair,

• which flops and hinders the refledion of the found, it is rea-

fonable to conclude that it is not by refledion that the found is

tranfmitted into the ear.

When afterwards we obferve the form given to acouftic horns. Ear- trumpets

which is that of a cone, the fummit of which, flightly tf un- ^°^"°JJ^'^"j[-

cated, is placed in the ear, we are quickly led to conclude that reflexion.

the found is not tranfmitted by refledion ; for the angle of the

incident ray being increafed at each refledion by that of the

«one, aft,er a number of determinate reftedions, the angle

would'

.no

Horns of a
paraboloid form
difufed.

Cylindrical
acouftic tubes
tranfmlt found
without re-
fleSion to a
^re^c diilance*

According to
the theory of
reflexion the
enlarged part
(pavillion) is of
no }»fe.

SPEAKING TRUMPETS,

would become larger than a riglit angle, and the ray would re«
turn upon itfelf. Thus the greateft number of the rays would
infue out of the moulh, after being feveral times refle61ed, and
the quantity of the rays which thus reach the ear, and which
are proportionalby lefs numerous as the cone is longer, cannot
fenfibiy augment the intenfity of the found. Neverthelefs,
acouftic horns do ftrengthen the found conliderably; this aug-
mentation muft thereiore depend on another caufe.

It has been propofed to make horns of a paraboloidal form, as
being beft calculated to tranfmit found by refiedion; but whe-
ther they did not produce the effe<5l which was expe6ted from
them, or tiiat they were too difficult to conftrud, thefe horns
have been abandoned, and none but conic horns are made
ufe of.

The acouftic tubes employed to tranfmit the found to great
diftances, fo that it cannot be heard by perfons placed between
the two extreme points, are ufually formed of cylinders, which
ferve to conduft the found. Lambert had already ftated that
refle6tion did not increafe the intenfity of found in cylinders,
becaufe whatever might be the direction of the incident rays,
being conftantly refleded between two parallels, the angle
which they form with the axis of the cylinder muft be the fame
at entering and quitting it; that thus the found muft experi-
ence a diminution at its iflue, which will be fo much the greater
as the number of refledions is more confiderable. Never-
thelefs the found is tranfmitted to a great diftance by means of
thefe tubes, and I have afcertained that the beating of my
watch, which ceafes to be audible at the diftance of 1"*. 10,
the medium of feven experiments (A), is heard at the dif-
tance of 2™ 23, the mean diftance of feven experiments (J)
when I place it in the mouth of a pafteboard tube, 0"". 038 in
diameter and 0™. 6 in length ; whence it follows that this tranf-
xniflion muft proceed from another caufe.

All thefe confi derations have therefore induced me to ex-
amine the effedls of the fpeaking trumpet with the greateft
care. It follows from the theory of the refle£lion of found,
applied by Lambert to the fpeaking trumpet, that the opening
by which it is ufually terminated, ftiould be at leaft ufelefs, if
not injurious, for it has no influence on the concentration of
the reflefted rays; and therefore this gentleman propofed to
lay it a^gle entirely. The ^njilogy of form betv^eeu the trum-
pet

9'PEAKING TRUMPETS,

287

pet and the fpeaking trumpet not being a fufficient reafon for
retaining it, it is probable that it would have been laid afide,
in the fame manner as the contour of the trumpet was aban-
doned, when the form and dimenlions moft fuitable to this in-
ftrument were fought for by experimental trials. There would
alfo have been another inducement to difpenfe with it, becaufe
HatTe had already omitted it in the fpeaking trumpet which
he indicated as preferable to thofe of Morland and Caflegrain.
I afcertained by experiment that two fpeaking trumpets of the Which is con-
fame length and the fame diameter produced different efFeds ^"jJ^J° ««?«"-
when they were terminated by an enlarged aperture or not,
and that in general this enlargement confiderably increafed the
intenfity of the found. The beating of my watch which I
heard at 4"*. 2, the mean diftance of feven experiments (a)
by placing it at the mouth of a fpeaking trumpet of 0". € long
and 0™. 38, mean diameter of the tube, was not heard beyond
2"^. 25, mean diftance of feven experiments (a) when I placed
it in a tube of the fame length and the fame diameter. Thus
the caufe which occafions this aperture to ftrengthen the fooner
is different from the reflection of the fonorous rays.

Since the refled^ion of found does not in any manner concen- This Is further
Irate the fonorous rays in a cylindrical tube, it muft follow, as Fo^ed by the
Lambert has concluded in his Theory of Refledion, that fpeak- augmented in
ing trumpets with cylindrical tubes fliould notfenfibly augment ^P^^^"g trum-
the found. To prove whether experiment agreed with this drical tubes ^ as'
theory, I immediately conflrudted a fpeaking trumpet, with a ftrongly as in
cylindrical tube of 0«. 26, the length of the cylinder, 0'". 25, ^^.^^^fj^! ''''"''
the length of the enlarged part, 0". 035, the diameter of the ,

cylinder, and 0*". 190, the greateft diameter of the enlarged
part, and, by comparing the intenfity of the found which it
produced, with that of a conical fpeaking trumpet of the fame
height, and of a fimilar mean diameter, J afcertained that tiie
jftrength of the found was fenfibly the fame. In both, the beat-
ing of my watch, which I did not hear in the open air beyond
1". 08, fnean diftance of five experiments (h) was heard at
3". 94, mean diftance of five experiments (b) when I placed
it at the mouth of either fpeaking trumpet. Since the cylin-
drical fpeaking trumpet ftrengthens the found in the fame man-
ner as that which is conical, and iince, on the contrary, the
theory of reflection fhows that it ftiould not be ftrengthened,
it follows that the augmentation of found in thefe inilrumen.t*
.»rifes from a caufe different from reflection.

One

288 SPEAKING TRUMPETS,

The intenfity of One decifive experiment remained to be made with thefc in-

kffencrbVde-"' ^rumenfs, this was to deftroy and to reftore the adion of the

Uroying the re- refle6lion in a rpeaking trumpet, fuppofing it to take place,

rcfleftionby and to compare the intenfity of the found obtained in thefe
means of an . ' ^

internal woollen two circumftances, in order to determine the proportion of the
•ovcnng. effed produced by this refle6lion. I confequently procured a

fpeaking trumpet of woollen Huff, which I placed within one
of tin, and I obferved tiiat the intenfity of the found obtained
with or witliout the fluff in the infide, w^as fenfibly the fame;
whence it follow<} that the refleflion has 'no appreciable influ-
ence on the augmentation of found in a fpeaking trumpet.
Except inaf- I have faid that the intenfity of the found was fenfibly the

mbiihes the" ^^'"^' nevertheleffs I muft obfervfe that it was diminifhed; for
diameter of the the beating of my watch, placed in th6 mouth of the bare
mftrument. ; fpeaking trumpet was heard at a diflartce of 3". 94, mean of
five experiments (b), while when placed in the mouth of the
fame inftrument covered in the infide with the fluff, it was not
heard beyond 2". 48. This difference, which at the moment
might be fuppofed to arife from the refledion of the found tak-
ing place in the one cafe, and not in the other, feems to de-
pend folely on the diminution of the diameter of the cylinder
of the fpeaking trumpet and of the Enlarged parts occafioned
by the fluff placed within them: I fatisfied myfelf that the
fpeaking-trumpet which I made ufe of (h), preferring all its
dimenfions and experiencing no difference except in the diam-
ettr of the tube, produced a diminution in the intenfity of
the found, whenever a fmaller diameter was made ufe of;
thus, in the fpeaking trumpet already mentioned (h)^ the beat-
ing of my watch was heard at adiflance of 3*. 94, when the
-diameter of the tube was 0". 035 ; it was not heard beyond
3"". OS, when the tube was only'0™.OS2; finally, it was not
■heard beyond 2'". 34, when the tube was 0*". 028. It is evi-
-dent, therefore from thefe experiments, that the diminution in
the intenfity of the found by covering the interior of a fpeak-
ing trumpet with fluffs, arifes from the diminution of the di-
ameter of its tube.
The diminution- I fiiould obferve that if the internal flufl^ occafions an incon-
*" ^'y^ '"^^"5^7 fiderable diminution in the intenfity of the found, it, on the

of the found is i i

compenfated by' Other hand, produces a great advantage by rendering the arti-
its clearnefs. . culaled founds clearer and lefs confufed.

Gcncp^lcon- It follows from all which has been fliewn on the auricles of

^lufions, animals, on horns, and acouflic tubes, and on fpeaking trum-

pets.

SBtAKiHG tRUMPETS.

289

pets, that the augmentation of found, in every circumftance. General con^
is not owing to the reflection of fonorous rays, confequently
there exifts no reafonfor feparating the caufe which augments
the found in thefe inllruments, from that which ftrengtbens it
in trumpets and hunting horns; that the different founds pro-
duced in the two cafes are owing to the vibration of the air in
the tubes, and their ftrengths or their inteniities, to the aug-
mentation of the amplitude of their vibration, arifing from the
greater impulfe which the air neceflarily receives when it is
enclofed in a tube.

Experiment (A).

The tubes and the fpeaking trumpet of pafleboard.

The interior diameter of the tube of the fpeaking trumpet is
0™. 038, that of the exterior diameter of the enlarged part =
0™. 210. The length of the tube = 0". 4, and the length of
the enlarged part == 0™. 2.

^ Diftance at which the
a> beating of the
3 watch was heard.

With a tube of the
length of

The

fpeaking
trumpet.

Without
tube or
fpeaking
trumpet.

Obfervations.

m.
0,4

m.
0.6

m.
0.10

The great differ-
ence between
thefe experi-
ments arifes,
ift, from the
difpofition of
the organ ;—
2d, from the
greater or lefs
noife produced
in the neigh-
bourhood of
the place where
the experi-
ments were
made.

1.33
2.24
2.16
1.33
1.92
1.58
2.54

1.66
2.90
2.66
1.79
1.95
2.16
2.66

2.33
3.33
3.33
1.85
2.00
2.66
3.17

4.00
4.66
5.00
3.00
5.00
3.66
4.00

1.00
1.16
1.33
0.83
1.33
1.00
1.00

12.86

15.78

18.67

29.33

7.65

1.83

2.25

2.67

4.20

1.10

Experiment (B)*

The fpeaking trumpet was of tin, as well as the tubes.

The interior diameter of the tube of the fpeaking trumpet
= 0"*. 035, that of the exterior diameter of the enlarged part
= O'^. 290, the length of the tube = O"*. 36^ and that of the
enlarged part = 0.25.

e Vol, IX.— December, 1804.

U

With

^0

ACCOVNT OF CERIUM.

Diftance at which
the beating of
the watch was
heard.

With an

internal diameter of

Without
fpeakin»
trumpet
or tube.

0.035

0.032

0.028

4.88
3.53
3.25
4.39
3.58

3.58
2.93
2.76
3.58
2.58

t,76
2.28
2.28
2,44
1.95

m.
1.48
0.97

1.30
0.82
0.82

Sum
Mean

19.78

15.43

11.71

5.39

3.94

3.08 2.34

1.08

XVII.

Account of Ceriu7n, a new Metal found in a mineral Suhjlanct
i from Bufifuis, in SKedcn. By W. D*Hesincek. ard
J. B. Bergelius *.

DlfcoTery of a
new fubftance
m tungftein.

Where found.

Dtfcription of the Tungfiein of Bafinas,

i\LTHOUGH this fubftance has been formerly affayed hj
Scheele and D'Elhuyar, under the name of wolfram, its con-
iiderable weight, neverthelefs, determined us to fubmit it to
farther enquiries. Our principal object was to find yttria in
it, which, being unknown at the time in which thefe chemifts
operated, might have efcaped their attention. Our fuppofi-
tion was not well founded, fince, inftead of an earth, we
difcovered a fubftance which, according to every appearance,
is hitherto unknown, as will be feen in the fequel.

The tungftein of Baftnas, which we call cerite, for reafons
which will be prefently given, was found, in the year 1750,
in a copper-mine called Baftnas, or Saint-Gorans Koppar-
grafva, at Riddare-Hyltan, in Weftraannia, of which, with
an)eftos, it formed the matrix : but after this time it was Im-
bedded in quartz and mica, to the depth of feventeen toifes.

* From the Swedlfti, by G. A. Linbomi but here tranflated from
the Apnales de Chimie> L. 145.

The

The tungfleln is alraoft always mechanically mixecl with Defcripdon of
Llack amphibole (hornblende), ftriated adinote, of a clear '^"^°'^^*
green colour (JhnrlJ, mica, fulphurated copper^ bifriiulh, and
fulphurated molybdena> which may be eafily known by ex-
pofing it to the fire.

The cerite, properly fo called, is tranfparent, of a flefli Phyfical proper^
colour, fometimes deep and fometimes bright, feldom yellow-^^" °^""^'^*
ifli. In a mafs, or in fmall fpecimens, the (lone is of an ir-
regular form ; its fra6lure is indeterminate, compafl, and a
little brilliant, with obtufe edges; its conliftence is tenacious
and flrong; it gives fire with fteel with difficulty, but does
not fcratch glafs ; it is not attra6led by the magnet ; after
having been made red-hot in the fire, it lofes its bardnefs,
and fix or feven per cent, of its weight : by this operation it
becomes friable, and acquires a bright yellow colour : it does
not melt alone.

On account of its weight, Cronftedt has placed it among Is the falfe tung-
the tungfteins, in his Mineralogy. In pure fragments, it is ^^^^^ °^ S*^^^^^^«
to that of water as 4.733 and 4.935 to 1.000. Scheele not
having found wolfram in it, called it falfe tungftein.

The conftituent principles of this mineral were given by Conflituent
Bergman, in the Memoirs of the Academy for the year 1784,''''^'"'^^^^''
page 121, from an analyfis of D'Elhuyar: they are as fol-
lows : —

Silex, - - - 0.22
Iron, - - - 0.24

Lime, » * - 0.54

1.00

Heated with borax by the blow-pipe, it forms a globule of Mabltude with
glafs, which, while hot, appears greenifh, but is colourlefs ^'*'^^'^*
when cold. Urged with carbonate of foda in a platina fpoon
it is not diflTolved.

§ n.

Analyfis of the Proportions of Cerium^

TO fcparate the yttria which was fuppofed to be in it, it Treatment o^
was reduced to a fine powder in a porphyry mortar ; pure . "^"^^j^'? *^**
concentrated nitric acid was then poured upon if. The acid
was decompofed, and a coniiderable quantity of nitrous gas

! U2 and

292 ACCOUNT OF CERIUM.

and carbonic acid gas were difengaged. The ftony powder
was repeatedly treated with this acid, until the infoluble refi-
due appeared white.

The folution diluted with water was of a yellow colour,
which became greenifh by boiling, and afterwards red : com-
pletely dried, it became of a yellowifli white, but regained
its red colour by attrading humidity. It is entirely diffolved
in alcohol ; and the folution, (lightly digefted, depofits a con-
fiderable quantity of oxide of iron. It likewife depofits more
oxide of iron by .remaining for fome days undifturbed in a
window. The decanted folution, being almoft clear, was
evaporated to ficcity, and the calcined fait was in the form of
a powder, of the colour of bricks. Water could only diflblve
the calcareous earth. Diftilled vinegar could only take up a
very fmall portion, and was not faturated, though affifted by
the heat of ebullition. The evaporated acetic folution gave
fraall granulated cryftals, of a faccharine aftringent tafte.
They were not totally foluble in alcohol. The part of the
Acetous fait which was not diiTolved in alcohol, gave, by cal-
cination, a brick-coloured powder, refembling that which had
not been dilfolved.

Ammonia precipitated the alcoholic folution in a white
powder, which became yellowidi in the air. It was a little
ibluble by carbonate of ammonia, and acquired the colour of
bricks by calcination. The fediment being feparated, the
carbonate of ammonia produced a white precipitate, which
was pure carbonate of lime. The acetous fait did not there-
Indications of a fore contain yttria. The powder from which the calcareous
metallic fub- earth had been feparated, diflblved in muriatic acid, with a
difengagement of oxigenated muriatic acid gas, which indi-
cated that there was a metallic oxide.

Was it oxide of manganefe combined with oxide of iron ?
To afcertain this, we endeavoured to develope the pure
oxide of manganefe by means of tartrite of potafh, according
to Richter's method. We decompofed in this manner, a fo-
lution of this fubftance in muriatic acid, perfectly neutralized
by tartrite of potafli ; and after having waflied the precipitate
well, we fubmitted it to a flow calcination ; but it only pro-
duced the brick-coJoured powder.
Does not contain Cauftic alkali had no adion on the infoluble part of the
aiumine. nitrate j which proves that it did not contain alumine.

To

ACCOUNT OF CERIUM. ' 293

To obtain the pure metallic matter in a fufficient quantity
U> make feveral affays, another portion of cerite was diffolved
in nitric acid, and the folution evaporated to ficcity. Water
was poured on the relidue, and it was precipitated with am-
monia. The waflied precipitate was diflblved in nitric acid.
The (blution, well neutralized with the alkali, was afterwards
precipitated by tartrite of potafli. A white powder was alfo
precipitated from the fame folution by carbonate of potafh,
but it was in fmall quantity. Thefe precipitates were fepa-
rately calcined, and both of them acquired the colour of bricks.
The precipitate formed by the carbonate of potafli, was not
diflblved by potafli aided by digeftion ; it therefore did not
contain alumine. The iron contained in the folution, preci-
pitated with tartrite of potafli., was feparated by hidro-fulphu-
ret of ammonia. The remainder of the folution of cerite in
nitric acid, which had been precipitated by cauftic ammonia,
gave carbonate of lime by carbonate of ammonia.

From thefe aflays it refults, that cerite contains nearly 23 Component
parts of filex, 5.5 of carbonate of lime, 22 of oxide of iron, P^"^ of the ore,
and a quantity or this metallic matter, the weiglit or wliicn, o^ide of cerium.
after calcination, rather exceeded 50 per cent. But this fub-
ftance being then, as well as the iron, united with more oxi-
gen than they contained in the cerite, we have, inftead of a
lofs, an augmentation of weight, which probably arifes from
the oxigen. Neither is the lofs which the cerite experienced
in the calcination, included in this account. We alfo found
traces of manganefe, but in fo fmall a quantity, that potafli,
melted with the cerite and diflblved in water, did not give
any colour.

Not having the pradice which complete proportionate ana-
lyfes require, we oflfer thefe refultij with diffidence, and in the
hope that fcientific men of more experience will employ them-
felves on this fubje6^.

§ III.

Examination of the Metallic Oxide found in the Cerite,

A PASTE was made of 37 grains of this oxide and linfeed Examination «f
oil, which was reduced in charcoal in a covered crucible. ^h« oxide.
Although it retained fome carbon, it loft half a grain of its
weight. This mafs was inclofed in a lined crucible with-
out

g^^ ACCOUNT OF CERIUM.

out any flux, and M. Hjelm expofed it for half an hour to
the degree of fire neceflary for the redu6lion of manganefe.
The oxide was not melted, but reduced into a very fine pow^
der : it exhibited brilliant particles in the daylight, and
ftained white paper black. It difiblved in muriatic acid, dif-
engaging, at the firft, fulphurated hidrogen gas, and after-
wards pure hidrogen gas. This colourlefs folution had a fac-
charine tafte. Thus it appeared to us that the metal was re«
duced in part. The origin of the fulphur may be traced to
the fulphuric acid, from which the matter had been feparated
by the cauftic ammonia. The influence which this acid ex-
ercifes in thefe aflays, will be feen by the fubfequent en-
quiries.

M. Gahn, at Fahlun, having more convenient furnaces,

has promifed to undertake the reduftion of this fubftance with

more power: if this operation fucceed, we fliall give an ac-.

count of it hereafter.

It is the oxide Thefe appearances, and thofe which follow, determined

pfa metal not yj (q confider the fubftance found in the cerite, as the oxide

^ ' of a metal hitherto unknown, to which we have given the;

name of Cerium, from the planet Ceres, difcovered by Piazzi.

Manner of obtaining the pure Oxide of Cerium.

ProcefTesfor ob- T-^O Pure uncalcined cerite was diflblved innitro-muriatic,

taining the pure and, after faturating the clear folution with the alkali, was

precipitated by tartrite of potafli. The precipitate well

wathed, calcined, and digefted in vinegar, contains the pure

oxide of cerium.

Or otherwife decompofe a folution of cerium in nitro-mu-
riatic acid, ftill warm, but not faturated, by fuccinate of am-
monia : a fuccinate of iron is gradually depofited. The pre-
cipitation is to be continued by means of fuccinate of ammonia,
as long as a red precipitate is formed : the folution is then
nearly deprived of iron. After having feparated the fuccinate
©f iron, more fuccinate of ammonia is poured into it, until a
■white precipitate appears. The folution is then left at reft,
in order that the fraall portion of fuccinate of cerium may be
depofited. The iron diflblved by the free muriatic acid, is
depofited at the fame time, and the folution is freed from this
metal. The cerium may afterwards be precipitated by am*^
XPOni^i, and then waflied and calcined*

ACCOUNT OF CERIUM. 295

Of the Properties of Oxide of Cerium.

(B.) This oxide may appear in different degrees of oxida- The oxide is
tion. The alkalies precipitate a white oxide from its foliitions,"J'g*jj^*^jj° g^,^'^^
which (hows of a yellowifli colour in the air, but, when per- oxidation.
ie&.\y dried, becomes dark. Expofed to a brifk and long-
continued fire, it takes a deep brick-colour. The oxalate and
acetate of cerium, calcined in velTels not completely clofed,
yield a white oxide, which, in an open fire, becomes of the
colour of bricks. It does not melt by itfelf.

Treated with borax by the blow-pipe, it melts readily and Fufionwith
("wells. The globule heated by the exterior flame, aflumes "^"*
the colour of blood ; which, by cooling, palTes to a yellowith
green, and at length becomes colourlefs, and perfectly tranf-
parent. Melted by the interior flame, thefe changes do not
take place ; it is then reduced into a colourlefs glafs ; but, ex-
pofed for a (hort time in the exterior flame, the fame pheno-
mena are produced. If too much oxide of cerium is made
ufe of, the glafs refembles an opake yellowifli enamel. Thefe
changes are more eafily manit'efted with the phofphate of foda
and ammonia. If two clear and colourlefs globules are melted
together, one of which was prepared with borax and the
other with the phofphate, they form a tranfparent glafs, which,
on cooling, becomes opake and pearl coloured.

Thefe chara6lers, taken together, fufficienlly diflinguifh the
oxide of cerium from the oxide of iron. The latter alfo ofl^ers
the fame changes of colour, but its glafs, on cooling, has a
deep green colour, Vjhich fades. The globules made with
borax and the phofphate melted together, yield an opake
glafs, the colour of which is a little deeper.

Oxide of Cerium treated with Sulphuric Acid.

(C.) When oxide of cerium is digefled with fulphuric acid. Sulphate of ce-
thefe two fubftances unite, and the refult is a red infoluble '^'"'^ ^l ^ *"/*''
fait, which is fulphate of cerium at a maximum of oxidation, fion.
If the acid is concentrated, it fcarcely diflTolves any of it. If
it i& diluted with half its quantity of water, or a little more,
the refult is a yellowifli oily liquor, which does not adhere to
the glafs, nor does it wet it. If the acid is mixed with fix or
feven times its quantity, or even more, of water, and em-
ployed in a fufficient quantity, the , oxide is diflolved of an

orange

296

ACCOUNT OF CERIUM.

Acidulous ful-
phate of cerium

Neutral acid.

orange colour. By a flight evaporation of this folution, it
yields fmall, prifmatic, coherent cryftals, of the colour of
gold. This fait is an acidulous fulphate of cerium at a max-
imum. Thefe cryftals, thoroughly dried between blotting-
paper, and expofed to the air, are gradually reduced to a
yellow, almoft cryftalline powder. ReditToIved in water,
they experienced a decompolition ; a white powder is depo-
fited, and the folution becomes colourlefs. This white pow-
der is a fulphate of cerium, but little oxigenated. If tlie fo-
Acidulous ful- lution is evaporated to drynefs, it gives an acidulous fulphate
but fli\tiy"o3d-"^^^*^''"^^ ^''^ '^^^ oxigenated. Thefe cryftals are feldom cu-
bical, but almoft always prifmatic, ftriafcd and colledled in
bundles. Their tafte is four, but they aftervi^ards become fac*
charine and aftnngent.

Treated with Houriatic acid, the yellow acidulous fulphate
of cerium yields part of its oxigen to the acid^ which is volatir
lized in oxigv^iated muriatic acid gas. The fait remains co-
lourlefs. An augmentation of temperature alone is fufficient
for the yellow acidulous fulphate of cerium to lofe its colour by
perature, which ^^^ ^^^ ^^^^^^ ^p j^^ oxigen. If the heat is increafed ftill

aftf'.rwarcls arjves '^ ^ ^

off the acid, and more, the furplus of the acid is carried off, and a fat u rated
fulphate of cerium remains. By a continued calcination, it
regains oxigen, becomes red, and yields a fulphate of cerium
at a maximum. The fulphate of cerium, difoxigenated by tlie
muriatic acid, is more difficult to re-oxidate by calcination.

In the humid way, the alkalies only decompofe the fulphate
of cerium incompletely. Ammonia precipitates an oxide
from the acidulous fulphate of cerium, which is only in a fmall
•quantity, but neverthelefs contains part of the fulphuric acid.
The fulphate of cerium is not perfe6tly decompofed, except
by calcination with three times its weight of carbonate of foda
or potafti. The calcined oxide is of a brown colour. By di-
geftion, ammonia can deprive it of part of its acid : the oxide
takes a diftindt flelh colour, which becomes brighter by dry-
ing. Digefted with concentrated muriatic acid, or with ni-
tric acid, a fmall quantity diffolves, having its yeHow colour.
Sulphate of ce- If a folution of acidulous fulphate of cerium is precipitated
riuman pota • j^^ p„ja(j^^ a triple combination of cerium, fulphuric acid, and
potafli, is feparated, before the acid is faturated. If too much
potafli is added, the combination is partly deftroyed. The
fulphate of cpriunj and potafl^, at a maxiviumi is pf an orange

colour;

genaccd.

Muriatic acid
deprives the aci
dulous fulphate
of part of Its
oxigen :
As does an in-
creafe of tern-

forms a neutral
ifuiphate.
Calcination re-
ftores the oxi-
gen.

Action of the
alkalies on the
fulphates ot ce-
rium.

ACCOUNT OP CERIUM. ^97

colour ; that which is at a minimum, is white. A fimilar com-
bination is alfo obtained by pouring muriate of cerium into a
folution of lulphate of potafli. Sulphate of ammonia does not
form any precipitate in it ; but, on adding a calcareous fait
to it, fulphate of cerium combined with potafli is rapidly
depofited.

Thefe chara6lers offer a ready method of feparating the ful- Sulphuric acid
phale of cerium from iron. It muft however be obferved, ^^j j^^^^g ^^'^^.^^
that when the folutions are faturated, a little iron is alfo de- um from iron,
pofited, which gives a yellow colour to the precipitate; but
by adding a little fulphuric acid in excefs, the iron is redif-
folved, and leaves the precipitate entirely white. This com-
bination is only didblved in part by dilute fulphuric acid, and
the greateft quantity of that feparates afterwards.

The lulphate of cerium and potalh melts by a flrong heat. Sulphate, zni
Feated with charcoal, it gives fulphuret of potafli and ful-
piiuret of cerium. Melted with carbonate of potafli, in clofed carbonate of cc-
vefiels, it yields carbonate of cerium and fulphate of potafli. '^^""**
This fait contains only one-third of oxide of cerium.

It is diflblved in concentrated nitric acid, and, during the Concentrated
cooling, an acid fait, formed of acidulous fulphate of potafli"^^**^ J^^^^j-^j*;'
and a little fulphate of cerium, cryftallizes. Thus the fulphate phate of cerium
of cerium combined witii potafli, is decompofed by concen- *"^ P°^^^*
trated nitric acid. This ac id carries off the metal, and the
fuiphuric acid is directed wholly upon the potafli, with which
it forms a fait with excefs of acid.

Qxide of Cerium with Nitric Acid.
(D.) Nitric acid diflblves the calcined oxide with difficulty, Nitrate of ccri-
but that which is precipitated by pure or carbonated alkalies,
with eafe. When the folution is faturated with oxigen, it is
of a greenifli yellow colour ; but colourlefs, when lefs oxided.
Evaporated to the confiftence of honey, it depofits lamellated
cryflals, which atlrad the humidity of the air. The folution
has a faccharine tafte : like all the other faturated folutions of
cerium, it lets fall an oxide of cerium, at a maximum of oxi-.
llation, in the open air. This precipitate is frequently formed
of oxide of iron. When dry, this fait is of a yellovvilli white
colour ; but becomes colourlefs on being diflfolved in a fuffi-
• (cient quantity of water. |t difl'oives readily in alcohol.

4 A con-

298 * ACCOUNT OF CtftJUM.

A concentrated folution of this fait takes a blood colour,
on account of a fmall quantity of iron, which, by drying,
patTes to yellowifh white, but is reftored by a new folution.

A colourlels and lefs oxided nitrate of cerium, is obtained
by dilTolving the yellowith fait in alcohol; the (blution inflames
and yields a white fait.

It is deftroyed by fire, which drives off its acid.

With Muriatic Acid.

Muriate of ce- (E.) The calcined oxide of cerium is flowly diflblved in
vium. muriatic acid in the cold, and more readily by heat ; an effer-

vefcence is produced, owing toadifengagement of oxigenated
muriatic acid gas. The tafte of the folution is faccharine and
aflringent; the colour is a very faint greenilh yellow: the
dried faline mafs is yellowilli white, and attracts humidity.
We only fucceeded once in obtaining it cryflallized. The
cry(]als were white, brilliant, in four fided prifms, with the
points cut off. The fait difFolves readily in alcohol, and its
concentrated folution burns with a yellow and fparkling flame.
The refidue of the fait is white and gives a colourlefs fo-
lution. It is muriate of cerium at a minimum of oxidation.

Heated in clofed vefTels, the water of cryftallization is firfl
diflipated, afterwards the acid palTes in the form of oxigenated
muriatic acid gas. If the operation is flopped before the acid
is entirely volatilized, an undecompofed muriate of cerium, at
a minimum of oxidation remains.

If the muriate of cerium contains iron, it all fublimes in a
brown deliquefcent mafs. Nothing remains in the matrafs but
a white oxide of cerium, which attracts the humidity of the
air, and becomes yellow. Thus, fublimation with muriate of
ammonia may be employed to purify a muriate of cerium which
contains a little iron.

With Phojphoric Acid.

Phofphate of ce- (F.) Free phofphoric acid, faturated with an alkali, preci-
T('^^^» pitates muriate of cerium. The precipitate is white, and

ibluble in muriatic acid and in nitric acid employed in fufficient
quantity.

This fait is alfo obtained by digefling pure oxide of cerium,
moiflened with phofphoric acid. It is not foluble in an excefs
of this acid.

With

Accori^T OP ciRiuM. Qgg

With Carbonic Acid.

(G.) The carbonate of ammonia precipitates muriate of Carbonate of ce»
cerium without effervefcence. After the precipitation, car-""™'
bonic acid is flowly difengaged in the form of bubbles. The
refidue retains its acid, even after deiiccation.

Dry carbonate of cerium has a white colour tending a littlo
(o bluifh or greenifli. It diflblves in the acids with efFer-'
vefcence. It does not lofe its acid in an open fire. In clofed
veflels, without the conta6l of oxigen, it fupports a gentle
calcination, without being decompofed.

With Arfenic Acid.

{H.) Free arfenic acid does not produce any change on Arfeniate aa^
muriate of cerium. The oxide digefted with this acid, forms ^'^'^"J!°"^^'^^'^*'•
an infoluble fait. An excefs of this acid dlffolves it, and gives
an acidulous arfeniate of cerium. The faturated arfeniate of
cerium is depofited in the form of a powder during the evapo-
ration. The refidue does not cryftallize, but by deficcation,
becomes a gelatinous, clear, and colourlefs mafs.

With MoUhdic Acid,

(L) The acidulous falts of cerium are not decompofed by Molybdate ©f cc-
molybdate of ammoniac. The molybdate of cerium is precipi* ^*^™'
tated from its faturated folutions, in the form of a white fait,
which is not foluble in the acids.

With Oxalic Acid,

(K.) Either the acidulous or faturated folutions of cerium Oxalate of ccri-
are precipitated by oxalic acid. According to the degree "™*
of oxidation of the metal, the precipitate becomes red or
white: This combination is alfo obtained by digefting the
oxide with free oxalic acid. An excefs of acid does not dif-
folve it, but ammonia readily effedts its folution, giving it a
yellow colour.

A fmall quantity of oxide is depofited by evaporation.
The folution afterwards yields regular cryftals in the form of
peedles, Fare alkalies do not occafion any precipitate.

Wiih

^QQ ACCOUNT OF CERIUM.

With Tartareous Acid,

Tartrite of cc- (L.) Free tartareous acid has no aSion on muriate of
"""*• cerium. The recently precipitated oxide unites with this

acid by digeftion, and yields a tartrite of cerium, which
diflblves readily in water. This fait is alfo precipitated from
faturated folutions by tartrite of potafh. Like the oxi-
late of cerium, it diflblves in pure ammonia, but does not
cryftallize.

Tartrite of cerium is not entirely foluble in water; the folu-
tion is precipitated by carbonate of foda.

With Benzoic Acid,
Bcnzoatc of cc- (M.) This acid does nota6l on the muriate of cerium; but,
rium. by digeftion, well concentrated benzoic acid diflblves the oxide

of cerium recently precipitated. On cooling, the folution firft
depofits cryftals of the acid in excefs, and afterwards ben^
zoate of cerium in the form of a white powder, which adheres
to the cryflals of benzoic acid.

The refinous matter with which this acid is frequently united,
combines with the benzoate of cerium, and forms an infoluble
brown powder.

With Citric Acid.

Citrate and acU C^-) Muriate of cerium is not precipitated by citric acid.

dulous citrate of g^t the oxide digfefted with citric acid forms an infoluble fatu-

cerium. rated combination, which an excefs of acid diflTolves. The

acidulous citrate of cerium is of a yellow colour and does not

cryftallize. Alcohol deprives it of its water, and of part of

its acid, but does not diirolve it.

With' Acetic Acid,

(O.) The calcined oxide of cerium js only very imperfe6tly
difiblved in acetic acid, even with the afliftance of heat; but
that which is recently precipitated by the alkalies, is diflblved
with facility. The faturated acetate of cerium is foluble in
water ; it has a fweet tafte, and gives granulated cryftals, by
evaporation, which do not change in the air, ahd are but
flightly foluble in alcohol.

This fait fwells in the fire, and is deftroyed,

(To be continued.)

SCIENTIFIC

Acetate of ce-
rium.

«CIElfTlFlC NEWS* 30l

SCIENTIFIC NEWS.

Extract of a Letter from Mr, Bode, Jjironomer Royal at Berlin, i

to Mr. A. F. Thoelden. Dated the 23d of October, 1 804. j

T ♦

A HEREWITH tranfmit to you fome of my own obferva- New planet
tions of the new dilcovered third planet, (which is to be called J""^'
JunoJ made at our Obfervatory.

Sept.

21

Mean Time.
- n** 55' 2\'f -

Apparent R A.
359^' 27' 46'''-

DecUn.
3« 38' 23 "South.

25

- U 37

4 -

358 47

16 -

4 32 10

27

- 11 28

0 -

258 27

21 -

4 58 35

28

- 11 23

29 -

358 17

18 .

5 11 35

oa.

10 ■

- 10 28

42 -

356 29

13 -

7 36 56

14

- 10 U

9 -

356 1

14 -

8 18 51

20

- 9 45

22 -

355 29

24 -

9 12 46

I alfo inform you, that an anonymous admirer of aftronomy Aftronomical
of Berlin, has depofited with me the fum of 20 Frederics d'or, P"'^*
for any important difcovery, treatife, or fatisfadory folution of
any difficult problem, of, or relating to, aftronomy, to be fent
to me between this and the end of Auguft, 1805. (The con-
currents are requefted to write their diflertations either in
French, or in German, affixing a motto to each, with a fealed
note containing their name and addrefs}. After the expiration
of the above-mentioned period I am to confult with my aflro-
nomical friends refpedling the merits of the papers fent, and to
adjudge the premium accordingly, on condition, however,
that I may be at liberty to make ufe of fuch papers, addrefled
to me, as I think proper to infert into my aft ronomical journals.

Signed, J. E. BODE.

N, B, Any aftronomical gentleman who intends to become .
a competitor, may fend his paper to me, and I will forward it
to Mr, Bode without any expence.

A. F. THOELDEN.
No, 10, St, Alhan's Street, Pall-Mall,
Nov. 3d, 1804.

Experiments

502 JdlfeNtltlC NEWS*

Experiment on the Heed which is developed during the Comprdjjioii
of the Air *,
Heat by com- A VERY curious experiment has been lately repeated be-
pttflionofair. fere the National Inflitute. If the air be very rapidly com-
prefled in the ball of an air gun, a conliderable quantity of
heat is difengaged from the firft flroke of the pifton, which is
fo great that it is capable of fetting fire to a piece of fungus
match (amadou) placed within the pump. If the body of
the pump be terminated by a moveable end formed of a piece
of (lee! firmly fere wed in, and furniftied in its centre with a
glafs lens, which admits of the infide being feen, at the firft
itroke of the pifton, a ray of vivid brilliant light will be per-
ceived, which is fuddenly difengaged.

This obfervation is owing to accident ; it was made for the
firft lime by a workman in the raanufa6lure of arms of Saint
Etienne, who, on difcharging an air gun in which the air was
ftrongly coraprefled, perceived a very fenfible light at the end
of the barrel.

Exirad of a Letter from Vrofessor Proust to J. C. Dela-

METHERIE f.

AMONG the memoirs which I have had for a long while
to fend to you, you will find one on Berth ollet's work, and on
what he fays of the hydrates, and alfo theanalyfis of a ftone
fallen from the atmofphere, at Sigena, in Arragon, which was
found to be perfedly fimilar to all thofe which have been hi-
therto analyzed.
iJrindy from the I do not know whether I ftiould mention to you a fort of
e«robctrcc. difcovery, which, however trifling it may appear to be, will,
neverthelefs be one day of great importance in Spain, parti-
cularly in the provinces where the carobe tree (carouhier) is
cultivated. It is known that the fruit of this tree is only cul-
tivated along all the coaft of the Mediterranean, to feed cattle.
However, after a fuitable fermentation it yielded me a quar^
tillo (about the bulk of a pound of water) of excellent brandy,

* Bulletin des Sciences, III. p. 209. The latter obfervation of
the flafh from an air-gun has been feveral times obferved before : See
our Vol. IV. p. 280. It Angularly contrafts the former fa£V. N,

^ From Journal de Phylique, &c. Meflidor, An, XII.

Dutch

SCIENTIFIC NEWS. 303

Dutch proof, from five pounds of the dried fruit. This brandy,
although it retains a flight odour of the fruit, is by no means
difagreeableto the tafte, and I have made liqueurs with it in no
refpect inferior to thofe of commerce. I fhall not delay the
pubhcation of the details of this difcovery, from which I claim
no credit except on account of the influence which it may have
on a part of the commerce of the eaftern provinces of Spain,

Method of obtaining pure Cobalt. By Tr o m s d o r f f *•

LET four parts of finely pulverized zafl^re be inlimately PurccoWti
blended with one of very dry nitrate of potafli and half a part
of charcoal powder; introduce this mixture by fma!) quantities
at a time into an ignited crucible, and repeat this procefs for
three fucceflive times, by again adding to the detonated refi-
duary mafs new quantities of nitrate of potafli and charcoal.
This being done, mix the mafs with one part of black flux,
and expofe the mixture to a red heat for one hour. When
cooled, feparate the metallic cobalt, pulverife it, blend it to-
gether with three times its own weight of nitrate of potafli,
and detonate this mixture as directed before. The iron which
was prefent will thus became highly oxidized, and the arfenic
acidified, and combined with the potafli. To feparate the
latter, pulverife the mafs, treat it repeatedly in water, and fe-
parate the infoluble part by the filtre. The arfeniate of potafli
being thus got rid of, digefl the refidue in nitric acid ; the
cobalt will now be diflfolved, and the highly oxidized iron re-
main untouched. Evaporate the folution to drynefs, rediflblve
it in nitric acid, re-filtre the folution, in cafe fome oxide of
iron fliould have efcaped unfeparated, decora pofe the folution
of nitrate of cobalt by potafli, wafli the precipitate, and re-
duce it by heat.

Metliod of coatiitg Copper with Platina, Bj/ Strauss.

Mr, Straufs, who has made a number of good ej^periraents Coating copper
on platina, has fucceeded in applying this metal to defend the^^'^ platma.
face of copper. The folution of platina was precipitated by

» Gehlen's Journal of Chemiftry, Vol. IV, p. 6, 117.

jnuriate

304» SCIENTIFIC NEVfS..

muriate of ammonia, then wz^flied and dded, and expofed to
a graduated red heat for half an hour in a covered crucible.
The produft was a grey coagulated powder; confiftingof me-
tallic platina in a fiate of extreme divifion. One part of this
powder with three parts of mercury did not combine by half
kn hour's trituration ; but upon adding two parts more of mer-
cury and flightly heating the mortar, he foon obtained a tena-
cious amalgam, which was rendered very foft by the addition
of two other parts of thelaft mentioned metal.

A fmall quantity of this amalgam was rubbed upon a plate
of copper, which became perfedly covered. The plate was
then ignited, and was found to have retained a coating of pla-
tina. In the next place he mixed a little of the amalgam with
chalk, fprinkled the mixture with water, coated the plate of
copper a fecond time, and again ignited it. The coating u'as
now found to be very perfe<^, and aflTumed a (hining filver co-
lour under the burnither.

This chemift remarks that his application of platina to cop-
per veffels rauft be fuperior to that of tin; not only in its re-
liilance to acids and faline matters, but in its durability from
the greater hardnefs of platina; and he adds that the procefs
here defcribed, is not more difficult to be eflfeded than th^
common operation of tinning.

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INDEX.

A, A. on ,;i?rofeflbr Parrot's filtering

machine, 40
^Abforption by charcoal, experiments on
the, ^iss

Acetate of cerium, 300

Achard, 37

Acid, Pruffic, its unalterabllity at a high
temperature, 278. — Its combinations
wiih different bafes, 279

Acouftic tubes, tranfoiit found without rc-
fleftion, a86

Affinity, chemical, the caufe of the gal-
vanic aftion, 121

Air, atmofpherical, is not a mechanical
mixture of oxigen and azote, 107.— Is
a gazeous oxide of azote, 109. — Expe-
riments on the abforption of it by char-
coal, 262. — Yields light and heat by
compreflion, 302

— — gun, light and heat produced by the
compreffion of the au: in an, 302

Alcohol does not diflblve ftarch, 74. — Not
fo good a menftruum as fpirit of tur-
pentine for copal varnifhes, 155

Aldini, 175

Alexander commanded his army with a
fpeaking trumpet, 283

Amicus on the fufpenfion of zinc in hidro-
gen, and confequeat ignition and fufion
of platina, 24

Ammonia, its ufe in the preparation of
copal varnilh, 154

Analyfis of a liquor for rendering ftuffs
impermeable to water, 253

' of a triple fulphutet of lead,

antimony and copper, 14

Animah do not hear by the refleaion of
found, 285

Vox.. IX. 1804.

Antis, Mr. J. defcriptjcm of his inftrti*
ment for counting the lifts from a mine>
114

Apparatus for locking wheel carriages, 177
' philofophical advantages of pub-
lifhing improvements in, 225

•— ■ — fimple and cheap for filtering

water, 95
Arfeniates of cerium, 299
Artillery, propofed method of deftroylnj

it, 232
Aftronomical prize, 301
Azote gas, vegetables die in it for want of

their proper ftimulus, 2x9.— >A£lioaof

charcoal on it, 264

B.

Bacon, Lord, 87

Beaupoil, on the virtues and principles of

cantharides, 41
Bees, mechanical operations of, i82.-«

Different kinds of, 186.— Real wantaK

of, 192
Bees-wax, on the latent heat of, 45 — Oa

the origin of, 182.— Its principles are

contained in honey, and in fugar, 191
Benzoate of cerium, 300
Bergman, 27, 30, 49, 67, 291
Berthollet, 80, 247
Bifmuth, on the latent heat of, 45
Black, Dr. 45
Blow-pipe, afting by the preffure of water,

*5i H3
Bode, Profeffor, on a new planet, 14a,

301
Bodies, cold deprefs the temperature by

radiation, 194
Bofwell, Mr. defcrlption of his lamp for

burning tallow, 145. — On the improved

conftrudion of the fhip economy, i66
b Boultoaji

INDEX.

JSoulton, Mr. 414

Bowler, Mr. defcription of his apparatus

for locking wheel-carriages, 177
Brandy from the carobc-tree, 30a
Brafs, expanfionof by heat, 230
Brouffbnel, 142
Bucholz, on pruffic acid and its combina-

nations, 278
Buee, Abbe, on themlneralogical fyftems
of Rome de Tlflc and the -Ahbc Hauy,
a6, 78
Buffon, 27
Bulbs, vegetable, ferifli without bxigcn^

218
Burnenj, 183

Camphor, its ufe in the preparation of

copal varnifli, 155
Cantharides, on the virtues and principles

of, 41
Carbon in vegetables, prize queftion on

the fourccs of, 141
Carbonate of cerium, 297, 299
— of lime, adion of hgat on, 99

Carbonic acid gas, aftion of charcoal on,

463
Carobe-tree, brandy from the, 30a
Caffegrain's fpeaking- trumpet, 283
Cavalb, 19

Cerium, a new metal, defcription and ai^*
alyfis of its ore, 290. — Origin of the
name of, 294
Chalk, threat contrafiion of by heat, 100
Chamoying of leather, memoir on, 251
Chaptal, 108
Charcoal, on its power of abforbing the

gafes, 255
Chemiftry, vegetable negkfted, 68
Chladni, 113
Citrate of cerium, 300
Ci 1-. on the horizontal moon, 235
Clafps, acting on the naves of wheel car- '

riages, 177
Clement, 9*

Clifford, Mr. on mincralogical fyftems,
26

4

Clock, new ftriking part for a, 9^
Clothing, experiments on its cffe£ls on

the paffage of heat, 60, 201
Coal, produftion refembling, blind, 103.

— Is probably of animal as well as vege*

table origin, ib.
Cobalt, method of obta'ming pure, 305
Cold, the contraftion of bodies by, fup^

pofed to prove the want of contaft in

their elementary parts, 247.— Argu-,.

ments againft this opinion, 249
Colours of natural bodies, remarks on,

139

Cnmpenfation pendulum, new, 225
Compounds, mineral, theory of, 98
Compreffion, its effefts in modifying thofe
of heat, 98. — On the air in an air-gun»
30a
Condenfation, is not a proof of the want
of contad in the elementary parts of
bodies, 249
Condenfcr, compound eleftrlcal, 1$
m — of forces, 275

Copal, method of diflblving it in fpirit of

turpentine, 154
— — varniihes, on M. Tingry's errors re*

fpeding, 151 .

Copper, method of communicating the
properties of fteel to, 267.— Method of
coaring it with platina, 303.
Coulomb, 113
Counter, Mr. 5, 124.
Cronftedt, 27, 291
Cryftallography, on the theories of, 27.

—Laws of, 78,
Cubes, on the computations of tables of,

4» "3> '7J

Cumming, 93

Curaudau, application of his pyrotechnic

obfeivations to evaporating furjuccs,

204
Cuthbertfon, Mr. »4, 246
Cuvicr, 142

D'Alerabert, 87

Dalton, Mr. bis obfcrvatipjxs on Mr.
Cough'c

INDEX.

•Cough's ftrJdlures on his theory of
mixed gafes, 89, 113, 126. — Mr.
Cough's reply, 160, 177, 269

"Dauvin, Dr. his hypothcfis of fairy rings, 3

Daval, Mr. 135

Davy, Mr. 104, 170

Deafnefs cured by pundufing the mem-
brana tympani, 149

De Lalande, 142

Delambre, ib>

Delamatherie, 203

D'Eihuyer, 290

De Luc, 96

Denfity of water, maximum of, iia

Defagulicrs, 215

DeSaufTure, 9(J, i6a, 196

Deformes, 92

Dilatation does not alter the contaft of the
elementary parts of bodies, 249

Dormice, prize queftion refpefl:ing the tor-
pidity of, 141

E.

Ear-trumpets do not tranfmit found by re-
flexion, 285

Eggs of hens, on the commerce of, and on
their prefervation, 264

Ekeberg, 237

Elafticity of bodies, experiments on the,

Eleftrical condenfer, new compound, 19

Eleftriclty, obf^rvations on, 175.— Pofi-
tive and negative, probably not diftindl
fluids, iSo.— Frothing of oil by, 221

Elementary particles of bodies, on the con-
taft of, 247

Enamel, red, 268

Englefield, Sir H. C. on the pmrification
of water by filtration, 95

E. O. on the computation of fquares and
cubes, 4, 123, 17X

E. T. on the method of eftimating the va-
lue of fteam-engines in horfe powers,
214

Ether, does not diflblve ftarch, 74
Evaporating far&aces, on the conftruaion
•f, 204

Expanfion doea not require a ceflatlon of

contaft, 249
Extraftive matter of pepper, 71

Fairy rings, obfervations on, 5
Ferments, prize queftion refpefting, 142
Filtering machine. Prof. Parrot's, 40,—

SirH. C. Englefield's, 95
Firft mover, method ©f obtaining the.

greateft poffible effefts from, 275
Flame does not communicate heat to water,
203 . •,

Fluids, obfervations on their power of con-
ducing heat, 207
— — eleftric, one of the conftituent prin-
ciples of water, 120
Fourcroy, 95
Framings, triangular, advantages of. 111

fhips, 168
Fringes of light, experiments on, 63, 130
Fulminating filver, accident with, 203
Furnaces, evaporating, on the conftrudion
of, 204

G.

Gahn, Mr. 294

Galvanic, 175

Galvanifm, its efteds afcribed to chemical
affinity, 121.— Obfervations and ex-
periments to elucidate the powers of,
179. — On the laws of, 240 — Experi-
ments on the decompofition of water by,
243.---Curc of rheuraatifm and palfy
by, 246

Gafes, experiments on the abforptlon of
the, by charcoal, 262

— — mixed, on the conftltution of, 5a,
89, i6o

Gaufs, Dr. iiz

Gibbs, Dr; 180

Geobert, 222

Glue, facilitates the paflTage of heat, 60

Gough, Mr. on fome uncommon effefts
of lightning, i.— Obfervations on fairy
rings, 3. — Reply to Mr. Dalton on the

con-

INDEX.

eonftitutlon of mixed gafea, 52, 160.--
On atmofpheric air, 107, ia6. — On the
neceflity of atmofpheric oxigcn to the
procefs of vegetation, 217, 141

Graham's pendulum) 229

Greenough, Mr. on a blow- pipe a&ingby
the preffurc of water» a5»— His correc-
tion of the account, 143

Gridiron pendulum, difficulty of prevent-
ing flexure in, 228

Grimaldi, 130

Gripe, afting on the naves of wheel-car-
riages, 177

Grubbens, Michael de, on the preparation
of Chinefe foy, 237

Gum, is a generic term, 70

■ Arabic, fubftitutes for, 232

H.

Hall, Sir James, his experiments on the
tfft&s of heat modified by compreffion,
98

Halley, 212

Harding, Mr. his difcovcry of a new mov-
ing ftar, 112, 142

Hanifon, F. Efq. on the laws of galva-
nifm, 240

HalTe, 283

Haffenfratz, on the caufes which incrcafe
the intenfity of the found In fpeaking-
trumpets, 283

Hatchett, C. Efq. his analyfis of a triple
fulpburet of lead, antimony, and cop-
per, i4.—0n a method of preparing
malleable platina, 65

Hauy, Abbe, obfervations on his theory
of cryftallography, 27, 79

Hearing is not the confequence of the re-
fleftion of found, 285

Heat, enquiry into the nature of, and the
modes of communication, 58, 193.—
Experiments on its efFefts when modi-
fied by compreffion, 98. — Analogy with
light, 202.-~Obfervations on the pro-
pagation of, in fluids, 207.— -Increafes
the dimeniions of bodies^ Z47.-*>Aug-

ments the abforbent power of charcoal*
260— Developed during the compreffion
of air, 302.

Heat, invifible rays of, experiments on the
140 ,

— latent, of different fubftanccs, ex-
periments on, 45

— -— radiant, Inftruments for meafuring,
62

Henry, Mr. his reply to Mr. Cough on
mixed gafes, 126

Hens, on the commerce of their eggs, 264.
— Modes of management of, 265

Herfchell, Dr. 141

Hewfon, Mr. 139

H. G. on the computation of fquares and
cubes, 123, 171

Hidrogen gas, fufpenfion of zinc in, 24.
•— A£lio» of charcoal on, 263

Hjelm, 294

Honey is converted into wax by the bees,
184.— The principles of wax refide in
the faccharine part of, 191

Horizontal moon, on the enlarged appear-
ance of the, 164

Horn, total volatilization of, 104

Horfe-powers, method of eftimating the
value of fteam engines in, 214

Huber, on the origin of wax, 182

Hutton, Dr. 3, 98

I.

Ice, on the latent heat of, 51. — ^Deprefles
the temperature by radiation, 195. — Cy-
lindrical part of water in a mafs of, 207.

Jeffi)p, W. Efq. on an improvement In the
procefs of blading rocks with gunpow-
der, 230

Images, optical, do not vary with the pu-
Pil^ ^35

Ingenhouz, M. 217

Inftrument, compound eleftrical, 19

— — — for counting the lifts from a
mine, 114

"- ■■' for delineating ovals, 123

■"' ■ for drawing in perfpeilive from

nature^ 122

Inftrument

INDEX,

Inftrument for meafuring theabforptlon of
gafes, ZSS

..» — for meafuring radiant heat, 6z

J. P. on the coft of making phofphorus, 94

Iron, method of preparing prulfiate of
potafli from, 280

Irvine, Mr. W. on the latent heat of dif-
ferent fubftances, 45

Junker, 155

Juno, a new planet, 301

Jurine, Mr» 150

K.

Keir, Mr. 103

Kennedy, Dr. 99

Kercher, 183

Kirwan, 27, 47, 57, 107, 162, 270

Klaproth, 37

L.

La Grave, 175

Lambert, 284

Lamp for burning tallow, defcription of a,

145

Landriani, 45

Langwith, Dr. 135

Launoy, 37

Lavoifier, 24, 107, 11 1. — An aflertion

of his controverted, 247, 270
Lead, on the latent heat of, 45
Leather, memoir on the chamoying of,

251
Lefage, 249
Leflie, Mr. 154

Lifts, from a mine, defcription and draw-
ing of an inftrument for counting them,

114

Light, experimental demonftiation of the
general law of the interference of, 63.
— Comparifon of the meafures of the
fringes of, 131. — Argumentative in-
ference refpcdting the nature of, 137.
•—Strongly refembles found, 138.— An-
alogy with heat, 202.— Increafes the
abforbent power of charcoal, 260. — Is
produced by the coropreifion of air> 30Z

Lightning, on fome uncommon effefts of, i
Lily, mucilaginous powder from the roots

of the white, 233
Linborn, M. 237, 290
Linen, facilitates the paflage of heat, 60
Liquor for rendering ftufts waterrproof,

analyfis of, 252
L'llle, R*me de, on his theory of cryftal-

lography, 27, 78
Llandaff, bifhop of, 54
Lloyd, Mr. 148

M,

Machines, filtering, Prof. Parrot's, 40»<-«

Sir H. C. Englcfield's, 95
Magnefia, native, 222
Magnitude of objefts, caufe of the appa«

rent variation in, 165
Malton, J. Efq. defcription of his method

of making large port folios, 128
Marcet, Dr. on a cafe of deafnefs cured by

punfturing the membrana tympani, 149
March, Mr. 145
Margraff, 267
Maunoire, Mr. on a cafe of deafnefs cured

by puncturing the membrana tympani,

149
Melograni, Abbe, defcription of his blow-
pipe, 25, 143
Membrana tympani, deafnefs cured by

puncturing the, 149
Mendoza, Capt. 5
Metal, a new, defcription and analyfis of

the ore of, 290
Metallic furfaces, all radiate equally, 194
Mineralogical fyftems of Rome de I'lfle and ,

Abbe Hauy. outlines of the, 26, 78
Molybdale of cerium, 299
Moon, horizontal, its enlarged appearance

accounted for, 164.— Examination of

the theory, 235
Morland's fpeaking-trumpet, 283
Morozzo, C. L, on the abforption of the

gafes by charcoal, 255
Moufiin Poufhkin, Count de, his method

of preparing malleable platina, 65

Mucila-

INDEX.

Mucilaginous vegetable powders fropofcd is

fubftitutes for gum Arabic, 232
Muriate of cerium, 298
^~-m. I triple, of platina, 67

N.

Neumati) 154

Newman, Mr. 129

Newton, Sir I. 31, 53, 88, 128, 131, 139

Nitrate of cerium, 297

Nomcnclatuie of vegetables, defeftlve, 62

Oil, probably reflefts frigorlfic rays, 190

— — Frothing of by eleftricity, 221

•"——of pepper, 71

Olbcrs, Dr. 143

Optics, phyfical, experiments and obfer-

vations relative to, 63, 130
Ovals, fimple and cheap inftrument for

delineating, 113
Oxalate of cerium, 299
Oxide of cerium, chemical examination

of, 293
Oxigen, on the neceffity of atmofpherical

to the procefs of vegetation, 217

P.

Paint facilitates the pafTage of heat, 61
Pallas, prize queftion refpedling the planet,

141
Palfy, cure of by galvanifm, 246
Pappus, 162
Parallel rule, defcription and drawing of a

new, 213
parkinfon's organic remains, 143
Parmentier, on the commerce of Jien's eggs

and on their prefervation, 264
Parrot, Prof, defcription of his filtering

machine, 40
Pelletier, 267 ,
Pendulum, defolptlon of a tubular one,

fuperior to the gridiron, 225
Pepper, chemical examination of, 68
Perpetual motion, new projed for a, 212

Perfpe^live, inftrument for drawing from
nature, in, 121

Philips, Mr. R. 18

Phofphate of cerium, 298

Phofphorated copper, 267

Phofphorus, on the coft of making, 94.
— Readieft method of uniting it with
copper, 267

Plana, 257

Piazzi, 142, 274

Piftct, 194, 207

Piles, galvanic, power of different ones In-
burning wire, 241

Planet, a new one, 301

Platina, ignition and fufion of in hidrogen
gas, 24. — Method of preparing malle-
able, 68.' — Triple muriates of, 67.—'
Method of coating copper with, 303

Play fair, Mr. 104

Pollen of flowers, examination of the, 183.
—Is not neceflary to the production of
bees' wax, 184.-11. the food of the lar-
vae of the bees, 188

Port-folios, cheap and fimplc contrivance
for making large, 128

Prevofl, ProfeflTor, on an aflertion of La--
voifjer, 247

Prieftley, Dr. 4, 55, no, 180, 217, 270

Principles, elementary of bodies, on the
contaft of, 247

vegetable, complicated nature

of, 69

Prior, Mr. account of his new ftriking
part for a clock, 92

Prize, aftronomical, 301

Prony, 142.— On a condenfer of forces,

275

Prouft on the preparation of brandy from
the carobe tree, 302

Prufllate of potaih, beft method of obtain-
ing it free from iron, 280

Pruffic acid. Its unalterability by heat, 278

Pyrotechnic obfervations, applied to the
conftruftion of evaporating furnaces, 204

Q.

Quellions, prize, 141

INDEX.

Haaktion of heat, inftrument for meafur-

ing the eftefts of the, 62.— Is increafed

by bodies which facilitate the paffage of

heat, 194

Rainbow, fupernumerary, caufed by the

interference of light, 1 35
Raflileigh, P. Efq. 14
Raymond, 142
Rays, calorific and frlgorific may be the

fame, 197
— — dark folar, experiments on, 140
R. B. dcfcription and drawing of his in-
ftrument for drawing in perfpeftive, laa.
—Another for delineating ovals, 123.—
Projeft for a perpetual motion, 211, —
Defcription and drawing of his new pa-
rallel rule, 213
Reaumur, 182
Red enamel, 268

Rheumatifm, cure of by galvanlfm, 246
Richter, Mr. 180
Ritter, 140

Rocks, improved procefs for Hafting, 230
Roy, Gen. 112, 230
Rule, parallel, defcription and drawing of

a new, 213
Rumford, Count, on the nature and mode
of communicating heat, 58, 193, 102,
142.— Account of a curious phenome-
non obferved on the Glaciers of Cha-
BQOuny, 207

S.

Sage, B. G. on a method of giving the
colour, grain, and hardnefs of fteel to
copper, 267

Salop, mucilaginous powder from the root
of, 234

Salts, triple of platina, 67

Sand, its ufe in blading rocks with gun-
powder, 231

Sauffure, la, 57

Scheele, 290

Sealing-wax, cxperimentt on its power of
abforbing air; 26s

Seeds, perifh when deprived of oxigen,

Seguin, M. on chamoyinjf leather, 251

Sennebicr, 196

Seymour, Lord Webb, 104

Sheldrake, Mr. T. on Tingry's errors re-

fpedting copal varnifhes, 151
Ships, on an improved method of con-

ftrufting, 166
Silex and carbonate of lime, combination

of, lOI
Silver, the true melting point of, 99 (note)
■ ■■■■■, fulminating, accident with, 203
Smeaton, Mr. 215. — His pendulum, 229,

230
Smith, Dr. 162

Smoke from a candle facilitates thepaflfage
of heat, 61, — Prevents water from boil-
ing, 202
Soda and platina, method of preparing a

muriate of, 67
Solard, 283

Sound, ftrong refemblance of it to llght„
138.— On the caufes of the augmenta-
tion of its intenfity in fpeaking trum-
pets, 283.— Is notdiminiihed by an In-
ternal covering of wool, 288.— Nor does
its Intenfity arife from refledlion, 289
Soy, Chinefe, method of preparing, 237
Speaking trumpets, on the caufes of the
augmentation of the intenfity of found
in, 283."— -Hiftory of the Invention ot,
ib.— Proportions of a conical, aS4,—
Augmentation of found in thofe with
cylindrical tubes, 287. — It is not owing
to the refiedion of the fonorous rays,
289
Spermaceti, on the latent heat of, 45
Squares, on the computation of tables of>

4, 123, 171
Squills, vernal, mucilaginous powder from,

232
Star, difcovery of a new moving, iix
Starch, Is a generic term, 70.— Noteafily
decompofed, 74.— Experiment on its
union with tan, 75.— Chemical exami-
nation of, 76
— — ' of pepper, 77

Steam,

INDEX.

Steam, latent heat of, J^t

»- I.. .^ .. engines* method of eftimatlng
their value in horfe powers, 214

Steel, cxpanfion of by heat, 230. — Method
of communicating its properties to cop-
per, 267

Straufs on a method of coating copper with
platina, 303

Stream of water, ftrudlure for purifying
a, 96

Striking part for a clock, new, 92

Sturm, 283

Sugar, is a generic term, 70.— Contains
the principles of bees' wax, 191.— Ex-
periments on its power of abforbing »t-
mofpheric air, 261

Sulphates of cerium, 295, 296

Sulphur, on the latent heat of, 45.— Ex-
periments on its power of abforbing at-
mofpherlc air, 261

Sulphuret, triple of lead, antimony and
copper, analyds of, 14

Swammardam, 182

Sylvefter, Mr. on the operation of the gal-
vanic power, 179

T.

Tables of fquarei and cubes, computation

•f, 4, 123
Tallow, defcription and drawing of a lamp

for burning, 145
Tan, experiment on its union with ftarch,

75

Tartrite of cerium* 300

Temperature is deprefled by the radiation

of cold bodies, 194
Teflier, 142

Thickncfie, Ra. Efq. on galvanifm, 120
Theolden, M. on a new planet, 301
Thomfon, Dr. 17. — On pepper, 68, 211
Thouvenal, 42

Tin, on the latent heat of, 45
Tingry, M. on his errors refpefting copal

varniflies, 151
Torpidity of animals iti winter, prize qu^f-

tion refpefting, 141

Tromfdorff, on obtaining pure cobalt, 303

Troughton, Mr. E, defcription and draw-
ing of his tubular pendulum, 225.— His
mercurial pendulum perfedlj but not
portable, 229

Tungftein, new metal found In a fuppofed
ore off 290

Turpentine, procefs for diflblvlng copal la
fpirit of, 154.— 19 a better menftruum
than alcohol, 155

Van Mens, 22 i

Vapour, aqueous, its aftion dn Water, jii

Varnifh, copal, letter from Mr. T. Shel-
drake on, 151. — Safe and eafy method
of making, 157

fpirit facilitates the paflage of

heat, 61

Vauquelin, 37.— -His analyfis of a liquor
employed to render fluff's Impermeable
to water,, 252

Veau de Launay, on an accident with ful-
minating fiiver, 203

Vegetables, loofe nomentlature of, 69.—
Prize queftion refpefting the fources of
carbon in, 141. — Die In azote for want
of their proper ftimulus, 219.— On the
mucilaginous powders obtained from
fome, as fubftitutes for gum Arabic, 232

Vegetation, on the neceflity of atmofphe-
rlcal oxigen in the procefs of, 217

Vibration injures the artlculateuefs of
found, 284

W.

Walker, Mr. E. on the apparent fize of
the horizontal moon, 164.— Examina-
tion of his theory, 235

Water, Prof. Parrot's machine for filtering,
40. — Its aftion on pepper, 70.— Is not
a folvent of ftarch, 74. — A£tion of
aqueous vapour on, 90.— On the puri-
fication of, by filtration, 95. — Maxi-
mum of its denfity, 112. — Compofition
of, I20.'—Enquiry into the aftion of
galvanifoi

INDEX.

galvanifm on, 179. — Cannot be made to
boil in a fpoon blackened with the fmoke,
ao2. — Is not heated in the flame of a
candle, 203.— A cylindrical pit of, in a
mafs of ice, 207. — Experiments on its
decompofition by different galvanic ar-
rangements, 243,— ^ompofition of a
liquor for rendering fluffs impermeable
to, 25a

Watt, Mr. 45,48, 215

Weather, moft favourable for the labour
of bees, 187

Wedgewood, Mr. 99

Werner, 30

Wheel kept in perpetual motion by a ma-
rine barometer, 212

Wheel carriages, defcription of an appara-
tus for locking, 177

Wilkinfon, C. Efq. on galvanifm and elec-
tricity, 175.— On the laws of galva-
nifm, 240

Willis, Mr. T. on the mucilaginous matter
of certain vegetables and their ufe as a
fubflitute for gum Arabic, 232

Wilfon, Rev. J. on fome uncommon cf-

fefts of lightning, i
Mr. W. defcription and drawing

of his compound eledtrical condenfer and

doublcr, 19
Winter fleep of animals, prize queflion re-

fpe£ting, 141
W. N. on fairy rings, 4. — On the power

of a firil mover, 278 (note).
Wollafton, Dr. 139, 140, 176

Young, Dr. his experiments and calcula-
tions relative to phyfical optics, 63, 130.
^-On a new moving flar, 112.— On the
maximum of denfity in water, ib.— Oa
the elafticity of bodies, 113. — Remarks
on the colours of natural bodies, 139

Z.

Zinc, fufpenfion of in hidrogcn, 24.-
On the latent heat of, 45.

END OF THE NINTH VOLUME.

ERRATUM.
In Plate XII. Fig, 3, by an omiflion in the defign, the lower ruler has not the fame
connexion with the frame as the upper. It mufl be joined by prolonging the rod from
the left hand angle, and adding a rod from thence to the bar upon the ruler j as is feen
above.

Printed by W. Stratford, Crown-Court,^ Temple-Bar.

1

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