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THE
LONDON, EDINBURGH, ann DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
CONDUCTED BY
SIR DAVID BREWSTER, K.H. LL.D. F.R.S.L.&E. &c.
RICHARD TAYLOR, F.L.S. G.S. Astr.S, Nat.H.Mosc. &c.
SIR ROBERT KANE, M.D. M.R.I.A.
WILLIAM FRANCIS, Pu.D. F.L.S. F.R.AS. F.C.S.
“Nec aranearum sane textus ideo melior quia ex se fila gignunt, nec noster
vilior quia ex alienis libamus ut apes.” Just. Lres. Polit. lib. i. cap. 1. Not.
VOL. IV.— FOURTH SERIES.
JULY—DECEMBER, 1852.
LONDON.
TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET.
Printers and Publishers to the University of London ;
SOLD BY LONGMAN, BROWN, GREEN, AND LONGMANS; SIMPKIN, MARSHALL
AND CO.}; S. HIGHLEY; WHITTAKER AND CO.; AND SHERWOOD,
GILBERT, AND PIPER, LONDON : — BY ADAM AND CHARLES
BLACK, AND THOMAS CLARK, EDINBURGH} SMITH AND SON,
GLASGOW ; HODGES AND SMITH, DUBLIN; AND
WILEY AND PUTNAM, NEW YORK,
““Meditationis est perscrutari occulta; contemplationis est admirari
perspicua..... Admiratio generat questionem, quzestio investigationem,
investigatio inventionem.”—Hugo de S. Victore.
—‘ Cur spirent venti, cur terra dehiscat,
Cur mare turgescat, pelago cur tantus amaror,
Cur caput obscura Phoebus ferrugine condat,
Quid toties diros cogat flagrare cometas ;
Quid pariat nubes, veniant cur fulmina ccelo,
Quo micet igne Iris, superos quis conciat orbes
Tam yario motu.”
J. B. Pinelli ad Mazonium.
CONTENTS OF VOL. IV.
(FOURTH SERIES.)
NUMBER XXII.—JULY 1852.
Prof. Powell’s Remarks on Lord Brougham’s “ Experiments
and Observations on the Properties of Light,” &c. inserted
in the Phil: Trans. 1850, Part I. .........0---- 22-2200:
Prof. Thomson on the Dynamical Theory of Heat, with nume-
rical results deduced from Mr. Joule’s equivalent of a Thermal
unit, and M. Regnault’s Observations on Steam........-.
Mr. W. Crowder on the Fatty Acid of Cocculus indicus .....-
Mr. T. T. Wilkinson’s Additions to the late Mr. T. S. Davies’s
Notes on Geometry and Geometers. The Swale Manu-
RR teehee ap ste gs sas nee Sp heecteu et setseis feta eee a:
Mr. M. Donovan on the supposed Identity of the Agent con-
cerned in the Phenomena of ordinary Electricity, Voltaic
Electricity, Electro- magnetism, Magneto-electricity, and
Thermo-electricity (continued) .......+.- eh Ae RAe Seer
Mr. T. H. Henry on the Composition of Wootz, or Indian Steel.
Mr. J. Napier on Copper Smelting ..........-.---0-+-+ es
Captain Lefroy’s Second Report on Observations of the Aurora
Borealis, 1850-51, made by the Non-commissioned Officers
of the Royal Artillery, at the various Guard-rooms in Canada.
Notices respecting New Books:—Captain W. H. Smyth on
JEdes Hartwellianz, or Notices of the Manor and Mansion of
PRD CU cks or 2,0 reyatedeicl ae .8\ o's cay Ser ele aitva\asea''« hs Pe eyo ee ehors, ole
On the Composition of Human Fat, by Dr. Heintz.........-
New arrangement of the Voltaic Pile, by M. Fabre de Lagrange.
On the preparation of Pure Silver from Chloride of Silver,
SRAM MESIUMME? itis es)e\s Yolo gcuee ait Win. peels se joie e aesieye
The Bomerang, by J. E. Gray, F.R.S. 1.2.2... 20 0e-e meters
Meteorological Observations for May 1852........+...+++--
Meteorological Observations made by Mr. Thompson at the
Garden of the Horticultural Society at Chiswick, near
London; by Mr. Veall at Boston; and by the Rev. C.
Clouston at Sandwick Manse, Orkney.....+..--02.+ 000.
NUMBER XXIII.—AUGUST.
Dr. Barry’s Renewed Inquiries concerning the Spiral Structure
of Muscle, with Observations on the Muscularity of Cilia.
CWith- Two. Plates.) .«.iojecoje'00.0,0 o0.0.e0e.ap.0,0 0.0/0,6,0.0.4 winlejeie
Page
80
§1
iv CONTENTS OF VOL. IV.—FOURTH SERIES.
Mr. J. D. Perrins on the Occurrence of Berberine in the Co-
lumba Wood of Ceylon, the Menispermum fenestratum of
BSOIADISES Oh Fy Sets ors hw hodate, cin ste b\aie tens Metetefede pe cheer ena ae eman
Prof. Chapman on Artesian Wells near Silsoe in Bedfordshire.
Prof. Thomson on the Dynamical ‘Theory of Heat, with nume-
rical results deduced from Mr. Joule’s equivalent of a Thermal
Unit, and M. Regnault’s Observations on Steam (continued).
Prof. Rammelsberg on the Chemical Constitution of Childrenite.
The Rev. J. Bashforth’s Remarks on Mr. Dresser’s Experiments
on the Conducting Powers of Wires for Voltaic Electricity,
and on Mr. Joule’s Experiments with a powerful Electro-
TAR EMCE 5 0 i alas sats + wees sree eer nee piel calle toh Bla
Mr. J. Napier on Copper Smelting.—Calcination of the Ores
(continued) 0... 1. ce evens cee e cc eens ce eeeteeesen cece
Proceedings of the Royal Society......-...--++ sees eeeees
New Method of precipitating Oxide of Tin and separating it
from other bodies, and of combining it with Silk, Woollen
and Cotton Fabrics, by J. Lowenthal .............++---
Remark on Art. LVIII. (of Phil. Mag. for November) by Mr.
Sylvester, “‘ that the Non-existence of real Roots in Analytic
Geometry corresponds to the reductio ad abswrdum of Euclid,”
by S. M. Drach........-. sha cistesh Be ok bint ainieinke oe
Meteorological Observations for October 1852 ......++--+-
ee Table e616 2.6 2 pwieie 218 @eeveveee eerer eoevreeeeeee
NUMBER XXVIII.—SUPPLEMENT TO VOL. IV.
Mr. J. P. Joule and Prof. Thomson on the Thermal Effects
experienced by Air in rushing through small Apertures... ..
Mr. J. Cockle on the Method of Symmetric Products........
Dr. Andrews’s Note on the Heat of Chemical Combination ..
Mr. W. R. Grove on the Electro-chemical Polarity of Gases.
(With a Plate.) .....--.ceeerseecerc revere si aiecabavarsiersts
Additional Note on the dark discharge, July 9, 1852 ..
Mr. A. Cayley’s Demonstration of a Theorem relating to the
Products of Sums of Squares .....0..0+.05: aiataiots auakglits
vil
Page
398
399
400
401
vill CONTENTS OF VOL. IV.—FOURTH SERIES.
Page
M. H. Helmholtz on the Theory of Compound Colours...... 519
Mr. J. Newman’s Description of a new Evaporating Gauge .. 534
Notices respecting New Books :—Mr. J. Farren’s Life Contin-
gency Tables.—Part I.; Mr. W. D. Snooke’s Brief Astrono-
mical Tables for the Expeditious Calculation of Eclipses in
GU) AMES oS s 9sti0s cpa o's lee hints cle Ei Se ie eat 535-538
On a remarkable Deposit of Tin-ore at the Providence Mines
near St. Ives, Cornwall, by W. J. Henwood, F.R.S., F.G.S. 538
On the Nature and Name of Ozone, by C. F. Schénbein .... 542
On the Quantitative Determination of Ozone, byC.F. Schénbein. 545
On the Motion of Fluids from the Positive to the Negative Pole
of the closed Galvanic Circuit, by M. Wiedemann........ 546
Fd em aici nyse aie otes shay's a taarergiened ace Darke eal ne ee 548
ERRATUM.
Page 359, line 7, for unchangeably read unchangeable, and insert a comma.
PLATES.
I, and Il. Illustrative of Dr. Barry’s Paper on the Spiral Structure of
Muscle.
III. Illustrative of Dr. Andrews’s Paper on a new Aspirator.
IV. Illustrative of Dr. Tyndall’s Paper on the Reduction of Temperature
by Electricity.
{at atueeeare of Mr, Grove’s Paper on the Electro-chemical Polarity of
ases,
THE
LONDON, EDINBURGH anv DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
[FOURTH SERIES.]
JULY 1852.
I. Remarks on Lord Brougham’s “ Experiments and Obser-
vations on the Properties of Light,” &c. inserted in the Phil.
Trans. 1850, Part I. By the Rev. Baven Powetr, M.A.,
F.R.S, &c., Savilian Professor of Geometry, Oxford*.
cs Pace publication of Lord Brougham’s optical researches, in
which a number of experimental facts connected with the
phzenomena now usually called “ diffraction,” are viewed accord-
ing to a peculiar theory of certain new properties of light, and in
some respects held to be irreconcileable with the principle of in-
terference, seems to render desirable some examination into the
actual bearing of the results on the theory of undulations, by
which not only all the pheenomena of diffraction, hitherto known,
have been so perfectly explained, but which has also been applied
so extensively to other large classes of facts, as to render it unphi-
losophical to resort to theories assumed on independent grounds
to meet apparent exceptions in limited classes of phenomena.
These researches having been briefly alluded to by the Astro-
nomer Royal in his opening address to the British Association
at Ipswich}, and having also myself made a few observations on
the subject at the same meeting}, my object in the present com-
munication is to follow up the question in somewhat more detail ;
and without pretending to enter on any controversy as to the
author’s theory, to examine merely the eaperimental evidence ad-
duced, and inquire how far it seems accordant or not with the
undulatory theory.
During the summer of last year I took the opportunity of
* Communicated by the Author. + See Athenseum, No, 1236.
t See Ibid. No. 1237,
Phil. Mag. 8. 4. Vol, 4. No. 22, July 1852. B
2 Prof. Powell’s Remarks on Lord Brougham’s
repeating the experiments with the utmost care, for all the most
material cases considered; since which time various causes have
delayed the publication of my results.
The whole of the author’s investigations are expressed with
reference to his peculiar hypothesis of certain forces of “ de-
flexion ” and “inflexion”’ supposed to be exerted upon the rays
of light by the action of the edge of an opake body near which
they pass: nor is it always an easy matter to disentangle the
actual facts from the language of this theory, so as to see to
what the experimental evidence really amounts.
Of those of the author’s propositions which refer solely to the
exposition of his theoretical views, I do not propose to enter on
any discussion. There are also other portions of the investiga-
tions, which, though of a more experimental character, will not
call for much observation, as they either tend to establish phe-
nomena in exact conformity with well-known results, or are of a
nature not having much bearing on theory either way.
Of this class are the preliminary experiments (Prop. I. Exp. 1,
2, 8); though with respect to the last it ought to be remarked,
that Newton by no means limits the number of fringes to three,
and in one modification of the experiment expressly mentions
that four or five were rendered visible*. When (as in Exp. 4)
the origin of light is not the single point absolutely requisite in
all accurate investigations, but an extended object, such asa flame,
the moon, &ec., it may be questioned how far the fringes may be
properly termed images of it. In Prop. II. Exp. 2, that the nature
or form of the edge makes no difference in the result, accords
exactly with the long-known experiments of Biot, Haldat, and
others. Indeed, as is equally well understood, the frmges may
be produced without any opake edge at all, as at the junction of
two faces cut on a glass, slightly inclined to each other. Again,
the hyperbolic fringes of an acute angle (in Prop. V. Exp. 3), as
well as the measures of the fringes at successive distances from
the edge determining the locus of any given fringe (in Prop. X.,
and additional remarks, (2) p. 252), appear to agree with previous
observations ; though, according to the author’s theory, each
fringe seems to be regarded as an individual ray, while in the
interference theory it is the locus of the intersections of a series
of rays.
At another part of his discussion the author assumes (Prop. XI.)
an aggressive position, and endeavours to refute the application
of the interference theory. In reply I think it will suffice to
remark, under the several heads,—-(1) the theory of interference
explains perfectly both the internal and external fringes of a
shadow ; (2) the breadth of the fringes has no dependence on
* See Opticks, book 3, part 2. obs. 2.
«< Experiments and Observations on the Properties of Light.” 3
the denyth of route of the rays, but it has on the angle at which
they intersect ; so that (3) in the case represented in the author’s
fig. (20), supposing abstractedly two pairs of interfering rays
(such as BC, AC, and BD, AD), it is evident that the fringes at
D ought to be broader than those at C, not owing to any differ-
ence in the routes, but because the angle BDA is less than BCA ;
while (4) interference perfectly explains fringes, even when the
action is wholly on one side of the ray or edge.
But passing from these points of confessedly less importance,
we will proceed to the most material and fundamental experiment
(Prop. 11. Exp. 1), in which, when fringes are formed by the edge
of an opake bedy, if a second edge be placed at a greater distance
along the ray from the origin on the same side as the first edge,
it produces no change in the fringes, but on the opposite side it
does, the fringes being shifted in position towards the first side ;
or in other words, in the one case it has no power of producing
further diffraction, in the other it has: and this is viewed by
the author as supporting his theory of a peculiar action exerted
by the edge upon the ray passing near it, by which it is disposed
or indisposed for further flexure according to the conditions above
expressed.
The experimental fact in general is easily verified. There is,
however, one material condition necessary to be attended to for
reproducing the result exactly as described by the author.
When two edges are at the same distance from the origin and
from a narrow aperture, they give, as is well known, fringes on
each side extending into the shadow, with a white centre (fig. 1).
As one edge is removed successively further from the origin and
nearer to the screen, the fringes on that side dilate (fig. 2),
Fig. 1. Fig. 2. Fig. 3.
rm
mili LL hs
become faint, and at length disappear (fig, 8) ; so that beyond a
B2
4 Prof. Powell’s Remarks on Lord Brougham’s
certain distance there remain only the fringes on the other side,
or on that of the edge nearest the origin, which diverge further
into the shadow on that side as the breadth of the effective aper-
ture is diminished.
In this way, then, the second edge, if beyond the limits of
distance mentioned, will cause an appearance of fringes on the
side towards the first edge diverging into the shadow.
With regard to the bearing of this experiment on theory, it is
in the first instance necessary to bear in mind, that, according to
the undulatory theory, neither the formation of fringes, nor any
shifting of those fringes, implies a FLEXURE in the rays; in this
theory no such idea is introduced or needed.
In the particular case in question, when the two edges are at
the same distance from the origin forming a narrow aperture,
the nature of the fringes is perfectly explained and reduced to
quantitative results by Fresnel’s theory.
When the second edge is placed as in Lord Brougham’s ex-
periments, at a greater distance along the ray, this would be
equivalent to a wide aperture placed obliquely to the direction
of the ray, so as to be effectively as narrow as before. Now this
case is one which has not yet been reduced to calculation.
The formulas of Fresnel, even in the simplest cases, are con-
siderably complicated, and involve integrations which cannot be
generally exhibited in a finite form. In the cases of a single
edge, or that of an aperture when it is a long narrow parallelo-
gram, an equilateral triangle, or a circle, the integration has
been performed in a way sufficient for calculation*.
In the case of the oblique aperture, at my request, a friend
eminently versed in the analysis of the subject, undertook to
work out the formulas; and he pursued the inquiry far enough
to be able to say that they became immensely complicated ; still
it could not be certain that they might not be made to yield to
proper treatment, should anyone think it worth while to follow
up the attempt.
But further, this particular case has been considered, though
only in a general way, by Fresnel+. Upon the obvious geome-
trical construction he poimts out the general conditions for de-
termining the position of a fringe, and shows that the fringes
will in this case undergo a modification, and will not be symme-
trical, but more expanded on one side than the other, which
exactly agrees with observation.
* See Airy’s Tracts, Undulatory Theory, art. 73 et seg. Journal of
Science and Phil. Mag. vol. xv. Dec. 1839; and vol. xviii. Jan. 1841.
+ Mém. sur la Diffraction, Mém. de V Institut, vol. y. note, p. 452, for
1821, published in 1826.
«“ Experiments and Observations on the Properties of Light.” 5
The simple facts affirmed in Prop. II. Exp. 1 and 2, when di-
vested of all theoretical language, His.’
appear to be, that if three edges, rH
E, F, G, be placed at successive di-
stances from the origin in the order
of the letters, E and G being on
one side of the ray and F on the
other; then if E and F alone give
fringes as at o (fig. 4), and G be
then made to act upon them, or if
F and G alone give fringes and E
be made to act upon them, in either
case the fringes will be shifted to p
towards the side on which EK and G
lie, and become broader; and the
conclusion which the author chiefly
insists upon is that all three edges
act in producing the ultimate result :
the same thing being further con-
firmed by exp. 3, in which a curved
form given to the edge H, is still ex- Pea ne P
hibited in the form of the fringes after the action of F and G.
That all three edges should be in some degree effective in pro-
ducing the ultimate character of the fringes, would, on a general
View, be obviously consistent with the wave theory; since, on
that theory, a new set of waves originates at cach edge, all of
which conspire to produce the ultimate result ; though antecedent
to exact calculation, it would be impossible to say what would be
the precise action of each.
On repeating the experiment, however, in regard to the parti-
cular appearances described by the author, I have found consider-
able difficulty : consistently with the conditions before remarked,
if the edges E and F forma narrow aperture so as to give a white
centre, and within such limits of distance along the ray as to
produce fringes on each side (as in fig. 2), then if G be also
within the same limits, and be advanced so near to the ray late-
vally as to make a still narrower aperture, the friges on each side
will expand further into the shadow. If the edges be beyond
those limits (which seems to be implied in the author’s description,
since he speaks of only one set of fringes), then B and F will give
a white centre with fringes on the side towards K, as at 0; and
when G is introduced it will narrow the aperture and give new
fringes on the side towards F, at p', that is, just the opposite way
to that which the author describes. In repeating the experiment
a great number of times at very different distances, and under
varied conditions, I have never been able to obtain any other re-
6 Prof. Powell’s Remarks on Lord Brougham’s
sult: indeed it would clearly be inconsistent with the former
experiments that it should be otherwise. '
Prop. VI. appears precisely to express Fresnel’s conclusion
(above referred to), that with two edges at unequal distances from
the origin, the fringes will be broader on the side towards the
edge most remote from the origin, which is again more precisely
exhibited in Prop. VIII., when the aperture is sufficiently narrow
to give a white centred image ; the same regard being had to the
limits in distance as before.
In Prop. VII. the meaning is by no means obvious ; but it seems
to amount experimentally to this,—that with one edge only, the
fringe nearest that edge is the broadest ; and that when a second
edge acts opposite to it at some distance along the ray, but so as
to give the fringes of an aperture, then among the fringes of each
set, those towards the middle of the aperture are the broadest :
the first being obviously the case of the external fringes; the
second easily verified, and agreeing with the ordinary case of an
aperture with edges at the same distance ; while as to the appli-
cation of the undulatory theory, we can only make the same re-
marks as before.
In the Additional Observations, (3), p. 254, the truth of the
general assertion, that when fringes are formed by two edges, a
third can affect them only when parallel and not when at right
angles to them, is indeed obvious ; but the precise conditions of the
experiment mentioned are difficult to understand. It would seemn
to consist in first forming the fringes of a narrow aperture with
a broad white centre in the ordinary way ; and then in that white
centre producing new fringes by a third edge nearer to the screen :
these, however, the author affirms, will be formed only when the
third edge is parallel to the aperture and not when at right angles
to it; they are also described as brighter and narrower than the
ordinary fringes. The author cautions us against confounding
them with the ordinary external fringes, and proceeds to argue
that they are of a different nature, for several reasons, but
chiefly because (Exp. 1) they do not increase in breadth when
the aperture is narrowed, and (Exp. 2) because their breadth
increases as the distance of the third edge from the aperture is
diminished, the third edge remaining at the same distance from
the screen.
The last results (which I have fully verified) do not appear
to me to eyinee any peculiarity: relatively to the third edge,
the aperture may be regarded as a new origin of light, in which
light the third edge gives its external frmges.
But with respect to the first part of the proposition, viz. that
these fringes are only formed parallel to the aperture, on re-
peatedly trying the experiment, I have uniformly found them
“ Experiments and Observations on the Properties of Light.” 7
formed equally, whether the edge be parallel or perpendicular to
the aperture; though in the latter case they may for obvious
reasons be less distinct and conspicuous.
It might indeed be fully admitted that the rays forming the
white centre may be in some respects under different conditions
from the ordinary rays, and that thus the fringes formed in them
might possibly be different: I can only say that I have never
been able to detect any such difference.
If, indeed, the author’s meaning be that these fringes extended
in any degree into the lateral fringes, it is obvious that they
would be mutuaily affected in a way conformable to previous ex-
periments.
One other remark of the author deserves especial attention* ;
that, but for what he considers the incapacity for further flexure
in the same direction, induced in a ray after one inflexion, that
ray might be continually bent round an opake body; and thus a
luminous object might be seen, though the whole of the body
intervened, or in other words, that we might see round a corner.
Now if such inflexion took place it would clearly be always
accompanied by a considerable diffusion of the light, so that
after a few successive inflexions it might be so much weakened
as to become imperceptible.
It is however a remarkable fact, that such an apparent in-
flexion does take place to a very great extent, as I have pointed
out in a paper “On Luminous Rings round Shadows” (Me-
moirs of the Royal Astronomical Society, vol. xvi. p. 806), and
which (as I have there mentioned) I believe to be a modifica-
tion of the same phenomenon, described rather obscurely by
Newton+ and more distinctly by Hooke, and apparently ac-
cordant with the theory of undulations (Ibid. p. 310).
* Additional Observations, 4.
+ Opticks, book 3. part 1. obs. 5.
+ As this curious point seems to have been much overlooked, J shall
perhaps be excused in annexing a brief notice of Dr. Hooke’s experiment,
from a fragment on Light, appended to the Essay on Comets and Gra-
re in his posthumous works : London, 1705, p. 186.
ight being admitted into a dark room through a very small hole and
received on a screen at some distance, on holding an opake body in the cone
of light, besides a “ zone or fascia of light much brighter than the rest of
the surface,” along and outside the edge of the shadow (which was pro-
bably the first diffraction fringe), he observed a faint light extending from
the edge into the shadow ; and when the opake body was held so as to cover
nearly the whole of the luminous circle, “ rays were seen darting downwards
perpendicular to the edge of the shadow, like the tail of a comet, striking
downwards more than 10 times, probably 100 times their breadth, or very
near to a quadrant,” and growing fainter at greater distances. The “rays”
were obviously occasioned by irregularities in the edge; the rays were per-
8 Prof. Thomson on the Dynamical Theory of Heat.
I have thus, I trust with perfect impartiality, gone through
all the main experimental points of the author’s mvestigations,
and upon the whole I can perceive nothing substantiated which is
positively irreconcileable with the principle of interference, while
the new modifications of the phenomena here presented, so far
as general considerations can be relied on, seem sufficiently con-
formable to the undulatory theory : but as to their more exact, or
quantitative explanation, no definitive opimion can be pronounced,
until certain analytical investigations of almost impracticable
length and complexity, shall have been gone through, by which
alone that theory can be brought into exact and satisfactory com-
parison with experiment.
II. On the Dynamical Theory of Heat, with numerical results
deduced from Mr. Joule’s equivalent of a Thermal Unit, and
M. Regnault’s Observations on Steam. By Wi1111AM THomson,
M.A., Fellow of St. Peter’s College, Cambridge, and Professor
of Natural Philosophy in the University of Glasgow*.
Introductory Notice.
1. GIR HUMPHRY DAVY, by his experiment of melting
two pieces of ice by rubbing them together, established
the following proposition :—“ The phenomena of repulsion are
not dependent on a peculiar elastic fluid for their existence, or
caloric does not exist.” And he concludes that heat consists of
a motion excited among the particles of bodies. “‘ To distinguish
this motion from others, and to signify the cause of our sensation
of heat,” and of the expansion or expansive pressure produced
in matter byheat, “the name repulsive motion has been adopted +.”
pendicular to the edge; if circular, tending to the centre; if angular, bi-
secting it; if concave, spreading out, &c. A representation of the appear-
ance is given in Plate ii. fig. 8 (p. 155). At p. 190, the Editor adds a me-
morandum found among Dr. Hooke’s papers, stating, that on March 18,
1674, he “read a discourse” on several new properties of light ; which he
sums up as follows :—
“That there is a deflexion of light differing both from reflexion and re-
fraction, and seeming to depend on the unequal density of the constituent
parts of the ray, whereby light is dispersed from the place of condensation
and rarefied or gradually diverged into a quadrant;” 2ndly, that this
takes place “ perpendicularly to the edge ;” and 3rdly, that “ the parts de-
flected by the greatest angle are the faintest.”
1 have fully referred to and commented upon Newton’s description of the
same phzenomenon, conveyed in terms so singularly coincident, in my paper
before referred to.
* From the Transactions of the Royal Society of Edinburgh, vol. xx. part2.
Passages added in the present reprint are enclosed in brackets.
+ From Davy’s first work, entitled “ An Essay on Heat, Light, and the
Combinations of Light,” published in 1799, in “ Contributions to Physical
Prof. Thomson on the Dynamical Theory of Heat. 9
2. The dynamical theory of heat, thus established by Sir
Humphry Davy, is extended to radiant heat by the discovery
of phenomena, especially those of the polarization of radiant
heat, which render it excessively probable that heat propagated
through “vacant space,” or through diathermanic substances, con-
sists of waves of transverse vibrations in an all-pervading medium.
3. The recent discoveries made by Mayer and Joule*, of the
generation of heat through the friction of fluids in motion, and
by the magneto-electric excitation of galvanic currents, would
either of them be sufficient to demonstrate the immateriality of
heat ; and would so afford, if required, a perfect confirmation of
Sir Humphry Davy’s views.
4, Considering it as thus established, that heat is not a sub-
stance, but a dynamical form of mechanical effect, we perceive
that there must be an equivalence between mechanical work and
heat, as between cause and effect. The first published statement
of this principle appears to be in Mayer’s Bemerkungen iiber
die Kriifte der unbelebten Natur+, which contains some correct
views regarding the mutual convertibility of heat and mechanical
effect, along with a false analogy between the approach of a
weight to the earth and a diminution of the volume of a conti-
nuous substance, on which an attempt is founded to find nume-
rically the mechanical equivalent of a given quantity of heat. In
a paper published about fourteen months later, “On the Calorific
Effects of Magneto-Electricity and the Mechanical Value of
Heatt,” Mr. Joule of Manchester expresses very distinctly the
consequences regarding the mutual convertibility of heat and
mechanical effect which follow from the fact, that heat is not a
substance but a state of motion ; and investigates on unquestion-
able principles the “absolute numerical relations,” according to
which heat is connected with mechanical power ; verifying expe-
rimentally, that whenever heat is generated from purely mecha-
nical action, and no other effect produced, whether it be by
means of the friction of fluids or by the magneto-electric excita-
and Medical Knowledge, principally from the West of England, collected
by Thomas Beddoes, M.D.,” and republished in Dr. Davy’s edition of his
brother’s collected works, vol. ii. Lond. 1836.
* In May 1842, Mayer announced in the Annalen of Wohler and Liebig,
that he had raised the temperature of water from 12° to 13° Cent. by agi-
tating it. In August 1843, Joule announced to the British Association,
“That heat is evolved by the passage of water through narrow tubes ;”
and that he had “ obtained one degree of heat per Ib. of water from a me-
chanical force eapable of raising 770 lbs. to the height of one foot ;” and
that heat is generated when work is spent in turning a magneto-electric
machine, or an electro-magnetic engine. (See his paper “ On the Calorific
Effects of Magneto-Electricity, and on the Mechanical Value of Heat.”—
Phil. Mag., vol. xxiii. 1843.)
+ Annalen of Wohler and Liebig, May 1842.
{ British Association, August 1843; and Phil. Mag., Sept. 1843,
10 Prof. Thomson on the Dynamical Theory of Heat.
tion of galvanic currents, the same quantity is generated by the
same amount of work spent ; and determining the actual amount
of work, in foot-pounds, required to generate a unit of heat,
which he ealls “ the mechanical equivalent of heat.” Since the
publication of that paper, Mr. Joule has made numerous series
of experiments for determining with as much accuracy as possible
the mechanical equivalent of heat so defined, and has given
accounts of them in various communications to the British
Association, to the Philosophical Magazine, to the Royal Society,
and to the French Institute.
5. Important contributions to the dynamical theory of heat
have recently been made by Rankine and Clausius; who, by
mathematical reasoning analogous to Carnot’s on the motive
power of heat, but founded on an axiom contrary to his funda-
mental axiom, have arrived at some remarkable conclusions.
The researches of these authors have been published in the
Transactions of this Society, and in Poggendorff’s Annalen, du-
ring the past year; and they are more particularly referred to
below in connexion with corresponding parts of the mvestiga-
tions at present laid before the Royal Society.
[Various statements regarding animal heat, and the heat of
combustion and chemical combination, are made in the writings
of Liebig, (as, for instance, the statement quoted in the foot-note
added to § 18 below,) which virtually imply the convertibility
of heat into mechanical effect, and which are inconsistent with
any other than the dynamical theory of heat. ]
6. The object of the present paper is threefold :—
(1.) To show what modifications of the conclusions arrived at
by Carnot, and by others who have followed his peculiar mode
of reasoning regarding the motive power of heat, must be made
when the hypothesis of the dynamical theory, contrary as it is
to Carnot’s fundamental hypothesis, is adopted.
(2.) To point out the significance in the dynamical theory, of
the numerical results deduced from Regnault’s observations on
steam, and communicated about two years ago to the Society,
with an account of Carnot’s theory, by the author of the present
paper; and to show that by taking these numbers (subject to
correction when accurate experimental data regarding the den-
sity of saturated steam shall have been afforded), in connexion
with Joule’s mechanical equivalent of a thermal unit, a complete
theory of the motive power of heat, within the temperature limits
of the experimental data, is obtained.
(3.) To point out some remarkable relations connecting the
physical properties of all substances, established by reasoning
analogous to that of Carnot, but founded in part on the contrary
principle of the dynamical theory.
Prof. Thomson on the Dynamical Theory of Heat. ll
Part I1.—Fundamental Principles in the Theory of the Motive
Power of Heat.
7. According to an obvious principle, first introduced, how-
ever, into the theory of the motive power of heat by Carnot,
mechanical effect produced in any process cannot be said to have
been derived from a purely thermal source, unless at the end of
the process all the materials used ave in precisely the same phy-
sical and mechanical circumstances as they were at the beginning.
In some conceivable “ thermo-dynamic engines,” as for instance
Faraday’s floating magnet, or Barlow’s “ wheel and axle,” made
to rotate and perform work uniformly by means of a current
continuously excited by heat communicated to two metals in
contact, or the thermo-electric rotatory apparatus devised by
Marsh, which has been actually constructed; this condition is
fulfilled at every instant. On the other hand, im all thermo-
dynamic engines, founded on electrical agency, in which discon-
tinuous galvanic currents, or pieces of soft iron in a variable
state of magnetization are used, and in all engines founded on
the alternate expansions and contractions of media, there are
really alterations in the condition of materials; but, in accord-
ance with the principle stated above, these alterations must be
strictly periodical. In any such engine, the series of motions
performed during a period, at the end of which the materials are
restored to precisely the same condition as that im which they
existed at the beginning, constitutes what will be called a com-
plete cycle of its operations. Whenever in what follows, che
work done or the mechanical effect produced by a thermo-dynamic
engine is mentioned without qualification, itmust be understood
that the mechanical effect produced, either in a non-varying
engine, or in a complete cycle, or any number of complete cycles
of a periodical engine is meant.
8. The source of heat will always be supposed to be a hot
body at a given constant temperature, put in contact with some
part of the engine; and when any part of the engine is to be
kept from rising in temperature (which can only be done by
drawing off whatever heat is deposited in it), this will be sup-
posed to be done by putting a cold body, which will be called
the refrigerator, at a given constant temperature in contact with it.
9. The whole theory of the motive power of heat is founded
on the two following propositions, due respectively to Joule, and
to Carnot and Clausius.
Prop. I. (Joule)—When equal quantities of mechanical effect
are produced by any means whatever from purely thermal sourees,
or lost in purely thermal effects, equal quantities of heat are put
out of existence or are generated.
12 Prof. Thomson on the Dynamical Theory of Heat.
Prop. II. (Carnot and Clausius).—If an engine be such that,
when it is worked backwards, the physical and mechanical agen-
cies in every part of its motions are all reversed, it produces as
much mechanical effect as can be produced by any thermo-
dynamic engine, with the same temperatures of source and refri-
gerator, from a given quantity of heat.
10. The former proposition is shown to be included im the
general “ principle of mechanical effect,” and is so established
beyond all doubt by the following demonstration.
11. By whatever direct effect the heat gained or lost by a
body in any conceivable circumstances is tested, the measure-
ment of its quantity may always be founded on a determination
of the quantity of some standard substance, which it or any equal
quantity of heat could raise from one standard temperature to
another ; the test of equality between two quantities of heat bemg
their capability of raismg equal quantities of any substance from
any temperature to the same higher temperature. Now, according
to thedynamical theory of heat,the temperature of a substance can
only be raised by working upon it in some way so as to produce
increased thermal motions within it, besides effecting any modifi-
cations in the mutual distances or arrangements of its particles
which may accompany a change of temperature. The work neces-
sary to produce this total mechanical effect is of course propor-
tional to the quantity of the substance raised from one standard
temperature to another; and therefore when a body, or a group
of bodies, or a machine, parts with or receives heat, there is in
reality mechanical effect produced from it, or taken into it, to an
extent precisely proportional to the quantity of heat which it
emits or absorbs. But the work which any external forces do
upon it, the work done by its own molecular forces, and the
amount by which the half vis viva of the thermal motions of all
its parts is diminished, must together be equal to the mechanical
effect produced from it; and consequently, to the mechanical
equivalent of the heat which it emits (which will be positive or
negative, according as the sum of those terms is positive or ne-
gative). Now let there be either no molecular change or alte-
ration of temperature in any part of the body, or, by a cycle of
operations, let the temperature and physical condition be restored
exactly to what they were at the beginning; the second and
third of the three parts of the work which it has to produce
vanish ; and we conclude that the heat which it emits or absorbs
will be the thermal equivalent of the work done upon it by ex-
ternal forces, or done by it against external forces ; which is the
proposition to be proved.
12. The demonstration of the second proposition is founded
on the following axiom :—
Prof. Thomson on the Dynamical Theory of Heat. 13
It is impossible, by means of inanimate material agency, to de-
rive mechanical effect from any portion of matter by cooling it
below the temperature of the coldest of the surrounding objects*.
13. To demonstrate the second proposition, let A and B be
two thermo-dynamic engines, of which B satisfies the conditions
expressed in the enunciation ; and let, if possible, A derive more
work from a given quantity of heat than B, when their sources
and refrigerators are at the same temperatures, respectively. Then
on account of the condition of complete reversibility in all its
operations which it fulfills, B may be worked backwards, and
made to restore any quantity of heat to its source, by the expen-
diture of the amount of work which, by its forward action, it
would derive from the same quantity of heat. If, therefore, B
be worked backwards, and made to restore to the source of A
(which we may suppose to be adjustable to the engine B) as
much heat as has been drawn from it during a certain period of
the working of A, a smaller amount of work will be spent thus
than was gained by the working of A. Hence, if such a series
of operations of A forwards and of B backwards be continued,
either alternately or simultaneously, there will result a continued
production of work without any continued abstraction of heat
from the source ; and, by Prop. I., it follows that there must be
more heat abstracted from the refrigerator by the working of B
backwards than is deposited in it by A. Now it is obvious that
A might be made to spend part of its work in working B back-
wards, and the whole might be made self-acting. Also, there
being no heat either taken from or given to the source on the
whole, all the surrounding bodies and space except the refrige-
rator might, without interfering with any of the conditions which
have been assumed, be made of the same temperature as the
source, whatever that may be. We should thus have a self-acting
machine, capable of drawing heat constantly from a body sur-
rounded by others at a higher temperature, and converting it
into mechanical effect. But this is contrary to the axiom, and
therefore we conclude that the hypothesis that A derives more
mechanical effect from the same quantity of heat drawn from the
source than B, is false. Hence no engine whatever, with source
and refrigerator at the same temperatures, can get more work
from a given quantity of heat introduced than any engine which
satisfies the condition of reversibility, which was to be proved.
14. This proposition was first enunciated by Carnot, being
the expression of his criterion of a perfect thermo-dynamic en-
* If this axiom be denied for all temperatures, it would have to be ad-
mitted that a self-acting machine might be set to work and produce me-
chanical effect by cooling the sea or earth, with no limit but the total loss
of heat from the earth and sea, or, in reality. from the whole material world.
14 Prof. Thomson on the Dynamical Theory of Heat.
gine*, He proved it by demonstrating that a negation of it
would require the admission that there might be a self-acting
machine constructed which would produce mechanical effect inde-
finitely, without any source either in heat or the consumption of
materials, or any other physical agency ; but this demonstration
involves, fundamentally, the assumption that, in “a complete
cycle of operations,” the medium parts with exactly the same
quantity of heat as it receives. A very strong expression of doubt
regarding the truth of this assumption, as a universal principle, is
given by Carnot himself+; and that it is false, where mechanical
work is, on the whole, either gained or spent in the operations,
may (as I have tried to show above) be considered to be perfectly
certain. It must then be admitted that Carnot’s original de-
monstration utterly fails, but we cannot infer that the proposition
concluded is false. The truth of the conclusion appeared to me,
indeed, so probable, that I took it in connexion with Joule’s
principle, on account of which Carnot’s demonstration of it fails,
as the foundation of an investigation of the motive power of heat
in air-engines or steam-engines through finite ranges of tempe-
rature, and obtained about a year ago results, of which the sub-
stance is given in the second part of the paper at present com-
municated to the Royal Society. It was not until the com-
mencement of the present year that I found the demonstration
given above, by which the truth of the proposition is established
upon an axiom (§ 12) which I think will be generally admitted.
It is with no wish to claim priority that I make these statements,
as the merit of first establishing the proposition upon correct
principles is entirely due to Clausius, who published his demon-
stration of it in the month of May last year, in the second part -
of his paper on the motive power of heatt. I may be allowed
to add, that [ have given the demonstration exactly as it occurred
to me before I knew that Clausius had either enunciated or de-
monstrated the proposition. The following is the axiom on
which Clausius’ demonstration is founded :—
It is impossible for a self-acting machine, unaided by any ea-
ternal agency, to convey heat from one body to another at a higher
temperature.
It is easily shown, that, although this and the axiom I have
used are different in form, either is a consequence of the other.
The reasoning in each demonstration is strictly analogous to that
which Carnot originally gave.
15. A complete theory of the motive power of heat would
consist of the application of the two propositions demonstrated
above, to every possible method of producing mechanical effect
* Account of Carnot’s Theory, § 13. + Ibid. § 6,
{ Poggendorff’s Annalen, referred to above.
Prof. Thomson on the Dynamical Theory of Heat. 15
from thermal agency*. As yet this has not been done for the
electrical method, as far as regards the criterion of a perfect
engine implied in the second proposition, and probably cannot
be done without certain limitations; but the application of the
first proposition has been very thoroughly investigated, and veri-
fied experimentally by Mr. Joule in his researches “ On the Ca-
lorifie Effects of Magneto-Electricity ;” and on it is founded one
of his ways of determining experimentally the mechanical equi-
valent of heat. Thus, from his discovery of the laws of genera-
tion of heat in the galvanic eircuitt, it follows that when mecha-
nical work by means of a magneto-electric machine 1s the source
of the galvanism, the heat generated in any given portion of the
fixed part of the circuit is proportional to the whole work spent ;
and from his experimental demonstration that heat is developed
in any moving part of the circuit at exactly the same rate as if
it were at rest, and traversed by a current of the same strength,
he is enabled to conclude—
(1.) That heat may be created by working a magneto-electric
machine.
(2.) That ifthe current excited be not allowed to produce any
other than thermal effects, the total quantity of heat produced is
in all circumstances exactly proportional to the quantity of work
spent.
16. Again, the admirable discovery of Peltier, that cold is
produced by an electrical current passing from bismuth to anti-
mony, is referred to by Joulet, as showing how it may be proved
* «There are at present known two, and only two, distinct ways in
which mechanical effect can be obtained from heat. One of these is by the
alterations of volume which bodies experience through the action of heat;
the other is through the medium of electric agency.” —Account of Carnot’s
Theory, § 4. (‘Transactions, vol. xvi. part 5.)
+ That, in a given fixed part of the circuit, the heat evolved in a given
time is proportional to the square of the strength of the current, and for
different fixed parts, with the same strength of current, the quantities of
heat evolved in equal times are as the resistances. A paper by M. Joule,
containing demonstrations of these Jaws, and of others on the relations of
the chemical and thermal agencies concerned, was communicated to the
Royal Society on the 17th of December 1840, but was not published in the
Transactions. (See abstract containing a statement of the laws quoted
above, in the Philosophical Magazine, vol. xviii. p. 308.) It was published
in the Philosophical Magazine in October 1841 (vol. xix. p. 260).
{ [In the introduction to his paper on the Calorifie Effects of Magneto-
electricity, &c., Phil. Mag, 1843.
I take this opportunity of mentioning that I have only recently become
uainted with Helmholz’s admirable treatise on the principle of mecha-
nical effect (Ueber die Brhaltung der Kraft, von Dy. H, Helmholz. Berlin.
G. Reimer, 1847), having seen it for the first time on the 20th of January
of this year; and that I should have had occasion to refer to it on this, and
on numerous other points of the dynamical theory of heat, the mechanical
theory of electrolysis, the theory of electro-magnetic induction, and the
16 Prof. Thomson on the Dynamical Theory of Heat.
that, when an electrical current is continuously produced from a
purely thermal source, the quantities of heat evolved electrically
in the different homogeneous parts of the circuit are only com-
pensations for a loss trom the junctions of the different metals,
or that, when the effect of the current is entirely thermal, there
must be just as much heat emitted from the parts not affected
by the source as is taken from the source.
17. Lastly*, when a current produced by thermal agency is
made to work an engine and produce mechanical effect, there
will be less heat emitted from the parts of the cirewit not affected
by the source than is taken in from the source, by an amount
precisely equivalent to the mechanical effect produced ; since
Joule demonstrates experimentally, that a current from any kind
of source driving an engine, produces in the engine just as much
less heat than it would produce im a fixed wire exercising the
same resistance as is equivalent to the mechanical effect produced
by the engine.
18. The equality of thermal effects, resulting from equal
causes through very different means, is beautifully illustrated by
the following statement, drawn from Mr. Joule’s paper on mag-
neto-electricity F.
mechanical theory of thermo-electric currents, in various papers communi-
cated to the Royal Society of Edinburgh, and to this Magazine, had I been
acquainted with it in time —W. T. March 20, 1852.]
* This reasoning was suggested to me by the following passage con-
tained in a letter which I received from Mr. Joule on the 8th of July 1847.
“Tn Peltier’s experiment on cold produced at the bismuth and antimony
solder, we have an instance of the conversion of heat into the mechanical
force of the current,’ which must have been meant as an answer to a re-
mark I had made, that no evidence could be adduced to show that heat is
ever put out of existence. I now fully admit the force of that answer ;
but it would require a proof that there is more heat put out of existence at
the heated soldering [or in this and other parts of the circuit] than is
created at the cold soldering, [and the remainder of the circuit, when a
machine is driven by the current,| to make the “evidence” be experi-
mental. ‘That this is the case I think is certain, because the statements of
§ 16 in the text are demonstrated consequences of the first fundamental
proposition ; but it is still to be remarked, that neither in this nor in any
other ease of the production of mechanical effect from purely thermal
agency, has the ceasing to exist of an equivalent quantity of heat been
demonstrated otherwise than theoretically. It would be a very great step
in the experimental illustration (or verification, for those who consider such
to be necessary) of the dynamical theory of heat, to actually show m any
one case a loss of heat; and it might be done by operating through a very
considerable range of temperatures with a good air-engine or steam-engine,
not allowed to waste its work in friction. As willbe seen in Part II. of this
paper, no experiment of any kind could show a considerable loss of heat
without employing bodies differing considerably in temperature; for in-
stance, a loss of as much as ‘098, or about one-tenth of the whole heat used,
if the temperature of all the bodies used be between 0° and 30° Cent.
[t+ In this paper reference is made to his previous paper “ On the Heat
Prof. Thomson on the Dynamical Theory of Heat. 17
Let there be three equal and similar galvanic batteries fur-
nished with equal and similar electrodes; let A, and B, be the
terminations of the electrodes (or wires connected with the two
poles) of the first battery, A, and B, the terminations of the
corresponding electrodes of the second, and A; and B, of the
third battery. Let A, and B, be connected with the extremities
of a long fixed wire ; let A, and B, be connected with the “poles”
of an electrolytic apparatus for the decomposition of water ; and
let A, and B, be connected with the poles (or ports as they might
be called) of an electro-magnetic engine. Then if the length of
the wire between A, and B,, and the speed of the engine between
A, and Bg, be so adjusted that the strength of the current (which
for simplicity we may suppose to be continuous and perfectly
uniform in each case) may be the same in the three circuits, there
will be more heat given out in any time in the wire between A,
and B, than in the electrolytic apparatus been A, and B,, or the
working engine between A, and B;. But if the hydrogen were
allowed to burn in the oxygen, within the electrolytic vessel, and
the engine to waste all its work without producing any other
than thermal effects (as it would do, for instance, if all its work
were spent in continuously agitating a limited fluid mass), the
total heat emitted would be precisely the same in each of these
two pieces of apparatus as in the wire between A, and B,. Itis
worthy of remark that these propositions are rigorously true,
being demonstrable consequences of the fundamental principle
of the dynamical theory of heat, which have been discovered by
Joule, and illustrated and verified most copiously in his experi-
mental researches*.
19. Both the fundamental propositions may be applied in a
of Electrolysis’ (published in vol. vii. part 2, of the second Series of the
Literary and Philosophical Society of Manchester) for experimental de-
monstration of those parts of the theory in which chemical action is con-
cerned.
ie ‘i aave recently met with the following passage in Liebig’s Animal
Chemistry (3rd edit. London, 1846, p. 43), in which the dynamical theory of
the heat both of combustion and of the galvanic battery is indicated, if not
fully expressed :—* When we kindle a fire under a steam-engine, and em-
ploy the power obtained to produce heat by friction, it is impossible that
the heat thus obtained can ever be greater than that which was required to
heat the boiler; and if we use the galvanic current to produce heat, the
amount of heat obtained is never in any circumstances greater than we might
have by the combustion of the zinc which has been dissolved in the acid.”
A paper “On the Heat of Chemical Combination,” by Dr. Thomas
_ Woods, published last October in the Philosophical Magazine, contains an
independent and direct experimental demonstration of the proposition
stated in the text regarding the comparative thermal effects in a fixed me-
tallic wire, and an anoelenie vessel for the decomposition of water, pro-
duced by a galvanic current.—W. T. March 20, 1852.]
Phil. Mag, 8. 4. Vol. 4. No. 22, July 1852. C
18 Prof. Thomson on the Dynamical Theory of Heat.
perfectly rigorous manner to the second of the known methods
of producing mechanical effect from thermal agency. This ap-
plication of the first of the two fundamental propositions has
already been published by Rankine and Clausius ; and that of
the second, as Clausius showed in his published paper, is simply
Carnot’s unmodified inyestigation of the relation between the
mechanical effect produced and the thermal circumstances from
which it originates, in the case of an expansive engine working
within an infinitely small range of temperatures. The simplest
investigation of the consequences of the first proposition in this
application, which has occurred to me, is the following, being
merely the modification of an analytical expression of Carnot’s
axiom regarding the permanence of heat, which was given in my
former paper*, required to make it express, not Carnot’s axiom,
but Joule’s.
20. Let us suppose a mass} of any substance, occupying a
yolume v, under a pressure p uniform in all directions, and at a
temperature ¢, to expand in yolume to v+dz, and to rise in tem-
perature to¢+dt, The quantity of work which it will produce
will be
odo ;
and the quantity of heat which must be added to it to make its
temperature rise during the expansion to ¢+ dt may be denoted by
Mav + Ndt.
The mechanical equivalent of this is
J(Mdv + Ndt),
if J denote the mechanical equivalent of a unit of heat. Hence
the mechanical measure of the total external effect produced
in the circumstances is
(p—JM)dv—JINdt.
The total external effect, after any finite amount of expansion,
accompanied by any, continuous change of temperature, has
taken place, will consequently be, in mechanical terms,
S\(p—IM)do—INat} 3
where we must suppose ¢ to vary with v, so as to be the actual
temperature of the medium at each instant, and the integration
with reference to v must be performed between limits correspond-
ing to the initial and final volumes. Now if, at any subsequent
time, the volume and temperature of the medium become what
they were at the beginning, however arbitrarily they may have
been made to yary in the period, the total external effect must,
* Account of Camot’s Theory, foot-note on § 26.
+ This may have parts consisting of different substances, or of the same
substance in different states, provided the temperature of all be the same.
See below, part 3, § 53-56,
Prof, Thomson on the Dynamical Theory of Heat. 19
according to Prop. I., amount to nothing; and hence
(p—JM)dv—JINdt*
must be the differential of a function of two independent vari-
ables, or we must have
d(p—JM) _ d(—JN) 1
at gat vliiearengan Pouce 2 mi)
this being merely the analytical expression of the condition, that
the preceding integral may vanish in every case in which the
initial and final values of v and ¢ are the same, respectively.
Observing that J is an absolute constant, we may put the result
into the form
dp _ ae dN
di. =J “di. be dv . . . . . . (2)
This equation expresses, in a perfectly comprehensive manner,
the application of the first fundamental proposition to the ther-
mal and mechanical circumstances of any substance whatever,
under uniform pressure in all directions, when subjected to any
possible variations of temperature, volume and pressure.
21. The corresponding application of the second fundamental
proposition is completely expressed by the equation
d
; =eM, Libs ancl der oSatvenm yall! (By
where » denotes what is called “ Carnot’s function,” a quantity
which has an absolute value, the same for all substances for any
‘ given temperature, but which may vary with the temperature in
a manner that can only be determined by experiment. To prove
this proposition, it may be remarked in the first place that
Prop. II. could not be true for every case in which the tempera-
ture of the refrigerator differs infinitely little from that of the
source, without being true universally. Now, if a substance be
allowed first to expand from v to v+dy, its temperature being
kept constantly ¢; if, secondly, it be allowed to expand further,
without either emitting or absorbing heat till its temperature
goes down through an infinitely small range, to ¢—7; if, thirdly,
it be compressed at the constant temperature ¢—7, so much
(actually by an amount differing from dv by only an infinitely
small quantity of the second order), that when, fourthly, the
volume is further diminished to » without the medium’s being
allowed to either emit or absorb heat, its temperature may be
exactly ¢; it may be considered as constituting a thermo-dynamie
[* The integral function /{ (JM—p)dv+JNdt} may obviously be called
the mechanical energy of the fluid mass; as(when the constant of integration
is properly assigned) it expresses the whole work the fluid has in it to
produce. The consideration of this function is the subject of a short paper
communicated to the Royal Society of Edinburgh, Dec. 15, 1851, as an ap-
pendix to the paper at present republished, }
C2
20 _— Prof. Thomson on the Dynamical Theory of Heat.
engine which fulfills Carnot’s condition of complete reversibility.
Hence, by Prop. IL., it must produce the same amount of work
for the same quantity of heat absorbed in the first operation, as
any other substance similarly operated upon through the same
range of temperatures. But apt is obviously the whole work
done in the complete cycle, and (by the definition of M in § 20)
Madp is the quantity of heat absorbed in the first operation.
Hence the value of
dp dp
di TT. dv 60 dt
TMae 2 °° o™..”
must be the same for all substances, with the same values of ¢
and 7; or, since Tis not involved except asa factor, we must have
dp
dt
TT oe, er i en OC ae On TL (4)
where « depends only on ¢; from which we conclude the pro-
position which was to be proved.
dp
22. The very remarkable theorem that sis must be the same
for all substances at the same temperature, was first given
(although not in precisely the same terms) by Carnot, and de-
monstrated by him, according to the principles he adopted. We
have now seen that its truth may be satisfactorily established
without adopting the false part of his principles. Hence all Car-
not’s conclusions, and all conclusions derived by others from his
theory, which depend merely on equation (3), require no modifi-
cation when the dynamical theory is adopted. Thus, all the
conclusions contained in Sections I., IT.; and IIL., of the Ap-
pendix to my Account of Carnot’s Theory, and in the paper im-
mediately following it in the Transactions, entitled “ Theoretical
Considerations on the Effect of Pressure in Lowering the Freezing
Point of Water,” by my elder brother, still hold. Also, we see
that Carnot’s expression for the mechanical effect derivable from
a given quantity of heat by means of a perfect engine in which
the range of temperatures is infinitely small, expresses truly the
greatest effect which can possibly be obtained in the circum-
stances ; although it isin reality only an infinitely small fraction
of the whole mechanical equivalent of the heat supplied; the
remainder being irrecoverablylost to man, and therefore “wasted,”
although not annihilated.
28. On the other hand, the expression for the mechanical
effect obtainable from a given quantity of heat entering an engine
Mr. W. Crowder on the Fatty Acid of Coceulus indicus. 21
from a “source” at’a given temperature, when the range down
to the temperature of the cold part of the engine or the “ refri-
gerator ” is finite, will differ most materially from that of Car-
not; since, a finite quantity of mechanical effect bemg now
obtained from a finite quantity of heat entering the engine, a
finite fraction of this quantity must be converted from heat into
mechanical effect. The investigation of this expression, with
numerical determinations founded on the numbers deduced from
Regnault’s observations on steam, which are shown in ables I.
and II. of my former paper, constitutes the second part of the
paper at present communicated.
[To be continued. ]
Ili. On the Fatty Acid of Cocculus indicus.
By Mr. W. Crowner, Assistant to Dr. Anderson of Edinburgh*.
1 ta a paper published several years ago in the Annalen der
Chemie und Pharmacie+ upon the substances obtained from
Cocculus indicus, Dr. Francis pointed out the existence of a fatty
acid which had not previously been subjected to investigation, to
which he gave the name of stearophanic acid; and after analy-
sing it, its ether and silver salt, he gave the formula C*H*O*
as representing its constitution. The recent researches of che-
mists having pointed out that all the fatty acids have the same
general formula (C?H?)"0*, and the acid under consideration
being evidently a member of that series, it seemed probable that
its true formula would be C*H*04, with which the results ob-
tained by Dr. Francis, when calculated with the corrected atomic
weight of carbon, closely agree. This formula has indeed been
since assumed by Dr. Francis himself and by other chemists, as
the true expression of his results; and as the investigation of
the fatty acids has since the date of his experiments made great
strides, I thought it desirable to submit the fat of Cocculus
indicus to a new examination, the result of which has fully con-
firmed the correctness of Dr. Francis’s numbers, and conclu-
sively established the formula C**H°®O#, and consequently the
identity of the acid with the bassic acid since described by
Mr. Hardwicke}. My experiments were performed in the labora-
* Communicated by the Author.
+ See also Phil. Mag. for September 1842.
+ [Why, under these circumstances, the author retains the name of bassic
acid we are at a loss to understand. The name stearophanic, derived from
the properties of the substance, is surely preferable to either that of cocculo-
stearic suggested by Berzelius, or of bassie proposed by Mr. Hardwicke
from its occurrence in Bassia latifolia; especially as the recent researches of
Heintz go to prove that its occurrence is not restricted to the vegetable king-
dom, but that it likewise forms one of the constituents of human fat.—W. I’. |
22 Mr. W. Crowder on the Fatty Acid of Cocculus indicus.
tory of Dr. Anderson, for whose kindness and valuable sugges-
tions I am greatly indebted.
In order to obtain the substance in sufficient quantity for
experiment and for thorqugh purification, I commenced upon
fourteen pounds of the berries. The kernels (which contain the
fat) were separated by cracking the shells and picking them out
with a pointed instrument, a process sufficiently troublesome and
involving a great loss of time. The kernels were next beaten
into a paste in a warm mortar, and after being heated for some
time at 212° in order to melt the fat, they were subjected to
hydraulic pressure between two plates of hot lead. In a short
time a great quantity of perfectly colourless oil made its appear-
ance, which upon cooling solidified into a mass resembling stea-
rine. ‘The residue in the cloths, being reheated and pressed a
second time, gave a small additional quantity of fat.
The quantity of kernels obtained from the berries amounted
to 28 per cent. The quantity of fat obtained from the berries
amounted to 153 per cent.
The fat is exceedingly soluble in ether, sparingly soluble in
absolute alcohol, and almost insoluble in rectified spirit. It begins
to melt at 72° F., but is not completely fused till the temperature
rises to 78° F. Like other fats, it crystallizes in warty masses
from its solution in hot ther, and in an arborescent form when
its hot alcoholic solution is cooled. The fat was saponified with
caustic soda, and the soap formed separated from the solution
by common salt. The soap was allowed to become hard by cool-
ing, repeatedly mixed with small quantities of water to wash
away the salt, the soap pressed, dissolved in water, and decom-
posed by sulphuric or hydrochloric acid. Upon cooling, the acid
was subjected to very cautious pressure in order to separate it as
far as possible from oleic acid, which was present in consider-
able quantity. The product was then crystallized from aleohol
till its fusing-point became constant at 159° F.
The acid when pure is highly crystalline ; it melts at 159° F.,
and, like all the acids of the fatty series, is volatile to a certain
extent without decomposition. It reddens litmus distinetly,
and decomposes the alkaline carbonates with effervescence when
boiled along with them. It is exceedingly soluble in hot alcohol
and in «ther, and from its solution in the former liquid it is
almost entirely separated on cooling.
The accurate analysis of this substance was attended with some
degree of difficulty. In the earlier analyses, in which oxide of
copper alone was used, results were obtamed which in all but
one instance gave the per-centage of carbon decidedly too low.
In my subsequent analyses I therefore used from ten to fifteen
grains of chlorate of potash with my oxide of copper or chromate
My. W. Crowder on the Fatty Acid of Coceulus indicus. 23
of lead, and then sueceeded in obtaining results closely correspond-
ing to the calculated numbers. The following were the results :—
I. 4°49 grains of acid, burned with oxide of copper alone, gave
12/49 carbonic acid and 5°35 water.
II. 4315 grains of acid, burned*with oxide of copper and
chlorate of potash, gave 12-080 carbonic acid, and 5°455 water.
Ill. 4°345 grains of acid, burned with chromate of lead and
chlorate of potash, gave 12-165 carbonic acid and 5:088 water.
Experiment.
Calculation.
L Il. Il. —_——_
Carbon . 75°86 76:33 = 76°34 76:05 C® 216
Hydrogen = 13°22 14°04 13:01 T2074 «Be. 236
Oxygen . 10°92 963 10°65 11:28 O* 382
Pore tLe Vee TON owe eS re ere
100:00 100:00 100:00 100:00 284:
In No. II. the hydrogen is evidently too high, arising from the
necessity of mixing the substance with the oxide nearly cold.
These results agree sufficiently well with the formula C*H50?,
which is that of bassic acid, and were further confirmed by the
analysis of its ether.
Bassic Aither.—This compound was prepared by passing a
eurrent of dry hydrochloric acid gas into a solution of the
acid in alcohol, taking care to keep the fluid quite hot during
the first part of the operation, since the acid would otherwise
crystallize out. After the lapse of some time an oily and colour-
less liquid floats to the top, which on cooling coneretes into a
brittle crystalline mass. This is the ether which must be washed
with water to free it from hydrochloric acid, and erystallized from
alcohol once or twice to free it entirely from any adhering fatty
acid. It is moderately soluble in hot aleohol, very sparingly so
in the cold, and is deposited from its hot alcoholic solution upon
cooling in needles. It fuses at 92°, and is slightly volatile when
kept in the water-bath at 212°. It is without smell, and when
placed on the tongue it melts, producing a slight sensation of ~
cold.
The same difficulty of combustion was observed in burning
this substance as in the case of the acid. Of six combustions
made with oxide of copper alone, only two gave the theoretical
result for the carbon, the other four gave numbers evidently too
low. 1 therefore made one combustion with chromate of lead
and chlorate of potash, in order to control the two analyses which
gave higher per-centages of carbon.
The following are the details :—
I, 4-230 grains of the «ther, dried a vacuo and burned with
oxide of copper, gave 11+945 carbonic acid and 5-000 water.
24 Mr. W. Crowder on the Fatty Acid of Coceulus indicus.’
II. 4:835 grains of the ether, dried at 212° and burned with
oxide of copper, gave 13°645 carbonic acid and 5°850 water.
III. 4°555 grains of the ether, fused durmg a quarter of an
hour at 212° and burned with chromate of lead and chlorate of
potash, gave 12°815 carbontic acid and 5°372 water.
Experiment.
Calculation.
at II. Iil. Fae =
Carbon .. 77:01 76:96 76°73 76°95 C? 240
Hydrogen 13:13 13:44, 13:11 12°82. H® 40
Oxygen . 9°86 9°60 10:16 10°23 O* 382
100°00 100:00 100:00 100-00 312
These results correspond exceedingly well with the formula
CHO + C4H5O = C*?H°04, or the acid combined with one
atom of oxide of zthyle.
Bassiate of Potash.—This salt was prepared by dissolving the
acid in an aqueous solution of boiling carbonate of potash, eva-
porating to dryness and taking up with strong alcohol, when the
carbonate of potash in excess is left behind. . The salt on cooling
separates as a jelly, which may be freed from alcohol by squeezing.
It is then redissolved in alcohol, allowed to cool and squeezed
a second time, and the purification is complete. It is exeeed-
ingly soluble in. hot alcohol, from which it separates as a jelly
when allowed to cool; it is also soluble in ether when a very
small quantity of alcohol is added, and from this solution. ery-
stallizes in needles when allowed to evaporate spontaneously.
Bassiate of Soda.—This salt is prepared in exactly the same
manner as the preceding, substituting carbonate of soda for car-
bonate of potash. When dry and in masses, it has a shining
semi-crystalline appearance ; but when in powder, it is destitute
of all appearance of crystallization, even under the microscope.
It is insoluble in ether, soluble in alcohol, from which it sepa-
rates almost entirely as an opake jelly on cooling, scattered
through which may sometimes be observed a few minute needle-
like crystals; but my attempts at obtaining a regular crop of
crystals were entirely unsuccessful.
This substance is also, soluble in boiling-hot water, from which
it again separates as a jelly on cooling. A large addition of hot
water to the solution of this salt causes it to become opake, arising
no doubt from decomposition.
The determinations of soda are as follows :—
I, 6°33 grains of soda salt, ignited and afterwards treated with
sulphuric acid, gave 1:455 sulphate of soda = 10°35 per cent.
of soda. 6°225 grains of soda salt, treated as before, gave 1°450
sulphate of soda = 10°17 per cent. of soda—Mean = 10°26.
Mr. W. Crowder on the Fatty Acid of Coceulus indicus. 25
If. 4-935 grains of soda salt; treated as before, gave 1°135
sulphate of soda = 10-03 per cent: of soda. | 5°35 grams of soda
salt gave, on ignition, 0°92 of carbonate of soda = 10-05 per
cent. of soda.—Mean 10-04.
Mean of four determinations.
Calculation.
Experiment.) \°_,_-————-_
oh dcatis a ed ane Toe CO. 216
EAT LETTS Ege egae 11:43. H® 35
Oxygen Pha a ee 7°36. OF = 24
0 nena a RR iia lige lia Yl 3, 10°13 NaO 31
< 100-00 306
No. I. was prepared by adding an alcoholic solution of caustic
soda to an alcoholic solution of the acid. The salt separates on
cooling, and is to be purified by re-solution in rectified spirit.
No. II. was prepared in the same manner as the potash salt,
substituting carbonate of soda for carbonate of potash.
So far as the determination of soda in this substance is con-
cerned, it may be inferred that the formula given is correct ; but
as the combustion required the use of chlorate of potash, I did
not deem it necessary to incur the trouble of performing that
operation.
Bassiate of Ammonia.—This salt may be prepared by dissol-
ving the acid im a hot dilute solution of caustic ammonia and
allowing it to cool, when it crystallizes in innumerable small
needles. A clear solution of this salt, if kept hot for any length
of time, becomes opalescent from decomposition ; and even the
addition of a fresh quantity of ammonia does not cause the pre-
cipitate, once formed, to redissolve entirely. It is soluble in
alcohol and in zther, and is very prone to decomposition from
loss of ammonia.
Bassiate of Baryta—This salt was prepared and purified with
very great ease by dissolving the acid in a small excess of caustic
ammonia, and whilst still quite hot, adding a solution of chloride
of barium. A white ewrdy precipitate is formed, which is to be
filtered and washed with boiling water till free from chloride of
barium, and dried at 212°. It is a white powder, without any
apparent crystalline structure, insoluble m water, alcohol, and
ether of high specific gravity.
Analysis gave the following results :—
I. 6:460 grains of baryta salt gave, on ignition, 1°810 of car-
bonate of baryta = 21°74 per cent. baryta.
II. 5°820 grains’ of baryta salt gave, on ignition, 1°635 of
carbonate of baryta = 2182 per cent.
5°865 grains of baryta salt gave 13°270 of carbonic acid and
5°445 of water.
26 Mr. W. Crowder on the Fatty Acid of Cocculus indicus.
Experiment.
Calculation:
a Il. —nw—_—_—_
Carbon .. ......61°68 vse 61-44 C8 216
Hydrogen . 10°31 ae 9:95. HH? op
Oxygen ‘ 6°27 eae 6°84 OF 24
Baryta . . 21°74 21°82 21:77 BaO 76°55
100-00 100-00 351°55
These numbers correspond closely with the theoretical result,
leading to the formula C**H®O? + BaO.
Bassiate of Silver —I next attempted the preparation of a
silver salt, and after three or four trials, found that the best
method of preparing it free from excess of acid was to make an
exceedingly dilute solution of soda in alcohol, and also an ex-
ceedingly dilute solution of nitrate of silver in the same men-
struum.
The proportions used were about 20 grains of soda salt dis-
solved in 5 or 6 ounces of rectified spirit, and about 12 or 13
grains of fused nitrate of silver also dissolved in the same quan-
tity of alcohol. The solution of soda salt was added to the solu-
tion of nitrate of silver in small successive quantities with vigor-
ous stirring in the intervals, and the mixture was made in the
cold; since I found that, by mixing them together hot, more or
less decomposition invariably took place. The white curdy pre-
cipitate is allowed to subside in the dark, the supernatant liquid
is drawn off, and the precipitate filtered im the dark, as the salt
blackens by exposure to the light when alcohol is present. It
was then washed with alcohol till free from excess of silver, dried
first in vacuo and then at 212°.
Thus prepared, it is a light white powder, without any appear-
ance of crystallization ; it is highly electrical, insoluble im water,
aleohol, and in «ther. It speedily blackens in contact with
alcohol, but when freed from that liquid it undergoes decompo-
sition much more slowly.
The following are the results of analysis :—
I, 6:258 grains of silver salt, prepared as above detailed, gave,
on ignition, 1°733 silver = 27°69. 6°825 grains of silver salt, of
the same preparation, gave 1:875 silver = 27:46.—Mean 27‘57.
If. 6515 grains of silver salt, prepared with aqueous solu-
tions, gave 1°825 silver = 28°01 per cent. 5-66 grains of silver
salt, of the same preparation, gave 1°58 silver = 27°91 per cent.
—Mean 27°96.
III. (a) 4°93 grains of silver salt, prepared as No. L., gave
1°35 silver = 27°38 per cent. (b) 4°922 grains of silver salt, of
of any preparation, gave 1346 silver = 27°34 per cent.~-Mean
7°36.
Mr. W. Crowder on the Fatty Acid of Cocculus indicus. 27
Experiment.
a
I. II. Ill.
o_O Calculation.
a. b. a
Carbon . ss 55°90 55°33 55°37 65:24 C® 216
Hydrogen bes 903 9:27 1010 895 H® 35
Oxygen. ik “ALS SOO. ~.3:19.5'O* = 32
Silver. . 27:57 27:96 27:36 27:36 27:62 Ag 108
——
100-00 100-00 100-00 100:00 100-00 391
a was burned with chromate of lead; 4 was burned with oxide
of copper; the excess of hydrogen arose from an accident in the
laboratory during the time of mixing. The formula of this sub-
stance agrees quite well with C°®°H°0%+ AgO.
The evidence of this substance being bassic acid appears by
the preceding experiments to be in every way complete, and also
exceedingly interesting, since the occurrence of the acid has been
clearly made out in two entirely distinct natural orders of plants.
Possibly, by a more rigorous search among the acids contained
in the fatty matters of plants, this substance will be found to be
much more widely distributed than has hitherto been supposed ;
and thus the loose statements of the occurrence of stearic acid in
vegetables, without any analysis appended, may be proved incor-
rect by demonstrating the existence of bassic acid instead.
Besides the acid just described, the fat contains a very consi-
derable proportion of oleic acid, or at all events of an oily acid,
and a quantity of another fatty acid which I have not attempted
to isolate, but which appears to be the same as one also observed
by Mr. Hardwicke in Bassia latifolia. He says, that in the fat
of that plant there are two acids present, viz. bassic acid, and
another having a melting-point between 152° and 134°; and
that if a drop of an alcoholic solution of this last acid be allowed
to evaporate on the surface of a glass plate so as to form a thin
film, it presents, on solidifying, the curious appearance of a series
of concentric rings, which may not unaptly be compared to a
section of bone under the microscope; and that this appearance
is also seen when the bassie acid is impure, but it disappears
when completely purified.
These appearances have been observed by myself in the acid
from Cocculus indicus when it has been melted in the water-bath
and allowed to cool; and from it I conclude that the specimen
must have been contaminated with the acid melting at 132° to
134°, and the formula of which is either C®°H°O4, the missing
member of the fatty series, or that of palmitic acid, C°*H**O*.
28 Mr. T. T. Wilkinson’s Additions to the late
I shall conclude this communication by appending a tabular
view of all the combinations I have examined.
passic aid ae (OO a HU,
Bassic ether. . ., C%*H*®O8+ C*H®0.
Bassiate of soda. C%*H*®0+4 Na0.
Bassiate of baryta . CH%°0?+ BaO.
Bassiate of silver . C®H®0O°+Ag0.
IV. Additions to the late Mr. T. 8. Davies’s Notes on Geometry
and Geometers. The Swale Manuscripts. By T..T. Wit-
KINSON, Esq., F.R.A.S.*
HEN Professor Davies wrote No. VI. of his “Geometry
and Geometers” (Phil. Mag. Sept. 1850), he adopted
an opinion of mine, in correction of his own, to the effect. that
Mr. William Chapple was the first English geometer who had
formally stated the property, that “the perpendiculars from the
angles of a plane triangle on the opposite sides intersect in the
same point.” Since that time, I have been led to examine the
matter more fully, and in two papers printed in the Mechanics’
Magazine, Nos. 1430 and 1458, I have shown that not only was
the property published in the “ Miscellanies, or Mathematical
Lucubrations of Mr. Samuel Foster, sometime Publike Professor
of Astronomie im Gresham Colledge in London, 1659,” where it
is annexed to a commentary on the “ Lemmata Archimedis” by
the Arabian commentator Abi Alhonin Ali, but that it was un-
doubtedly known to the ancients, since it is implied in and fol-
lows as an easy inference from “Theorema LVII., Propositio LX.”
of ‘‘ Pappi Alexandrini Mathematice Collectiones. A. Frederico
Commandino. Venetiis 1589, folio 195 6;” and that from these
sourees probably those geometers derived the property previously
to its being formally enunciated by Mr. Chapple m the Mis-
cellanea Mathematica. The noteto No. VI., page 208, therefore
requires correction, and before entermg upon other matters it
will perhaps not be out of place if I notice one or two other over-
sights which elsewhere occur in this singularly exact and inter-
esting series of papers.
In No. VIIL., the first issue of the “Mathematical Repository”
is put down as ‘ March 1, 1796,” and this date appears to have
been deduced by reckoning backwards two half-years from the
date of the publication of thethird number... The excellent prac-
tice of binding up the covers of each number with each volume
of periodical works, seems to have been partially followed in the
copy from which Professor Dayies quotes, but the titie-page printed
along with the first number of the work must have been omitted,
* Communicated by the Author:
ee
Mr. T. §. Davies’s Notes on Geometry and Geometers. 29
In my copy the full title runs thus :—‘ The Mathematical Repo-
sitory : containing many ingenious and useful Hssays and Ex-
tracts, with a collection of Problems and Solutions, selected from
the correspondence of several able Mathematicians, and the works
of those who are eminent in the Mathematics. London, 1795 ;”
and as all “ Letters for the use of No. I]...... . must come to
hand before the first of January 1796,” it seems almost certain
that the first number was published about the beginning of
October, 1795.
The “ Mathematical Companion” was projected by several
active members of the Spitalfields Mathematical Society, and,
with the exception of the last number, was edited by its members
Messrs. Davis and Hampshire from its commencement in No-
vember 1797, to its close in November 1826. On its projection
it was proposed to designate it “ A Companion to the Gentleman’s
Diary, or a Preparation to that useful work,” and the first number
was actually printed with that title ; but smce the then Editor of
the “Gentleman’s Diary,” the Rev. Charles Wildbore (not Dr.
Hutton), had not been consulted respecting the new publication,
he declared in the Diary for 1798 that he “would discourage it
all in his power,’ and consequently the second number was
issued as the “ Gentleman’s Mathematical Companion,” to which
the title of the first number was altered on its being reprinted in
1809. The reasons for this change are fully stated in the “ Ad-
vertisement” prefixed tothe reprint of 1809, and must have been
overlooked by Professor Davies when writing the remarks con-
tained in “‘Geometry and Geometers, No. VIII’ The “open
field” alluded to is also liable to correction, for Mr. Whiting’s
‘Scientific Receptacle” and “Geometrical Delights” had ap-
peared at intervals for several years previously to the appearance
of the Repository, Mr. Leybourn himself being a joint proprietor
in the latter work with Messrs. Whiting and Davis.
The whole of No. VII. of this series of papers is devoted to
an analysis of Mr. Swale’s merits as a geometer, and to a short
notice of his ‘ Geometrical Amusements,’ the “Apollonius,” —
and his manuscript remains. Had the hand of death not so
prematurely arrested his progress, we should have had much
more on this interesting topic, smce the MSS. could have fur-
nished much available matter for Mr. Davies’s versatile and dis-
cursive genius; and it is much to be regretted that the task, if
ever it be accomplished, should have devolved upon others so
much less able and experienced. Most of the inferences and de-
ductions respecting Mr. Swale’s speculations in mathematical
publications, &¢c. have been confirmed to me in private correspond-
ence with his son, the present Mr. J. H. Swale; nor will any one
who is at all acquainted with his father’s writings, hesitate for a
30 Mr. T. T. Wilkinson’s Additions to the late
moment to accept Mr. Davies’s estimate of his abilities as a
eeometer in the fullest acceptation of the terms ; but with regard
to existing manuscripts, it may be observed that the followimg are
in existence ‘of a date prior to 1828,” which, however, I have
not yet seen, nor were they sent by Mr. Swale amongst the rest
for Mr. Davies’s inspection.
No. I. Geometrical Disquisitions. Christmas. 1811.
II. Geometrical Amusements. Christmas. 1818.
IIL. a ‘ Midsummer, 1819.
Christmas.
IV. PY r Christmas. 1820.
Midsummer. ) 18238.
V. Geometrical Sketches. Christmas. 1823.
Christmas. 1824.
VI. Geometrical Papers.
Several of the other manuscripts bear evidences of having been
transcribed from some of older date, since they contain original
investigations which had previously appeared in different peri-
odicals, and amended solutions to questions which had been
proposed in “ Burrows’s Diary,” and various other mathematical
publications of the last and present centuries. This is more
particularly the case with two of the oldest MSS. ; the rest appear
to have resulted from his practice of “ spinning geometrical cob-
webs” as an amusement during the leisure hours of declining age.
Up to the time when the “ Geometrical Amusements” were pub-
lished in 1821, no attempts had been made to improve the style
of printing geometrical demonstrations: the old hackneyed form
had been rigidly adhered to by both editor and author, nor had
any geometer appeared who had ventured to deviate from the
established usage of printing entirely across the page. Mr. Swale,
however, had learnt that the eye had something to do in geometry
as well as the intellect, and in his anxiety to aid both, he adopted,
to a considerable extent, the practice of printing each step in a
separate line, which has since been so fully carried out by Mr.
Potts in his excellent editions of Euclid’s Klements. The pages
of the “Amusements” therefore presented a somewhat novel
aspect to the mathematicians of his acquaintance, and this,
rather than his practice of making verses, induced them to banter
him respecting his “‘ poetical geometry.”
The “ Geometry of the Circle,” or as dis son has not unaptly
endorsed the manuscript volumes, the “ Mascheronian Geometry,”
had peculiar attractions for him ;—several of the MSS. contain
short tracts on the subject, but volumes VIII. and IX. are wholly
devoted to its consideration. Mascheroni’s Géométrie du Compas
was for a long time his favourite work, and is contained in a list
SS ae
i te
Mr. T. 8. Davies’s Notes on Geometry and Geometers. 31
of mathematical treatises which he was in the habit of taking
along with him when he set out on his annual excursions into
the country. The results of his study are the two manuscript
volumes already noticed, both of which contain numerous in-
teresting extensions of the use of the circle in geometrical con-
structions, and many examples of the highest mgenuity in its
application. No. I., as Mr. Davies terms it, or No. VIII. ac-
cording to Mr, Swale’s enumeration, commences with the division
and subdivision of lines, the division of ares of circles, the drawing
of common tangents, and finding proportionals. He then proceeds
to the deseription of polygons, their inscription in circles and in
each other, the inscription and circumscription of circles in tri-
angles, &c., to many of which four or five different methods of
construction are given. “Fertility in resource is increased
power” was ever his favourite maxim, and throughout the whole
of his writings he has endeayoured fully to illustrate its truth,
No. II., or more correctly No, [X., is by far the most curious and
valuable, He commences with the problems of having “ given
three or four tangential circles inscribed in a given circle, to de-
seribe another circle that shall touch the given one and any two
of the inseribed circles,” and after having given elegant con-
structions to these, he proceeds to the construction of the various
eases of the Apollonian problem of tangencies, with the exception
of that where a tangent circle to three given circles is required to
be deseribed, the enunciation only of which is given. Professor
Davies regrets this cireumstance, owing to the “ probability that
had Mr. Swale succeeded in this, it might have opened the road
to a new system of treatment of the general problem ;”—but if
we are to be guided in our conjectures by what is already done
in the MS. with respect to the subsidiary problem of “de-
seribing through a given point, a circle which shall touch two
given circles,” to which the case of a tangent circle to three given
ones may always be reduced, we may safely infer that Mr. Swale
had obtained no clue to any essentially new process for the general
case left unconstructed. In his valuable paper “ On Tangential
Cireles” printed in the first number of the “ Apollonius,” he
considers the cases when the three given circles “ touch each
other,” and when they are “ anyhow posited ;” both cases are
constructed solely from the properties of what are now termed
the poles of similitude, the first agreeing in principle with the
construction given in Anderson’s “ Variorum Problematum
Practice,” of which a translation accompanies the construction
in the “ Apollonius,” and the second redueing it by means of the
same properties to the subsidiary problem previously noticed,
The enunciation and construction of the subsidiary problem itself
are given in the manuseript, as follows :—
32 On Mr. T. S. Davies’s Notes on Geometry and Geometers.
“ Problem.—A point P, and two circles, radii AT, BV, are given
in position ; to describe a circle through P, that shall touch the
given circles.
* Construction I1.—Draw the tangents PM, PN ; take AH : HB
=AM : BN, and AI: IB=PM?: PN®; tothe circle centre I and
radius a fourth proportional to HB, HI, BN ; draw the tangent
PR, and let the direction RH meet the circles in K, L; then
PL, PK, will meet them in T, V, the required points of contact.
“ Construction 11.—Take AH : HB=AT': BV;; inflect the tan-
gent HR (in the are through H to centre P) to I and K; to
which centres and radius IH, describe ares mtersectmg in Q:
the circle through the points P, Q, to touch the circle AT, is the
one required.” —(MS. pages 113-4.)
The first of these constructions is ¢dentical with that given by
M. Cauchy in the Correspondance sur ? Ecole Polytechnique,
vol. i., a translation of which may be seen in Leybourn’s
“ Ladies’ Diaries,” vol. iv. pp. 269, 270, whose process has been
elegantly extended to the general case of tangencies by “ Cen-
turion” in No. 1154 of the Mechanics’ Magazine, and which
again is almost identical with a construction given by Mr. Swale
himself in MS. vol. ii. p. 384. ‘The second construction is de-
rived from a discussion of the tangencies contained in pp. 383-6
of the volume just cited, where the whole are most ingeniously
reduced on Simpson’s principles (Select Exercises, Prob. 57),
to the subsidiary problem of determining “a point in a night
line given in position, such, that lmes drawn thence to two given
points may have a given difference.” The remainder of the
volume is occupied with the construction of numerous other
problems relating to the intersection of circles, tangents to them
from given points or in given ratios, many of which are equally
curious and interesting. A remarkably neat construction of the
problem, “to describe a circle that shall bisect the cireumferences
of two given circles, centres A and B, and have a tangent from a
given point D of a given length P,” is given in page 141*; and
also the construction of a fourth circle “to bisect the circum-
ferences of three given ones” in page 144, which has been pub-
lished as Quest. 343 of the “Educational Times.” His objects ,
throughout appear to have been to extend and diversify Mas-
cheroni’s methods, for he remarks at the foot of a construction
which closes the volume, “TI find this is similar to Mascheroni’s,”
and in these respects he has succeeded to a greater extent than
* Construction.—Posite the diameter FG of the circle (A), and the ra-
dius BL of the cirele (B) perpendicular to the direction AB, which meets
the circle FGL in P and Q;; inflect the line P (in the are through D to
centre P) to I and K; to which centres and radius ID describe arcs inter-
secting in R: the circle PQR is the one required.
Site ts
On the Constitution of the Electric Fluid. 33
it is possible for any verbal statement to describe. It does not
appear that Mr. Swale ever actually wrote out for the press those
portions of his geometrical sketches intended for Parts IT. andIII.,
of his “ Geometrical Amusements,” although the MSS. contain
much available matter, which, to him, would have required little
more than transcription and arrangement. ‘The titles of the
manuscripts previously enumerated have no reference to their in-
tended destination, but are adopted as somewhat indicative of the
geometrical character of their contents; he did not hesitate to
term those amusements which to others less gifted would be found
a severe mental exercise. Even were this not so, all further
speculations in the way of publication would have been effectually
stopped by the losses attendant upon the unsaleable character of
“ Part I.”; the reactionary taste for the Geometry of Coordinates
had already been created, and the Ancient Analysis, unable to cope
with this more powerful instrument of research, rapidly sunk into
disuse : the “ Geometrical Amusements” were of too antiquated
a cast to secure many purchasers, nor did the “ Avollonius” secure
a better fate :—the first number “ did not pay,” whilst the second
proved almost “a dead failure,” partly from the above causes,
but principally, as Mr. Marrat informs me, from Mr. Swale’s
admitting into its pages a long and intemperate attack upon the
eng System of Astronomy, by his friend Bartholomew
rescot.
Burnley, Lancashire.
Feb. 28th, 1852.
V. On the supposed Identity of the Agent concerned in the
Phenomena of ordinary Electricity, Voltaic Electricity, Electro-
magnetism, Magneto-electricity, and Thermo-electricity. By
M. Donovan, Esq... M.R.IA. ©
[Continued from vol. iii. p. 457.)
Sxcrion VI.
I NOW proceed to the consideration of another alleged proof of
this identity, found in the magnetic properties known to be
exercised by common and yoltaic electricity. Notwithstanding
the difficulty of collecting the precise opinions of philosophers
concerning the mutual dependence on each other of magnetism
and electricity, loosely expressed as they sometimes are, it will
probably be a safe enunciation to say, that by some, the two
powers are supposed to be identical; by others, that being each
sui generis they reproduce each other ; by others, that although
different they are always concurrent ; while others speak obscurely
about “the current” and its power of producing magnetism, the
Phil. Mag. 8. 4. Vol. 4. No. 22. July 1852.
34 Mr. M. Donovan on the supposed Identity of the Agent
term current being used in a sense which I conceive cannot be:
reconciled with the laws of electricity.
Without examining these opinions separately and m any par-
ticular order, it will answer the purpose and save trouble to make
mixed observations calculated to bring what I conceive to be
their defects under observation.
Whatever difference of opinion may exist relative to the nature
of positive and negative electricity, whether they are states of
one fluid, or two distinct fluids, or vibrations of a peculiar fluid
or of matter, I believe it is a position universally agreed to
amongst electricians, that when equal to each other and at liberty
to act, they mutually neutralize and destroy each other’s proper-
ties. To quote authorities would be to enumerate all the authors
who have written on the subject, I shall merely quote the ex-
pression of the fact as stated by Sir H. Davy :—“ In all cases of
electrical action, the two electrical states are always comeident,
either in different parts of the same body, or in two bodies, and
they are always equal and capable of neutralizing each other.
If a connexion be made by a wire between the positive and ne-
gative conductors of the electrical machine during the time of its
action, all electrical effects cease*.” Instances without number
might be adduced in support of the truth of this position ; but
to proceed with them would be to prove what nobody doubts.
Universally, if the two electricities be equal in quantity and in-
tensity and are at perfect liberty to neutralize each other, all
symptoms of both disappear, a condition of absolute quiescence
results, that of equilibrium, in which all bodies naturally exist,
is induced ; and in this state they manifest no electrical pro-
perties. ;
The poles of a voltaic series being in the positive and negative
states, conform to the general law. When the poles are uncon-
nected, they manifest their electrical condition to a gold-leaf
electrometer ; but as soon as they are connected by a good con-
ductor, the positive and negative states and all symptoms of
electricity vanish.
This is a fact, which, so far as electrical appearances are con-
cerned, is universally admitted ; yet it may not be without use
to advert to the very striking exemplification of it lately given
by Mr. Gassiot, on a scale of expense and magnificence rarely
equalled by an individual. With a water battery consisting of
3520 pairs of copper and zine cylinders, each pair bemg placed
in a separate glass vessel well varnished, Mr. Gassiot made the
following observation :—“ The tension was so great that the gold
leaves of an electroscope diverged when that mstrument was
* Elements of Chemical Philosophy, p. 132. The thickness of the wire
must be proportional to the quantity to be conducted.
concerned in the Phenomena of ordinary Electricity, &e. 35
placed within two or three inches of either end of the battery,
or over any of the terminal cells... Advantage was taken of this
to test whether any effect of tension could be observed when the
circuit was completed; but the instant this was effected, the
leaves of the electroscope as instantly collapsed, nor could I de-
tect, either by the aid of the condenser or otherwise, the slightest
trace of tension; it however immediately reappeared when the
circuit was again broken*.”
Thus, it is abundantly proved that as soon as the positive and
negative poles of a voltaic series are brought in communication
with each other, they comport themselves exactly as the positive
and negative poles or conductors do of a common electrical ma-
chine; all symptoms of electricity cease. It is at this moment,
however, and not until now, that the connecting wire of the vol-
taic series becomes magnetic. Is there not in this fact something
repugnant to the idea that electricity is the agent ? The magnetic
properties appear when all electricity is neutralized and extin-
guished ; and the moment that electricity is made to reappear
by disconnecting the poles, the magnetism ceases. Professor
Faraday himself, when treating of a different subject, expressly
admits the neutralizing effects of the two electricities. Speaking
of yoltaic action, he says “ it produces a current in which the op-
posite forces are so equal as to neutralize each other.” What
can neutralization mean if it be not that the properties of each
are for the time suspended, and can no longer act.
To admit that the two states of electricity, after having neu-
tralized and virtually annihilated each other’s properties, should
nevertheless at that moment be more active than ever in calling
into operation an energetic power of a totally different nature, is
contrary to every agency of electricity of which we have any
real knowledge. By the neutralization of the positive and ne-
gative states of electricity, the natural condition of equilibrium
is produced ; the electricity is then quiescent as it was previously
to the excitation that rendered it active ; it is, in short, in the in-
sensible state of the element as it exists throughout all nature.
If in that state electricity be competent to excite magnetism, it
must be admitted by the defenders of this hypothesis, that all
bodies in nature are magnets, and even magnets of great power,
a position which carries its own refutation.
This objection applies to the opinion of those who maintain
that electricity considered as a simple element is the cause of, or
is identical with, or excites magnetism; but not to the view
which I suggested in the beginning of this essay of the com-
ound nature of the electric fluid, one of its constituent elements
elng magnetism.
* Philosophical — 1844, p. 290.
2
36 Mr. M. Donovan on the supposed Identity of the Agent
It is no doubt true that frictional electricity has the power of
communicating, reversing and destroying magnetic polarity ;
but it never does so while traversing a conductor inthe silent
quiescent way which voltaic electricity is known to do, ‘To pro-
duce magnetie polarity, it must be in the state of high ten-
sion, and the circumstances must be otherwise peculiar. In this
state it acts with much dynamic violence, and will communicate
magnetism, as hammering, filing, and other’ mechanical causes
are known to do. Of the peculiar condition of electricity im the
state of flash, and how it differs from a current traversing acon-
ductor, we know nothing further than that there is a great dif-
ference.
The boldest of all the hypotheses of magnetism and the most
ingeniously supported is that of Ampére. This philosopher de-
nies the existence of a magnetic fluid, or of a magnetic agent
called into action by electricity ; but affirms the absolute identity
of both powers, an opinion first advanced by Beccaria and sup-
ported by Azais. Notwithstanding the address, ingenuity, and
resources of invention with which M. Ampére has constructed
and applied his hypothesis, it does not seem to have made much
advance in public opinion in the British Isles. This doctrme
scarcely comes within the province of my essay, as it does not
indicate magnetism as a property common to frictional and: vol-
taic electricity; but as identical with both. Mr. Sturgeon’s ar- .
guments* appear to me sufficient to mvalidate the assumed iden-
tity, yet it may not be superfluous to describe two experiments
which I made on this subject ; especially as they both refer to
the question whether electricity is magnetism, or whether elec-
tricity produces magnetic effects. Their results were of course
foreseen ; | made them merely to permit me to use them as ar-
guments.
A cylindrical rod of soft iron twelve inches long was wound
round in the usual manner, from end to end, with copper wire
covered with sewing silk. This was supported in the middle ho-
rizontally by an upright glass pillow set ina wooden stand. The
ends of the copper wire were connected with a Smee’s battery con-
sisting of four triads of silver and zine plates, acted on by very
dilute sulphuric acid. To the smooth, flat ends of the cylindrical
rod were adapted two pendent flat iron armatures, each having a
pair of gilt pith-balls attached by means of gilt strmgs. In this
state of things, the cylindrical iron rod being converted into a tem-
porary magnet, its ends would hold the pendent armatures at-
tracted; and the attractive force would, according to the hypo-
thesis of Ampére, be the difference of electrical state between the
ends of the eylimdrieal rod and ‘the armatures. Application of a
* Proceedings and Transactions of the London Electxjcal Society, 1838.
concerned. in the Phenomena of ordinary Electricity, &. 37
powerful permanent magnet over either end of the cylindrical rod,
the permanent and temporary magnets thus presenting contrary
poles to each other, ought by the neutralization, of the opposite
states of electricity to cause the armature of that end to fall off.
On making the trial with a powerful horseshoe magnet the arma-
ture.of that end, as might be expected, did fall.
So far the result corresponded, with the hypothesis; but if
electricity be really the agent, the transmission of a stream of
common electricity from the; prime; conductor. of a large and
powerful cylinder machine should act like the permanent magnet
in detaching either of the: pendent, armatures from the ends of
the temporary magnet. On throwing a torrent of sparks, which
to the eye, appeared a continuous stream of fire from a cylinder
capable at the moment of affording twelve-inch sparks, on the
temporary magnet, the pith-balls, hitherto of course unaffected,
diverged to a maximum, but the pendent armatures remained in
their places.
It will be said by the supporters of the hypothesis in question,
that the quantity of voltaic electricity passing through the coated
copper wire, coiled round the cylindrical iron rod, was so much
greater than that furnished by the glass cylinder machine, that
the electrical state of the poles of the temporary magnet and of
the armatures was not destroyed, and hence the armatures were
still attracted. If this be so, it must be inferred, that as the
voltaic electricity of the pole of the temporary magnet was neu-
tralized by the opposite electricity of the permanent magnet when
‘approached, so ought it also to haye been neutralized by the
stream of opposite electricity thrown in by the conductor of the
electrical machine. That the quantity of the frictional electricity
was sufficient for such a neutralization, was abundantly proved
by the maximum divergence of the pith-balls with the same
electricity as that of the prime conductor which supplied it.
Why then were not the laws of electricity obeyed? Why did not
the armatures fall off as well as when the permanent magnet was
applied, if the agent in both cases were electricity ?
Doubts founded on the foregoing objections, although they
may not have been expressed, seem to have influenced the
language of those who have alluded to the reaction of magnetism
and electricity ; and we discover remarkable reserve amongst
writers and experimenters on this subject, arising no doubt from
appreciation of the difficulty... Dr. Roget, in his excellent article
on Electro-magnetism*, thus expresses himself :—* At all events
we know that two currents of electricity in motion, impress by
their mutual action, a force differing very essentially from those
commonly considered electric, and which affects the magnetic
* Encyclop, Metropolit., par. 53.
38 Mr. M. Donovan on the supposed Identity of the Agent
needle.” M. Colladon says that the two electricities unite and
form a current which “ produces” magnetism. Professor Faraday
says that electricity and magnetism are “ essentially associated.”
From none of these do we learn the nature of the connexion of
the two agents, or the manner in which they reproduce each other.
To have entered on this question would at once have led to the
disclosure that neutralized electric states or fluids cannot exert
any known agency.
A word has of late years come into common use, which, while
it explains nothing, conceals the solecism contained in the notion
of neutralized electricities retaming their respective energies.
This word, “the current,” has the effect of keeping out of view
the counter-current, which is the grand difficulty, because it must
antagonize and destroy the current. This modern current cannot
have been derived from the old well-ascertained positive and ne-
eative currents of frictional electricity ; for these can be seen,
felt and understood. But the new current consists of both ; and
instead of being rendered powerless, as it was formerly the nature
of oppositely electrical currents to be when commingled, it is
only in this state of combination that the positive and negative
electricities are said to be capable of exerting peculiar powers.
The current seems to have been modified to meet the exigences
of recently discovered phenomena ; but in its new acceptation, it
no longer harmonizes with those from which our knowledge of
the true current was derived.
The current bemg now used in the explanation of every voltaic
fact, and its meaning not well-defined, it is important to discover
what is really intended to be conveyed by the term. Professor
Faraday says “it is a most important part of the character of
the current, and essentially connected with its very nature, that
it is always the same. The two forces are everywhere in it.
Any one part of the current, may, as respects the presence of the
two forces there, be considered as precisely the same with any
other part. It appears to me to be as impossible to assume a
current of negative force alone, or of two at once with any pre-
dominance of one over the other, as to give an absolute charge to
matter*.” He explains that “a current is produced both by
excitement and discharge.” “ Excitement may occur in many
ways, as by friction, chemical action,” &e.+ We are therefore
to understand that these observations are applied to the streams
of electricity which pass from the conductors of an electrical
machine, as well as to the currents from the poles of a voltaic
series. The currents being in both cases, as is stated, always the
same, and in every part the same, and the two forces everywhere
present in it, it is to be inquired what is the nature of the stream
* Researches, p. 518. + Ibid. p. 515,
concerned in the Phenomena of ordinary Electricity; Sc. 39
of electricity which passes in sparks from either conductor of an
electric machine, when any conducting substance is approached ;
are both streams mixtures of positive and negative electricity in
equal ratio? if so, why do these torrents of fire appear ? why do
they not neutralize each other while on the conductor, and fall
into inert equilibrium, instead of flashing through the air? why
does a body charged with one kind of electricity attract a body
charged with the other, and repel a body charged with the same ?
and lastly, if the composition of the positive and negative currents
bethe same, what is the difference between positive and negative
electricity, and why have they different properties? That they
have different properties, in respect of the class of phenomena
under consideration, appears from the researches of Faraday
himself; for in his decompositions of salts by frictional electri-
city, the results are described to be the same with regard to the
distribution of the separated elements as would have been pro-
duced by the voltaic apparatus ; and he concludes his observa-:
tions on this subject by declaring that there cannot be a doubt
“that voltaic and common electricity have powers of chemical
decomposition alike in their nature, and governed by the same
law of arrangement*.”
The difference between the positive and negative conditions of
the current is thus represented by Professor Faraday: he says
the current is neither a compounded nor complicated influence,
but “an axis of power having contrary forces exactly equal in
amount, in contrary directions}.” But here no real distinction
appears to be established between positive and negative electrical
currents ; for in every part{ of both the two electrical forces are
present “in equal amount,” “ travelling §” in opposite direc-
tions; there is therefore no difference. As to the affirmed dif-
ference of direction in which the currents are said to travel, it is
not easy to understand how that can give origin to the great
difference of properties manifested by the positive and negative
poles of a voltaic series. An absolute direction of the currents,
in contradistinction to a relative one, can have no effect ; for if
it had, reversing the position of a voltaic trough ought to reverse
its poles. It must then be the relative direction of the currents
with regard to each other that is meant. What the influence
of even relatiye direction may be is not very intelligible ; for
— : ——
current seems not to differ from current —-~ when both
constituent forces are exactly of the same constitution, as is
affirmed,
* Researches, par. 331. + Ibid. par. 517.
{ Ibid, par. 1642. § Ibid. par. 1635.
40 Mr. M. Donovan on the supposed Identity of the Agent
If, then, the current consist of positive and negative electricity,
equal to each other in amount. and force, how does the state re-
sulting from this commixture differ from that of the natural
equilibrium of electricity, which, in\a well-known state of qui-
escence, pervades all nature and manifests no properties ? How
is this state of quiescence compatible with the idea of a current ?
A eurrent of what ?—is it of sensible electricity without mani-
fest properties, neither positive nor negative ?) If so, how is its
presence recognised ? The existence of a thing is known by its
properties; if there be no properties, the thing, contemplated
exists only in imagination.
The nature of the current is explamed by Faraday as follows :—
“By current I mean any thing’ progressive, whether it: bea
fluid of electricity, or two fluids moving in opposite directions,
or merely vibrations, or speaking more generally progressive
forces*.” Supposing the current for the present to consist in
vibrations, it seems very difficult to associate in the mind the two
conditions assumed to be compatible, viz. vibrations of solid,
rigid matter+, along with progressive forees. Were electricity
assumed to be a fluid, a current or progressive force is conceivable,
or two such; but if there be no fluid, the idea of a foree which
progresses or moves forward is difficult to comprehend ; and in
that case, what is it that constitutes the current? what flows in
it? can vibrations of the particles of an electrified substance be
permanently progressive during the whole: period in which the
electric state is maintained ?. The vibrations of all the consti-
tuent particles of an electrified mass being once established, they
may coutinue ; but can they be progressive, especially in opposite
directions ? For my own part I do not conceive the meaning
of the expression “ progression of permanent vibrations of fixed
particles,” for the current resolves itself into this: and is the
idea of a current included in the expression of it, when it is at
the same time declared that probably nothing flows? I by no
means intend to insinuate any doubts concerning the assumption
of vibrations amongst the constituent particles of rigid matter:
the theory of Boscovich relative to the constitution of solids, pro
vides for the possibility of such. Professor Faraday, without ad-
mitting or rejecting the doctrine of two fluids, or one fluid, or
none, or vibrations of the subjective matter, endeavours to har-
monize the idea of a current of progressive forces with all these
contingent opinions. But if we abstract from all consideration
of fluids and vibrations, it strikes me that “ progressive forces”
* Researches, par. 283.
t+ This is the sense in which Faraday intends “ vibrations” to be taken.
Ibid. 1667.
ey
concerned inthe Phenomena of ordinary Electricity, &c. 41
are words which do ‘not represent any change, and cannot serve
in the explanation of phenomena.
«ltas also to be: observed that the’ theory in question assigns
no cause for the assumed progression of forces, or for the current
ina metallic conductor. Admitting thatithe particles of the sub-
jective matter are thrown into a state of electric vibration ; ad-
mitting also that such a state can be thrown into a progressive
eurrent, however difficult. that may be to comprehend, one sees
no reason why the particles should not quietly vibrate, each in
its respective place, no cause being assigned for the abnormal or
forced condition of a progression. Besides, the electric vibra-
tionsare in: this theory turned to no account; they explain
nothing ; they are not represented as producing any results;
thereis:no evidence of their existence ; they are gratuitous as-
sumptions, which may be admitted or denied without benefit or
detriment to the theory.
In what then does this current consist ? what is it that pro-
duces such remarkable phenomena? wherein is the use of assu-
ming its existence? and what advantage do we derive from the
employment of a term to which no definite object or meaning
isattached? A current of electricity in which no electricity is
affirmed to flow, which is said to be independent of one or-two
fluids or of vibrations of matter or ether, the nature of which is
admitted to be utterly unknown, appears to be a creation of the
mind which has no archetype in nature.
I have thus freely expressed my opinions relative to the cur-
rent, fearing that the old legitimate sense has been lost sight of ;
that many have understood it to mean something more than is
warranted by any proved properties; and that the universally
admitted identity of the agent im electric and voltaic phenomena
has emboldened philosophers to attribute qualities to the former
which belong only to the latter.. On the whole, I conceive that
the current, in its modern acceptation, instead of explaining vol-
taic phenomena, is calculated to mislead, and that it is of no
avail in obviating the difficulties which beset the alleged simul-
taneous operation of the two states of electricity after commix-
ture; which states, instead of being at that moment in their con-
dition of greatest energy, should be destitute of all sensible pro-
perties.
[To be continued. ]
42 Mr.T.H. Henry on the Composition of Wootz, or Indian Steel.
VI. On the Composition of Wootz, or Indian Steel.
By T. H. Henry, Esq., .R.S.*
HE high degree of estimation in which wootz has been held
in this country appears to rest more upon the supposition
that the celebrated scimitars of Damascus were made from this
variety of steel, than on any results obtained with it here; for
notwithstanding the late Mr. Stodart, an eminent authority, was
of opinion that woote was superior ‘for many purposes to any
steel commonly used in this country, the attempts to bring it
into use have not been successful, owing, it is said, to the diffi-
culty of working it.
Under these. circumstances, it appeared to me desirable to
ascertain as accurately as possible the chemical composition of
this steel, with the hope of throwing some light upon the causes.
of its peculiar physical properties.
An examination of wootz was made by Dr. Faraday in the
year 1819+. ‘The amount of carbon was not determined by him,
the only substances eliminated were silica and alumina; and he
obtained in two analyses 0-0128 and 0:0693 per cent. of alumi-
nium.
From these results Messrs. Faraday and Stodart drew the
conclusion, that the peculiar excellence of wootz depended chiefly
on the small quantity of aluminium combined or alloyed with
the steel {, and this opimion appeared to be strongly supported by
ingenious synthetical experiments.
On the other hand, Karsten could only detect dubious traces
of aluminium in wootz; and Elsner § attributed the improvement
in the quality of the steel produced m Messrs. Faraday and
Stodart’s experiments, not to the small quantity of the foreign
metals, aluminium, silver, platimum, &c., alloyed with them, but
entirely to the operation of remelting, and this seems to be the
practical conclusion come to at Sheffield at the present day. The
fact, however, of the perfectly damasked surface obtained in the
alloys of Messrs. Faraday and Stodart so closely resembling that
of wootz, seems to militate against the conclusions of Elsner.
M. Breant attributes the damask of the Eastern blades to the
crystallization of two distinct compounds of iron and carbon, and
draws a distinction between the oriental damask and that pro-
duced by alloys of steel. This opinion is confirmed by the ex-
periments of M. Anocoff, a Russian engineer, published in the
Annuaire du Journal des Mines de Russie, a few years back. He
* Communicated by the Author.
+ Quarterly Journal of Science, vol. vii.
{ Annales de Chimie, tome xv.
§ Journal fiir Prakt. Chemie, vol. xx. p. 110.
Mr. T. H. Henry on the Composition of Wootz, or Indian Steel. 43
pretends to have produced blades so nearly emulating those of
Damascus, as to allow of their being bent at a right angle,
and capable of dividing a film of gauze floating in the atmo-
sphere*.
I obtained from my friend Mr. Trenham Reeks of the Govern-
ment School of Mines, two samples of wootz, furnished to him
by Mr. Lewis Humbert of the military department of the India
House ; one was in the form of a cake, such as would be produced
by allowing the melted steel to cool in the crucible; the other
was forged into a small bar, about 4 inches long and 1 inch
square, and weighed 4760 grs., or rather more than 11 oz.
These are the forms in which it is imported into this country. I
preferred operating on the bar, for in steel m this form small
particles of slag are often so intimately mixed with the metal as
to defy separation ; and it is possible, as all the alumina found
by Dr. Faraday in wootz was in an insoluble form, that it might
have existed as silicate of alumina.
The specific gravity of this specimen was 7*727 at 62° F.
Analysis.
To determine the total amount of carbon, the steel in its soft
state was reduced by means of good files to such a minute state
of division that it passed through copper-wire gauze containing
8100 holes to the square inch. The files employed were those
used for polishing, being “ single cut ;” they are not so hard as
the “cross cut” files, and consist of sharp edges instead of points,
and consequently are not so liable to abrasion; when used with
care there is no danger of any particles of the file mixing with
the steel operated on.
It was then burnt with oxide of copper only, as Kudernatsch
recommends. I believe the most accurate results are obtained
by this method. I could not find any iron remaining in the
metallic state after combustion ; it appeared all in the state of
magnetic oxide.
T obtained in two experiments, operating in one case on 60
grs. passed through the gauze of 8100 holes to the square inch,
and on 50ers, passed through gauzeof 14,400 holes to the inch,—
1% Il.
1645 por cent. 1:652 per cent.
The amount of uncombined carbon in the form of graphite,
was determined in the usual manner, by dissolving in hydro-
chloric acid, in a platinum vessel, evaporating to dryness without
filtration, separating the silica from the graphite hy caustic pot-
* A specimen of his damask steel is to be seen in the Museum of the
Government School of Mines in Jermyn Street.
44 Mr. T. H. Henry on the Composition of Wootz,or Indian Steel.
ash, and igniting the residue. I obtained thus 0°312 per cent.
of graphite; the solution in caustic potash was acidulated_ by
hydrochloric acid and evaporated, to dryness; the silica remain-
ing was equivalent to 0°045 per cent. of silicium; hydrosul~
phuric acid afterwards precipitated 0:037 per cent. of arsenic ;
not a trace of alumina could be obtained from this solution by
hydrosulphate of ammonia. )
The solution of the iron m hydrochloric acid was treated by
carbonate of baryta, the precipitate redissolved, the baryta re-
moved by sulphuric acid, the iron precipitated by ammonia dis-
solved in. hydrochloric acid and boiled with pure caustic potash :
no alumina was extracted.
The solution of the steel from which the iron had been sepa-
rated was, after separating the baryta, evaporated to dryness in
a platinum dish ; the residue did not yield a trace of manganese,
magnesia, lime, cobalt or nickel.
To determine the amount of sulphur to control, the determi-
nation of the silicium and arsenic, and also to give me another
opportunity of searching for aluminium, I treated 50 grs. of the
steel in thé above minute state of division with pure nitrate of
soda, mixed with a little carbonate of soda, at a red heat, in a
crucible of pure gold* ; the action was easily controled, and the
oxidation was complete; the mass was treated with warm water,
the solution acidulated with hydrochloric acid and evaporated to
dryness. I obtained thus 0:04: per cent. of silicium, and after-
wards by chloride of barium 0°181 per cent. of sulphur, and in an-
other experiment 0°170 per cent. of sulphur ; the excess of baryta
was removed by sulphuric acid, and the arsenic precipitated by
hydrosulphuric acid gave 0:036 per cent.; no alumina could be
found in this solution, and only faint traces of phosphoric acid.
I have not been able to determine the amount of sulphur in steel
or cast iron nearly so accurately, by the methods of Berzelius or
Karsten, as by the above process.
I was not able to detect alumina in the residue left on dis-
solving 500 grs. of this steel in acid, nor on decomposing 117:87
grs. by means of a cake of fused chloride of silver. The residue
left on the cake of silver weighed 3°81 grs., and lost 2213 on ig-
nition, which required to be continued some time before the odour
of arsenic disappeared ; if we deduct the amount of sulphur and
arsenic from the loss, this will give 1660 for the total amount of
carbon ; but I do not consider this method so accurate as that of
* I have found it better to alloy the gold with 5 per cent. of platinum,
which increases the hardness and renders it one of the most useful instru-
ments which can be employed in delicate analysis ; gold alloyed with 10 per
sh of platinum does not appear to be acted on by nitrates, and is very
ard.
— =
Mr. J. Napier on Copper Smelting. 45
combustion with oxide of copper, although it may appear to con-
firm the result in this case.
The composition of this steel then will be :—
I. II.
Carbon combined ; 1:333 1:340
Carbon uncombined 312 *312
Silicium |... 6.6! /o5» (0045 0:042
Sulphur... ... 0-181 0-170
ATSEMC 16 oaptivimanci O08 t 0:086
ITD ren orice tiivad AooeOOe 98-100
100-000 100-000
[To be continued. ]
VIL. On Copper Smelting. By Jamus Narigr, F.C.S.*
A® no description of copper smelting in all its details has
been published in this country, it may not be uninterest-
ing, or without use to the readers of this Journal, were such a
descriptive account given of this extensive and useful branch of
manufacture.
Copper is one of the seven metals which were known to the
ancients ; and it, seems to have been known from the very earliest
times, and used extensively for instruments of war and for
domestic purposes. The oldest remnants of the metallic art are
composed of copper and tin. The great beauty which many of
the ores of copper have, and the ease with which such ores are
reduced to the metallic. state, may have brought it early into
notice and use; and that the metal was obtained from the ore
by fusion or smelting, is indicated in, one of the earliest writings
extant. Job says,—
“Copper is molten out of the stone.”
Copper is occasionally found in nature in the metallic state in
considerable quantities, both in this country and abroad. The
great masses found at Lake Superior form an eminent example
of this; but the chief source of copper is its ores, which con-
stitute, in combination with other substances, such as oxygen,
sulphur, carbonic acid, &c., an. extensive variety of minerals of
distinct forms and character, most of which have been the sub-
ject of careful chemical investigation. The following table of the
names and composition of some of these minerals will give some
idea of their variety,
* Communicated by the Author, who requests us to state, that he re-
serves to himself the copyright, and that any infringement thereof will in-
voke legal proceedings, —Eps.
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Mr. J. Napier on Copper Smelting. 47
The above table is exceedingly valuable to the chemist and
mineralogist, from its exhibiting the various combinations of
copper with other matters, and illustrating the chemical action
gomg on in the bowels of the earth; still tables of this sort are
of little use to the mere practical man. The minerals here named
and analysed have been carefully selected and freed from every-
thing mechanically mixed ; many of them have been found only
in minute quantities, and therefore can form no distinct division
or department in the practical operation of smelting ; and whether
the peculiar ingredients that give the distinctive character to
the mineral be deleterious or otherwise, their separation me-
chanically is altogether impracticable. The smelter may be
said to have only two classes of ores, those that contain sulphur,
and those that contain no sulphur; however, from the know-
ledge that some ores contain matters which make them more
fusible than others, and also matters that combine with the cop-
per, making it of inferior quality, a more extensive division is ob-
served, such as su/phurous ore (copper pyrites), mundicy ores (ores
containing mundic or iron pyrites), gray ore, tiny ore(containing tin),
&c. Many of these distinguishing characters depend more upon
the foreign matters mixed mechanically with the copper mineral
than forming a chemical constituent of it; hence the smelter
has a far more extensive class of substances to deal with in his
practice than is named in the table of copper minerals given above.
Metallic minerals or ores are found filling up cracks or fissures
of the rocks forming the crust of the earth, and are termed veins.
The minerals composing a vein are generally of a great variety
of kinds, contaiming often copper, tin, antimony, bismuth, iron,
nickel, cobalt, arsenic, manganese, silver, &c., besides what are
termed the earthy minerals or matrix, such as quartz, lime, slate,
&e. In mining, the contents of the vein are taken out, so far
as it contains any of the metal or metals sought after; so that
what is technically termed a copper ore is often a mixture of
everything that the vein contains. And when it is mentioned
that the average per cent. of copper in the ores raised in this
country is 8, it will be seen that the matters mixed with the
copper mineral forming the ore must act a prominent part in the
smelting operation; and the action and reaction of these sub-
stances, when passing through these operations, must be at-
tended to by the practical smelter.
The principal substance forming the matrix in copper ores is
quartz. The relation of this to the other ingredients is the first
thing to be considered by the smelter, as it is the first thing to
be got ‘quit of; and for this purpose the relation of the four
substances, copper, sulphur, iron and quartz, is the leading fea-
ture. To give some idea of the character of the copper ores in
this country in respect to these matters, we append the following
table of ores from various mines of Cornwall and Devonshire,
tested for their smelting quality, which we shall occasionally
have to refer to,
48 Mr. J. Napier on Copper Smelting.
Name of mine. Copper. Iron, Sulphur. Silica.”
Poldice™ 220.5... .ca.6 8-7 32-2 10-1 38°6
HEY) | ogy peerage see: 75 33:0 135 30°4
Great St. George Fluccan| 12°5 8 15 63°2
Wellington Mines ......... 10 22-5 17:3 45-1
Great Mitchell Consols ... 41 34 26 19°8
Grambler............... ete 11-2 19-4 16 409
Wheal Sisters ............5 - 7:5 26 17 40:1
Mast PQO!. Pk. cdeas as saunas 795 21-3 10-4 46°5
Wheal Maria ............... 9:3 36:8 22-1 12-1
Wheal Bucketts ............ 75 18-2 8:6 54:3
Tincroft Fluccan....... Baise 9°5 21-8 72 | 46°7
MPPEMANE s:,. sass depacrddi> La 19-1 16-2 19-1 391
Condurrow ....... ces on $1 37-1 15:3 21-7
Noxth Pool 27.250) WAL 10-6 278 19-3 31-1
Wheal. Jane,.. ciecotsyeens zx 78 25:1 19:6 36°5
South W. Basset..........+. 8-4 10°5 13°3 62°3
Wheal Williams ........... 4 10-9 341 14:9 25
United Mines ............... 77 20-3 12-6 46°8
W. Rodney ...... udssheds ey 41 24:5 19-6 43:5
Gwinear Consols,........... 11-12 22-3 11-9 40
WOMsUlsiakecentescccte: tates 9-4 22 165 43-4
Wheal Friendship, Devon| 15 25-5 20-7 24:5
Wheal Henry ............... 10-1 22 15-4 38:4
South Wheal Turbine .,,, 8-7 ll 8-4 65°38
Treleigh Consols........ seal ae 22°83 15-0 38°4
Tingtang Consols ......... 56 12 59 66°6
Wheal Ellen ..........0500. 87 16:9 13 515
Treviskey} =. 0.0 cdecsdeoet 8:7 15°6 13°4 51:8
East-Crinnis’ €4....4.0¢20004 12-5 168 16:9 41°5
Par Consolsee22. ..b.saserk 108 28-9 15°5 43
Trethellan .......... eouctete 46 26-8 115 37:5
Great St. George .....,.4. 6-3 20-7 16 48-2
Wheal Comfort ............ 36 22-8 21-7 38:2
Wheal Harriett ............ 75 28-7 101 26-7
Trymainhayle ............. ts 56 8-4 136 50
North Roskear ........ AR? 75 22-4 14:7 43
Wheat Agar.3.5 50.22). esbeae 6°6 178 12-1 53°5
Bast: Crofpy 0 .0:3.. cdaoseetee 6-9 3l 12:5 33°7
South Caradon ............ 9-4 31-8 14:1 317
Fowey Consols .......+s... 141 318 17-6 23°1
Wheal Seton ..... odesh quent 8-4 24-1 14:9 40'6
Dresayean 7.2"... poche 56 178 12-6 48:3
South Wheal Francis ...,.. 8] 3:0 6:1 76-0
Wheal Jewel 17:8 35 56 76°5
West Caradon 11-2 27:2 14:8 380°7
Carn Brea Yellow Mine.,,) 11°3 175 14:2 475
Wheal Tremayne ......... 12-2 16:1 9-1 51:5
South W. Tolgus ......... 66 23'5 14-4 42-2
W. Andrew Nangiles .,....) 11:3 23°1 93 42
Carn Brea Fluccan....,..,, 10°6 13:3 78 60:1
Consols Fluccan ..........,. 56 18:2 11-6 54:4
Wheal Clifford,........0." 96 19°5 7 537
North Basset ......d.0.0000. 10 16°5 24 41-1
Walwpaper Ao do ne 4:4 17:5 8:9 53°5
W. Mary Consols .....,... 10 28:7 19°5 29-5
Tresavile Barrier .....,.. ‘ 8:7 15+1 10-3 57-2
Bedford United Mines .,, 10 32°8 176 BF,
Doleoath ....0-...0606 Of 10 82 15:3 26°6
Great Work,...........5 oad | 14:1 18-9 14 43°5
We Maidens s.9,... 04000 s10c6 56 171 11:8 54:0
Camborne Vean ............ 87 34:8 13-2 28-5
The mines here named may contain most of the minerals enu-
merated in the first table in small quantity ; but when the whole
Mr. J. Napier on Copper Smelting. 49
contents of the vein are crushed and mixed, they assume a same-
ness of character. Many of them contain lime, alumina, and some
other earths; most of them contain antimony; some of them
tin, arsenic, manganese, &c., all of which play an important part
in the after operations. There are also a great many other ores
not referred to in the above table, all of which, when mixed, as
they must be in smelting, exhibit the same general character.
Besides these ores of Cornwall and Devonshire, great quan-
tities come from Ireland and different parts of Wales: and
vast quantities are also imported from other countries, all of
which coming into the smelting-house to be worked up together,
must be taken into account in the general description ; and as
many of the foreign ores are very rich in copper, more so than it
is found ceconomical to work by the ordinary process of smelting,
the smelter is thus not only enabled, but somewhat necessitated,
to buy poor ores to mix with and dilute these rich ones. Thus
very poor ores in this country, which might otherwise have been
unsaleable, are required; so that the importation of rich ores is
not, as has been often asserted, destructive to our poor mines.
Copper. Tron. Sulphur.
——_—_———— | |
Name of mines and locality.
Trish Ores —Knockmahon .....2..5046 83 19-9 14-2 57°6
BO ii) sdietidvessce 11-5 16°6 16-7 55-4
ASHEEM cacvocedatsciecscsl) aD 12:3 10:2 58-7
Berehaven 10:2 10:8 14:8 63:9
Holyford ..... 8:2 36°3 40'8 14:3
Anglesea.—Parys Mines ......+ 220 | 272 | 280 | 208
Cuba.—Cobre ..ccccccceesseeees 23°2 30°4 20°8 19-6
dnd) | nba De cabasese a biae Eve seab 13-5 34-1 21:3 311
sEheee les seaves eeiteettssccs|) Thon 33°8 28:8 19-2
Sf Bee See pitccedtiecsevselt 1 LAc4 28-0 24-0 34:0
Cobre Dust ..... Adias aaUee soap 12-0 24-3 18-1 44-2
Cobre Rough Ore ....seseeeee 19:3 18:3 20:7 40°]
Cuba Dust ....... Pa seclt 4 26-1 271 32:0
Cuba Rough Ore ........ “AES 20°5 28-4 30-2 21:0
Chili.—Chaco Mines .....ceeeeseeeeess 58°3 14:9 23:7 30
DOOPIANO i adene scp sosonepates sso. , 4 19:3
54 PA Dipl SSR 16°8
Sek ichdbbasesustsaselieye soe ss 14:0
Le ae ae 3-2
wat ae 46
New Zealand ...+.+..... a 18:3
obs ss dudethaasacedeckankeueys sed 53°3
Australian Ores.—Burra Burra ...... ( . any
44-0 42 A ee 20-2
37:0 47 aan 38°6
22-0 33°7 sir 23°2
16-0 57 xt} :
dveve 18°] 3-0 ray cks
32'0 195 “fae
22-0 17:8 Bas
176 18-4 7°.
Phil, Mag, 8. 4, Vol, 4, No, 22, July 1852, E
50 Mr. J. Napier on Copper Smelting.
The preceding table of the same constituents in ores from other
mines brought into market, will bring out the distinguishing
features of the variety of ores the smelter has to operate upon.
By comparing this table with the former, we find a far
greater variety of ores, and, taking the mines separately, a far
more distinctive character, as will be observed by comparing the
Cobre, Chili, and Australian together. At the same time there
is a decided sameness about the character of the ores from the
same locality, as will be seen in the Irish, the Cobre, and Burra
Burra. As the latter mines are probably the wonder of the pre-
sent age in regard to their richness and abundance, and as many
of the ores found in them are too poor to be brought to the smelt-
ing-works of this country, I here subjoin a table of analyses from
this mine alone, furnished me by my friend Mr. A. D. Thomas,
chemist at the Burra Burra smelting-works.
Burra Burra Ores.
oniet Pate | Cate | aie, [Scat] ro
22°50 2:90 10°94 2:00 61:70 | 100-04
18:75 40:00 17-44 175 22:00 99°94
18-75 31:40 12-60 1:50 37:00 | 100-75
25°37 28°35 16°15 1:00 28:50 99°37
23°75 8:55 11°05 1:00 55°55 99°90
27:00 | 35°00 12-20 5:00 20°50 99°70
19°75 25:00 9:40 4:20 41-50 99°85
25-00 19°35 12:50 3°20 39:50 99°55
25°25 34:00 10°50 3°70 26°50 99:95
10 26:25 20:25 11-20 4-00 38:00 99°70
11 25:62 34-68 13-40 1:80 24:50 | 100:00
12 21°31 88:25 8-94 2:50 29:00 | 100-00
13 20:60 48-00 12-00 2:40 17:00 | 100-00
14 18-75 36°85 8:00 3°40 33°00 | 100-00
15 19-00 39°50 11-00 1:40 32°00 | 102-90
16 26:50 43-00 11:00 2:00 17:50 | 100-00
7 36°85 9:00 13°46 1:10 40:00 | 100:37
18 20:00 | 35-00 12°50 1:50 31-00 | 100-00
19 34:00 7:00 15-00 2-00 42:00 | 100-00
20 18-12 37°80 13-88 171 28:50 | 100-00
21 18-75 28°50 12-70 2°50 37°50 99°95
22 35°62 2:00 17:00 1:90 43°50 | 100:02
23 18°75 32°85 12-90 2:50 33°00 | 100-00
24 18°75 34-15 11-10 1:00 35:00 | 100-00
25 18°75 32°85 16:10 1:30 31:00 | 100:00
26 26°37 35°55 12-60 1:50 31:00 | 100-00
27 21:25 | 42-75 16:00 2-00 18-00 | 100-00
28 23°41 33°75 16:60 2°30 22:50 | 100°56
29 21:90 40°50 17-40 1:70 18°12 | 100-00
30 37°62 10:35 17°83 1:70 32:50 | 100-00
31 34:40 7°20 17:50 2:00 38:50 99°60
32 29°30 12:15 12°10 2°40 44:00 99°95
33 32:25 20°25 17:10 2:30 28:00 99°90
34 30°60 10:00 13:80 2°10 43:50 | 100-00
35 34°40 6:50 15:10 2-00 42:00 | 100-00
WOON Ste ODD
It may be remarked, that the ores given in the above table
Mr. J. Napier on Copper Smelting. 51
are not selected specimens, but are taken from and after the mass
is crushed and ready for the furnace; and they are mostly all
poorer in copper than those from the same mines that are im-
ported into this country.
The two grand divisions of ores in the smelting-house are those
with and without sulphur, constituting oxides, carbonates and
sulphurets, a few of which we will briefly describe. There are
two oxides of copper, the black and the red. The former, as its
name denotes, is a black erystallme mineral inclining to brown
and blue; it often occurs as a friable mass, and forms a sort of
coating over the surface of other ores, such as the sulphurets
when they have been subjected to exposure to air and water.
Black oxide is not found in great quantities in a pure state, but
in combination with iron it is abundant in some of the Australian
mines. When pure, the composition is—
Copper . . . 79°82
Oxygen. . . 20°18
100-00
It is abundant in the Burra Burra mines. The average of a
good many analyses of selected specimens may be stated to be—
Copper | sie. | ante
Cpyeen | Fr te tak
Protoxide of iron. 4:3
Siliet: | vecl. |code
99°5
Red oxide of copper differs from the black oxide by containing
less oxygen; it is more abundant as an ore than the black, has
a reddish-brown colour, often approaching to rich red, espe-
cially when crushed, When native copper occurs, it is generally
surrounded by red oxide; it is associated in the Australian mines
both with the black oxide and carbonate. When pure its com-
position is—
Copper . . . 888
Oxygen | och. 4d L'2
100°0
This oxide has occasionally been termed (ile ore, said to be
from its colour; but we think this a corruption. There are
many poor ores which have the same colour, in mass, from the
matrix being a rich red clay, red fluccan: the copper made
from some of these ores being inferior, is termed tile copper,
hence probably the error. We have specimens of red oxide
from Cornwall forming small veins through other qualities of
ore, which contain upwards of 82 per cent. of copper, with a little
silica and iron as impurity, A massive specimen from Burra
E2
52 Mr. J. Napier on Copper Smelting.
Burra forming a vein between black oxide, gave—
Red. oxide... 01; +, 98°
SUIGH Fissecin vials sa) sft Aan SIS
Oxide ofiron . . Il
99°8
A specimen from Chili diffused through carbonate of lime,
gave— ;
Red oxide . . / . 483
Carbonate of lime . 48°5
Oxide of iron’ 2s) 12
NilfeHP10%, MT ey mSToLb Sis
99°3
The colour of this mineral is a rich red: the lime is mecha-
nically mixed, and can be seen by the microscope.
There is another red ore which we have seen in considerable
quantity, resembling much the red oxide in appearance, only
wanting in lustre and specific gravity ; it generally occurs, mas-
sive, having occasionally fine red veins through it. A specimen
from Cornwail gave—
Oxide of copper... 248
Peroxide of ron. . 51°5
Silicaizid ylese bas srdOQ
Water bis aow dirty .bsidsh
99°4
A specimen from Chili, of a similar colour and appearance,
gave—
Oxide of copper . . 35°5
Peroxide of iron . . 30:2
Nifeg~ su: . . 180
Carbonic acid... ... 7:2
WY StEES eee ae ee
99:9
These two would rank as tile ore from the colour, but would
produce excellent copper.
Carbonates of Copper are of two kinds, blue and green, and
are very easily distinguished by their appearance; or they may
be easily tested by effervescing when put. into an acid. The
blue carbonate is of a deep azure; when crystallized; the azure
blue is permanent ; but when massive, the colour is much paler,
especially when dry, becoming very rich and deep when moistened.
This ore may be easily distinguished from the blue vitreous ore
from the colour being more intense; it is also softer when
scratched with a knife.
j
[
;
Mr. J. Napier on Copper Smelting. 53
Green Carbonate of Copper is easily distinguished by its rich
grass-green colour; it has a considerable lustre, is harder than
the blue carbonate, and the crystals are generally fibrous. A
variety of this mineral, which is generally found in nodules formed
of a series of concentric layers, is known as malachite, which, when
cut and polished, is of great beauty, and is consequently used
for ornamental purposes... The Russian nines were long famed
for their malachite ore, but it is now found in great quantities in
some of the Australian mines. The; difference of composition
of the blue and green carbonate) of copper is, that the one con-
tains more chemically combined water than the other, which is no
doubt the cause of the difference in colour, The following is
their composition when pure :—
Blue. Green.
Copper oxide... 70 70°5
Carbonic acid. . . 24 18:0
Waters oval av doulw 96 11:5
& 100 1000
~ For the composition of the various carbonate ores, we refer to
the table of Burra Burra ores.
Sulphuret of Copper.—This is a very abundant ore, and has
a great many varieties ; the colour is lead-gray ; it is vitreous in
appearance, and compact, often assuming a blue tint upon the
surface ; it is very heavy, and easily distinguished. As an ore,
it is generally associated with iron and silica; it is an abundant
ore in Chili. A great mass of this ore, which was exhibited in
the Great Exhibition, gave—
OPPEl es) so: Sneed
Sulphur. . .. 25
aS Pr
ALP ao le ian ad
100
It is often found richer than this, but this analysis may be
taken as the average composition.
Gray Copper Ore is named from its having a steel-gray colour.
It isa very common ore of copper, and is the principal mineral
found in some of the Cornish mines. This mineral is very variable
in its composition, scarcely two localities giving the same. The
following analyses will illustrate this variety :—
Cornwall. Devonshire. Algeria.
Copper... 4) 155 12°5 20°3
Sulphur... . 28'7 15°6 14°2
Tron» vecosh frre clot? 15-0 46
Antimony. . . 56 4°], 75
Arsenic. . . . dl 08 5:0
Zine 3 We ode lel
Benet tthe GG 516 47°3
981 99°6 1000
54: Mr. J. Napier on Copper Smelting.
Copper Pyrites.—This is by far the most abundant ore of
copper brought to the smelting-works. It is easily distinguished
by its rich brass tint from iron pyrites, which is generally not so
yellow ; neither is it so hard, copper pyrites yielding easily to the
knife. The two pyrites are often mixed together ; and when so
in a massive state, a trial of the hardness may give some idea
of the quality of the ore. The composition of copper pyrites
is a double sulphuret of copper and iron chemically combined.
When pure, it is composed of—
Coppers.) See Op oars
Stale hee? tO te Loe ae oe
TNONORe et ete OT ee Oe
100
As an ore, it is almost invariably associated with iron pyrites.
The quantity may be easily ascertained by an analysis being
made for the quantity of copper, sulphur and iron. As an
illustration, take what is termed Cobre dust, which is a mixture
of iron and copper pyrites. A fair sample gave the following
composition :—
Copperiisise. on. shih torch eels
Brant genie bem uveelse
Sulphurysiods ut). gintasorR6
Silicas 2 ee ee 8a
100
The copper, to form copper pyrites, will require—
Coppaband bie oes oie 14
Tron: bine.evod-hodaatioith wee
Salphar oro ue-owd brlaccebas: why
leaving sone a as iron pyrites, which is not far from
being correct; the composition of that mineral bemg 28 iron
and 32 sulphur; but im analyses of copper and iron pyrites
mixed, the iron almost always prevails, probably from a portion
being combined with the silica. We thus see, that by observing
the chemical character of ores, much may be done, even in com-
mercial samples, to distinguish the kind of mineral present ; but
we shall have occasion to refer to this subject more fully in future
papers.
To return to the obtaining of the ores from the mines. When
the ores are raised from the mines, they are broken up and
dressed, separating by mechanical means, as far as possible, the
earthy matters from the mineral; they are then crushed into
ane) bie, and collected into a heap preparatory for sampling
or sale.
atti tae
Mr. J. Napier on Copper Smelting. 55
Each smelter has a resident assayer near the mines. All the
ores to be put up for sale on a given day are announced; and
two or three weeks previous, the different assayers, or others
appointed as samplers along with the agents appointed by the
sellers of the ore, proceed to the yard where the ores are, and
take samples, which is done by taking a portion from every part
of the heap, mixing them together, grinding the whole fine, and
spreading it out upon the ground. It is then divided by lines
drawn at right angles thus—
The two opposite portions, such as 1
and 3, are taken, the others thrown back
into the heap. This is again repeated
with the parts kept until the quantity
remaining be sufiicient to allow every
sampler about 1 lb. weight. These sam-
ples are carefully examined bythe assayers,
each for his own employer. A few days
before the sale takes place, the assayers
meet, and a list of the lots taken, with
the sellers’ produce, according to assay, is annexed ; each assayer
gets a copy of this list, which he sends to his employer with
his own private assays and remarks. The sale is effected by
what is termed ticketing. On the day appointed for sale, the
purchasers and sellers meet, when a neutral person is appointed
to the chair, who is furnished with a list of the various lots for
sale. He begins by reading over the number and particulars
of the lot, when each purchaser writes upon a slip of paper the
price per ton of ore he offers, and hands it to the chairman.
These are read out and marked down, and the highest bidder is
declared purchaser ; should two or more bid the same, the ore is
divided among them in equal parts. No second bid is allowed,
nor any parcel of ore withdrawn. By this simple means, many
thousand pounds’ worth of ore are sold in a few minutes. The
question has been put, whether this be a public sale. Certainly no
stranger is allowed to bid. An intended purchaser must give a
month’s notice previously before being allowed to offer, to ascer-
tain the responsibility of the party ; but what common law would
say is doubtful were a purchaser present with cash.
After the sale is over, an account is printed of the particulars
of the sale, containing every offer; by which means, and com-
paring past accounts of sales, a very accurate approximation may
e made of the stock of each class of ores which any of the pur-
chasers have on hand; this does much to regulate the market,
for a certain class of ores is sometimes of more value to a pur-
chaser than at other times; and the object of the other buyers
being to make the ore as dear to his neighbour as possible, the
value of the ore is thus maintained. The following is a copy of a
ticketing paper, which will illustrate our remarks :—
9 SI OFFI
0 S SI “10 OL FI 0 91
0 OLZ@ 0 81
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0 ore "ig. Sr Ex Orne
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LO © 84S S22 10 -<01
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9 10 0 F110 © ello «
0 10 2180 O18 \o 61
0 10 #18/0 O18 lo Tt
9 30 6 8/0 ¢ 810 OI
0-0 118 /0-¢-$ 1/9 Zt
9°20 £810 ¢ gio FI
9 0° 9 510 ¢ PID *F
0 9 8t b110 SE ello FI
0 ZO 1 el0 0 et9 FT
9 €0 SI F110 0 #19 2
9 00 0 e10 ¢ ato z@
9 10 I 10 ¢ eto FF
010 1 FIO ¢ E19 FI
010 0 gtlo ¢ eti9 z
10 OL StO ¢ 19 FI
‘pp esp
*ss00 | apt
“Xxq
Tigpwmoonw +o +
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ecoooeococoec 3
——
rI\°
sas 3 ag Dee 5 22
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auyog | ‘Op yehoy} 10780,7
ac SOUTWL | ‘SUNRITTIAA
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F6LF
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9 110 0
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SI 1/0 OF
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gt rly cy
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& FO LI
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‘TON [109 xoddoo] *suog pure
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4u10 ZI 91/0 OL 91/0 6I “8%
£\0 912|0 OL Z lo sereseess BETS 19qS90N0]H *
E10. ZI S10 OT ZI ZO FI EI) t1z 198
110 6 S110 OT ZTlo Zo Sr Erté
80 £ sjo 3g 410 0 sit “P8090 —*Bqny
S1l0 ZI FIO SI FIO FLO SI Fl fez \g¢ “S [6S § ‘st
FII0 SI FII0 & FIO FIO 91 FU teZ\Ig ft wnrssna.ug “LE
e110 #1 S119 St 1/0 €l0 SI et} €1z 09 5
€110 SI S10 OL eI E10 0 FILLETS 99 |“ uosuang wong
8/0 918/10 SIs 8 |0 0 8 | tI 166 <
gio £18 |0 618 80 0 8 | PI OL “
8|0 818 |9 © 6 8/0 0 8 |2FLILOL ah
8/0 F18|/9 & 6 610 0 8 | EFL FOL > ‘II
80 O18 9 88 0 8 810 O 8 | FFI gor | “2oyPMtg ApvT “Ol
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£110 OL FII9 OL FI cl ar ‘
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£10 OL FIO O FIO OL Stilo OT etl Fezlog wefan e0asyqg—IQ0Q *]
le ge So Re eo Ve F
‘09 put jog rzoddog}:a0np | +40
16 “SOUT
td *s % bah
"LI Aunung ‘vasunng yo pos pun ‘Qg% wequosag payduns ‘sang uaddoy
Mr. J. Napier on Copper Smelting. | 57
The origin of this mode of sale was lately given in the
Morning Herald, from which we extract the following notice
of it :—
“ Origin of the Ticketing for Copper Ores.—About the year
1700, some merchants at Bristol bought the Cornish ores at
prices varying from £2 10s. to £4: per ton. About twenty years
afterwards, other parties, at the same place, covenanted with
some of the principal mines to buy all their copper ores for a
term of years at a stated price. About the years 1725=27, great
quantities of copper. ore- were raised from three. mines-- Hue
Fortune (in Ludgvan), Roskear (in Camborne), and Pool Audit
(in Illogan)—the produce of which mines were to be sold to the
few buyers at their own price. _ The four copper companies then
existing were the Brass Wire Company, the English Copper
Company, Wayn and Co., and Chambers and Co., who being
. united and confederated, had it then, as their successors have at
present, their own way. They were interrupted by a gentleman
from Wales, who visited the country in order to improve his
business. At that time, 1400 tons of copper ore, which had
been lying unsold at Roskear and Huel Kitty, were offered to
him, for which the associated monopolists would give only £4 5s.
per ton. So contracted were the principles of the mmers in
those days, that they obliged the purchaser to deposit a sum of
money equivalent to the supposed amount of their ores, before
they would consent to weigh them off at the advanced price they
agreed to take. 1400 tons of ore were purchased at the ad-
vanced price of £65s. perton, which was paid for in cash ; the
returns on this were over 80 per cent. What must have been the
profits of the companies confederated to serve their own interests
without limitation or control? ‘This new comer then purchased
900 tons more at Roskear, at £7 per ton; and in less than six
months: before. he left Cornwall, he purchased 3000 tons, on
which it is supposed. he made a profit of 40 per cent. Soon after
this the buyers and sellers mutually agreed to ticket for all cop-
per ores which should be ready for sale at stated periods, and
the highest bidder or ticket should be the purchaser. On the
very outset of this compact, 300 tons of ore, belonging to the
same mine, were to be ticketed for in Redruth, when the agent of
the mine having absented himself beyond the limited hour of
sale, a certain gentleman, of great address, power and fortune,
declared himself the purchaser, by private contract, at £8 17s.
per ton, when one of the ticketers produced his ticket before all
the company, whose offer was £9 17s., to the shame and confu-
sion of all the adventurers. ‘To this nefarious system is to be
ascribed the present mode of ticketing. The proprietors found
themselves in a distressing and ridiculous predicament, possessing
a commodity whose value they could not ascertain ; and the
58 Mr. J. Napier on Copper Smelting.
buyers formed themselves into a confederacy, the most pernicious
and destructive to the mining interest. The secret transpiring,
other companies were formed, and a better price was given for
the ore, yet far beneath its just value. At the ticketing day
then (as now) a dinner was provided at the expense of the mines,
in proportion to the ores they had on sale; and the system ap-
pears to have experienced but little modification since it was first
mtroduced.”
Formerly another column was in the ticket, marked standard,
giving the relative value, which indicated the rise or fall of the
ore at once. To obtain this, some arbitrary sum was fixed as
the smelter’s cost for obtaining the copper, and the standard
then deduced from the price given; but the constant misappre-
hension of the standard led to the suspicion, that it was a mere
scheme to puzzle and lead the miners astray as to the real value
of their ores. The fixing of a standard for general comparison
was exceedingly useful for all parties. The true standard cannot
be fixed, each smelter having his own standard, and this is
always varying, as a rise or fall in coals, wages, &c. will change
it ; and this every smelter keeps to himself, which is the safeguard
of the miner. Notwithstanding, from long experience and a same-
ness in working, with attention to the market, an average rate
may be easily attained for bidding at the ticketings. The fol-
lowing may be given as near to that rate at present, and also the
method of procedure for fixing the price to be offered for the ore:—
1. Fix the price which you determine the copper contained
in the ore shall yield when delivered into the works; say, for
example, you fix upon £65 per ton, and the ore to be bid for has
ray per cent. Multiply the per-centage by the price, and divide
100 :—
“ 65 x 144=918+100=£9 3s. 7d. per ton of ore.
But there are 21 ewts. given to the ton, and other general
allowances amounting to 7 per cent. to be added, makmg—
18s. 6d.+ £9 3s. 7d.=L£9 17s. 1d.
2. From the above sum is now to be deducted the returning
charges, which are the net cost that practice has shown for
smelting such an ore, and this differs with different smelters, but
for illustration we keep by the rule. An ore of 9 per cent. pro-
duce cost 22s. per ton smelting; ls. per ton is added for every
per cent. above, and 1s. deducted for every per cent. below 9.
Thus 142 per cent. will cost 27s., which deducted from the
£9 17s. 1d. leaves £8 10s. 1d. as the sum to be bid for the ore.
A little less or more is given according to requirement. Thus
the purchaser is guided by the general standard deduced from
past sales; and if he, by any improved method or otherwise,
smelts at a lower rate, the profit goes into his own pocket.
The ores, when bought, are taken from the place of purchase
Second Report onObservationsof the Aurora Borealis, 1850-51. 59
to the smelting-house at the cost of the purchaser. They are
all carried to Swansea or the neighbourhood, where almost all
the smelting-works are placed.
The ores coming from Ireland, Wales, and abroad are taken
to Swansea, and there crushed, sampled, and sold in the same
manner as described for Cornwall. There are now generally two
sales each month in Swansea ; and nothing can show better the
great increase of imports of copper ore into this country than a
reference to the sales at Swansea. These sales began about the
year 1815 ; and according to an interesting table lately published
by Mr. Polkinghorne, there was sold in that year £19,203 worth.
The average money value of these sales for five years, since 1819
to 1848, stands as under :—
From 1819 to 1824 . . £83,713
From 1825 to 1830 . . 82,792
From 1831 to 1836 . . 168,785
From 1837 to 1842 . . 628,622
From 1843 to 1848 750,403
The increase of the money value of the ores sold in Cornwall
is about one-third in the same period of time :—
5 years ending 1824, being £742,508
5 years ending 1848, bemg 999,529
The methods by which the ores are assayed will form the sub-
ject of the next communication.
VIII. Second Report on Observations of the Aurora Borealis,
1850-51, made by the Non-commissioned Officers of the Royal
Artillery, at the various Guard-rooms in Canada. By Captain
Lzrroy, #.4., F.R.S.*
EGISTERS of Aurora have reached me from the following
quarters :—
Latitude, Long.
ee
a Peel’s Riverssrey04- Oct. 1850 to Apr. 1851 .,.)Mr. A. Peers ....0000 67 27N,|8 58 W.
@ YOUCON © ....c0cce00e January to May 1851......|Mr. Hardisty......... 66 0 {9 48
a Fort Good Hope.../November 1850 ..........4. Mr. McBeath ...... 66 16 =|8 34
a Fort Confidence ...|Oct. 1850 to Apr. 1851 ..,|Dr. Rae ...+ssse0. weet 66.54 17.55
a Fort Simpson ......,Oct. 1849 to May 1850 .../Dr. Rae vcseeceeeeeee 6151 |8 6
a Fort Simpson ....., September 1850 ............/Mr. Bernard Ross.
2 -, J |Messrs. R, Campbell)
a Pelly and Lewis ...|Dec. 1850 to Apr. 1851 { mgr Poe igs isn }o1 30 |s 40
a Fort Chipewyan ...|Noy. 1850 to Apr. 1851.,.|Mr. J. Anderson ...)° 58 43 |7 25
b Moose Factory...... June 1850 to Mar. 1851...|Mr. Clouston........., 51 10 {5 24?
b Martin’s Falls ...... Sept. 1850 to Mar. 1851 ../Mr. Wilson ......00 5152 «5 47
6 Nipegon ....4sss++-.|1842 to April 1850,....,. +-|Mr. J. Anderson.
6 Matawagomingen ..|July 1850 to Mar. 1851.,.|Mr. Colin Campbell.) 47 30? |5 28?
4 Michipicoton ,,....|Nov, 1849 to July 1851.../Mr. Swanston ...... 47 56 =|5 40
* Communicated by the Author. For First Report, with Instructions
for Observing, see Phil. Mag., June 1850,
60 Captain Lefroy’s Second Report on
To each and. all of these gentlemen, as well. as to those who
may haye kept journals which haye not yet reached me, I beg to
tender my warmest thanks. Nothing can exceed the care and
attention displayed by many of the registers, and thei interest
has fully equalled my expectations. Without meaning to draw
inyidious comparisons, 1 cannot deny myself the pleasure of
especially naming here those of Mr, Swanston, Mr. Clouston,
and Mr. Anderson ; the first of these isa model of completeness
and conciseness, Mr. Swanston having generally recorded the
state of the sky and the weather every hour from dark to 10 P.M.,
and in terms which are always definite and expressive.
The registers have been continued at the Military Guard-
rooms of the Royal Artillery in Canada, and at a great number
of stations of observation in the United States. I have now in
my hands, through the kindness of Professor Henry, Secretary
to the Smithsonian Institution, returns from upwards of a
hundred observers, for 1849, 1850, and part of 1851, at stations
scattered through all the States, from the Atlantic to the Mis-
sissippl. Not having received observations from any of the sta-
tions on the Saskatchawan or Lake Winnipeg, there is a pretty
wide blank, extending from Lake Athabasca to Lake Superior,
in the chain by which it was hoped to trace and identify dis-
plays from the polar circle downward to Canada, but I trust in
future years some at least of the intermediate posts will oblige me
with a journal ; and if each observer will bear in mind that others,
hundreds, and some of them thousands of miles off, are noting
down the features of the very displays he may be looking at, as
it appears to them, and that from a comparison of all these ac-
counts it is hoped to arrive at definite views concerning this most
singular phenomenon, he cannot fail to see the value which
every clear, distinct, and definite record of facts and particulars
will possess, and to acquire a greater interest in the subject than.
ie penal repetition of familiar descriptions might otherwise
afford.
It has been often stated vaguely that aurora appears every
clear night. This is certainly not true of any one station, as far
as the earlier hours are concerned; we are still short of proof
that it is true in the widest meaning; indeed, the statement, if
true, would carry little weight with it without the addition of
dates, facts and particulars. These, however, our registers pro-
mise, for the first time, to supply. Observations begin to be
general in October 1850. In that month we have evidence of
it every night except five, 20, 21, 22, 23, 26, one of them
clouded everywhere, one of them full moon, the rest partially
clouded. In November 1850, every night but two, 22 and 23;
the former, however, of these was generally clear and no moon.
Le
Observations of the Aurora Borealis, 1850-51. 61
In December 1850, every night but five, 5, 10, 18, 19, 20, but
all the displays of a feeble character. In January 1851, every
night but two, 5, 12; many of the displays very feeble, several
of them seen only by Mr. Anderson at Athabasca, and on the
whole a much smaller proportion than usual, extending to low
latitudes. In February we have it every night*, some of the
displays of great beauty, although I imagine they will have been
far exceeded by those of February 1852. The display of Fe-
bruary 18th, 1851, was one of those remarkable instances of the
simultaneous absence of cloud, and intense development of au-
rora over a very large part of the northern hemisphere, which,
from thei frequent occurrence, appear to have more than an ac-
cidental connexion. It was seen at every station, with excep-
tion only of the Pelly Banks, from the polar circle to the United
States, where no less than thirty-eight stations have forwarded
accounts of it to the Smithsonian Institution ; it extended also
to Europe, having been recorded at Sandwick Manse, Orkney.
The display of February 28th was almost as universal. It is
remarkable that in both cases the phenomenon was first seen,
in absolute time, at the most eastern stations, notwithstanding
the earlier commencement of darkness at the extreme north,
where the difference of latitude in some cases more than com-
peusates the difference of longitude; it would appear from this
that the aurora does not commonly appear at a station upon any
meridian until that meridian generally is in darkness; a result,
which, if established by the whole body of evidence, will be both
new and interesting. For example, in the following list I have
entered the hour of sunset in mean time of Gottingen at each
station, and the hour at which the aurora is first recorded in the
same; it is not to be supposed that each observer seized the
exact time of first visibility, but in two of the examples at least
the general result is sufficiently clear, namely, that it was seen
at the lower and eastern stations sooner than at the northern
but more westerly stations, although there is no reason to be
given why it should not have appeared at the latter as soon as
at the former, daylight having ended there.
* Every night but two, February 2 and 16,
62 Captain Lefroy’s Second Report on
Table I.
Feb. 18,1851. | Feb. 28, 1851,
January 27, 1851. © Dec.—113. © Dec.—8.
© Dec,—18$°. Eq.—13m, Eq.—14m, Eq.—13m,
Ww.
long. | Sunset, | Aurora | Sunset.| Aurora | Sunset, | Aurora
N, lat. | from Git- first Git- first Git- first
Green- | tingen. | seen. |tingen.] seen, | tingen. | seen.
wich
o 3 .} h mj] bh mj h mj} bh mj) bh m m
Toronto ...+0+.....|43 89} 5 17 |10 56)19 Oj}11 26)14 0/11 39)16 0
FAWIIRS Uaseagasusees 44 39} 414/10 1]...... {10 18}11 49
Quebec ......000.5. 46 49] 4 45 |10 14} 14 25}10 85/12 24/11 4/15 35
Newfoundland ...|47 83| 3 381 | 8 58] ...... | 9 32/20 11] 9 48/12 40
Michipicoton ...... 47-56-40 tt Geer 1] 50)16 40}11 57/13 55
Il 37) 12 49
12 0|13 1
13 24}15 25
Moose Factory ...}51 10} 5 24 |10 389} 14 54} 11 37} 12 44
Martin’s Falls...... 51 52) 5 47 | 10 58) 14 30/11 386/13 1
Athabasca .....4..- 58 43) 7 25 }12 3/14 30)13 16/15 55
Lewis and Pelly...|61 30} 8 40 |138 8/21 30/14 16] ...... {18 41) 15 58
Fort Simpson...... GLO Ss” Gls Sr ia. [le 1a
MONEON ees ccccase 66 0} 9 48 }13 21/20 0) 14 56)18 58) 15 27118 38
Fort Confidence...| 66 54) 7 55 | 11 21)17 0)12 55/16 25
Peel’s River ......|67 27] 8 58 {12 19/16 38|13 50/17 38) 14 31 Jatdark.
I do not offer these instances as conclusive, but they are
somewhat remarkable ; and I may state, that, having marked the
Gottingen hour of the first appearance against every observation,
the great majority give direct support to the inference I have
drawn, and there are few or no instances contradicting it. The
question will soon be decided if the time of commencement of
each display is recorded, and a note also made of the latest hour
at which it may have been noticed that there was no aurora.
For example, the observer takes a look out at 7 P.M., no aurora ;
again at 8, aurora, which is duly entered. In this connexion,
the fact that there was no aurora at 7 is almost as important as
the fact that the phenomenon was visible at 8, and should be duly
entered. On the 29th of September, 1851, at 6" 30™ p.m., there
was no trace of aurora at Toronto; at 6 36™, a brilliant, heavy
serpentine band occupied the northern sky. In this instance,
and in various others, the time of appearance is fixed to five or
six minutes, and if at any northern station it happens to have
been fixed with anything like the same exactness, the question
will be answered.
In March 1851, we have evidence of aurora every night save
three, 13, 17 (full moon), 19; these, however, were pretty gene-
rally clear nights. Registers for April 1851, have reached me
from a few stations only, but as far as they go give evidence of
aurora every night save four, 4, 14, 15 (full moon but clouded
everywhere), and 21. The 16th of December is the only instance
Observations of the Aurora Borealis, 1850-51. 63
in the winter of aurora seen in Canada which escaped notice at
every northern station; the number seen at northern stations
which do not descend to Canada is of course considerable, as
will appear from Table III.
Table IT.—Showing the number of nights the aurora is recorded
at each station m 1850 and 1851, and the total number of
nights in each month in which there is evidence at present to
show that the phenomenon was developed somewhere or other
on the American continent. The returns will, no doubt, be
extended, and some observations at present omitted as doubt-
ful be confirmed, and included in the totals at certain stations.
50. Bi 2 SIelS1815| Sl ei8) 81812
app S|E/2/2/e/2)/2/2)s)o]2/4l2
@ Peel’s River....,..0+| «2. | os dial abachiced Lavell ced |isentiane,| OV RED S
a Fort Good Hope...}... | ss. | se | saificed | ee | age |sen sae
a Fort Confidence ...| ... |... | «.. cau livaenl cae (US Ue xO
a Fort Simpson ......) 3] 5] 5 HF ee Se
@ Lewis and Pelly ...} ... | ses | soe | ose | eee “nn iene (ec jo 4
@Eake Athabasca 273] 5.0] sc. | ccc | cea | coe | coe | ces an 12/19
B Marian’s, PANS. cgeyic| dest cce} wees] venifane jpvey| ices 10 |10 | 10) 11
6 Moose Factory ...|... oie lees Maved oot bo/ G[Le Neca ILO tL Mt 1s
b Matawagomingen..|...]...]...|...|s0/../ 3] 7/4 /4] 2) 0
4 Lake Nipegon...... oe | F| 6) TT
6 Michipicoton ...... 8] 4] 3}7] 1)/6|5]2]| Ig) 3 | 2) 2| 39
ec Newfoundland...... 1] 6] 6| 1] 8} 8/}8{6]6]9] 0} 3] 52
© Quebec......seeereess 0| 2} 3) 8] 1) 8d) Gel Ge| 7c) 5c} 5} 3} 44
¢ Montreal ......6664.- Dale ania hd
C Halifax ......cscscees 1] 4] 6| 4] 3] G6 {13 |10|9 |11 | 8) 4) 79
e Fredericton .........| ... |... yoepeeeitads | exe 4)}415/51°9
e Kingston 0} 4) 1;}3}) 0}0)6)3)5)5] 1) 0} 28
e Toronto 3| 8] 3|6| 5|8)5.;|41)5)9] 3] 1) 50
¢ London, C. W. .....) 1} 3] 3/5] 8}0/3]2)]5]5 1) 0] 0| 30
ce Somerville, N.Y..... 0} 7} 9; 8 | 6] 8] 9 {14 |12 | 7} 3] 4) 87
23 19 |13 (21 (27 |25 [21 25 |27|26 26)
(a) From 16th to 30th June. (2) Observed by Sergeant Maiden at Grose Isle,
near Quebec—none observed at Quebec. (¢) Including observations at Grose Isle.
e Begins on the 30th. (e) From Ist to 18th. (/) Begins on the 30th.
g) Begins on the 21st.
* Twilight too strong. + Register ends.
64 Captain Lefroy’s Second Report on
Table IL. (continued).
3
7
6
3
8
5
d
3
5
Aono 6&6 wes
ho
iv)
to
oO
(a) Commencing on the 19th. (4) Down onthellth. (¢c) Down to the 10th.
In these enumerations, doubtful entries are not included unless
supported by an observation elsewhere in the same region. I
have added the number of observations made by a most indefa-
tigable observer (Dr. Franklin 6. Hough) at Somerville, near
Ogdensburg, on the St. Lawrence, both as properly belonging
to the Canadian chain of stations, and to show that even in low
latitudes a single observer, by great attention, may make a sur-
prising advance on the number of instances of aurora, which
attract the attention of those who are less zealous or less favour-
ably situated. The stations may be arranged in three groups;
the first comprising all those marked (a), which are from 500
to 1000 geographical miles distant from the magnetic pole; the
second, those marked (+), which are from 1200 to 1500 miles
distant ; and the third, those marked (c), including the great
majority of stations in the United States, which are from 1600
to 2000 miles distant, from the same point. Lake Athabasca,
contrary perhaps to first impressions, is the nearest permanent
station to this assumed centre of influence. Fort Confidence,
which is not a permanent station, is of course nearer; but Fort
Simpson and the other posts on McKenzie’s River, notwith-
standing their northerly position, are somewhat more distant.
Observations of the Aurora Borealis, 1850-51. 65
Table I1I.—Observations arranged according to position of Sta-
tion with reference to the Magnetic Pole. The figures under
the heading Proportion shows the per-centage of observation
of Aurora, to nights on which observation appears to have been
possible, as regards the state of the sky.
‘ b).
In first circle, a 4 to 1000 miles|| In second circles an 1200 to 1500
distant. miles distant.
n { 43 n pe
. & ! 1 r=] . i=] J : g
Date. 22. 2 3 His |e ae ts 3 lee} 8
se js°ls (8 [s/o 5 [sei2 [8 |es) g
eis 18 | jo#/ EF 2 ls |& |& les] 2
1850.
January ...... 3 12) 16 | 16 1 Sd hs LODE Ng
February ......| 1 6 10 } 12} 33 |) 2) 5]... | 20) 38} 62
March ..,..... eho aia 10 | 16 | 24 || 2 7S a as) 8 | 47
April ..2.c.00 1 O;. AS? PAG} vst Bo EDS. .de vd 6 | 62
May........ soeel Cake 2 117A ops 1 1 TA 16
JUNE: sive. <>. ] 6; 1 4 Cd BS 26} 10} 3 | 138 7 | 59
Th re reg te ete Pmewers use ag) oa (4 1b | 9 3 | 94
August....,.... biel. a pallies Hi8 [22a 7 3 | 92
oy ie 9|... |100 || & | 17a 1 7 6 | 74
os, Baas 16 11 41/979 \|\.4.).19 1]... 6 5 Wao
25 6} 3.)93}' 4) 16; 1 9 5,| 79
25 3) 3] 88)| 4/16) 1 | 107) 5 |.76
_| 28 2 1 | 96 || 4 | 15 11 5 | 79
25 1 2/93 || 4 | 17 9 2 89
ivesaiad 25°) 1 4 | '83' || 4 | 21 4 6 | 78
PS a Bi to | 82 1 16 5 | 64
are 1
1
(a) Down to the 19th May. There is no night, properly speaking, at Fort
Simpson in May; that is to say, twilight lasts from sunset to sunrise. (d) Re-
gister at Moose Factory begins on the 17th of June, (c) including Mr. Anderson’s
observations en route. (d) No observations made at Michipicoton from the 21st
of August to the 20th of September, but probably no conspicuous aurora occurred.
(©) Four stations up to the 10th, from 14th to the end, only two. (f) Register
m the 2nd to the 18th of September.
In the third circle (c) or stations from 1600 to 2000 miles from the magnetic
pole.
Phil. Mag. 8. 4. Vol, 3. No, 22. July 1852. F
66 Captain Lefroy’s Second Report on .
Table III. (continued).
1848 1849. 1850 1851 lg
FES.) aleele.laleele.|e Eels lel als
galeg| 6 (2s |22| & (2s |e2| & |s/22/ 2/4 &
Bese] 8 as Se 1.8 as p>? | 3 |85 53 EI & o
JSS/SE| 2 /OS/SE!] & JOG/SE| & /OR/ SE] & | ols
Cals| 2 og/E2) 2 (Se 134| 2 (Sk/S4) 2) 8 13
ag/e | jag/e |S jagig) © jzg|e je 424%
NANUALY ere ON ee gee Toro) osc Oo 4/9 8) 8 | 11} 9-7) 70
February ..| 13 | 1 | 14] 17]... | 17] 138] 6] 20] 1] 6 | 138/16 (127
March 13 | 1 | 14] 41] 5 | 16] 12] 10 | 22; 15| 5 | 20)18 |159
April ...... 17 17 | 20| 2 | 22) 12} 5/]17)13] 8 | 16/18 |185
May" ty. Th} | AD 0 7 az 0: |S) IS 8 9 B14 TS 40)
June. AWG: a ee 6; 9] 3 ).12) 11 6;18] 5) 3 8 j|1l |141
July) Gees 9) 1.) 10]12| 6 |18)-17 | 4] 21 7 | 6 | 13} 15-5191
August ...| 6| 3 | 9] 8| 6/14/15] 4] 18] 8| 38 | 11] 132/143
September] 7]... | 7| 12] 7} 19] 16] 3] 19] 12) 6 | 18 | 15-7148
October...| 14} 1 | 15) 12] 2 | 14) 17 1/18) 12) 1 | 18})15, |124
November | 10} ... | 10 | 12) 2 | 14] 15 Dial Sb) op Glalivear 6|12 |.89
December | 12 | 1 | 53 6 [P4— 80! [LO co 12 S12" a Ree ee
126 )11 |... |187 }44 |... [154 ) 51 |... [114 | 42
The figures in the last column are found by dividing the average of auroras in
each month, by the number of hours Jess one, from sunset to sunrise at Toronto
(taken as a middle latitude), on the 15th of that month; they show in a striking
manner the diminished frequency of the phenomenon about the winter solstice,
and its great development at the vernal equinox. The returns for the last three
months of 1851 are not all collected. ‘
The stations of observation in the first and second groups
are not yet numerous enough to decide the question, whether
the aurora ever appears in the exterior when it is absent in the
interior circles ; but in forming an opinion on the number which
extend from the interior to the exterior of them, we must not
forget, that, notwithstanding the large number of observers,
both regular and occasional, im the third group, and their wide
distribution, a considerable proportion of the entries in Table III.
rest at present upon an observation at only one station*; and
unless particulars are given, which is unfortunately not always
the case, may be reasonably regarded as doubtful. Where par-
ticulars are given, there can be of course no doubt.
The observations made under the direction of the Smithsonian
Institution begin to be general in March 1849; and the stations
are so numerous, that we ought perhaps to consider observations
to have been possible every night. Table III. has been made as
complete as possible, by including some observations. kindly
* Of the total number of 261 observations in 1850, 54 are at one station
only; of the total number of 207 in 1851, 71 are at present at one station
only—the majority of these in the third group. The proportion to which
any doubt can attach is not large.
Observations of the Aurora Borealis, 1850-51. 67
communicated by Mr. EH. C. Herrick, together with any that
were found in the Regent’s reports for 1848-49, of which par-
ticulars were given, or which occurred at more than one station
on the same evening. Also observations by Mr. Dougald Stewart
at Ristigouche, L. C. The few observations at sea at present
collected, for most of which we are indebted to Captain Oliver
Eldridge, have not yet been included.
It results from the comparison of the six winter months,
October to March inclusive, 1850-51, that aurora was seen be-
fore midnight within the first circle on 88°5 per cent. of practi-
cable nights, in the second circle on 80 per cent., and in the
third on only 48°5 per cent., indicating a rapid falling off of the
causes producing it at distances exceeding 1600 miles from the
magnetic pole.
It is scarcely necessary to say, that these simple numerical
comparisons are but the first fruits of the observations; such as
they are, however, they suggest to the mind a spectacle, which,
if true in nature, must be of wonderful magnificence. The polar
light kindling on each meridian as that of day declines, some-
times with the splendour of prismatic colouring over half a hemi-
sphere; sometimes contracting its circles and paling its fires,
for a period of days or weeks; and sometimes spreading down-
wards over the globe with an intensity of which our highest
conceptions are probably most inadequate, since, if the region of
the display is as elevated as is usually supposed, about a third
of its hght must be absorbed by the atmosphere. To pursue
the subject into all its details would lead me much beyond the
limits of such a communication as this; but I am truly anxious
to convince any gentleman who may have doubts on the subject,
that to keep, in ever so plain a way, a journal of such appear-
ances as may occur at his station, will be a most acceptable con-
tribution to an inquiry which will owe much of its interest and
value to the scale on which it is pursued ; and especially to in-
duce those to whom I have not the advantage of being personally
known, and those resident at the remaining posts in the north-
ern, middle, and extreme western regions, to swell the list.
With respect to the influence of these displays upon the
movements of the magnetical elements registered by photography
at Toronto, I may say that I find the symbols which represent,
in the abstract, ‘ total absence of disturbance,’ ‘ moderate disturb-
ance,’ ‘ considerable disturbance,’ and so on, against almost every
variety of observation, and am not yet prepared to give any
settled opinion on the subject.
1 cannot close this letter without referring to the great value
of such observations as the following by Mr. Hardisty ; which,
probably, but for this attempt to follow up the phenomenon to
its fountain-head, would never have been added to the very few
F2
68 Observations of the Aurora Borealis, 1850-51.
and much-disputed observations of the same nature which are
on record. That gentleman writes,—%“ During a voyage in the
beginning of the past winter, I saw the most beautiful display of
aurora borealis that I believe I ever witnessed. On the 2nd of
December 1850, I encamped on the banks of a moderate-sized
river near the chain of the Rocky Mountains running westward
of Peel’s River, the opposite banks rising precipitously several
hundred feet until they joined the mountains beyond. Having
no time-piece with me, | cannot speak positively as to time ; but
it would have been probably between 10 and 11 P.m., with a
fresh breeze blowing from N.E. and very cold. The phzno-
menon was evidently very near the earth, for it appeared between
me and the trees on the opposite side of the river, which could not
have been 40 feet above the level of the stream; the trees toward
the top of the hill being high above it. Large compact masses
were moving from E. to W., and bright streamers passing in the
same direction in quick and vivid flashes ; then returning to the
zenith, would from thence spread out to the N. and S. in beau-
tiful waves or clouds, and sheets of light of the most beautiful
colours, until they disappeared altogether and left the sky en-
tirely clear. Every time the streamers passed over me from E.
to W. they were accompanied by a rustling noise, such as would
proceed from the gentle waving of a si/k flag; but m returning
from W. to E. I am not conscious of having heard any sound
proceed from them.” [The Italics are the writer’s.]_ It is a con-
firmation of the very remarkable proximity of this display to the
observer, that the following are the only other observations on
the same evening, although it was clear at four or five stations :—
“ Fort Confidence.—A very faint band of aurora near horizon
in the N. at 5 p.m.; at 72 30™ it formed a pale arch across the
zenith from N.N.W.toS.S.E. ; at 8250" it exhibited a broad arch
from N. by W. to 8.S.E., altitude towards S.W. about 9° at
vertex (true bearings). Moose Factory, at 8" 40™, a faint auroral
light in N.; 95 20™ brighter, but partly obscured by clouds ; 104
still visible, never higher than 30°.”
Mr. Bernard Ross remarks of a splendid display on the 1st of
February 1850, that “although very near the earth, no sound
was audible,” but does not mention on what grounds he supposed
it to be so near.
I shall look with much interest for the observations made in
the past winter, which in Canada has been remarkable for the
number of splendid displays of aurora, and the repeated occur-
rence of some of the rarest phenomena connected with it, such
as the formation of arches of dark vapour, of which Mr. C.
Campbell has given one instance.
Magnetical Observatory,
Toronto, April 13, 1852.
[ 69 ]
IX. Notices respecting New Books.
fides Hartwelliane, or Notices of the Manor and Mansion of Hart-
well, By Captain W. H: Smytu, R.N.
Le greater part of this volume, the original object of which
appears to have been to give an account of the Hartwell Ob-
servatory, is occupied with topographical and statistical details
respecting the parish and manor of Hartwell, historical notices of
the successive Lords of the Manor, and particulars relating to Hart-
well House, its apartments, paintings, library, museum, numismata,
and Egyptian antiquities. It would be out of the province of a
scientific journal to make observations on the subjects of this “‘ Mis-
cellany ;”” but we may be allowed to say that the work abounds in
interesting matter, treated with singular liveliness of style and great
variety of erudition, and that it is beautifully illustrated by plates
engrayed from drawings expressly made by the talented members of
the author’s family. Our remarks must be restricted to the contents
of Chapter IV., which is exclusively scientific, embracing the fol-
lowing astronomical subjects :—origin and description of the Hart-
well Observatory ; meridional observations; measures of double stars;
colours of the same; the story of y Virginis; Encke’s comet.
The Hartwell Observatory, which is the property of Dr. Lee, the
present Lord of the Manor of Hartwell, whose love and patronage
of astronomical science are well known, originated as follows :—
“In December 1828,” says Captain Smyth, ‘‘ soon after I had com-
pleted my observatory at Bedford, and mounted the instruments
lent by the Astronomical Society for that purpose, it was communi-
cated to me that the telescopes, clock, transit-circle, portable transit,
and numerous other articles, which had belonged to the late Rev.
Lewis Evans, were to be disposed of by private sale. On viewing
them I was rather chagrined at the circumstance not having occurred
before my arrangements were carried into effect; especially as the
circle seemed to me greatly superior in simplicity and efficiency to
Colonel Beaufoy’s, with which I had just commenced operations. On
mentioning this to Dr. Lee in the evening, he resolved to make the
purchase, and to present the circle to the Astronomical Society, with
the understanding that it was to change places with the one at Bed-
ford; a transaction which accordingly took effect.” The transit-circle
being thus disposed of, the small transit-instrument and a reflecting
telescope were mounted on pedestals at the south portico of Hartwell
House, and the clock with the rest of the instruments were located
in an adjoining strong-room. ‘The principal results of this incipient
observatory were to create a desire in Mr. Thomas Dell of Walton,
near Aylesbury, to possess also a clock and transit-room (subse-
quently erected under Captain Smyth’s superintendence), and to
inspire Dr. Lee himself with the wish to procure more powerful
astronomical apparatus. Accordingly in 1831 a transit-room was
built at the south-east angle of the mansion, for the reception of a
five-foot transit telescope, to be employed especially in observations
of the moon and moon-culminating stars for the determination of
70 Notices respecting New Books.
terrestrial longitudes. The room is eighteen feet by twelve, sixteen
feet in height outside, and ten feet five inches inside, and has a flat
and well-leaded roof. ‘The stone piers, six feet high, and cut from
a single block of Portland stone, are erected on a brick foundation
resting on the “live ” rock, and the flooring of the room is carried
so as not to touch them. The transit-clock, by Vulhamy, has two
peculiarities suggested by Captain Smyth: the steel rod of the pen-
dulum is immersed six inches in the mercury, that both may be
simultaneously affected by changes of temperature; and the clock-
weight consists of separate cylindrical pieces, by which the moving
force may be adjusted so as to produce any required arc of vibration.
Two meridian marks (mounted, characteristically of our author’s
antiquarian predilections, one on a representation of the temple of
Janus, the other on a miniature of the facade of the Temple of Con-
cord at Girgenti) are placed respectively at the distance of one hun-
dred feet north and south of the observatory slit, and by the inter-
vention of two lenses of one hundred feet focal length fixed in the
window-sills, are viewed by parallel rays entering the transit tele-
scope. ‘This meridian appliance, the theory of which (as we gather
from the statement at the top of page 236) was suggested to the
author by Baron de Zach, has the great advantage of enabling the
observer to ascertain at all times the error of collimation of his tele-
scope, without waiting, as in the use of a distant meridian mark, for
a favourable state of the atmosphere. The method of two collima-
tors looking into each other, which is that now employed at Green-
wich, involves the same principle, and has the further advantage of
not even requiring a reversion of the transit. ‘
Three years after building the transit-room, Dr. Lee determmed
upon enlarging his astronomical means by the addition of an equa-
torial. Under Mr. May’s able engineering, a tower, solidly built,
and of fifteen feet interior diameter, was surmounted by a hemisphe-
rical dome, covered with copper sheathing, moveable on three cannon-
balls, and opening by a single shutter extending from the zenith to
the wall-plate. After some delay, occasioned by the object-glass
purchased for the equatorial being pronounced by Mr. Dollond to
be unworthy of a costly mounting, it was arranged that the telescope
employed by Captain Smyth in making the observations recorded in
his ‘‘ Cycle of Celestial Objects,” being no longer in use, should be
transferred from Bedford to the Hartwell Observatory. The object-
glass, one of Tulley’s best, is 5°9 inches in diameter, and of 8 feet
84 inches focal length. The equatorial is mounted in a very simple
manner, has hour and declination circles each 3 feet in diameter, and
is moved by clock-work.
The meridional observations taken by Mr. Epps, late Assistant-
secretary of the Royal Astronomical Society, were begun in the
early part of 1838 and continued to August 1839, when they were
interrupted by the death of the observer. The observations of 315
of the stars, many of them taken with the moon, are discussed by
Captain Smyth, and absolute right ascensions deduced from them
are compared (pp. 256-283) with the Astronomical Society’s Cata-
LPR ea
Notices respecting New Books. 71
logue, for the sake of testing their trustworthiness in the determi-
nation of longitudes, the object to which the observations were pri-
marily intended to be applied. In fact, while absolute determina-
tions of celestial positions can only be effectively made in large public
astronomical establishments, the means of private observatories may
be most usefully employed in differential observations, in which class
moon-culminations, limited to the application just mentioned, are to
be included. In 1842 the observatory was trigonometrically con-
nected by Captain Smyth, and his son Henry Augustus, of the Royal
Artillery, with Aylesbury church-spire, and by inference from the
great Trigonometrical Survey, its longitude was found to be
3™ 225-63 west of Greenwich, and its latitude 51° 48! 14''6 north.
There appear to be ample means of verifying by independent astro-
nomical observations the assumed position of Aylesbury Church, as
no fewer than three observatories furnished with transit-instru-
ments, in addition to that of Hartwell, exist in the immediate neigh-
bourhood; Mr, Dell’s, already mentioned, one erected by the Rev.
J. B. Reade at Stone, and another by the Rev. C, Lowndes at the
Hartwell Rectory.
The measures of double stars (pp. 287-290) were taken with the
equatorial of the Hartwell Observatory, the instrument being obli-
gingly kept in readiness by Dr. Lee for the immediate and particular
service of its former possessor. They are re-examinations of objects
enrolled in the Celestial Cycle, and being made by the same observer
and the same instrumental means, are strictly comparable with the
measures recorded in that work.
Captain Smyth has paid particular attention to the colours of double
stars. In the work before us we are presented with a comparison,
probably the first of the kind, of two independent series of observa-
tions of this class. It appears that the Bedford Catalogue, in which
such colours are assigned to all the objects as struck the observer
at the time of observation, reached the hands of Signor Benedict
Sestini of Rome, after he had’ been engaged on a very extensive
series of observations of the colours of stars in general, and led him
to form a table of comparisons of his own estimates with those of
Captain Smyth on double-stars. The conclusions he had already
arrived at, which for their interest deserve to be mentioned here,
were, that “of 2540 stars (those of Baily’s Catalogue observed at
Rome) the yellow stars are about half the total number, and equally
distributed ; the white stars are one-fifth in scattered portions ; and
the orange rather more than one-fifth. The red and the blue are
rare from the pole to 30° of north declination; the blue then become
numerous (=+) to the equator, especially from AX. 18" to 20;
and the red abound from 0° to 30° south declination, and A. 16
to 20%.” But it would seem, when the result of the above-men-
tioned chromatic comparison is taken into account, that such con-
clusions require for their establishment the collective observations
of different observers in different circumstances, Pages 293-298
contain a table of the colours assigned to the components of 109 of
the brighter double-stars by Smyth in the years 1831-438, by Ses-
72 Notices respecting New Books.
tini in 1844-46, and again by Smyth in 1849-51... The two lists of
English observations agree well enough with each other, but: differ
in a remarkable degree, and in a large number of instances, from
that of the observations made in Italy.. Some of the discrepancies
are adverted to by Signor Sestiniin these terms :—‘* Now, beginning
with the comparison of y Andromede, we have Smyth emerald-
green, and Sestini white ; but Herschel and Struve at another: date
call it azure. Moreover, observing it again after a lapse of two
years, and four years after Smyth, I find it no longer white, but ia
strong blue!” ‘Now see B(95) Herculis: according to Smyth,
one is greenish and the other red; but we think them both a golden-
yellow ; A Ophiuchi, by Smyth, one ruddy and the other pale yel-
low; but we take them to be both orange. The contrary occurs in
« Bootis, the components of which by Smyth are both pale yellow ;
but we deem one to be orange and the other azure.”
What can be the cause of such differences? ‘‘ The disagreements
between the tints of stars as given by Sir William Herschel and
myself,” says Captain Smyth, ‘‘ are partly accounted for by his pe-
culiarity of vision and the tone of metal in his reflectors, But lam
at a loss why refractors should differ so widely as here shown; and
therefore hope the subject will be more closely pursued than it has
hitherto been.” The explanation proposed by Signor Sestini, viz.
that the colours of the stars vary in consequence of variations of
their velocity, is not admissible. Neither are we prepared to take
the view which Captain Smyth appears to advocate, viz. that very
minute differences in the velocity of transmission of rays of different
colour, cause variations of the colours of stars, Certainly on this
hypothesis, if a new star suddenly appeared in the sky, its existence
would be announced at successive epochs by the different rays of its
spectrum, and its colour would not be permanent till the rays had
all reached our position in space. Changes of colour in the reverse
order would occur on the extinction of a star. On the same hypo-
thesis, variations of colour would accompany variations of bright-
ness. But such variation of colour has not. hitherto been detected
in stars that notably vary in brightness. It seems probable that the
discrepancies in the estimates of the colours of stars are due to
various sources of error in judging of tints, which after all form but
a small portion of their total light; such, for instance, as the
general state of the atmosphere at the time of observation; the
effect of altitude above the horizon; the effect on the eye of
the observer of the artificial light used for the purposes of obser-
ving. Possibly, also, the achromatism, of the object-glass, which,
being adapted to the solar spectrum, may not, be suitable to the
spectrum of the star, ought to be taken into account; as well as the
necessity of a nice adjustment of the eye-piece for eliciting the proper
colour of each star. ‘‘ Chromatic personal equation,” thatis, the fa-
culty in a greater or less degree of appreciating differences of colour,
must be a fruitful source of discrepancy.. Many valuable hints are
given by Captain Smyth (pp. 306-310) towards obviating some of
these sources of error, and towards fixing upon a standard scale of
a
Notices respecting New Books. 73
reference in the chromatic observation of stars. Considering, how-
ever, the many difficulties that beset this inquiry, it is impossible
not to feel the force of Sir John Herschel’s assertion, that “ nothing
short of a separate and independent estimation of the total amount
of the red, the yellow, and the blue rays in the spectrum of each
star would suffice for the resolution of the problem of astrometry in
the strictness of its numerical acceptation ; and this the actual state
of optical science leaves us destitute of the means even of attempting
with the slightest prospect of success.” (P. 301.) Perhaps an ap-
proximation by instrumental means to the spectra of the brighter
stars ought not to be despaired of. An instance is adduced (p. 299),
in which Sir David Brewster accounts for the orange colour of the
double star { Herculis by an analysis of its light.
The “ Story of y Virginis” is one of great interest, this being
perhaps the most remarkable instance in which the components of a
binary star have been shown, by the combination of theoretical cal-
culation with observation, to be acted upon by their mutual attrac-
tions. Herschel, Encke, Midler, Smyth, Henderson, Hind and
Adams, are all astronomical names that have been enlisted in the
theoretical investigation of the orbit of y Virginis. But no astro-
nomer has so diligently observed this object as Capt. Smyth. His
observations extend over the twenty years commencing with 18381.
In the month of January 1836 he pronounced it to be round, and in
April and May of the same year saw it elongated. Sir John Herschel,
ina letter from the Cape of Good Hope under the date of Feb. 27,
1836, says, ‘y Virginis, at this time, is to all appearance a single
star.” The observations that have been employed by the theoretical
calculators, reach as far back as 1718. In that year Pound assigned
the relative position of the two stars by allineation with a known
star seen with the eye directed to the sky, while the other eye was"
looking through the telescope. In the years 1719 and 1722 Bradley
made like observations. This mode of observing, as Sir John Her-
schel has shown, requires a correction for a kind of optical equation
between the judgements of the two eyes.- Other observations were
made by Mayer, in 1756; Herschel I., in 1781 and 1803; Herschel
II. and South, in 1822; Struve and South, in 1825; Herschel II.
and Struve, in 1828 and 1829; Herschel II., in 1830; and Dawes,
in 1830 and 1831, which brings us to the date of Capt. Smyth’s
observations. Subsequent to these there are observations of Dawes,
Lord Wrottesley, Mr. J. Fletcher of Cockermouth, and Mr. J.F. Miller
of Whitehaven.
Sir John Herschel attacked the theoretical problem in an ad-
mirable and well-known communication to the Royal Astronomical
Society, inserted in vol. v. of their Memoirs. He uses measures of
distance, on account of their uncertainty, only for the determination
of the major axis, making the values of all the other elements de-
pend on measures of angular position. ‘The method is in other re-
spects essentially graphical, ‘‘ the aid of the eye and the hand being
brought in to guide the judgement in a case where judgement
only, and not calculation, can be of any avail.” The first essay gave
74 Notices respecting New Books.
a periodic time of 513 years. It is, however, to be remarked that
after the date (1832) of that communication, the stars went through
a critical part of their relative orbit, and subsequent observations
were more suited to an exact determination of the periodic time.
Sir John Herschel afterwards stated the period to be short of 150
years. Miidler found 145 years, Henderson, 143. Finally, in the
volume of the Cape observations, Sir John Herschel entered_upon a re-
investigation of the orbit, and concludes the research with the following
summary :—‘‘ Comparing the orbits which seem entitled to most
reliance, it appears certain that the eccentricity lies between 0°855
and 0°880, the inclination between 28° and 27°, the perihelion epoch
between 1836°20, and 1836°45, and the period between 140 and
190 years.” It may here be remarked that the apparent eclipse of
one star by the other which was observed in 1831, was not owing
to the passing of the plane of the orbit through the position of the
spectator, for all the calculations concur in giving a small inclination
of that plane to the surface of the celestial vault; but to an actual
approach of one star to the other, for the calculations as uniformly
assign a large eccentricity to the relative orbit. Such an approach
must have enormously changed the thermotic relations of the two
bodies to each other.
It will be an appropriate conclusion to this account to put in juxta-
position Sir John Herschel’s last elements, the elements obtained by
Mr. Hind exclusively from Capt. Smyth’s observations, and those
of Mr. Adams, which take for basis Sir John Herschel’s orbit, and
are formed on the principle of distribution of errors by the method
of least squares.
ELEMENTS oF y VIRGINIS.
Herschel. Hind. Adams.
Perihelion passage .......- 1836°39 1836°40 1836°34
Ascending node.,.......... 28° 42! 20° 34! 34° 45!
Position at Perihelion ...... SePrwbes 323° 50!
Inclination to plane of pro- 30° 39! 97° 93 95° 97!
Jection ...-..- serene
eats of Perihelion from 290° 30! 300° 13! 284° 53!
Excentricityns ts Cable’ 2h3 0°8860 0°8804 0°'87964
years. years. years.
Period of revolution........ 183° 14 171°54 174°187
The astronomical portion of the work concludes with a disserta-
tion on comets, accompanied by a representation of Encke’s comet,
as it was seen by Professor C. Piazzi Smyth with the Hartwell Te-
lescope, at its reappearance on the 22nd of September 1848, ‘This
comet, like Biela’s and others, seems to be entirely gaseous, and of
such tenuity of substance that the smallest stars are visible through
it without sensible diminution of their brightness.
Ee
Hee
[ 7 ]
X. Intelligence and Miscellaneous Articles.
ON THE COMPOSITION OF HUMAN FAT. BY DR. HEINTZ.
FHE fatty acids procured in the form of a soft mass by the decom-
position of soap prepared with human, fat, were pressed as much
as possible, and the residue dissolved in a third part of its weight of
boiling alcohol; the mass procured by exposing this to as low a
temperature as possible was again pressed, and this process repeated
until no trace of oleic acid was to be found in the remaining solid
acids. This mixture of solid acids was analysed by repeated precipi-
tation with acetate of lead, and four different acids procured from it.
The first of these acids, which is most readily precipitated in com-
bination with oxide of lead, exists only in very small quantity ;
from about 25 lbs. of human fat only about 0°2 grm. were pro-
cured in an apparently pure state. It crystallized from the alco-
holic solution in small, transparent laminz of a pearly lustre; on
fusion it solidified into peculiar scale-like crystals. Its melting-
point is at 156°, and was not raised by repeated crystallization from
alcohol. Its analysis led to the formula C36 H36 O#.
Found. Calculated,
ar bOnh. 5 nies 75°84 C30 nadie 76:06
Hydrogen ..., 12°70 ee vim by alte
Oxygen ...... 11°46 Of be rgletiem ioe
100:00_ - 100-00
Heintz considers it probable that this acid is identical with the
stearophanic acid discovered by Dr. Francis* in the berries of Coc-
culus indicus. ,
The second acid, which, next to that above mentioned, is most
readily precipitated by oxide of lead, is called anthropic acid by Dr.
Heintz. From 2} Ibs. of human fat only about 1 grm, of this
acid was procured. When pure it crystallizes from the alcoholic
solution in beautiful broad laminz of a pearly lustre, melts at 133°,
and solidifies on cooling into beautiful shining laminar crystals,
The alcoholic solutions of its alkaline salts solidify on cooling into
an opaline jelly; earthy and metallic salts produce insoluble preci-
pitates in these solutions. Dr. Heintz considers the composition of
this acid as not yet placed beyond doubt; his analyses gave for the
free acid the formula 03+ HS? Ot; for the silver salt, AgO, C3#H3103;
for the baryta salt dried at 212°, BaO, C3+ H3'! 03+ HO.
Free acid, Silver salt. Baryta salt,
Ao eens po —-——_—+~—
Found. Cale. Found. Cale. Found. Cale.
Ot 75°99... 76°12 C%# 53°87. 54°41 Cs 59°23 59°24
H%? 12°40 11°94 H3! 8:47 8:27 He 9'60 9°29
Of 11°61 11:94 O* 878 8°54 O# 9:03 Pt)
100°00 100°00 Ag 28°88 28°78 BaO 22°39 22°18
100°00 100°00 100:00 100:00
Dr. Heintz considers it possible that this acid may prove identical
with the acid procured by Luckt from the oil of Madia sativa.
* Phil. Mag. Ser. 3. vol. xxi. p. 161.
+ Annalen der Chemie und Pharmacie, xxxy. 210,
76 Intelligence and Miscellaneous Articles.
The third acid is margaric acid. Heintz procured it by numerous
recrystallizations of the portion of fatty acids chiefly containing it;
it crystallized from alcohol in fine scale-like crystals, which soli-
dified on fusion in shining, interwoven needles; its melting-point
was exactly 140°.
Free acid.
pes ———— - Baryta salt,
Found. Cale.
et a sat Found. Cale.
C3+ -.75°4055 75°51 75°55 C34. 60°18 60°46
Hs+ 12°70 12°59 12°59 H35 9°71 9°77
Ot 11°90..11°90 11°86 Os 7°38 7:12
BaO 22°73 22°65
100:00 ~—:100°00
Lastly, the fourth acid is palmitic acid; it is the last precipitated
by acetate of lead from the boiling solution of mixed acids, and ap-
pears to be contained in the greatest proportion in human fat. It
melted exactly at 143°°6, and solidified on cooling into indistinctly
crystallized, apparently laminar, shining masses, of a somewhat
pearly lustre. When it has a small portion of margaric acid mixed
with it, it crystallizes on gradual cooling after fusion in tufts of
acicular crystals. | From the alcoholic solution it crystallizes in
small white scales.
Free acid.
100:00 100:00 100-00
——_— + Silver salt. Baryta salt.
Found. Cale. —_—_—_-—A —_—-——
Found. Cale. Found. Calc.
ee
CO 74:85 74°88 74:95 75°00 C 52°58 52:91 C* 59:22 59-37
H® 1250 12°51 12:53 12:50 H® 852 854 H*®™ 9-62 9:59
Ot 12°65 12°61 12°52 12:50 O* 9:20 8-82 08 772 «7°42
700-00 100-00 100-00 100-00 Ag 29°70 29°73 BaO 23°44 23°62
100:00 100-00 100:00 100-00
Dr. Heintz considers the olidic acid procured by Varrentrapp*,
by the action of hydrate of potash in a state of fusion upon oleic acid,
to be identical with palmitic acid.
Dr. Heintz has also investigated the composition of the fluid portion
of human fat. The oleate of baryta, prepared according to Gott-
lieb’s + method, contained more baryta than accords with the for-
mula given by that chemist; Heintz obtained from 22°2 to 22°5 per
cent. of baryta, and a corresponding deficiency of carbon.
By repeated boilings of this oleate of baryta in so small a portion
of alcohol that there was never more than a part of the sait dissolved
at each operation, the residue contained at last as much as 22°7 per
cent. Atther extracted from this impure oleate of baryta a salt
which contained from 27 to 28 per cent. of baryta; the remaining
pure oleate of baryta gave the formula proposed by Gottlieb.
Found. Calculated.
CAN eadicla 6.6. «- 61°55 61°82
Fe se ae Celso bgt 9°54 9°44
Re tees aig ste Lore 6°94 6°87
eS eee 4 21°97 21°87
100°00 100°00
* Annalen der Chemie und Pharmacie, liv. 124. + Ibid, lvii. 33.
Intelligence and Miscellaneous Articles. 77
The fluid portion of human fat consists therefore essentially of
oleine, with which however a small quantity of some other fluid fat
is incorporated, which is distinguished from the former in that the
acid which it contains furnishes on saponification a baryta salt which
is more difficult of solution in alcohol than the oleate of baryta, but
on the other hand is more readily soluble in ether, and which con-
tains much more baryta.
When human fat is exposed in the winter during a long period
to a temperature about the freezing-point, the fluid fat separated
from the solid parts allowed to stand until the next winter, and
then again submitted for a long time to a similar low temperature,
a considerable portion of solid fat will again separate; and the
remaining fluid portion will again present the same phenomenon in
the ensuing winter. This does not depend on a conversion of oleine
into margarine ; but Dr, Heintz found that this solid fat, purified by
pressure and crystallization from alcohol, readily dissolved in a weak
boiling solution of carbonate of soda. Thus, if human fat be left for
a long time in loosely-stopped vessels, a gradual decomposition of
the glycerine will occur and the fatty acids of the fat be set free ;
these are more difficult of solution in the fluid portion than the un-
decomposed fat, and occasion this repeated separation. Annalen der
Chemie und Pharmacie, lxxx. 297.
NEW ARRANGEMENT OF THE VOLTAIC PILE.
BY M. FABRE DE LAGRANGE,
I have found a means of rendering the current of the voltaic pile
perfectly constant and invariable, even for weeks or months, of what-
eyer metals the electrodes may be formed, and whether they be set
in action by two liquids, as in the combination of Bunsen, or by one,
as in that of Volta. This continuity of electric action is obtained in
the same way that we obtain the continuity of the calorific action of
a stove, which is furnished below with a grating to let the ashes fall,
whilst we continually add fuel at the top.
The method which I employ is simple, and fulfills all the conditions
which can render it practicable in an industrial point of view—
instead of increasing the expense it diminishes it.
Let us first see the disposition of a single pair with one liquid.
Take a vessel with a hole in the centre of the bottom, such as a
flower-pot, and round the hole let one end of a cylindrical diaphragm
of cloth be attached by cement to the bottom of the pot. The axis
of the hollow cloth cylinder when erect will coincide with the axis
of the vessel, and its height is somewhat less than the walls of the
latter. Within the diaphragm is placed a stick of very hard coke,
such as is found in the gas-retorts, surrounded by small grains of
the same coke, and round the diaphragm a cylinder of amalgamated
zine and some acidulated water, furnished drop by drop from a reser-
voir above.
Let us now unite the two poles by a conducting wire, and see
what takes place in the interior of the apparatus. The acidulated
water, which continues to drop into the vessel, will pass in part over
the margin of the cloth diaphragm on to the grains of coke, which
78 Intelligence and Miscellaneous Articles.
will thus be continually bathed by the movement of the liquid with-
out being inundated, so that the polarization will be suspended and
the bubbles of hydrogen will be freely disengaged through the in-
terstices between the particles; besides which, the lower strata of
the acidulated water, in consequence of the pressure which they
have to support, will filter slowly through the cloth, which will not
be the case to any extent with the upper and middle strata. Now
these lower strata are precisely those which contain the sulphate of
zine which it is necessary to eliminate. The result is an electric
current, which is perfectly constant until the entire disappearance of
the zinc, and which is obtained with no more care than that of keep-
ing the reservoir filled.
My method of uniting a number of pairs is as follows :—The stone-
ware pots in which they are contained, which are 3 or 4 diameters
in length, and consequently have the appearance of tubes, are united
and cemented into a bundle or block, which is readily transported
from place to place. The upper surface being horizontal, small
gutters are employed to convey the acidulated water to each pot.
With this arrangement, by placing a second reservoir above the pile,
and altering the nature and elevation of the diaphragms, it is easy
to employ a second liquid, which may be made to fall directly drop
by drop on the grains of coke, such as nitric acid;—it may be
used with advantage when very weak, and when it will no longer
serve for the battery of Bunsen from its ceasing to absorb hydrogen.
The liquids on leaving the pots are collected and may continue to be
used until saturation.._Comptes Rendus, April 5, 1852, p. 533.
ON THE PREPARATION OF PURE SILVER FROM CHLORIDE OF
SILVER. BY C. BRUNNER.
It has long been known that pure silver for chemical purposes is
best prepared by the decomposition of chloride of silver. This de-
composition can be performed in various ways : Poggendorff* several
years ago described a process in which it was effected by galvanism ;
this appears to me to be preferable to all others hitherto known, and
the one here described can only be regarded ag a modification of it.
Well-washed precipitated chloride of silver is to be put into a cup
of silver, platina or copper, the outer surface of which is covered with
wax, in such a manner that only a round space of one or two inches
in diameter, according to the size of the cup, remains uncovered.
On the bottom of a larger earthen cup a disc of amalgamated zine
is to be laid, on the middle of which the cup containing the chloride
of silver is placed, in such a manner that the portion not covered with
Wax may come in contact with the zinc. Water slightly acidulated
with sulphuric acid is now to be poured into the apparatus, until it
rises above the margin of the inner cup, so that this will be com-
pletely sunk in the water. The decomposition of the chloride of silver
immediately commences at the edge of the cup containing it, and pro-
ceeds inwards to the middle : this is readily known by the dark gray
colour assumed by the silver as it separates; the decomposition will
be completed in from 24 to 48 hours ; its completion may be known
* Poggendorff’s Annalen, vol. xxv. p. 342.
~~. Meteorological Observations. 73
by there being no longer any chloride of siiver visible on stirring the
precipitate. ‘The silver thus procured is to be washed with water,
and any small residue of chloride of silver which it sometimes retains
may be got rid of by diluted ammonia.
The silver thus prepared is perfectly pure. It is readily seen that
any foreign metals that ‘may be contained in the zinc, can never mix
with it, as the disc of zinc lies during the whole operation below the
cup containing the silver, and never comes in contact with it.—
Poggendorff’s Annalen, vol. lxxxv. p. 462.
THE BOMERANG. BY J. E. GRAY.
If a common manilla or palm-leaf hat having a low crown, and
the margin of the rim sharply turned up about half an inch high, is
thrown into the air with the cavity of the hat upwards, it returns
back towards the thrower like the Australian bomerang. The angle
at which it returns depends on the angle at which it is thrown; and
if the angle is sufficiently acute, it will fall some distance behind the
thrower.
The experiment depends on the position of the hat; for if thrown
with the cavity downwards, it alights in the direction thrown, and
does not return. A pasteboard disc with a turned-up edge has the
same effect as a hat.
METEOROLOGICAL OBSERVATIONS FOR MAY 1852.
Chiswick.—May 1. Overcast: cloudy: clear. 2. Cloudy and cold: frosty at
night. 3. White clouds: fine: clear and frosty. 4. Dusky clouds: clear and
frosty. 5. Densely clouded: clear and frosty at night. 6. Cloudy: clear. 7.
Overcast: very fine. 8. Cloudy: fine. 9. Fine. 10. Fine: rain at night. 11.
Boisterous, with heavy shower, partly hail. 12. Heavy rain: thunder. 13, Cloudy:
overcast : boisterous at night. 14. Showery and boisterous: clear. 15, 16. Very
fine. 17. Slight drizzle : overcast : thunder, lightning and rain at night. 18. Very
fine: rain at night. 19. Very fine. 20, Hazy: fine: showers. 21. Overcast.
22. Cloudy: clear. 23. Cloudy. 24, 25. Overcast: fine. 26. Rain. 27. Over-
cast. 28. Densely clouded. 29, Rain. 30. Fine: cloudy. 31. Fine: cloudy:
clear and cold.
Mean temperature of the month ......... ... de sDhs ed axarse sce’ 51°45
Mean temperature of May 1851 ........seeessseeesssceseereere . 51°16
Mean temperature of May for the last twenty-six years ... 54 °07
Average amount of rain in May ......seesessssesessceeessceeeees 1°74 inch.
Boston.—May 1. Cloudy. 2. Cloudy: rain a.m. 3,4. Cloudy. 5. Cloudy:
rain a.m. 6. Cloudy. 7. Fine. 8. Cloudy. 9,10. Fine. 11. Cloudy. 12—
14, Cloudy: rain a.m. 15, 16. Fine. 17. Cloudy. 18. Cloudy: rain a.m. and p.m.
19. Cloudy: raina.m. 20. Fine. 21. Cloudy: rain a.m. andp.m. 22—25, Cloudy.
26. Cloudy: rain p.m. 27—29. Cloudy. 30. Fine. 31. Cloudy.
Sandwick Manse, Orkney.—May 1. Cloudy: fine. 2. Clear: fine. 3. Cloudy:
fine: clear: fine. 4. Cloudy: fine. 5. Drops: fine: cloudy: fine. 6. Clear:
fine: cloudy: fine. 7. Drops: rain: clear, 8. Drops: showers. 9. Rain: clear.
10. Drops: clear: aurora, 11. Cloudy: showers. 12. Bright: clear. 13. Rain:
clear: fine. 14. Bright: showers. 15. Clear: cloudy. 16. Clear. 17, Clear:
fine. 18,19. Clear: fine: aurora. 20—23. Clear: fine. 24. Bright: fine: clear:
fine. 25, Clear: fine. 26. Cloudy. 27. Cloudy: fine. 28. Bright: cloudy:
showers. 29. Bright: showers: cloudy: hail-showers. 30. Sleet-showers. 31.
‘Sleet-showers : showers.—This month has been fine, warm and dry.
Mean temperature of May for twenty-five years previous ... 47°88
Mean temperature of this MONth — .....s..seeeceenerseneeeenenes 50 49
Average quantity of rain in May for six years .ys.secseereeee 1°72 inch,
ssteshaline eo ae ae
£56.62
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-g | -ou | 5th of nitrate of silver in distilled water, using this
instead of the solution No. 2, but having proceeded as before
with the teasing out in solution No. 1. It is true that the ni-
trate of silver does not show the spirals with the same remarkable
distinctness as the solution No. 2, and besides, the preparation
is here and there defaced with a precipitate; but for prepara-
tions to be preserved for any length of time, it is to be preferred.
For immediate examination the author especially recommends
the solution No. 2.
The use of chemical reagents having been objected to, it may
be replied, as suggested to the author by his brother, J. T. Barry,
were anyone denying the existence of the structure in question,
then it might be very proper to object, that reagents had de-
stroyed it ; but when the existence of that structure is affirmed,
it cannot be objected that that structure has arisen through those
reagents, especially when, in order to bring it into view, sub-
stances so very different have been used, as corrosive sublimate,
nitrate of silver, and chromicacid. Least of all can those object
to the use of chemical reagents who in such researches employ
maceration, which, as is known, does not require much time to
produce in organic substance the greatest changes.
Adhering to his original views regarding the situations of the
stri in the fasciculus of muscle, as above quoted, the author
gives figures illustrative of the same (figs. 4 and 5). These
show the situations of the dark longitudinal striz to correspond
to the spaces between the edges of the fibrils, and the situations
of the dark transverse striz to correspond to the crossing places
of the winds of the spirals. It is obvious from the same figures
that both the longitudinal and transverse striz are produced by
the refraction of light ; for at the very part where the dark striz
present themselves, the rays from the mirror of the microscope
fall upon oblique surfaces, where they are diverted from their
direct course and do not reach the eye. The dark longitudinal
strie are produced by the cylindrical form of the elementary
muscular threads, and the dark transverse striz arise partly from
the same cylindrical form of the muscular threads, but chiefly
from the oblique direction of the same at their crossing.
Had observers paid due attention to the history of develop-
ment, they could not have failed to observe a pellucid gelatinous
substance to which the author has given a name suggested to
him by Professor Owen, that of hyaline; a name descriptive of
the appearance only, though the substance evidently performs
86 Dr. Barry’s renewed Inquiries concerning the
functions rendering it in importance second to none. In muscle,
this substance, hyaline, is often found within the winds of the
spiral threads; often the fibril is enclosed within a cylinder of
hyaline, fig. 3. It is very important to be aware of the little
difference in refractive power between the hyaline and the sub-
stance of the spirals, whereby the outline of the latter becomes
almost invisible. This is especially the case when the fibril still
lies in the primitive fasciculus, and even occurs after its separa-
tion from it. Hence the different views taken by observers of
the fibril, especially that assigning to it a structure comparable
to a row of varicosities or beads. It is therefore equally import-
ant to apply reagents that will serve to introduce a greater dif-
ference in the refractive power of the two substances in question,
and thus diminish the misleading influence of the hyaline.
This hyaline appears in another way to have misled observers.
Where contained within the winds of spiral threads, fig. 6a, it
holds together a row of cell-germs; which cell-germs, on the
wearing out as contractors of the old spiral threads, give the
material for new ones. And some observers, overlooking the
spiral threads, probably mistook such rows of cell-germs for
fibrils. This mistake is very likely to be made when the muscle
has undergone a slight degree of decomposition, fig. 6 6, whereby
the spiral threads dissolve and disappear sooner, leaving exposed
the axis of hyaline with its row of cell-germs. Prof. Bowman
appears to have figured such an axis of hyaline containing cell-
germs, as a fibril*¥. It may appear absurd to suppose that any
doubt on such a matter can be entertained; and yet, since the
mistake in question has been made, the author ventures to ask
physiologists which appears to them the more probable: that
spirals are formed first in order to produce cell-germs (!), or that
cell-germs are first formed in order that they may give origin
to spirals? ¢ and d in fig. 6, show division and subdivision of
the cell-germs for the production of minuter spirals. It must
be admitted that the changes in the structure of the fibrils,
attending their continued composition or decomposition, present
a series of transition states such as may mislead all engaged in ~
this most difficult field of observation.
It is known that in some states the primitive fasciculi during
manipulation break off short, that is transversely, and that in
other states they divide in a longitudinal direction ; but it is not
known on what this difference depends. The author explains it
thus :—He finds the tendency to transverse cleavage to be in
proportion to the amount of contraction the muscle happens to
* Cyclopzdia of Anatomy and Physiology, article “‘ Muscle and Muscular.
Contraction,” fig. 287 c. In his earlier work, Phil. Trans, 1840, no such
figure is to be found.
Spiral Structure of Muscle. 87
be in at the time of manipulation, while relaxation in the same
proportion causes the giving way in a longitudinal direction ;
and he offers the following as perhaps sufficient to account for
the difference. In contraction, where the transverse strize are
narrow, the spirals cross each other (7. e, antagonize each other)
at the acutest angles; and in such a state of course it is that
there occurs most easily a mutual cutting through, producing the
“discs”? of Bowman, to be again referred to. On the other
hand, in relaxation the spirals meet only at obtuse angles, whereby
the tendency to cutting through is in proportion lessened. The
cutting through of the spirals when crossing at acute angles is
illustrated by reference to a play with twine, familiar to school-
boys.
Ta the early stages of development, however, fasciculi are
sometimes met with in which the fibrille are so surrounded with
large spirals, that longitudinal cleavage would be difficult how-
ever complete the relaxation. Of such large spirals, not merely
two, but many interlace,—each surrounding its own cluster
of fibrils. These large spirals pass into membrane and form
septa*. Now within the winds of the larger spirals there arise
smaller ones, which in their turn enlarge and pass into mem-
brane, to be succeeded by another generation, and so on; by
which it is easy to understand the prevention of longitudinal
cleavage, as well indeed as the difficulty constantly met with
when endeavouring to obtain separate fibrils for microscopic
examination. Again, the state of the primitive fasciculus in
fig. 7 was met with; where the fibrillz, c, were shared by more
than one surrounding spiral, 4; the whole being surrounded b
a larger spiral, a. Here also cleavage in a longitudinal direction
would be very difficult. Further, the author saw states in which
there was absolutely no cleavage, the fasciculus before breaking
off becoming tapered to a point, fig. 8. This tapering to a point
seemed referrible partly to great distensibility of the sarcolemma,
and partly to a loose condition of fibrils already somewhat re-
laxed ; and it is beautifully demonstrative of a spiral structure.
(See the figure, and contrast the direction of the curves of the
spirals at a with that at 4.) Besides, at a the fasciculus was
thick, while at 6 it was thin; and as the spirals became more
and more drawn out, the fasciculus became more and more thin,
until it terminated in a point. (The arrow shows the longitu-
dinal direction of the fasciculus.)
It not a happens in the breaking off of twine, in which
the two threads composing it are of unequal extensibility, that
* Bowman observed that the inner surface of the sarcolemma often pre-
sented irregularities, which the author thinks were no other than remains
of septa such as those above mentioned.
88 Dr. Barry’s renewed Inquiries concerning the
one of them is more drawn out than the other, which becomes
coiled around it as around an axis. Such a state being not un-
frequently presented by twine-like muscular fibrils, fig. 9, after
the breaking of them up with needles, it is important that the
observer should be aware how the appearance is produced ; for
it may easily mislead him into the belief that he sees a row of
alternately longer and shorter “ beads.” :
The author is convinced that, with the exception of one case
already mentioned (fig. 6d), in all instances where Prof. Bowman
speaks of fibrils, he had before him, without recognising them,
nothing less than spirals. “ Very reluctantly,” says the author,
“should I again enter into a controversy with a fellow-country-
man whom I much esteem, were I not sure that his desire to
arrive at the truth in this matter is quite equal to my own.” .
He then gives copies of five of Bowman’s figures, fig. 10 a, b, ¢,
d, e, placing beside them five corresponding figures of his own,
fig. 1l a, b, c, d, e, and showing the former to be, not, as sup-
posed by Bowman, rows of beads, but different states of double
spirals. No doubt, it is added, Bowman’s fibrils had undergone
some change; for three out of five of the preparations from
which they were drawn had been preserved in spirit, while the
fourth had been exposed to maceration.
What the author states of Bowman’s figures of fibrils applies
equally to the drawings given by that physiologist of fasciculi,
though the latter are on a smaller scale. And no one, he thinks,
who will take the trouble carefully to compare Bowman’s figures
39 and 40, in his memoir, Phil. Trans. 1840, as well as those in
his (Bowman’s) Plate 19, in the same memoir, with what has
been said in the present paper of the change in breadth of the
transverse striz in consequence of the difference in direction of
the winds of the crossing spirals, will refuse to admit that the
latter serves fully to explain the former.
We are indebted to Bowman for representations of manifold
appearances presented by primitive fasciculi during their con-
traction and expansion, though from being unacquainted with
the spiral structure of muscle he could not explain them, and
wisely avoided the attempt to do so, except that he sought to
refer the approach towards, and withdrawal from one another of
the transverse striee, to contraction and expansion of his supposed
€‘dises.?”
But what are these “discs” of Bowman? Certainly not what
he thinks, layers of muscular substance, “ primitive component
particles,” an assemblage of which constitutes the primitive fas-
ciculus. Bowman’s discs are really nothing else than the bright
parts of the transverse strie, in which the single winds of the
spiral threads are arranged in adjacent order (fig. 5a, a, a), and
Spiral Structure of Muscle. 89
as it were, into ‘ éfages’ or series. (See fig. 12, where one of these
‘étages,’ the lowest, is separated from the rest by the cutting
of the spirals at their points of crossing.) The dark places in
the transverse striz correspond to those separating Bowman’s
discs. They are nothing else than the crossing places of the
spiral threads. Here the latter come into immediate contact with
one another,—can with pressure be made to exercise a cutting
power,—and, as before said, actually to cut each other through.
This, too, must take place more or less in stories or ‘ étages,’ as
the points of crossing are for the most part on the same level.
And when the cutting through has taken place, each story or
‘ étage’ represents one of Bowman’s discs*. (‘The author here
points out a difference between merely perspective crossing of
the spirals, and that crossing where they are in contact ; it being
of course at the latter only that there can be a cutting through.)
Whence comes it that, as was observed by Bowman, contrac-
tion at any part of the primitive fasciculus (characterized as this
is by greater nearness of the transverse strize) is attended, both
before and behind that part, in the longitudinal direction, with
a separation of the transverse strie ? The cause, according to
the author, is simply this: when the spiral threads extend more
in a transverse direction at one part than at another, this can
take place in no other way than at the expense in the longitu-
dinal direction of their continuations, the winds or loops of
which, thereby drawn out of the transverse direction, assume one
that is more longitudinal.
Bowman is right in maintaining that contraction of the primi-
tive fasciculus has nothing to do with zigzag inflexions of the
same. On the contrary, as Bowman remarks, it has been shown
by Owen that it is in relaxation that these zigzag inflexions may
arise ; and not only so, but that in the Filaria they are regularly
present in relaxation, being there indeed characteristic of the
relaxed state of muscle. The author inquires, How then does it
happen that such zigzag inflexions may arise m relaxation? He
thinks it may possibly be in the following manner :—Suppose
the extreme ends of the primitive fasciculus through any hin-
derance to remain fixed, and that the fibrille, after cessation of the
influence of the contractile force, strive by means of their own
elasticity, and in consequence of the relaxation of their spiral
* This, however, is not always the case; for at different parts in the
breadth of the same primitive fasciculus the fibrils may be in different de-
grees of contraction, and their points of crossing therefore on different
levels. In such states the transverse stria, viewed with changes of focal
distance, are seen to change their place continually, according as viewed
near the periphery or at greater depth, as was observed by Bowman, and
as every experienced microscopic observer must have noticed,
90 Dr. Barry’s renewed Inquiries concerning the
threads, to gain a greater length; but being prevented from
doing so by the hinderance above supposed at their ends, they
seek to gain that greater length through lateral inflexions, which
in such a case must produce a zigzag form. Were an antagoni-
zing force applied, the elongation could follow without the for-
mation of such zigzags.
We are indebted to Prof. Bowman for many microscopic
measurements of the primitive fasciculi in different classes of
animals. He found the largest in Fishes; they had a less size
in the Amphibia, were smaller in Mammals, and smallest in
Birds. Bowman’s measurements are very numerous, and were
no doubt made with the greatest care. He has, however, omitted
to draw general conclusions therefrom, and makes no remark as
to the cause of those differences in size. The author in this
respect follows the example of Prof. Bowman. He brings for-
ward no general conclusions of his own on the subject, and indeed
for this reason: because he thinks that we ought first to have
determined the mean size of the primitive fasciculi in the same
individual as well as in different individuals of the same species,
according to their different manifestations of activity, before we
undertake to draw general conclusions. Yet he cannot refrain
from here pointing to the following fact, mentioned in a former
part of his memoir. According to his observations, the primitive
fasciculi are at first merely double spirals, 2. e. they are no other
than fibrils. The metamorphosis of fibrils imto primitive fas-
ciculi is especially observable in the heart, where the young
fasciculi are found, at first flat and scarcely broader than the
fibrils themselves. The cause of these continued changes in the
muscle of the heart, as already said, it may well be supposed is
no other than the ceaseless activity ofthat organ. Scarcely is it
to be doubted that the same thing takes place in other muscle
also, though more slowly. (Certain muscles are then referred
to as affording examples of great activity, and it is remarked
that in different individuals of the human race the primitive
fasciculi in the muscle of certain parts are probably unusually
small.) Hence it occurred to the author to offer the following
remarks concerning the measurements of Bowman. In Fishes
the primitive fasciculi were found the largest, because of the low
degree of muscular activity required in the element in which
they live (though perhaps the muscles of the fins and gills may
be here excepted, and it is known that they present even exter-
nally an appearance different from that of the other muscles).
In Birds, on the contrary, the primitive fasciculi were found
the smallest, as was to be expected from the high degree of
muscular activity of this class. Amphibia and Mammals pre-
sented a middle average size, from their muscular activity oecu-
Spiral Structure of Muscle. 91
pying amiddle place ; but here it must be remarked, that striking
differences would certainly have been met with had Bowman’s
researches been of a more special kind; for it is probable that
the salamanders and other naked Amphibia would have presented
still larger fasciculi than even Fishes.
Schwann was the first to make us acquainted with the exist-
ence of the sarcolemma. An independent discovery of it was
made by Bowman, to whom it is that we are indebted for an
exact description of that structure and an appropriate name. Its
mode of formation out of spirally arranged cells, the author
believes to have been first seen and published by himself. That
mode of formation of the sarcolemma appears to be as follows :—
At a, fig. 13, is a coil of young cells (once a column of com-
pound cytoblast, as at fig. 20c). a, in fig. 18, is a drawing
from nature; b in the same figure is a diagram. @ passes into b.
That the spirals really do consist of cells is seen from fig. 14, a
drawing from nature, in which a represents a large double spiral
from the tail of the tadpole when very young, and 4 the remains
of a similar double spiral after the addition of acetic acid. The
acid removed the coalesced membranes of the cells, of which the
double spiral a was composed, and left the nuclei behind in
double spiral order. At c is seen the structure of one of those
nuclei. They contained the elements of division, by which divi-
sion the spirals pass into the state of membrane. And fig. 15,
also from nature, shows such division to have taken place; this
figure representing a stage in the formation of the sarcolemma.
With regard to the function performed by the sarcolemma, no
definite opmion appears to have been given. The author believes
that its function depends on elasticity. As the walls of the sar-
colemma-cylinder are distended during the contraction of the
double spiral threads, they return inwards as soon as relaxation
comes on. And it is in this manner that the active relaxation
of the fasciculus of muscle is to be explained.
Muscle from the thigh of the Grasshopper (of which many
individuals, including several species, were examined) having
uniformly presented a relaxed state nearly approaching to that
in fig. 16 (which, however, is merely a diagram), it appeared to
the author probable that such a state was not unconnected with
the sudden muscular contractions required by this creature for
its leaps. A sudden change from such a state of relaxation to
that of extreme contraction must here take place with the great-
est facility, and be combined with the manifestation of great
power. This opinion having been mentioned to Prof. Purkinje,
the latter recommended the author to examine the corresponding
92 Dr. Barry’s renewed Inquiries concerning the
muscle from the Flea, in which, from its enormous leaps, some-
thing similar would he thought be found. The author accord-
ingly examined some of these, and had the satisfaction to find in
them a degree of muscular relaxation even higher than that he
had observed in the grasshopper. In the two figures, fig. 16 and
fig. 5, the parts in fig. 16 marked 4, 6, correspond to J’, b! in
fig. 5. From a comparison of these two figures, it will be at
once seen how the extended 4, 6 in fig. 16, pass in contraction
into the narrower J!, 0’, fig. 5. Similar conditions no doubt
exist in other animals, but perhaps nowhere are they more re-
markable and constant than in those just mentioned. The
observation may possibly induce some to bestow their attention
upon this subject when examining leaping insects as well as
other animals. °
The author repeats a drawing he gave in the Phil. Trans. for
1842, of an artery from the pia mater of the Rabbit, fig. 17, of
which the following is an explanation :—a, longitudinal muscular
fibrils, represented merely by rows of dots, except a single one
on the left side in which is shown the double spiral; 4, outline
of a fibril surrounding the longitudinal ones; ¢, double spiral
structure of b; d, blood-corpuscles, for the most part young and
very small ; ¢, a line denoting the inner membrane of the artery.
He then gives a figure, fig. 18, representing more distinctly the
double spiral structure of such a fibril as 4 in fig. 17.
His observations on the history of development of muscle are
given in detail, with many illustrative drawings; but as only a
part of the latter can be given in this abstract, it is not intended
to offer here more than the substance of the principal facts he
observed, which were as follows :—
Cells having arranged themselves as at a, fig. 19, and their
membranes having passed through the states b and cin the same
figure, and a tube having been thus formed (stages known to
other observers), columns of compound cytoblasts are seen within
the tube, fig. 20 6,¢; which cytoblasts have descended by divi-
sion from the nuclei of the primitive cells, fig. 19 a. (The com-
pound cytoblasts in these columns are arranged with such regu-
larity as to produce, and explain the nature of, the strize seen by
Schwann, fig. 20a.) The membrane of the tube disappears, not
formimg, as Schwann thought, a permanent sarcolemma; and
the columns of compound cytoblasts having passed into coils of
cells, fig. 13 a, a spiral is formed of them, as shown by the dia-
gram 6 in the latter figure. A central row of cell-germs is left
for the formation of future spirals; and the spiral first formed
divides, and, as above shown, passes into membrane—the first
Spiral Structure of Muscle. 93
sarcolemma. Such future spirals in a far later stage are seen in
fig. 21; and fig. 22,a,6,c, shows the way in which the cell-
germs perpetuate themselves by division and subdivision, every
spiral havmg within its winds the elements of reproduction,
fig. 23; and the primitive fasciculus being often found to have
preserved cell-germs for a more general purpose in a central
line, fig. 21. The reproduction of muscle, when fully formed,
is probably no other than a continuation of its history of deve-
lopment, and has been already illustrated in fig. 6. By self-
division of its hyaline axis of cell-germs, every fibril may become
converted into a primitive fasciculus.
The laws of development in general are best studied in the
ovum ; and he who holds the wondrous process of cell-formation
in the germinal vesicle, 7. e. the history of development of the
germinal spot described by the author im the Philosophical Trans-
actions for 1840 as undeserving of particular attention, may
spare himself the trouble of inquiring into the history of deve-
lopment of muscle, or that of any other tissue, as his labour
would be thrown away. In that development of the germinal
spot, the hyaline in the centre of the spot is obviously the prime
mover. It is the hyaline in the centre of the germinal spot that
is the substance undergoing fecundation ; and no doubt it is the
hyaline seen in the head-like extremity of the spermatozoon that
is the real fecundating substance. (The author once saw, and
figured in the Philosophical Transactions for 1840, what ap-
peared to him to be a spermatozoon in the very act of entermg
the ovum of the rabbit; its head having already penetrated an
orifice discernible for a time in the zona pellucida*.) In the
* He mentions haying repeatedly found unaltered spermatozoa in the
interior of the ovum in its next stages, after it had passed into the Fallo-
pian tube; and having had the opportunity of showimg them to Professor
Owen, who declared himself fully convinced of the presence of the sperma-
tozoa within the ovum. Once the author counted as many as seven in a
single ovum. (A drawing of that ovum will be found in a paper by him
“On Fissiparous Generation,” in the Edinburgh New Philosophical Journal,
October 1843.) In all instances the spermatozoa were motionless; and
not among the cells in which the development of the essential substance
was proceeding, but in the colourless fluid between those cells and in the
zona pellucida. {While passing through Londonin May 1852, the author
learns that after the lapse of many years these observations have been in
two quarters confirmed by others; Dr. Nelson haying presented to the
Royal Society a paper announcing the presence of spermatozoa in the in-
terior of the ovum of a creature at the other end of the animal kingdom,
Ascaris mystax; and Mr. Newport having added a postscript to a paper of
his on the ovum of the frog, also presented to the Royal Society, in which
he candidly acknowledges haying erred when, in a former memo, he ques-
tioned the accuracy of the discovery made by the author of the present
paper, that entire spermatozoa do actually make their way mto the interior
of the ovum. |
94 Dr. Barry’s renewed Inquiries concerning the
ovum of the Rabbit, after fecundation, the germinal vesicle returns
to the centre of the ovum, and the fecundated hyaline passes to
the centre of the germinal vesicle. This hyaline, in consequence
of fecundation, now contains substances of two kinds,—one from
the female ovum, the other from the male fecundating fluid.
Through a process operating in the germinal vesicle before fecun-
dation, the hyaline of the ovum had prepared a sort of pabulum,—
minute globules of hyaline. With this pabulum, the new hya-
line, a compound of male and female elements, proceeds to nou-
rish itself; or, in other words, proceeds to assimilate the contents
of the germinal vesicle, whereby there arises a material for the
formation of two cell-germs into which it divides. These two
cell-germs grow at the expense of the remaining contents of the
germinal vesicle, which are nutrimental cells, until the whole
are consumed. The membrane of the germinal vesicle, the
mother-cell of the whole body, has now disappeared, and there
are seen in the place of that vesicle two young cells, which
together constitute the new organic being. How shall we desig-
nate the hyaline of this new being? If we call the hyaline of the
ovum, hyaline No. 1, and that from the fecundating substance,
hyaline No. 2, we have in the new organic being, hyaline No. 3.
No. 1 denotes the maternal hyaline, No. 2 the paternal fecun-
dating substance, and No. 3 composed of the first and second,
the hyaline of the offspring. Hence it is that the offspring
comes to resemble both parents; for, be the resemblance effected.
as it may, the so compounded hyaline of the offspring will never
lose a constitution inherited partly from the father and partly
from the mother. And how does the hyaline of the offspring
now begin to propagate itself, so that at last a creature shall
arise out of it, in stature and other peculiarities like the parents ?
This is effected by self-division and repeated self-division. Hach
of the two cells just mentioned, together constituting the new
organic being, becomes in its turn a mother-cell, so that now
there are four; and in like manner there arise 8, 16, and so on,
until the whole assumes the appearance of a mulberry. In the
centre of this mulberry-like aggregate of cells there now appears
one larger than the rest, like a queen-bee in the hive. This is
the only cell in the group that has an enduring existence, i. e. in
its progeny ; all the others serve but a temporary purpose. (We
thus have a sort of aristocracy of cells! first manifesting itself in
the two above-mentioned as arising in the germinal vesicle, and
nourished at the expense of all the surrounding cells.) This
large cell now moves from the centre of the ovum towards the
periphery, and here takes a fixed station. The hyaline nucleus
of this cell is now to be considered as the most peculiar germ of
the whole organism. Out of the nucleus of this cell, after many
intermediate stages of formation, there at length arises the “ pri-
Spiral Structure of Muscle. 95
mitive trace,” and Von Baer’s “chorda dorsalis.” For other
details, the author refers to his researches published in the Phi-
losophical Transactions for 1839 and 1840; not deeming it
suitable to the purpose of the present paper to add more, than that
the process through which the first and continually repeated self-
division of the hyaline is effected, is no other than a repetition
of the same process which operates in the germinal spot of the
germinal vesicle, as the original cell of the organism; in which
process the operation of certain functions required for an increase
of substance is implied, viz. absorption, assimilation, and secre-
tion. In the cells thus descending from the original mother-
cell down to the remotest generation, it is evident that the same
wondrous process is repeated, the same increase of the hyaline;
which at first takes a peripheral station in the cell in order
through absorption to be newly fecundated (for what in this
case is absorption, but the fecundation of the hyaline of the cell
through a relatively external substance maintaining the process of
division?) Then, after fecundation at the periphery, the hyaline
passes into the middle of the cell, there again to divide into new
generations of cells, which finally arrange themselves so as to
form the various tissues of the organism. But the germinal
spot process continues even here. (Compare the contents of the
cell in fig. 19 a, with the author’s delineations of the contents of
the germinal vesicle, Phil. Trans. 1840, Plate 22. figs. 159,
160, 162 c.)
Every one whohas noticed the author’s drawingsof a certain state
of the two cells succeeding the germinal vesicle, must have been
struck with the resemblance they bear to corpuscles of the blood.
He deems it important in this place to refer to observations he
long since published, that both have the same destination ;
through both these structures, as well the blood-corpuscles as
the cells of the ovum, is it intended to reproduce the hyaline,—
the one being floating, and the other fixed centres of that pro-
cess of assimilation which effects the reproduction of the hyaline.
The germinal vesicle may be regarded as a living being; and
every blood-corpuscle as one of the progeny of the germinal
vesicle, reproducing itself, as that vesicle itself does, by division
of its fecundated hyaline. We may consider the blood-corpuscles
as a floating shoal of Infusoria, receiving as thei nourishment
the chyle. So nourished, or rather (as regards their hyaline
centres) so fecundated, the blood-corpuscles repeat in thew in-
terior the whole germinal spot process, since in some of them
there proceeds the self-division and repeated self-division of the
hyaline, whereby new generations of blood-corpuscles arise, which
again repeat the same process; while others deposit upon the
walls of the capillaries their hyaline, which operates with fecun-
96 Dr. Barry’s renewed Inquiries concerning the
dating power upon cells lyimg in the parenchyma of the organs,
and becomes assimilated according to the specific constitution of
the same. Sometimes, instead of chyle, as the feeundating sub-
stance to be assimilated, there reaches the hyaline of the blood-
corpuscles quite another heterogeneous substance, for imstance
some sort of infectious matter, o organic or animal poison, &e.,
whereby there as surely arise diseased processes of formation,
which communicate themselves to the remaining oe of the
blood or to the parenchyma of the organs.
The author refers to a full confirmation of his observations on
the remarkable process of cell-formation im the germinal vesicle
of the mammiferous ovum, by those of Mr. H. D. 8S. Goodsir
on a cystic entozoon. And as this lies at the other end of the
series of organic existences, the operation of the process in ques-
tion there, implies its operation in all intermediate ones.
He then notices an objection made to his observations, pub-
lished in 1839 and 1840, when makimg known the fact that
cleavage takes place in the mammiferous ovum also,—that such
cleavage is effected by means of cells ; showing that madequate
research led to that objection, and concluding his remarks with
the following words :—“ After having examined 230 ova found
in the Fallopian tube, with the sacrifice of 150 rabbits for em-
bryological research, of which rabbits at least a score were de-
voted to anatomical mspection for the purpose of enabling me to
determine the time at which the ovum leaves the ovary,—no man
will wonder that I deem myself competent to judge whether the
divisions of the germ are, or are not effected by means of cells.
No man who does not examine mammiferous ova in large num-
ber mmediately before their exit from the ovary, or otherwise
through observations on animals or plants make himself ac-
quainted with the germinal-spot-process of division, is able to
comprehend the formative process in the mammiferous ovum in
any of its earher or later stages, or mdeed to understand the
physiology of cells*.”
A former drawing, fig. 13, shows the mode in which a spiral
arises out of cells. The following may serve to illustrate the
way in which the éwin or double spiral i is produced. Every mi-
croscopic observer must be familiar with segmented cytoblasts,
-
* [In the mammiferous ovum there is no substance that can be called a
food-yelk. The germ-cells therefore are not there obscured by a surround-
ing yelk-mass, the cleavage of which they govern, as seems to be the case
in ova since figured by other observers. i}
Spiral Structure of Muscle. oe
the annular arrangement of cell-germs in fig. 24, 5, c,d. Of
such rings of cell-germs, two are sometimes met with, connected
like two links of a chain, fig. 25. Let the diagram fig. 26 ¢
represent a pile of such pairs of connected rings. Now rings
such as those in fig. 24 are seen to pass into the state at 4 in
the same figure. And this change occurring in each ring of the
pile of pairs of rings, fig. 26 c, with a uniting at the extremities
of rmgs lyimg one upon another, would produce the twin or
double spiral d in the same figure*. Nature, it may be objected,
is a more skilful architect. She does not first form rimgs in
order afterwards to divide them and unite their extremities in
another way. All is from the first arranged in spiral order.
Without denying this, and fully admitting that there is from
the first a tendency to arrangement in spiral order, the author
still maintains that rings of cell-germs are constantly met with ;
and that since it is so ordered that spirals shall arise by the
union of separate cells, it is in perfect keeping with the form of
the cytoblast (fig. 24 a), that the germs of those cells when first
seen should be arranged in the form of rings. (It must not be
forgotten that each of the rings entering into the formation of
the spiral has its centre of hyaline, whence the cell-germs of the
next generation of spirals. See fig. 13.)
That which in nutrition is ascribed exclusively to the fibrin of
the lymph (and which probably corresponds to the author’s hya-
line), he believes to be derived from the blood-corpuscles them-
selves. And it is his opinion, that in the coagulation of the
blood Nature gives us an example of the coagulation of the
blood-corpuscles ; for, as he showed in 1842, many fibres arise
through coagulation within those corpuscles; whereby the latter
either pass entirely into fibres, as in the cytoblast blood-corpus-
cles of the Mammalia, or the coagulation takes place within
blood-cells, as in the other Vertebrata.
As already said, the reproduction of muscle seems to take
place by a process not differing essentially from that which
formed it, a process of division and subdivision of the germs of
cells. And what are these germs of cells? They consist of
nothing less than that wondrous substance hyaline, the unceasing
maintenance of which the author believes to be the main purpose
in the formation and division of cells. Each central row of cell-
germs within the windings of the spiral threads is really an axis-
cylinder of hyaline ; and when this divides, there arises a double
* (Or suppose a single pile of such bodies as that at h in fig. 24. The
union of their extremities would produce a single spiral; and longitudinal
division of this single spiral would produce a double one. |
Phil. Mag. 8. 4. Vol. 4. No. 23, Aug. 1852. gt
98 Dr. Barry on the Spiral Structure of Muscle.
cylinder, and so on. All these rows of cell-germs, arisen through
division and subdivision of the nuclei of the primitive cells which
arranged themselves in necklace-like order to form the first
muscle tubes, as well as the germs of those primitive cells them-
selves, are descended through division from those substances in
the ovum which again had arisen from the fecundated germinal
spot or nucleus of the germinal vesicle.
In a brief recapitulation concerning hyaline, the author states
his Researches in Embryology as well as his observations on the
Corpuscles of the Blood (Phil. Trans. 1838, 1839, 1840, 1841),
to have afforded him abundant opportunity for becoming ac-
quainted with it*. He found it in the so-called nucleolus of
cells in general, as well as in the germinal spot of the germinal
vesicle, to be the point of fecundation,—to be present in the
head-like extremity of the spermatozoon,—to constitute as glo-
bules, immeasurably minute, the foundation of cytoblasts, these
being the real germs of cells. He showed that this hyaline
forms as well the membrane as the contents of the cell,—that to
it belong the functions of absorption, assimilation, andsecretion,—
that so long as the vegetative process is in full activity it never
ceases to be in operation, but divides and subdivides to form new
cells, or rather to reproduce itself. For in the reproduction of
cells, the maintenance, the division, and the increase of the hya-
line appears to be the main purpose. It may be asked, What is
there, then, in the organic body which is not formed through
hyaline? Truly nothing. It is the essentially hving substance in
the body, the whole organism is the product of its formative force.
All cell-germs are really, through repeated self-division, effected
by aremarkable assimilative process, descendants of the hyaline of
the germinal vesicle, this having been fecundated by a substance
from the male ; whence the resemblance between the offspring
and both its parents. Finally, referring to his observations on
the mode of origin and structure of nerve and other tissues, the
author adds, that were it not that he would probably be blamed
for excessive phantasy, he would not hesitate to declare the hya-
line, as the foundation of the central nucleus of ganglion glo-
bules and of the axis-cylinders of nerves, to be the immediate
organ of sensation of every kind. \
[To be continued. |
* See the Edinb. New Phil. Journ. Oct. 1843, a paper “ On Fissiparous
Generation ;”? and in the same Journal, Oct. 1847, another “ On the Nu-
cleus of the Animal and Vegetable Cell.”
[ 99 ]
XII. On the Occurrence of Berberine in the Columba Wood of
Ceylon, the Menispermum fenestratum of Botanists. By
James D. Perrins, Esq.*
VHE following investigation was made in the chemical labo-
ratory of St. Bartholomew’s Hospital under the immediate
supervision of Dr. John Stenhouse. Dr. Stenhouse having had
for some time past a quantity of the wood of the Menispermum
fenestratum in his possession, suggested to me this investigation.
I am anxious therefore to acknowledge my obligation to him,
not only for the material, but also for several valuable sugges-
tions in the course of the inquiry.
Hitherto the chief source of the alkaloid berberine has been
the root of the barbery, Berberis vulgaris. Bodeker, however,
about four years ago, ascertained its existence in the columba
root of pharmacy, the Cocculus palmatus, where it occurs in
small quantity associated with columbine. The following remark
is made in the Chemical Gazette for 1849, vol. vil. p. 150 :—
“The occurrence of berberine in Berberis and Cocculus is re-
markable in a physiological point of view. Bartling places both
these families, the Menispermez and Berberidez, in the class of
the Cocculinz, which is in accordance with the fact of both con-
taining the same principle.” As berberine has now also been
found in another of the Menisperme, the accuracy of Bartling’s
view seems to be greatly confirmed.
The following was the process adopted for the extraction of
berberine from the Menispermum fenestratum. A quantity of the
wood, which had a bright yellow colour resembling that of quer-
citron, was rasped, and then treated with successive portions of
boiling water till it had become nearly tasteless. The aqueous
decoction acquired a deep yellow colour and an intensely bitter
taste. It was next evaporated carefully to the consistence of an
extract; then introduced into a flask and boiled with ten or twelve
times its bulk of rectified spirits of wine, filtered while hot, and
the residue boiled with a further quantity of spirits, which dis-
solved the berberine, and also a quantity of resinous matter by
which it was accompanied. The alcoholic solution was then in-
troduced into a retort, and the spirit carefully distilled off until
the residue on agitation appeared to have nearly the consistence
of oil of vitriol. It was then set aside in an open vessel, and in
the course of twenty-four hours the liquid became filled with a
mass of impure crystals.
After draining off the mother-liquor, these crystals were washed
with a small quantity of cold spirit, redissolved in boiling alco-
hol, and set aside to crystallize. Their complete purification was
* Communicated by the Author,
H 2
100 Mr. J. D. Perrins on the Occurrence of Berberine
attempted by repeated crystallizations. It was found, however,
that a small quantity of resinous matter adhered obstinately to
the crystals, causing them to remain of a brownish-yellow colour.
This brownish tint was ultimately entirely removed by solution
in spirits of wine and digestion with a little purified animal char-
coal, the pure berberine crystallizing from the solution in beau-
tiful bright yellow needles. The crystals were found to contain
nitrogen, and their behaviour with various reagents corresponded
exactly with those of berberine.
As these crystals were very soluble in boiling water, a quantity
of them was dissolved in that menstruum; and on the addition
of the requisite amount of hydrochloric acid, a crystalline preci-
pitate was immediately obtained in the form of long, slender,
golden-coloured needles, of a fine silky lustre.
This salt was dried in a water-bath at 212° F., and subjected
to analysis with the following results :—
6-25 grs., ignited with chromate of lead, gave 14°398 grs. of
carbonic acid and 3:2 grs. of water.
The nitrogen was determined by Wills’s method. 8°18 grs. of
salt gave 4-94 grs. of the double chloride of platinum and am-
monium.
The chlorine was determined as chloride of silver. 3°59 grs.
‘gave 13:5 grs. of chloride of silver.
Hydrochlorate of Berberine.
Calculated numbers. Found numbers.
42 equivs. Carbon . . 3150 62°75 62°79
20 equivs. Hydrogen . 250 4°98 5°67
lequiv. Nitrogen . 177 3°53 3°78
lequiv. Chlorme. . 442 8°85 9°02
10 equivs. Oxygen . . 1000 19-90
5019 100-00
These results correspond pretty closely with the formula of
hydrochlorate of berberine, which, when dried at 212° F., con-
tains 1 equiv. of water, and is consequently C*? H'* NOY, HCl
+ HO.
The hydrogen in this determination is considerably too high,
which however is easily accounted for, as the hydrochlorate of
berberine, after bemg dried in the water-bath, is eminently hy-
groscopic, and consequently absorbs moisture rapidly while being
mixed with the chromate of lead. This observation has already
been made by Fleitmann, who, while analysing this salt, obtained
an equally great excess of hydrogen.
A quantity of the double platinum salt was also prepared by
mixing a solution of the hydrochlorate of berberine with one of
chloride of platinum. The compound obtained corresponded
in the Columba Wood of Ceylon. 101
precisely in its appearance and properties with the salt prepared
in the same way by Fleitmann.
2°80 grs. of salt gave 0°49 gr. of platimum=17°5 per cent.,
the calculated quantity bemg 17°55 per cent.
A small quantity of the acid chromate of berberine was also
prepared by adding a solution of bichromate of potash to one of
hydrochlorate of berberine. The salt which precipitated likewise
perfectly agreed in its properties with the acid chromate examined
by Fleitmann.
The results of these analyses and reactions leave no doubt as
to the identity of the alkaloid, and also serve to corroborate the
correctness of Fleitmann’s formula for berberine, which I briefly
subjoin :—
Berberine‘crystallized at the ordi-
CC”? H!8NO9 + 12HO.
nary temperature . . .
Berberine dried at 212° F.. . . C*#H!®NO9+2HO.
The hydrochlorate dried at 212° F. C*H'®NO®+HC1+ HO.
Double chloride of berberine and C#218N09 + HC] + PCr.
platinum. . . .
The Menispermum fenestratum is, according to Ainslie, a large
tree, which is very common in Ceylon, and an infusion of which
has long been employed by the Cingalese as a valuable tonic
bitter.
Gray, in his Supplement to the Pharmacopceia, informs us
that this tree is known to the Cingalese by the names of Woni-
wol and Bangwellzetta.
Berberine may easily be obtained in very considerable quantity
from Columba wood, the whole of which it pervades, and of which
it is the colouring principle; and if, as I suspect, the resinous
matter accompanying it consists chiefly of altered berberme, im-
proved methods of extraction, such for instance as the employ-
ment of a vacuum pan apparatus, would in all probability still
further augment the amount of product.
I am informed that berberine is employed as a remedial agent
on the Continent, but its scarcity seems hitherto to have pre-
vented its introduction into the medical practice of this country.
As a good source for it has now been pointed out, it may be ex-
pected that berberine will take its place with the other alkaloids
in our materia medica. To prevent misconception from the
similarity of names, it may perhaps be as well to remark, that
berberine and bebeerine are very different substances,—the latter
being the active principle of the bark of the Bebeeree tree of
Guiana, and as yet has not been obtained in a crystalline form.
St. Bartholomew’s Hospital, July 20, 1852.
[ 102 ]
XIII. On Artesian Wells near Silsoe in Bedfordshire. By Evwarp
J. Cuarpman, Professor of Mineralogy in University College,
London*.
ee interest attached at the present time to all questions
connected with deep wells as a source of water-supply,
induces me to offer the following brief notice of a locality rich in
salient examples of thisnature. I am not aware that any account
of this locality has hitherto been published ; no mention, at least,
is made of it in Mr. Prestwich’s able and elaborate work on the
water-bearing strata around London, although m the immediate
vicinity of districts to which he has particularly referred. The
site In question was first pointed out to me by Mr. Homersham,
the engineer to the London and Watford Spring-water Company,
with whom, in conjunction with Professor Clark of Aberdeen,
and Mr. Snoulton of Dover, I first visited itt; but I regret that.
other duties have not allowed me to bestow that full attention
upon the locality that the interest of the subject demands.
The village of Silsoe is situated on the imner edge of the outcrop
of the Lower Greensand formation—the higher division, or étage
Urgonien or Aptien of D’Orbigny—which at that point forms a
range of lowhills running parallel, or roughly so, to the great chalk
escarpment of Bedfordshire and the adjoming counties. Between
the two hill-ranges lies an undulating valley, having,a general
inclination towards the north-east, and possessing, in the parti-
cular locality here referred to, an average breadth of about three
miles. This valley consists of chalk-marl passing by almost in-
sensible gradations (through, it may be presumed, the upper
greensand equivalents) into gaultt. The usual arenaceous cha-
racters of the upper greensand are, however, altogether undeve-
loped; and the true gault clay, lithologically speaking, is only
met with in isolated patches of small extent. One of these occurs
near Lower Gravenhurst, producing bricks of the well-known
light colour, combined with great uniformity of texture and with
great sectility. Gault bricks and tiles may, in fact, be cut
* Communicated by the Author.
+ The existence of deep wells in this neighbourhood was, I believe, made
known to Mr. Homersham by Mr. George Edwards of St. Albans, at one
time a resident in the locality. The water was presumed to come from the
chalk ; more especially as the surface streams of the valley are actually
derived from that source. Amongst other places at which the phenomenon
may be witnessed, a stream may be seen issuing from the chalk at “the
Bath,” a picturesque spot about half a mile north of Barton Church. Slips
and faults on a large scale have evidently taken place along this portion of
the chalk escarpment.
{ The transition of the gault into the calcareous clay may be traced more
particularly on the banks of the small stream-way near Ion Lodge, about a
quarter of a mile south-east of Wrest Park.
On Artesian Wells near Silsoe in Bedfordshire. 103
almost as readily as the “ Bath stones ” employed for household
purposes.
In the accompanying section—between Silsoe (1) and the hills
above Barton-in-the-Clay (2)—A represents the lower greensand,
B the impermeable calcareo-argillaceous strata (gault, upper
greensand, chalk marl), and C the middle chalk. Layers of drift
coat these more or less ; sy
and on some of the in-
tervening heights, as at
Higham Gobion, &c.,
the top of the hill is
capped by a thick mass
of chalk-like detritus mixed with rolled pebbles and a few fossils
of the gault and other strata, underlying two or three feet of
more modern alluvium or vegetable mould. The fossil speci-
mens consist principally of belemnites (B. minimus, &c.), and of
two or three species of Ostreze. All of these are much rolled and
water-worn, the Ostree presenting only single valves, and some
of the larger belemnite guards being split longitudinally so as
to show the phragmocone receptacle.
In other parts of the district, the drift-gravel contains pebbles
of different kinds of granite, granular quartz, clay-slate, sand-
stone, iron-sandstone, flint, and iron pyrites converted into the
hydrated sesquioxide of iron. The latter bodies are evidently
derived from the chalk, similar nodules, or rust-stained cavities
left by their entire decomposition, being seen in all the pits along
the chalk range.
The lower greensand strata consist of soft and coarse sand-
stone beds, interstratified with bands of iron-sandstone and a
few subordinate layers of clay. A section is exhibited in the
quarry a little to the west of Silsoe Church. The beds—apart
from their false stratification, of which peculiarity they offer an
interesting example—are there seen to dip towards the south,
thus constituting a large natural reservoir lying beneath the
impermeable strata of the valley; and as the chalk-marl and
gault series conjointly do not average more than 200 feet in
actual depth, a surface supply of water is readily obtainable.
The beds of the valley are perfectly impermeable, and except
where the patches of gault clay occur, they are of a chalk-like
aspect. In this valley, within an area of about ten square miles,
from one to two hundred borings have been executed; and in a
great number of instances the bore-holes produce an overflowing
stream. As a mean, it may be said that the water in a four-inch
pipe rises about four or five feet above the ground; but this, of
course, varies with the surface-configuration of the valley. In
the higher parts, the water stands at a few feet below the surface,
North. South.
104. On Artesian Wells near Silsoe in Bedfordshire.
but it remains constant at that level; whereas the ordinary wells.
sunk into the surface of the lower greensand, fluctuate im this
respect, as might readily be imagined, with every change of
season.
The bore-holes already executed vary in diameter from two to
four inches, and do not require tubing beyond the first ten or
twelve feet. Some of the smaller size, of an average depth of
about 170 feet, have been put down at a cost not exceeding £7*.
The water derived from this subterranean reservoir is of a
slightly chalybeate nature, depositing on exposure to the atmo-
sphere a yellowish slime of hydrated sesquioxide of iron. Its
temperature is 51° F. The ferruginous taste is at first strongly
perceptible ; but this, of course, becomes less apparent when the
water has stood for some time, and I did not hear any complaints
in respect to quality from persons in the daily habit of using the
water for culinary and other purposes. On the contrary, it was
generally considered to be very wholesome. Compared, indeed,
to that taken from the brooks, in which organic matter is largely
prevalent, the marked superiority of the deep-well water does
not admit of the slightest doubt.
When first drawn, it is beautifully clear, but after the lapse of
three or four hours it becomes clouded from separation of carbo-
nate of iron; regaining, however, its transpareney on the depo-
sition of the precipitate. Mr. Dugald Campbell has kindly ex-
amined for me, by Dr. Clark’s test, a specimen of this water taken
from an overflowing well—showy in the annexed sketch—at White-
hall near Wrest Park, on the
property of the Earl de Grey.
This well is 186 feet deep,
with a bore of four inches in
diameter. The water gushes
out with great force, day and
night, in a continued stream,
and at the rate of about 76
gallons a minute.
The following are the results obtained by Mr. Campbell :-—
Hardness . . . 9°38
Alkalinity . . . 8°50
It is difficult to arrive at any very accurate conclusions as to
the quantity abstracted daily from this subterranean source ; but
judging from the number and power of the overflowing wells,
and from a fair estimate of the amount drawn from those which
do not overflow, there must certainly be a daily consumption or
* On the authority of William Arnold of Greenfield, by whom the greater
part of the deep wells in this district were bored.
Prof. Thomson on the Dynamical Theory of Heat. 105
abstraction of at least three or four millions of gallons over the
area indicated above. As these wells do not aftect one another,
however, in the slightest degree—and severa of them have been
flowing uninterruptedly for many years—we may fairly assume
that the reservoir is capable of yielding a very much larger sup-
ply without detriment to existing interests.
There are perhaps few localities in which the subject of Arte-
sian wells can be better studied than in this valley between Silsoe
and Barton-in-the-Clay ; the latter village lying under the bold
escarpment of the chalk with its projecting spurs and rounded
hollow coombes, and the former on the opposing range of the
lower greensand. The relative heights, the mineral characters,
and the dip of the strata are readily observable ; and from various
positions the eye can take in at a glance the physical and geolo-
gical nature of the whole of the surrounding district—the marl
impervious valley extending between the sandstone hills and the
projecting chalk, and resting upon the under-dipping beds of the
former strata.
In these examinations, besides other points of minor import-
ance, five conditions have to be more particularly considered.
First, the general levels of the country; secondly, the relative
positions, inclination, and thickness of the strata; thirdly, their
permeable or impermeable nature; fourthly, the outcrop area
“and surface configuration of the water-supplying beds; and
fifthly, the chemical composition, &c. of the same, as likely to
affect or not the quality of the water. Mineralogical characters,
therefore, although useless, and even hurtful in their attempted
interpretations, in questions of pure or abstract geology, become,
in these local and practical investigations, of the highest value.
XIV. On the Dynamical Theory of Heat, with numerical results
deduced from Mr. Joule’s equivalent of a Thermal Unit, and
M. Regnault’s observations on Steam. By W11t1L1AM THomson,
M.A., Fellow of St. Peter’s College, Cambridge, and Professor
of Natural Philosophy in the University of Glasgow.
[Continued from p. 21. ]
Parr I].—On the Motive Power of Heat through Finite Ranges
of Temperature.
24. i is required to determine the quantity of work which a
perfect engine, supplied from a source at any temperature,
S, and parting with its waste heat to a refrigerator at any lower
temperature, T’, will produce from a given quantity, H, of heat
drawn from the source.
25. We may suppose the engine to consist of an infinite
106 ~— Prof. Thomson on the Dynamical Theory of Heat.
number of perfect engines, each working within an infinitely
small range of temperature, and arranged in a series of which
the source of the first is the given source, the refrigerator of the
last the given refrigerator, and the refrigerator of each interme-
diate engine is the source of that which follows it in the series.
Each of these engines will, in any time, emit just as much less
heat to its refrigerator than is supplied to it from its source, as
is the equivalent of the mechanical work which it produces.
Hence if ¢ and ¢+ dé denote respectively the temperatures of the
refrigerator and source of one of the imtermediate engines, and °
if q denote the quantity of heat which this engine discharges
into its refrigerator in any time, and g+dg the quantity which
it draws from its source in the same time, the quantity of work
which it produces in that time will be Jdq according to Prop. I.,
and it will also be gudt according to the expression “of Prop. IL,
investigated in § 21; and therefore we must have
Jdq=qudt.
Hence, supposing that the quantity of heat supplied from the
first source, in the time considered is H, we find by integration
Hoes
But the value of g, when ¢=T, 1s the final remainder discharged
into the refrigerator at the temperature T; and therefore, if this
be denoted by R, we have
1 Ss
log ap = 7 J, ma at scheme anh
from which we deduce
1 Ss
RoHe srl oh ae eee
Now the whole amount of work produced will be the mechanical
equivalent of the quantity of heat lost ; and, therefore, if this be
denoted by W, we have
Wea IC IY SP re aria eee aa
and consequently, by (6),
Ls
Wedlchmensdut ys vedi: ae
Ss
26. To compare this with the expression H if pdt, for the
re
duty indicated by Carnot’s theory*, we may expand the expo-
nential in the preceding equation, by the usual series. We thus
* “ Account,’ &e., Equation 7, § 31.
Prof. Thomson on the Dynamical Theory of Heat. 107
find
0 ? oe
Mire (i- Tati —&e.) Hf nat
where 1 3)
This shows that the work really produced, which always falls
short of the duty indicated by Carnot’s theory, approaches more
and more nearly to it as the range is diminished ; and ultimately,
when the range is infinitely small, is the same as if Carnot’s
theory required no modification, which agrees with the conclusion
stated above in § 22.
27. Aga, equation (8) shows that the real duty of a given
quantity of heat supplied from the source increases with every
increase of the range; but that instead of increasing indefinitely
(9).
Ss
in proportion tof pdt, as Carnot’s theory makes it do, it never
T s
reaches the value JH, but approximates to this limit, as [ pdt is
T
increased without limit. Hence Carnot’s remark* regarding the
practical advantage that may be anticipated from the use of the
air-engine, or from any method by which the range of tempera-
tures may be increased, loses only a part of its importance, while
a much more satisfactory view than his of the practical problem
is afforded. Thus we see that, although the full equivalent of
mechanical effect cannot be obtained even by means of a perfect
engine, yet when the actual source of heat is at a high enough
temperature above the surrounding objects, we may get more
and more nearly the whole of the admitted heat converted into
mechanical effect, by simply increasing the effective range of
temperature in the engine.
28. The preceding investigation (§ 25) shows that the value
of Carnot’s function, yu, for all temperatures within the range of
the engine, and the absolute value of Joule’s equivalent, J, are
enough of data to calculate the amount of mechanical effect of a
perfect engine of any kind, whether a steam-engine, an air-engine,
or even a thermo-electric engine; since, according to the axiom
stated in § 12, and the demonstration of Prop. II., no inanimate
material agency could produce more mechanical effect from a
given quantity of heat, with a given available range of tempera~
tures, than an engine satisfying the criterion stated in the enun-
ciation of the proposition.
29. The mechanical equivalent of a thermal unit Fahrenheit,
or the quantity of heat necessary to raise the temperature of a
* © Account, &c.”’ Appendix, Section IV.
108 Prof. Thomson on the Dynamical Theory of Heat.
pound of water from 32° to 33° Fahr., has been determined by
Joule in foot-pounds at Manchester, and the value which he
gives as his best determination is 772°69. Mr. Rankine takes,
as the result of Joule’s determination, 772, which he estimates
must be within ;1,, of its own amount, of the truth. If we take
7722 as the number, we find, by multiplying it by 3, 1390 as
the equivalent of the thermal unit Centigrade, which is taken as
the value of J in the numerical applications contained in the
present paper. /
30. With regard to the determination of the values of y for
different temperatures, it is to be remarked that equation (4)
shows that this might be done by experiments upon any sub-
stance whatever of indestructible texture, and indicates exactly
the experimental data required in each case. For imstance, by
first supposing the medium to be air; and again, by supposing
it to consist partly of liquid water and partly of saturated vapour,
we deduce, as is shown in Part III. of this paper, the two ex-
pressions (6), given in § 30 of my former paper (“ Account of
Carnot’s Theory”), for the value of w at any temperature. As
yet no experiments have been made upon air which afford the
required data for calculating the value of « through any extensive
range of temperature; but for temperatures between 50° and
60° Fahr., Joule’s experiments* on the heat evolved by the ex-
penditure of a given amount of work on the compression of air
kept at a constant temperature, afford the most direct data for
this object which have yet been obtained; since, if Q be the
quantity of heat evolved by the compression of a fluid subject to
“the gaseous laws” of expansion and compressibility, W the
amount of mechanical work spent, and ¢ the constant tempera-
ture of the fluid, we have by (11) of § 49 of my former paper,
- WE
EV iQdaabey?
which is in reality a simple consequence of the other expression
for » in terms of data with reference to air. Remarks upon the
determination of « by such experiments, and by another class of
experiments on air originated by Joule, are reserved for a sepa-
rate communication, which I hope to be able to make to the
Royal Society on another occasion.
31. The second of the expressions (6), in § 30 of my former
paper, or the equivalent expression (32), given below in the pre-
sent paper, shows that 4 may be determined for any temperature
from determinations for that temperature of—
(10)
* “On the Changes of Temperature produced by the Rarefaction and
Condensation of Air,’ Phil. Mag. vol. xxvi. May 1845.
eS ee eee
Prof. Thomson on the Dynamical Theory of Heat. 109
(1.) The rate of variation with the temperature, of the pres-
sure of saturated steam.
(2.) The latent heat of a given weight of saturated steam.
(3.) The volume of a given weight of saturated steam.
(4.) The volume of a given weight of water.
The last mentioned of these elements may, on account of the
manner in which it enters the formula, be taken as constant,
without producing any appreciable effect on the probable accu-
racy of the result.
32. Regnault’s observations have supplied the first of the
data with very great accuracy for all temperatures between —32°
Cent. and 230°. .
33. As cegards the second of the data, it must be remarked
that all experimenters, from Watt, who first made experiments
on the subject, to Regnault, whose determinations are the most
accurate and extensive that have yet been made, appear to have
either explicitly or tacitly assumed the same principle as that of
Carnot which is overturned by the dynamical theory of heat ;
inasmuch as they have defined the “total heat of steam” as the
quantity of heat required, to convert a unit of weight of water
at O°, into steam in the particular state considered. Thus Reg-
nault, setting out with this definition for “ the total heat of satu-
rated steam,” gives experimental determinations of it for the
entire range of temperatures from 0° to 230°; and he deduces
the “latent heat of saturated steam” at any temperature, from
the “total heat,” so determined, by subtracting from it the
quantity of heat necessary to raise the liquid to that tempera-
ture. Now, according to the dynamical theory, the quantity of
heat expressed by the preceding definition depends on the manner
(which may be infinitely varied) in which the specified change
of state is effected; differimg in different cases by the thermal
equivaleuts of the differences of the external mechanical effect
produced in the expansion. For instance, the final quantity of
heat required to evaporate a quantity of water at 0°, and then,
keeping it always in the state of saturated vapour*, bring it to
the temperature 100°, cannot be so much as three-fourths of the
quantity required, first, to raise the temperature of the liquid to
* See below (Part III. § 58), where the “negative” specific heat of
saturated steam is investigated. If the mean value of this quantity between
0° and 100° were —1°5 (and it cannot differ much from this) there would be
150 units of heat emitted by a pound of saturated vapour in having its tem-
perature raised (by compression) from 0° to 100°. The latent heat of the
vapour at 0° being 606°5, the final quantity of heat required to convert a
pound of water at 0° into saturated steam at 100°, in the first of the ways
mentioned in the text, would consequently be 456°5, which is only about
§ of the quantity 637 found as “ the total heat” of the saturated vapour at
100°, by Regnault.
110 Prof. Thomson on the Dynamical Theory of Heat.
100°, and then evaporate it at that temperature; and yet either
quantity is expressed by what is generally received as a definition
of the “total heat” of the saturated vapour. To find what it is
that is really determined as “total heat” of saturated steam in
Regnault’s researches, it is only necessary to remark, that the
measurement actually made is of the quantity of heat emitted by
a certain weight of water in passing through a calorimetrical
apparatus, which it enters as saturated steam, and leaves in the
liquid state, the result being reduced to what would have been
found if the final temperature of the water had been exactly 0°.
For there being no external mechanical effect produced (other
than that of sound, which it is to be presumed is quite inappre-
ciable), the only external effect is the emission of heat. This
must, therefore, according to the fundamental proposition of the
dynamical theory, be independent of the intermediate agencies.
It follows that, however the steam may rush through the calori-
meter, and at whatever reduced pressure it may actually be con-
densed*, the heat emitted externally must be exactly the same
as if the condensation took place under the full pressure of the
entering saturated steam ; and we conclude that the total heat,
as actually determined from his experiments by Regnault, is the
quantity of heat that would be required, first to raise the liquid
to the specified temperature, and then to evaporate it at that
temperature ; and that the principle on which he determines the
latent heat is correct. Hence, through the range of his experi-
ments, that is from 0° to 230°, we may consider the second of
* If the steam have to rush through a long fine tube, or through a small
aperture within the calorimetrical apparatus, its pressure will be diminished
before it is condensed ; and there will, therefore, in two parts of the calori-
meter be saturated steam at different temperatures (as, for instance, would
be the case if steam from a high pressure boiler were distilled into the open
air); yet, on account of the heat developed by the fluid friction, which
would be precisely the equivalent of the mechanical effect of the expansion
wasted in the rushing, the heat measured by the calorimeter would be pre-
cisely the same as if the condensation took place at a pressure not appre-
ciably lower than that of the enterimg steam. The circumstances of such
a case have been overlooked by Clausius (Poggendorff’s Annalen, 1850,
No. 4, p. 510), when he expresses with some doubt the opinion that the
latent heat of saturated steam will be truly found from Regnault’s “total
heat,” by deducting “the sensible heat”’ ; and gives as a reason that, in the
actual experiments, the condensation must have taken place ‘“ under the
same pressure, or nearly under the same pressure,” as the evaporation.
The question is not, Did the condensation take place at a lower pressure
than that of the entering steam? but, Did Regnault make the steam work
an engine in passing through the calorimeter, or was there so much noise of
steam rushing through it as to convert an appreciable portion of the total
heat into external mechanical effect ? And a negative answer to thisisa suf-
ficient reason for adopting with certainty the opinion that the principle of
his determination of the latent heat is correct.
EE
Prof. Thomson on the Dynamical Theory of Heat. 111
the data required for the calculation of ~ as being supplied in a
complete and satisfactory manner.
34. There remains only the third of the data, or the volume
of a given weight of saturated steam, for which accurate experi-
ments through an extensive range are wanting; and no experi-
mental researches bearing on the subject having been made since
the time when my former paper was written, I see no reason for
supposing that the values of « which I then gave are not the
most probable that can be obtained in the present state of science ;
and, on the understanding stated in § 33 of that paper, that
accurate experimental determinations of the densities of saturated
steam at different temperatures may indicate considerable errors
in the densities which have been assumed according to the
“gaseous laws,” and may consequently render considerable alte-
rations in my results necessary, I shall still continue to use
Table I. of that paper, which shows the values of w for the tem-
peratures 3, 13, 23 . . . 23803, or, the mean values of wu for each
of the 230 successive Centigrade degrees of the air-thermometer
above the freezing-point, as the basis of numerical applications
of the theory. It may be added, that any experimental researches
sufficiently trustworthy in point of accuracy, yet to be made,
either on air or any other substance, which may lead to values
of » differing from those, must be admitted as proving a discre-
paney between the true densities of saturated steam, and those
which have been assumed*.
35. Table II. of my former paper, which shows the values of
t '
Va pdt for t=1, t=2, t=3, . . . t= 231, renders the calculation
0
of the mechanical effect derivable from a given quantity of heat
by means of a perfect engine, with any given range included
between the limits 0 and 231, extremely easy; since the quan-
tity to be divided by J+ in the index of the exponential in the
* I cannot see that any hypothesis, such as that adopted by Clausius
fundamentally in his investigations on this subject, and leading, as he shows
to determinations of the densities of saturated steam at different tempera-
tures, which indicate enormous deviations from the gaseous laws of varia-
tion with temperature and pressure, is more probable, or is probably nearer
the truth, than that the density of saturated steam does follow these laws
as it is usually assumed to do. In the present state of science it would
perhaps be wrong to say that either hypothesis is more probable than the
other [or that the rigorous truth of either hypothesis is probable at all].
+ It ought to be remarked, that as the unit of force implied in the de-
terminations of » is the weight of a pound of matter at Paris, and the unit
of force in terms of which J is expressed is the weight of a pound at Man-
chester, these numbers ought in strictness to be modified so as to express
the values in terms of a common unit of force; but as the force of gravity
at Paris differs by less than z;4;5 of its own value from the force of gravity
at Manchester, this correction will be much less than the probable errors
from other sources, and may therefore be neglected.
112 — Prof. Thomson on the Dynamical Theory of Heat.
expression (8) will be found by subtracting the number in that
table corresponding to the value of T, from that corresponding
to the value of 8. [Tables I. and II. of the former paper are
reprinted here, for the sake of convenience in referring to them. ]
Tables extracted from “ Account of Carnot’s Theory,” Trans. R.
S. Ed. vol. xvi. part 5.
Explanation of Table 1.
The mean values of mw for the first, for the eleventh, for
the twenty-first, and so on, up to the 231st* degree of the air
thermometer, have been caleulated im the manner explained in
the preceding paragraphs. These, and interpolated results,
which must agree with what would have been obtained by direct
calculation from Regnault’s data to three significant places of
figures (and even for the temperatures between 0° and 100°, the
experimental data do not justify us in relying on any of the
results to a greater degree of accuracy), are exhibited in'Table I.
To find the amount of mechanical effect due to a unit of heat,
descending from a body at a temperature 8 to a body at T, if these
numbers be integers, we have merely to add the values of j% im
Table 1. corresponding to the successive numbers,
Tap geo pL oegey,
Explanation of Table II.
The calculation of the mechanical effect in any case, which
might always be effected in the manner described in § 37 (with
the proper modification for fractions of degrees when necessary),
is much simplified by the use of Table II., where the first number
of Table I., the sum of the first and second, the sum of the first
three, the sum of the first four, and so on, are successively ex-
hibited. The sums thus tabulated are the values of the integrals
1 2 3 4231
Swit, J uat, fo nat, ff pat
0 0 esi | 0
t
and if we denote of pdt by the letter M, Table II. may be re-
0
garded as a table of the values of M.
To find the amount of mechanical effect due to a unit of heat
descending from a body at a temperature 8 to a body at 'T, if these
numbers be integers, we have merely to subtract the value of M, for
the number T +1, from the value for the number S, given in Table II.
* In strictness, the 230th is the last degree for which the experimental
data are complete; but the data for the 231st may readily be assumed in a
sufficiently satisfactory manner.
Prof. Thomson on the Dynamical Theory of Heat. 113
Table 1*.—Mean Values of jz for the successive Degrees of the
Air Thermometer from 0° to 230°.
, fe ie ; [ee : ie : fe.
1 | 4960|| 48 | 4:366)) 94 |.3:889|| 140 | 3-549/| 186 | 3-309
2 | 4946)! 49 | 4:355|] 95 | 3880) 141 | 3543] 187 | 3-304
3 | 4932) 50 | 4:343 96 | 3°871)|) 142 | 3:537|| 188 | 3-300
4 | 4918) 51 | 4-331|| 97 | 3863)! 143 | 3-581] 189 | 3-295
5 | 4905 || 52 | 4-319 98 | 3854 || 144 | 3:°525|/ 190 | 3-291
6 | 4892); 53 | 4-308|| 99 | 3°845]| 145 | 3-519/| 191 | 3-287
7 | 4878)| 54 | 4:296)| 100 | 3-837|| 146 | 3:513|| 192 | 3-282
8 | 4865) 55 | 4-285 |] 101 | 3-829|| 147 | 3:507|| 193 | 3-278
9 | 4852)| 56 | 4:273]| 102 | 3°820|| 148 | 3:501|| 194 | 3-274
10 | 4839) 57 | 4-262|| 103 | 3-812), 149 | 3-495|| 195 | 3-269
58 | 4:250)| 104 | 3°804)| 150 | 3-490|| 196 | 3-265
59 | 4:239]) 105 | 3:796|| 151 | 3-484|| 197 | 3-261
60 | 4:227)| 106 | 3-788) 152 | 3-479|| 198 | 3-257
61 | 4:216)} 107 | 3:780)|| 153 | 3-473|| 199 | 3-253
62 | 4:205 || 108 | 3772) 154 | 3-468 || 200 | 3-249
63 | 4:194|| 109 | 3-764|| 155 | 3-462|| 201 | 3-245
64 | 4-183)|| 110 | 3:757|| 156 | 3-457|| 202 | 3-241
65 | 4:172|| 111 | 3:749|| 157 | 3-451|) 203 | 3-237
66 | 4:161|| 112 | 3-741|| 158 | 3:446|| 204 | 3-233
67. | 4-150|| 113 | 3:734|| 159 | 3-440/| 205 | 3-229
68 | 4-140|] 114 | 3:726|| 160 | 3-435|| 206 | 3-225
69 | 4-129|} 115 | 3:719|| 161 | 3-480)! 207 | 3-221
70 | 4:119)|| 116 | 3°712|| 162 | 8-424|| 208 | 3-217
71 | 4:109|| 117 | 3:704|| 163 | 3-419|| 209 | 3-213
72 | 4-098 || 118 | 3-697)| 164 | 3-414|| 210 | 3-210
3689 || 165 | 3:-409|| 211 | 3-206
74 | 4-078} 120 | 3-682|| 166 | 3-404|| 212 | 3-202
75 | 4-:067|| 121 | 3:675|| 167 | 3:399|| 213 | 3-198
3°668 | 168 | 3394) 214 | 3-195
77 +| 4:047'|| 123 | 3°661|| 169 | 3:°389|| 215 | 3-191
78 | 4:037|| 124 | 3:654'| 170 | 3-384|) 216 | 3-188
79 | 4:028)| 125 | 3-647|| 171 | 3:380|| 217 | 3-184
80 | 4:018|| 126 | 3-640] 172 | 3-375 || 218 | 3-180
81 | 4-009] 127 | 3633 | 173 | 3370) 219 | 3-177
82 | 3:999|| 128 | 3-627]! 174 | 3:365]| 220 | 3-173
83 | 3-990! 129 | 3-620|| 175 | 3-361 |] 221 | 3-169
84 | 3-980|} 130 | 3:614/] 176 | 3-356|| 222 | 3-165
85 | 3-971|| 131 | 3-607|| 177 | 3:351|| 223 | 3-162
86 | 3-961|| 132 | 3°601|| 178 | 3:346|] 224 | 3-158
“I
oo
re
—
oa
oo
_—
_—
©
x
for}
sng
&
~“\
—
bo
LS)
87 | 3:952|| 133 | 3:°594)|) 179 | 3:°342|| 225 | 3°155
88 | 3-943]! 134 | 3:586|| 180 | 3-387|| 226 | 3-151
89 | 3934 || 135 | 3579 || 181 | 3°332 || 227 | 3-148
90 | 3925)! 1386 | 3°573)|| 182 | 3:°328|) 228 | 3-144
91 | 3916) 1387 | 3°567'| 183 | 3°323'| 229 | 3-141
92 | 3°907)| 188 | 3°561|) 184 | 3:318)| 230 | 3-137
93 | 3:898]] 1389 | 3555 || 185 | 3:314)] 231 | 3-134
* The numbers here tabulated may also be regarded as the active values
of p for t=}, t=14, t= 24, t= 34, &e.
Phil. Mag. 8. 4. Vol, 4. No. 283, Aug. 1852. I
114
Prof. Thomson on the Dynamical Theory of Heat.
Table I1.—Mechanical Effect in Foot-Pounds due to a Thermic
Unit Centigrade, passing from a body, at any Temperature
less than 230° to a body at O°.
Superior] yfecha-
limit of | “jical
«| tempe- | effect.
rature.
ft.-lbs.
4-960
9-906
14-838
19°756
24-661
29:553
34-431
39-296
44-431
48-987
53-813
58-625
63-424
68-210
72-983
77743
82-490
87:225
91-947
96:656
101-353
106-037
110-709
115-368
120-014
124-648
129-269
133-878
138-474
143-058
147-630
152-189
156-736
161-271
165-793
170-303
174-801
179-287
183-761
188-223
192-673
197-111
201-537
205-951
210°353
214-743
219-121
© CO SD St CO DD tO
Superior| yyecha-
limit of | “ical
tempe- | effect.
rature.
5 ft.-lbs.
48 223-487
49 |227-842
50 (232-185
51 |286:516
240°835
245°143
249-439
253-724
257:997
262-259
266°509
270°748
274:975
279/191
283°396
287:590
291-773
295-945
300-106
304:256
308°396
312-525
316°644
320°752
324°851
328-939
333°017
337°084
341°141
345°188
349-225
353°253
357°271
361-250
365°279
369°269
373°249
377220
381-181
385'133
389-076
393010
396°985
400°851
92
93 |408-656
404-758 |
|
Superior] pfecha-
limit of nical
tempe-| effect.
ratures
> | ft.-Ibs.
94 | 412-545
95 | 416-425
96 | 420-296
97 | 424-159
98 | 428-013
99 | 431-858
100 | 485-695
101 | 439-524
102 | 443-344
103 | 447-156
104 | 450-960
105 | 454-756
106 | 458-544
107 | 462-324
108 | 466-096
109 | 469-860
110 | 473-617
111 | 477-366
112 | 481-107
118 | 484-841
114 | 488-567
115 | 492-286
116 | 495-998
117 | 499-702
118 | 503:399
119 | 507-088
120 | 510-770
121 | 514-445
122 | 518-1138
123 | 521-774
124 | 520°428
125 | 529-075
126 | 532-715
127 | 536-348
128 | 539-975
129 | 543-595
1380 | 547-209
131 | 550816
1382 | 554:417
133 | 558-051
134 | 561-597
135 | 565-176
136 | 568-749
137 | 572°316
138 | 575-877
1389 | 579-432
Superior] i
limit of eric
tempe-| effect,
rature,
6 ft.-Ibs.
140 | 582-981
141 | 586-524
142 | 590-061
143 | 593-592
144 | 597-117
145 | 600-636
146 | 604-099
147 | 607:656
148 | 611-157
149 | 614652
150 | 618-142
151 | 621-626
152 | 625-105
153 | 628-578
154 | 632-046
155 | 635-508
156 | 638-965
157 | 642-416
158 | 645:862
159 | 649-302
160 | 652-737
161 | 656°167
162 | 659-591
163 | 663-010
164 | 666-424
165 | 669-833
166 | 673-237
167 | 676-686
168 | 680-030
169 | 683-419
170 | 686°803
171 | 690-183
172 | 693558
173 | 696-928
174 | 700-298
175 | 708-654
176 | 707-010
177 | 710-361
178 | 713:707
179 | 717-049
180 | 720-386
181 | 723-718
182 | 727-046
183 | 780:369
184 | 733°687
185 | 737-001
Superior] yfecha-
limit of nical
tempe- | » effect.
rature.
a ft.-lbs.
186 | 740-310
187 | 743-614
188 | 746-914
189 | 750-209
190 | 753-500
191 | 756-787
192 | 760-069
193 | 763°347
194 | 766-621
195 | 769-890
196 | 773-155
197 | 776-416
198 | 779:°673
199 | 782:926
200 | 786:175
201 | 789-420
202 | 792-661
203 | 795:898
204 | 799-131
205 | 802°360
206 | 805-585
207 | 808-806
208 | 812-023
209 | 815-236
210 | 818-446
211 | 821-652
212 | 824-854
213 | 828-052
214 | 831:247
215 | 834-438
216 | 837-626
217 | 840810
218 | 843-990
219 | 847-167
220 | 850°340
221 | 853-509
222 | 856-674
223 | 859°836
224 | 862-994
225 | 866:149
226 | 869:300
227 | 872-448
228 | 875°592
229 | 878-733
230 | 881-870
231 | 885:004
36. The following tables show some numerical results which
have been obtained in this way, with a few (contained in the
t
lower part of the second table) calculated from values of f pdt
; 0
estimated for temperatures above 230°, roughly, according to the
rate of variation of that function within the experimental limits,
|
:
|
|
-
Prof. Thomson on the Dynamical Theory of Heat. 115
37. Hzplanation of the Tables.
Column I. in each table shows the assumed ranges.
Column II. shows ranges deduced by means of Table LL. of
Ss
the former paper, so that the value of y= pdt for each may be
vi
the same as for the corresponding range shown in column I.
Column III. shows what would be the duty of a unit of heat
if Carnot’s theory required no modification (or the actual duty
of a unit of heat with additions through the range, to compen-
sate for the quantities converted into mechanical effect).
Column IV. shows the true duty of a unit of heat, and a com-
parison of the numbers in it with the corresponding numbers in
column IIT. shows how much the true duty falls short of Carnot’s
theoretical duty in each case.
Column VI. is calculated by the formula
s
Rae won/ ah,
s ;
where e=2°71828, and for / pdt the successive values shown in
column III. are used. a
Column IV. is calculated by the formula
W=1390(1—R)
from the values of 1—R shown in column V.
88. Table of the Motive Power of Heat.
Ill. IVs V. VI.
Dutyofa |Duty ofa unit! Quantity of
unit of heat | of heat sup- |heatconverted} Quantity of
through the |plied from the| into mecha- g heat wasted.
Range of temperatures.
Il. whole range,| source. nical effect.
ui s T S fe pdt Ww i=R R
B 2 ft.-Ibs. ft.-Lbs.
0 31:08) 30 4:960 4-948 ‘00356 “99644
0 40°86, 30 48-987 48-1 0346 ‘9654
0 51:7 | 30 96°656 93:4 067 933
0 62:6 | 30 143-06 136 098 ‘902
0 736 | 30 188-22 176 127 878
0 84:5 | 30 23218 214 154 846
0 95-4 | 30 274:97 249 179 821
0 1063 | 30 31664 283 204 796
0 1172 | 30 357°27 315 227 773
0 128':0 | 30 396-93 345 248 752
0 {13885 | 30 435°69 374 269 731
0 149-1 30 47362 401 289 711
0 1603 | 30 510°77 427 308 692
0 1710 | 30 547-21 452 325 675
0 181-7 | 30 582°98 176 343 657
0 1923} 30 61814 499 359 641
0 |2080| 30 652°74 521 875 625
0 |2136 | 30 686-80 542 390 610
0 |2242) 30 72039 562 404 596
0 190 0 753°50 582 418 582
0 | 200 0 786:17 600 432 568
) |210 0 81845 | 619 445 555
0 | 220 0 | 85034 | 636 457 542
0 | 230 0 | 88187 | 653 ‘470 530
I2
-
116 Prof. Thomson on the Dynamical Theory of Heat.
39. Supplementary Table of the Motive Powers of Heat.
Ill. IV. V. VI.
Duty ofa |Duty of aunit) Quantity of
unit of heat | of heat sup- jheat converted! Quantity of
through the | plied from | into mecha- | heat wasted.
Range of temperatures.
I. | Il. whole range. | the source. | nical effect.
s 7, Ss ah Hi peat Ww 1—R. R.
“3 x 5 ft.-Ibs ft.-lbs.
101-1] 0 140 | 30 439°9 377 271 729
105°8| 0 230 | 100 446:2 382 275 “725
300 0 | 300 0-| 1099 757 “545 “455
400 0 400 0 1395 879 632 368
500 0 500 0 1690 979 “704 +296
600 0 600 0 1980 1059 762 +238
mn Des braces 0 | @ 1390 1-000 000
40. Taking the range 30° to 140° as an example suitable to
the circumstances of some of the best steam-engines that have
yet been made (see Appendix to Account of Carnot’s Theory,
Sec. v.), we find im column ITI. of the supplementary table, 377
ft.-lbs. as the corresponding duty of a unit of heat instead of
440, shown in column IJI., which is Carnot’s theoretical duty.
We conclude that the recorded performance of the Fowey-Consols
engine in 1845, mstead of being only 573 per cent. amounted
really to 67 per cent., or 2 of the duty of a perfect engine with
the same range of temperature ; and this duty being °271 (rather
more than 1) of the whole equivalent of the heat used; we con-
clude further, that =o or 18 per cent. of the whole heat sup-
plied, was actually converted into mechanical effect by that
steam-engine.
41. The numbers in the lower part of the supplementary
table show the great advantage that may be anticipated from the
perfecting of the air-engine, or any other kind of thermo-dynamic
engine in which the range of the temperature can be increased
much beyond the limits actually attainable in steam-engines.
Thus an air-engine, with its hot part at 600°, and its cold part at
0° Cent., working with perfect ceconomy, would convert 76 per
cent. of the whole heat used into mechanical effect ; or working
with such ceconomy as has been estimated for the Fowey-Consols
engine, that is, producmg 67 per cent. of the theoretical duty
corresponding to its range of temperature, would convert 51 per
cent. of all the heat used into mechanical effect.
42. It was suggested to me by Mr. Joule, in a letter dated
December 9, 1848, that the true value of « might be “ inversely
a i a i it iii i a a
Prof. Thomson on the Dynamical Theory of Heat. Lie
as the temperatures from zero*;” and values for various tempe-
ratures calculated by means of the formula,
; E
b= I THe
were given for comparison with those which I had calculated
from data regarding steam. This formula is also adopted by
Clausius, who uses it fundamentally in his mathematical investi-
gations. If were correctly expressed by it, we should have
PAG 1+ ES.
S pitas logs ar ;
and therefore equations (1) and (2) would become
iP gee Dintipke popen, og ay
(11)
et Dabs IP sit pa lb as apa apy
43. The reasons upon which Mr. Joule’s opinion is founded,
that the preceding equation (11) may be the correct expression for
Carnot’s function, although the values calculated by means of it
differ considerably-from those shown in Table I. of my former
paper, form the subject of a communication which I hope to have
an opportunity of laying before the Royal Society previously to
the close of the present session.
[To be continued. |
* If we take p=k where k may be any constant, we, find
E
I+Et
k
Val Ge 3
gt
which is the formula I gave when this paper was communicated. I have
since remarked, that Mr. Joule’s hypothesis implies essentially that the
coefficient k must be as it is taken in the text, the mechanical equivalent of
a thermal unit. Mr. Rankine, in a letter dated March 27, 1851, informs me
that he has deduced, from the principles laid down in his paper communi-
cated last year to this Society, an approximate formula for the ratio of the
maximum quantity of heat conyerted into mechanical effect to the whole
quantity expended, in an expansive engine of any substance, which, on
comparison, I find agrees exactly with the expression (12) given in the text
as a consequence of the hypothesis suggested by Mr. Joule regarding the
value of » at any temperature.—[April 4, 1851.]
[ 118 ]
XV. On the Chemical Constitution of Childrenite.
By Prof. RamMMELSBERG*.
AMONG the rarest crystallized minerals, and one that in a
chemical point of view may be said to be hardly known at
all, may be classed childrenite. This species, which was at first
met with in very minute crystals, many years ago, in piercing a
tunnel near Tavistock, has of late years been found im much finer
specimens at the George and Charlotte Mine, some of the cry-
stals indeed measuring full half an inch in length. Within the
last twelvemonth, two specimens of a peculiarly dark colour have
occurred at Wheal Crebor. Both these mines are situated near
Tavistock.
On exposure to heat, childrenite gives off a considerable quan-
tity of water. Before the blowpipe, it swells, and puts forth in-
sulated branches, tinging the flame distinctly of a blush-green
colour, and forms a fissured, rounded mass, black in part, and in
part brownish-red on the edges. With fluxes it gives the reaction
of manganese and iron. In the form of a fine powder, the mineral
is soluble by lengthened digestion in hydrochloric acid, leaving
generally a slight residue consisting principally of quartz. The
solution at length assumes a faint yellow colour; ammonia pro-
duces in it a voluminous dark blackish-green precipitate, which
turns brown on exposure to the air, and which consists of phos-
phoric acid, alumina and the oxides of iron and manganese. The
filtrate contains only phosphoric acid ; there is no alkali in it. A
freshly formed solution of the mineral showed a strong reaction
of the protoxide of iron; of the peroxide the reaction was far
less marked.
On exposure to a red heat in a covered platina crucible, the
powdered childrenite loses its water. In one experiment, where
the mineral was not altogether free from copper pyrites, this loss
amounted to 16°35 per cent., a small quantity of sulphurous acid
being given off. On employing the material in as pure a state
as possible, the loss was 16°30 per cent. The powder, thus
heated, is of a bluish-red, black internally; when heated with
access of air, it is red throughout.
The loss of weight on exposure to heat corresponds to the
amount of water in the mineral minus the oxygen, which the
protoxide of iron (and of manganese) has taken up in its con-
version into the peroxide.
As the crystals of childrenite are very firmly implanted on
their gangue, which consists of carbonate of iron, quartz and
* From Poggendorff’s Annalen, No. 3, 1852, with a few unimportant
additions as to localities. Communicated by W. G, Lettsom, Esq.
On the Chemical Constitution of Childrenite. 119
copper pyrites, it is no easy matter to detach a sufficient quan-
tity of them in a tolerable state of purity.
In the first analysis, the mineral in the state of powder having
been exposed to heat, was fused with carbonate of soda and treated
hike a silicate. The precipitate thrown down by ammonia was
exhausted several times with boiling potash, and then digested
with hydrosulphate of ammonia to extract the whole of the phos-
phoric acid. After supersaturation with hydrochloric acid, the
phosphate of alumina was precipitated from the potash solution
by means of ammonia, the remainder of the phosphoric acid in
the filtrate was next ascertained ; the precipitate, after exposure
to a red heat, was dissolved in acid, and the phosphoric acid was
precipitated with chloride of magnesium.
1:229 grm., when thus treated, gave—
Sica veo Sl ki bed gee Le
Phosphoric acid... . . 28:24 29°36
Miata VI Pe yee TON THOS 18°77
Protoxide of iron . . . . 29°58 30°75
Protoxide of manganese . . 5°89 6°12
Oxide of copper. . . . 0°65 0°66
Loss by exposure to heat. . 1635 17-00
102°59 102-66
In a second analysis, 0°454 grm. was first exposed to a red
heat, whereby the loss of weight amounted to 0:074.
2°804 grms. were next digested in hydrochloric acid, and left
a residue of 0°113. The solution, after evaporation in the water-
bath, was treated with ammonia and sulphuret of ammonium,
the residue dissolved in acid, the solution oxidized, precipitated
with ammonia, and the precipitate, after exposure to a red heat,
was analysed by fusing it with silica and carbonate of soda.
After deducting the residue, the results obtained from this
analysis, the materials for which were purer than those employed
on the former one as given above, were—
Oxygen.
Phosphoric acid . ... . . 2892 16°20
Alumina . . oe 2 ee Aaa 6°74
Protoxide of iron . . . . 80°68 6:81
Protoxide of manganese . . 9:07 2:03 8°89
MisPuerie ii ack Ne | OFA 0:14
Der We ONLI cer dos Las 15°09
100°23
The quantities of oxygen are here in the ratio of. a 4:1:1: 32: 2°24.
If instead we assume the ratio to be 2°5:1:1°32:2°5=15:6:8:15,
and this we are the more justified in doing Hei the impossibility
120. The Rev. J. Bashforth on the Conducting Powers of Wires
of the entire amount of water being indicated by the loss from
exposure to heat, childrenite may be looked upon as consisting
of 8 atoms RO, 2 atoms alumina, 3 of phosphoric acid and 15 of
water, which constitution is represented by the formula—
2(4RO, PO®) + 2A10%, PO® + 15HO.
The first term in this formula is contained in triphyline, and
triplite is asserted to have a similar composition. The second
term, with a third part of the amount of water, is met with in
calaite.
It is to the kindness of Mr. Brooke, M. Krantz, and Mr.
Lettsom that I am indebted for the materials on which I operated.
XVI. Remarks on Mr. Dresser’s Experiments on the Conducting
Powers of Wires for Voltaic Electricity, and on Mr. Joule’s
Experiments with a powerful Electro-magnet. By the Rev.
J. Basurortu, Hsq.*
ia the September Number of the Philosophical Magazine,
Mr. Dresser gave an account of some experiments with
respect to the conducting powers of wires, which appeared to
him to impugn the commonly received laws of their resistances
to the galvanic current. It is not rare to meet with objections
to well-established laws arising from a misapprehension of their
meaning, but objections of this kind are seldom founded on ex-
periments so good as these appear to be. Mr, Dresser has not
explained how he compared the results of theory and experiment ;
but or Table I. he observes, “‘.... it 1s evident that the often
quoted law of the conducting power of the wire being inversely
as the length does not obtain in short lengths. But there is an
evident intimation of some other law, and probably different for
different. metals.” Again, “ From this Table (II.), compared
with Table I., it does not appear that with a thicker wire there
is any nearer approach to the old law, but also that some other
law obtains.” On Table ILI. it is remarked, that “ Increase of
intensity does not appear to approach near to the supposed law.”
And lastly, “This Table (IV.) does not. coincide with the law of
conduction of wires of different diameters being as the squares
of the diameters.”
It seems to me that all these erroneous conclusions spring
from a wrong application of the laws quoted. The galvanic cur-
rent has other resistances to overcome besides that of the 1, 2,
* Communicated by the Author.
for Voltaic Electricity, &c. 121
3, &e. feet of wire which is introduced into the circuit for expe-
rimental purposes. It has to pass through the galvanometer
wire, the nitric acid, the porous cell, the sulphuric acid, &e. We
must therefore in our calculations suppose an addition of a length
of wire to that which is used in the experiments, and which
remains constant for one series of experiments. Thus suppose
E the electromotive power of the battery, R the resistance of
battery expressed by the length of wire (of the same kind as that
used in the experiment), which would offer the same resistance
as the fluids and solids of the battery actually do offer to the
passage of the current. Let # denote the length of wire intro-
duced into the circuit for the sake of experiment. Then we ex-
press the force of the current by E+(Ik+2), and not by E+2,
as has been very commonly and very erroneously done. From
two observations, the values of E and R (which may approxi-
mately be supposed constant for one series of experiments) may
be found; and then by giving to w the values 1, 2, 3... suc-
cessively, we may obtain corresponding calculated deflections of
the galvanometer which may be compared with the results of
experiments. I have thus calculated all the four tables of expe-
riments, and placed the results of theory and experiment side
by side. The number of observations recorded in the last three
tables is so small, that they are not of much real importance as
tests.
As Mr. Dresser thought that he found the greatest deviation
from the commonly received law when he experimented with
short lengths of wires, I am led to the conclusion that he em-
ployed the formula E~z in his calculations. This would amount
to a supposition, that the current had no other resistances to
overcome beyond that arising from its passage through the wire
introduced into the circuit, as had previously been done by Pro-
fessor Barlow, I believe, and others. The absurdity of such a
supposition will be seen by a simple illustration. Suppose that
a person wished to find experimentally the law of resistance to a
carriage carrying various numbers of passengers when propelled
on a railway at a given velocity. Suppose that the tractive
power required for 1, 2,3... 20 passengers of equal weights
was measured with great nicety, still very little confidence would
be placed in any general law connecting the number of passen-
gers and the tractive power when the heavy weight of the car-
riage itself was entirely neglected.
122 The Rev. J. Bashforth on the Conducting Powers of Wires
Table I.
Copper wire. Iron wire,
H=92538°32, R=22-2576. E=1848, R=4:6.
| ]
Length Observed | piffer- | calculated Length Observed |Differ- | Calculated
of wire deflec- | ence, | deflection. |ETTOF- || of wire.| eflee- | ence, | defiection. |EtTOr-
in feet. | tion. tion.
1 | 3898 18 397°9 |+0:1 1 330 | 50 330°0 0-0
2 | 380 15 3815 |—15) 2 280 | 40 280:0 0-0
3 | 365 13 366-4 j|—-14]| 3 240 | 30 243:2 |—3-2
r Miia es GS 12 352-4 |—0°4 4 | 210 | 20 214-9 |—4-9
5 | 340 10 3395 |+0°5 5 | 190 | 18 1925 |}—2°5
6 | 330 10 38275 |+2°5 6 172 | 14 1743 |—2°3
7 | 320 24 3163 |13-7 th 158 | 23 159-3 |—1:3
9 | 296 10 296-0 0-0 9 135 ‘a 135:8 |—0°8
10 | 286 17 2869 |—0-9|| 10 | 128 16 126-6 |+1-4
12 269 15 2701 j—1:1 12 112 12 1113 |+07
14 254 14 255-2 |—1:2)| 14 100 8 99:4 |+0°6
16 240 10 241-9 |—1°9|| 16 92 7 89:8 |+2:2
18 230 10 2299 |40:1 18 85 7 81:8 |+3:2
20 220 : 219°0 |+1:0)| 20 78 5 75:1 |+2:9
22 73 5 69°5 \43°5
a4 | 68 | 4 | 646 |43-4
26 64 4 60-4 |4+3°6
Las 60 bid 567 |+3°3
Copper. Table IL. Tron.
E=11660, R=40-4. * B=27648, R=9S.
Length |Observed | piffer-| Calculated Observed | pitfer-
of _ deflec- | ence, | deflection, | EtTor- | % meget deflec- —— jn ere Error.
tion, tion.
1 282 w 281-6 |+0-4 abd 256 | 21 256:0 0-0
2 yy eS) ey 275°0 0-0 2 235 18 2343 |107
3 268 | 6 268:7 |—07 3 217 17 2160 |+1-0
4 262 ' 6 262-6 |—0-6 4 200 | 13 2003 |—0°3
5 256 5 256°8 |—0°8 5 187 | 12 186-8 |+0°2
6 251* | 5 251:3 |—03 6 175 11 1750 0-0
7 ,246* | 5 246-0 0-0 7 LGA: |. 47, 1646 |—0°6
8 SAE oes 2409 |40-1) 8 157 = 155°3 |+1:7
Table III.
Copper wire. Iron wire.
E=18800, R=46. E=3882°83, R=8:529.
Length Observed | piffer- Calculated | Length [Observed Differ-| Calculated
of wire.| eflee- | ence. | defection. | EtTor- || of wire,| eflee- | ence. | deflection. |E1T0F.
tion. tion.
1 | 400 | 9 | 4000 | 00] 1 | 355 | 35 | 3550 | 00
2 391 | 9 | 3917 |—07 ] 2 | 3820 | 26 322°0 |—2-0
3 382 6 383:7.-|—1-7||' 3 | 294 24 2934 |+0°6
4 376 | 6«6—(| 88760 00); 4 | 270 18 2700 0-0
5 370 els 368-6 |+1-4 5 252 ies 250°0 |+2:0
_* These three numbers were apparently erroneously printed in the pub-
lished account of the experiments: the differences there given have been
used.
for Voltaic Electricity, &c. 123
Table IV.
Copper wire. Iron wire.
E=125'1845, R=0'58582. E=23'370, R='104.
Dee msatereil: Obarrved! | Galcalaiil Di GlvervedslPalealatza'|
Poke.” aeteeton. defletien, Error. iris lg poe ithe dcdectont om
370 190 | 190 0-0 300 129 | 129 | 00
480 195 | 19905 | —3-95 || 510 165 | 164-2 | +08
700 2063 | 206-5 00°! 640 182 | 182-0 0-0
740 | 207 | 207-2 | —02 || 720 188 189°5 | 15
The agreement between calculation and experiment above
shown is far nearer than could have been expected, considering
the many sources of error. The experiments must have been
very carefully conducted.
Lenz in 1832 showed by experiment with convolutions of wire
of diameters 0°73 inch, 6°57 inches, and 28 inches, that the elec-
tromotive power which magnetism produces in them remains the
same (Mém. Acad. St. Pét.; translated in the Scientific Memoirs,
vol. i. p.607). Again, in 1838, Lenz and Jacobi published ac-
counts of experiments, which showed that the magnetism excited
by the galvanic current in a long bar of iron, by comparatively
short spirals surrounding it, was, for a given strength of current,
independent of the diameter of tne spiral. It appears that
Mr. Joule was guided by this principle in the construction of
his powerful electro-magnets. Still it must not be concluded
that a wide convolution is on the whole as advantageous practi-
cally as a smaller one, The resistance of a wire varies as its
length ; consequently the wider the spirals, the more the strength
of the galvanic current is diminished for a given number of con-
volutions. Thus with Mr. Dresser’s battery, and the iron wire
of Exp. I., the effect of one circuit, 1 foot long, would be 330 ;
of one 2 feet long, 280; of one 3 feet long, 240, &c.; and of
one 28 feet long, 60.
It appears that Mr. Joule took no precautions for ascertaining
the exact strengths of the galvanic current with which he expe-
rimented. The arrangements of the sixteen cells which he adopted
were certainly calculated to produce currents as 1,2 and 4; but
the disturbing causes are so numerous, that in every case an
actual measurement was absolutely necessary. Again, the num-
ber of observations in each experiment is far too small; for
within the limits of errors which Mr. Joule appears to allow, it
would be possible to confirm a great variety of laws. In Exp. I.
the are of vibration is not given, but in Exp, II. it is said to have
been as large as a quadrant of a circle. Such a circumstance as
this deserved some explanation. 'The resistance of the air to the
bar of bismuth, making seventeen vibrations per minute through
124 The Rev. J. Bashforth on the Conducting Powers of Wires
an angle of 90°, must have been considerable. Mr. Joule
seems to have forgotten, that when a body oscillates under the
action of any force, that force varies as the square of the numbers
of vibrations only under very peculiar circumstances. In this
experiment a bar of bismuth, 13 inch long, vibrated between
the two temporary poles of the electro-magnet 14 inch apart.
The foree which caused the bismuth to vibrate is supposed to
have been dependent on imduction; and consequently during
every vibration of the bismuth bar through 90°, the force which
Mr. Joule was desirous of estimating must have gone through
very wide variations. It is certain that the angle of vibration,
instead of being 90°, ought to have been the least possible for
the purpose of obtaining any satisfactory comparisons of forces
resulting from a variation in the strengths of the galvanic current.
The number of vibrations per minute observed in Exp. I. with
assumed currents 1, 2 and 4, were 48,63 and 96. In Exp. VI.
the number of vibrations with a strength of current 2 was found
to be 63, as before. Onthis Mr. Joule remarks, that these three
numbers are evidently as the square roots of 1, 2 and 4. Now
48, 67°87(=63 + 4°87) and 96 are really as the square roots of
1,2 and 4. If we assume that the forces vary as the square of
the observed number of vibrations, we get 1, 1°72 and 4, mstead
of 1,2 and 4. On plotting Mr. Joule’s results of Exp. L, I
obtained three points very nearly in a straight line; and I am
thus led to a law which the experiment does very nearly satisfy,
namely,
303}-+-1x16=48—}3, 3114+2x16=63+4,
and 313+4x16=96—}.
I merely mention this as a fact, without any intention to propose
it as a general law.
The assumed currents of 1, 2 and 4, in Exp. II., gives 44,
93, and 17 vibrations through a quadrant per minute ; and hence
if we supposed the forces of the electro-magnet to vary as the
number of vibrations, we should have 1, 2°23 and 4 for the
strengths of the galvanic current, instead of 1, 2 and 4, Thus
if we suppose that the commonly received laws hold good, and
from Mr. Joule’s numbers of observed vibrations, endeavour to
deduce the strengths of the galvanic currents employed, in
Exp. I. we get 1, 1°72 and 4, in Exp. II. 1, 2°23 and 4, instead
of 1, 2, and 4. in both cases. It is remarkable, that im both
experiments consistent results are obtained in the first and last
observations ; but that the middle observations in the same two
experiments deviate very considerably, in opposite directions, from
the desired results.
On Exp. III. Mr. Joule remarks, that “In this mstance we
ee ee eee ee ee ee ee
om 4 ee
for Voltaic Electricity, &c. 125
notice a slight falling away from the theoretical attraction,”
owing no doubt to the gradual approach to the limit of magne-
tizability in the small bar of iron. And concerning Exp. IV., it
is said that “Here again we have evidences of an approach
towards the limit of magnetizability, for the attractions with a
current of 4: are only ten ¢imes instead of sizteen times as great as
those observed with a current of 1.” Experiments of this kind
are most difficult to perform in a satisfactory manner ; and cer-
tainly these can add little to our knowledge on this point after
the appearance of Dub’s paper on the subject in Poggendorff’s
Annalen*, which furnishes details of very numerous and most
carefully conducted experiments with various cylindrical electro-
magnets and keepers. Much depends on the size and form of
the keeper; for Dub found that, by merely changing the form of
a keeper (the mass remaining constant), the lifting power of the
same electro-magnet varied between limits of 1 and 10 at least.
Again, much must depend on the soft iron of the electro-magnet
itself ; and therefore no great confidence can be placed in the
result of Exp. V., which assigns the maximum attractive power
per square inch of surface of an electro-magnet. Mr. Joule does
not appear to have tried a sufficient variety of forms, both of
magnet and keeper, to warrant him in fixing this limit.
From Experiments I. and II. we see no mdication of an ap-
proach to the limits of magnetizability ; but with the same cur-
rents and magnet we find that this is the reason given for the
wide departure of experimental from theoretical attractions. -
Now from the first two experiments it 1s manifest that there
could only be an approach to the limit of magnetizability in the
keeper in Exp. 1V.; consequently a more massive keeper should
have been tried afterwards ; and this was the more necessary, as
some recent experimenters have denied the existence of such a
limit.
The rule for comparing the lifting powers of two similar elec-
tro-magnets does not appear to be by any means satisfactory.
As we are not told in what this similarity is supposed to consist,
it is impossible to test the theoretical correctness of the rule.
The two electro-magnets compared by Mr. Joule were provided
with 60 and 109 Ibs. of coils of copper wire, and with 10 and 16
cells respectively. Therefore by the rule, the attractive powers
ought to be as 60 x 10: 100 x 16=6:16=1:2°67. The attrac-
tive powers were found to be in the following ratios :—
At a distance of } inch as 480: 976=1 : 2°03
a (2p8h, 4 LOO, Oe eae OU
coe DS veser o, fulen toe eee Loe
St. John’s College, Cambridge.
* Phil, Mag., March 1851,
eee )
f 126 j
XVII. On the Electrical Condition of the Atmosphere.
By Revsen Purriies, Esg.*
182. {PAVING in former papers proved that the friction of
air against water produces electricity, and having
shown that the origin of atmospheric electricity can be found
in the friction of wind on drops of rain, I inferred that the upper
regions of the air were left by the descent of rain in a negative
condition. I look upon the following as a direct proof of the
existence of this negative state of the atmosphere, which leads
to some other conclusions.
183. The positive electricity which the earth receives from
lightning and rain must rapidly find its way back to the atmo-
sphere, for the earth is electrically neutral under ordinary cir-
cumstances, as is known by comparing its state with the abso-
lute electric zerot. Again, the atmosphere when explored by
rods or kites gives a positive charge when the air is clear; there-
fore the air itself, so far as the modes of exploration extend, is
positively electrified. But since the earth is neutral, the upper
regions must be negative; or we have a quantity of positive
electricity existing in the atmosphere, and its equivalent of ne-
gative electricity nowhere—which latter supposition the whole
body of electrical science forbids.
184. The atmosphere, then, may be regarded as consisting of
two spherical orbs, the lower one positively, and the upper one
negatively electrified; and these two orbs induce towards each
other, leaving the earth neutral. Now the positive electricity
will, both from conduction and convection, continually travel
upwards. This seenis to explain the fact, that the positive elec-
tricity is stronger at some distance than at the surface of the
earth.
185. Since the positive and negative orbs of the atmosphere
induce towards each other, they must mutually attract. This
attraction is counterbalanced by the elasticity of the atmosphere ;
consequently it is difficult not to admit that the atmosphere is
condensed by the electric force between the mutually attractive
volumes. There are not, so far as I am aware, any data whereby
to determine what the absolute intensity of the electrical state
of the atmosphere is, and it is therefore impossible to assign any
value to the amount of condensation thus effected. Aurora may,
perhaps, sometimes be occasioned by electricity forcing its way
along and between these oppositely electrified orbs, as well as
by its comme to the earth. The general tendency of the air to
rise in the warmer, and, as a concomitant result, its downward
tendency im higher latitudes, is possibly not without its effect in
* Communicated by the Author.
+ Faraday, Phil. Mag. vol. xxix. p. 257.
sant 2D GP manly ee
On the Electrical Condition of the Atmosphere. 127
producing aurora, by bringing the superior portions of the air
nearer to the earth.
186. On atmospheric electrical maxima and minima.—‘ It has
been ascertained by the observations of De Saussure, Schubler,
Arago and others, that the positive electricity of the atmosphere
is subject to diurnal variations of intensity, there bemg two
maxima and two minima ‘during the twenty-four hours. The
first minimum takes place a little before the rismg of the sun ;
as it rises, the intensity, at first gradually and then rapidly, in-
creases, and arrives at its first maximum a few hours after. This
excess diminishes at first rapidly and afterwards slowly, and
arrives at its minimum some hours before sunset ; it reascends
when the sun approaches the horizon, and attains its second
maximum a few hours after, then diminishes till sunrise, and
proceeds in the order already indicated. The intensity of the
free electricity of the atmosphere has also been found to undergo
annual changes, increasing from the month of July to the month
of November inclusive, so that the greatest intensity occurs in
winter, and the least in summer*.”
187. When the sun has but a small elevation above the horizon,
its rays enter the atmosphere so as to traverse large distances of
air, and the rays are thereby more freely absorbed by the air at
the place of observation than when the sun stands higher; and
at sunrising, the clouds which may have formed during night
will still further intercept the sun’s heat; and it is obvious, that
the air at little distances from the ground will be less heated
than the superior strata, which receive the more undiminished
rays. Now the effect of this will be to produce an expansior
of the atmosphere, and the expansion of the higher strata will
be greater than that of the lower strata; consequently that part
of the negative atmospheric orb, over-head at the place of obser-
vation, becomes lifted up, and more separated from the inferior
positive orb than it was before sunrise ; and the appearance pre-
sented to us is that of an increased positive tension of the atmo-
sphere, just as when the plates of an ordinary condenser are
separated. And this, I think, gives rise to the first maximum
after sunrise. With regard to the mimimum which next occurs,
it must be observed, that as the sun ascends, the proportion of
its rays absorbed by the ground increases, both absolutely and
in comparison with the quantity absorbed by the atmosphere
during their passage through it. Therefore the lower strata of
the atmosphere now become more especially the seat of the ex-
pansion produced by the sun’s heat; the result of which is, that
the oyer-head portion of the positive orb is uplifted, and its influ-
* Council of the Royal Society, Phil. Mag. S. 3. vol. xv. p. 219.
128 Mr. R. Phillips on the Electrical Condition
ence on projecting rods is consequently diminished, a minimum
being at last obtained.
188. When the sun is about to set, the temperature of the air
near the ground falls, and consequently the positive orb is low-
ered, while the sun’s rays still heat the upper regions of the air
as at sunrise, and the negative orb is also upborne by the expan-
sion previously communicated during the day; and when the
sun is set, the temperature of the air.near the ground rapidly
falls. Here are then the conditions for another maximum.
Lastly, during night, the temperature of the superior regions of
the atmosphere falls, which causes the portion of the negative
orb to descend nearer to the positive, and thus produces a dimi-
nished electrical effect; as when the plates of a condenser are
closed.
189, The annual variation is evidently connected with the
quantity of ram. Thus the quantity of electricity is greater in
winter than in summer, because more rain falls in the autumnal
than in the summer months. As far as I can see, there are
only two conditions under which rain or hail can ever be pro-
duced without begetting static electricity ; one is, when the fric-
tion to which the drops of water are exposed is so small that the
quantity of electricity produced is virtually nothing ; the other is,
when the insulation of the different parts of this natural electric
machine is so imperfect that the dynamic effect cnly is obtained.
And most probably neither of these two conditions is ever very
strictly fulfilled.
On the Colours of a Jet of Steam.
190. Professor Forbes some years ago observed, that a jet of
steam absorbed the more refrangible portion of white light*. It
happened durmg some experiments, that a blue jet of steam
caught my attention, and further experiments soon assured me
that it was easy to obtain a jet of almost any colour.
191. A blowpipe jet was screwed on a 'T-piece, and the oppo-
site opening of the T-piece was supplied with a stopcock, while —
the third opening of the T-piece communicated, by means of a
tube, with the cock of the boiler. The blowpipe jet had an ori-
fice about ;3,dths of an inch diameter, and its axis was elevated
about 28° above the horizon. The stopcock on the T-piece was
furnished with a little contrivance, for preventing the steam that
it discharged from interfering with the appearance of the steam
discharged by the blowpipe jet; the use of this stopcock was
to blow off the water which condensed in the steam passages. A
pressure was maintained in the boiler of about 40 lbs. on the inch.
192. On fully opening the cock of the boiler, a jet of steam
was obtained which appeared blue in nearly every position in
* Philosophical Magazine, 8. 3, vol. xiy, p. 121,
al i eels
of the Atmosphere. 129
which it could be viewed. Looking end on from below, the
steam-jet caused that part of the heavens obscured by it to appear
feebly orange-coloured—the day was bright, but the sky at this
quarter was overcast. On looking through the jet of steam from
below upwards, but in a direction inclined about 11° to the axis
of the jet-—in which position a portion only of the steam-cloud
could be viewed by the direct light of the clouds, the remaining
portion being sheltered by the side of the window—one part of
the jet appeared orange-red, namely that part which transmitted
the direct light of the clouds, while the other portion was blue.
The blueness of the jet increased with the above-mentioned angle
until the angle was perhaps 30°, after which the blueness some-
what diminished, but was far from being extinguished at 90°.
193. By partly closing the cock of the boiler, and so dischar-
ging steam from the jet of, perhaps, not a higher pressure than
10 lbs. on the inch, I could obtain a jet of steam, which, looking
end on from below, was blue. It was rather difficult to obtain
this blue jet, and when obtained, it kept alternating with violet.
On now viewing this blue jet under an angle, as before (192.),
of about 20°, it appeared reddish-orange in colour; this colour
was not visible at almost any angle, like the reflected blue (192.).
194. Looking end on, and adjusting the pressure, I have
occasionally seen for a moment at a time a bright green jet ; also,
and commonly, a blue purple. In the reflected tints I am not
sure that I have seen anything more than orange-red, violet and
blue. The transmitted colour appeared in my experiments more
intense than the reflected tints. This, perhaps, has its explana-
tion in the fact, that when looking end on, the eye receives light
which has shone through a columnar arrangement, whose length
is much greater than its diameter,—while the reflected lights
could only be seen by looking on the convex surface of the co-
lumnar stream of particles.
195. Prof. Forbes, after discovering the red colour of a jet of
steam by transmitted light, connected the red colour of the
clouds with this fact ; and the truth of this connexion is beyond
dispute. So far, however, as I have been able to go, the colours
of the steam-jet are manifestly only instances of ordinary inter-
ference, greatly resembling that produced by thin transparent
plates; the transmitted ray being always complementary to the
reflected. Thus in (192.) the transmitted light is red, as in
Prof. Forbes’s experiments, but the reflected light is blue. It
is therefore to be inferred, that all the colours of the clouds ori-
ginate in interference, caused by minute drops of water, the size
of which determines their colour ; while the blue jet (192.) is, I
think, strictly analogous to the blue sky.
7 Prospect Place, Ball’s Pond Road,
June 28, 1852.
Phil. Mag. 8. 4, Vol, 4. No, 23, Aug. 1852, K
Ry 1BOuivtes
XVIII. On the supposed Identity of the Agent concerned in the
Phenomena of ordinary Electricity, Voltaic Electricity, Electro-
magnetism, Magneto-electricity, and Thermo-electricity. By
M. Donovan, Esg., M.R.LA.
[Continued from p. 41.]
Szcrion VII.
O™ of the properties supposed in the early period of the
history of galvanism to constitute a difference between
the voltaic and electric agents, was the great power of the former
to cause chemical decomposition, and the total inefficiency, as
was then believed, of the latter. Dr. Wollaston first showed
that ordinary electricity could, by peculiar methods, be made to
effect a few decompositions, although with difficulty, Faraday,
a few years since, found means to effect decompositions with
greater facility, thus removing, as he conceived, one of the chief
objections of those who still denied the identity of the two agents.
It is not necessary to describe Faraday’s experiments in detail.
His general method was to place paper soaked in a solution of
the substance to be acted on between the extremities of two pla-
tinum wires, one connected with the positive conductor of an
electric machine, through which the current of electricity entered
the solution, and the other with a discharging train consisting
of the gas-pipes and water-pipes of the street. On passing the
electrical current through the arrangement, he states that the
elements arranged themselves round the wire which transmitted,
and the wire which received the electricity, in the same manner
as they would have done if the same substances had been sub-
mitted to decomposition by the positive and negative poles of the
voltaic battery. This he conceived to be further confirmation
of the opinion, that the two kinds of decomposition are produced
by the same agent.
It appears to me that these experiments go just as far to prove
difference as identity of the two agents. When a compound
body is to be decomposed by a voltaic series, the polar wires are
placed in contact with the body; the results are, that the ele-
ments of the compound separate and arrange themselves into
two classes, and each class collects round its proper pole. So
constant a result is this division of bodies into two great orders,
that Berzelius has founded on it a classification of elements into
electro-positive and electro-negative.
Such is the effect of the two polar wires; but. their conjoint
effect is indispensable ; remove either, and the other is power-
less,—the decomposition and all other symptoms of energy cease.
The negative wire attracts the more numerous denomination of
bodies round it; but both are equally important. Mr. Gassiot
On the Constitution of the Electric Fluid. 131
has strikingly proved the necessity of the direct application of
both poles, if proof were wanted, by perfectly insulating 320
cells of his great water-battery, connecting one pole with the
ground, and the other with solution of iodide of potassium. In
this state no decomposition resulted ; but when both polar wires
were placed in connexion with the iodide, decomposition took
place, and iodine was freely evolved*. Faraday has given an-
other instance: if two insulated voltaic troughs be placed in the
same right line, the two adjoining ends being connected by a
wire over which is suspended a magnetic needle, there will be no
deflection ; but as soon as the two distant ends are connected,
deflection takes placet.
In the decompositions effected by Faraday by means of common
electricity, it is remarkable that he made use of but one pole,
and that the positive. The wire connected with the positive
conductor of the electrical machine was the only real and legiti-
mate pole concerned. The wire which carried off the electricity
to the gas and water-pipes was not in the negative state; and if
of sufficient thickness, was not in any electric state; for it trans-
mitted to the general reservoir as fast as it received the electri-
city, and manifested no electrical properties. It is very true,
that if an insulated conductor be approached within a short di-
stance of one that is also insulated and electrified, the former
will become electrical by induction, one end being positive, the
other negative ; but if the conductor thus electrified by induction
be made to communicate with the ground, its electrical state is
destroyed. In the case of Faraday’s wire which carried off elec-
tricity to the discharging train, it cannot be supposed to be in
the negative state caused by induction; for induction can only
be manifested when an insulating medium is interposed between
the two conductors concerned}. In the present instance, the
interposed medium was a saline solution, an excellent conductor
of the electricity which an excited electrical machine is capable
of transmitting in a current. Beside all this, induction should
not enter into the comparison of frictional with voltaic electricity,
as no such thing is known or acknowledged in voltaic electricity
unless as an hypothesis. Here, then, was decomposition with
one pole only ; and hence there was no analogy with voltaic de-
ame for this always requires the cooperation of the two
poles.
Should any suspicion relative to the influence of induction be
entertained, Faraday’s own words prove that he did not conceive
such an influence to be in operation. A bit of turmeric paper,
* Phil. Mag., Oct. 1844, p. 290. + Researches, par. 282.
tT “ Induction can only take place through or across insulators.””—Fara-
day’s Researches, par. 1678.
K 2
182 Mr. M. Donovan on the supposed Identity of the Agent
about half an inch square, was moistened with solution of sul-
phate of soda, and placed on the edge of a glass plate within
about two inches of a point connected with the discharging
train. The end of a decomposing wire proceeding from the
prime conductor rested on the turmeric paper. The machine
being put in action, positive electricity passed through the de-
composing wire, in at one end of the turmeric paper, and out
again at the other end towards the distant point of the dischar-
ging train*. Here he expressly admits that nothing but posi-
tive electricity acted at the two extremities of the very small bit
of turmeric paper ; no negative electricity or negative pole could
be concerned; yet after forty or fifty turns of the machine, the
red stain on the end of the turmeric paper which discharged
positive electricity towards the point indicated the presence of
alkali derived from the decomposition of the sulphate of soda.
It is therefore true that one pole, and one kind of electricity
only, here produced a decomposition, which therefore is of a
different nature from one effected by voltaic electricity.
This was still more evident in an experiment where a large
strip of turmeric paper, wet with solution of sulphate of soda,
was hung from the prime conductor. On working the machine,
alkali was developed at that part where the positive electricity
was discharged from the papery.
In these cases, the alkali appeared at what, in point of fact,
was the positive pole as it was carrying positive electricity, con-
trarily to the voltaic law, according to which it should have ap-
peared only at the negative pole if there had been one. The
experiments, therefore, instead of supporting, seem to discounte-
nance the alleged identity.
In other experiments no pole whatever was employed, positive
electricity being received from the air at one end of the paper,
and the same electricity discharged into the air from the other
end: surely there is here no analogy with voltaic decomposition.
Professor Faraday nowhere refers to the employment of a
positive and negative pole in any one experiment; on the con-
trary, he says that the discharging train with its point “ repre-
sents” the negative polet.
The objections here made may be simplified and reduced to
one by the following variation of the experiment on decomposi-
tion. I placed a bit of turmeric paper well soaked in solution
of sulphate of soda, and the redundant liquid drained off, on the
positive conductor of a powerful electric machine. The end of
* “The machine was then worked, the positive electricity passing into
the memes paper at the point p, and out at the extremity n,”’— Researches,
par. 462. ;
+ Ibid, par, 464, t Ibid. par, 454.
concerned in the Phenomena of ordinary Electricity, §e. 138
a wire was gently pressed upon the paper, the other end was
held in the hand, and the cylinder was made to revolve. Ina
few moments alkali made its appearance under the wire, and
rendered the paper brown. Is not the operation of negative
electricity here excluded? is not the alkali detached by positive
electricity ? and is not the alkali found in a situation the oppo-
site of that which is indicated by the law of voltaic decomposition?
Faraday’s peculiar views relative to the current lead him to
believe that positive and negative electricity are always coexistent
and inseparable in it: hence the law of voltaic decomposition is
conceived differently by him; and the evolution of alkali at the
positive pole, and of acid at the negative, is not an irreconcileable
result, although such a distribution is contrary to that acknow-
ledged by Davy, Berzelius, and all the original experimenters on
this subject. If Faraday’s view be correct, and if the electricity
at both poles of a voltaic series be the same, viz. consisting of
both positive and negative electricity, it is difficult to assign a
cause for the separate appearance of the two classes of bodies at
their respective poles; it is difficult also to understand why, in
Faraday’s experiments, alkali or acid should have been developed
at all: if they were separated from their combination, they
should have appeared together in the same spot of the paper,
and no change of colour should haye ensued. More of this
hereafter.
With regard to voltaic electricity, he describes an elegantly
executed experiment* in which it was proved that decomposition
can be effected by the voltaic series when one of the poles is in
contact with the saline solution to be decomposed, and the other
with water lying as a stratum over the saline solution ; thus in-
tending to demonstrate that the separation and collection of the
elements round the poles are not attributable to any attractive
power of the polar wires or other conductors. But this experi-
ment does not obviate the objections which I have made against
the alleged proofs of the identity of frictional and voltaic elec-
tricity, inasmuch as two effective poles were really in operation,
although one of them acted through a quantity of water, while
the other acted directly ; the water was virtually the pole; or if
not, the virtue of the polar wire was exerted through it.
The final inference to be drawn from all the experiments is,
that to produce voltaic decompositions, the two different kinds
or states of electricity must be in operation mediately or imme-
diately. In all the experiments ever made there is not, within
my knowledge, one which dispenses with this condition ; while
it appears that, in the case of common electricity, one kind or
state is sufficient. The experiments in question cannot therefore
be admitted as proofs of identity, although they may of difference.
* Researches, par. 494,
134 Mr. M. Donovan on the supposed Identity of the Agent
It is very probable that Professor Faraday was induced to
adopt the discharging train, as a substitute for the negative pole,
by his peculiar views of the nature of voltaic excitement. In
his theory, it is assumed that the current of electricity is gene-
rated by the chemical action of the oxygen of the exciting fluid
on the zine, a state of polar tension bemg the result, which is
immediately relieved by the conducting power of the copper plate ;
and through this plate the electricity passes off. Here it is evi-
dent that the duty assigned to the copper plate is that of a mere
conductor; and this is precisely the function attributed to the
copper wire attached to the discharging train in the experiments
with common electricity just described. Such, however, appears
inconsistent with some well-known facts. On this subject Pro-
fessor Poggendorff observes, that were the office of the copper
plate that of a mere conductor, it should follow that, as copper
is the best conductor of electricity, a circle of copper and zinc
should form the most powerful battery, and platinum and zine
should be much inferior, whereas the direct contrary is the fact ;
for if the conducting power of copper be taken according to
Davy’s estimate at 100, that of platinum will be but 162.
To the argument of Poggendorff I may add, that if the copper
plate in the series acted as a mere conductor, a stout wire of
copper should answer as well; which is so far from being the
case, that in Wollaston’s battery the power is greatly increased
by the adoption of a plate of copper double the size of what is
commonly used. The copper is folded round the zine; but that
this is not the cause of the increased energy of the battery, is
shown by the experiments of Mr. Binks. This gentleman also
proves, that an increase of the copper beyond Wollaston’s double
plate is accompanied by a still greater display of power*.
There are some facts connected with the decomposition of
chemical compounds by common electricity which seem still
further to dissociate that agent from the voltaic. Several
eminent authorities have expressed their conviction, that che-
mical and electric attraction are different exhibitions of the same
power. This opinion, first promulgated by Volta, was adopted
and amplified by Su H. Davy, and has been accredited by
Faraday, Berzelius, Ampére and others, with more or less mo-
dification. Before I proceed to my argument, it may be remarked
that this doctrine leads to some speculations which do not appear
to correspond with notions tacitly admitted, or at least not ques-
tioned by these philosophers. An electric machine will emit
sparks twelve or twenty inches long. Are these to be consi-
dered sparks of affinity? can a flash of lightning be otherwise
named a flash of affinity? and what is the stream of light into
which a spark passed through the Torricellian vacuum resolves
* Phil. Mag. vol. xi. New Series, p. 75.
concerned in the Phenomena of ordinary Electricity, &c. 1385
itself? Is it affinity independent of matter, separated from and
no longer a property of matter, an existence per se? These are
questions not devised for the purpose of procuring startling ad-
missions, but difficulties which naturally present themselves and
demand an explanation. It answers no good purpose and means
nothing, to reply that electricity and affinity are different exhi-
bitions of the same power. ,
Well, granting that electricity is all these things, one of its
properties, insisted on as contradistinguishing the frictional from
the voltaic modification, is its high intensity. If, then, fric-
tional electricity be affinity at a high degree of intensity, how
comes it to pass that its decomposing powers are so trivial com-
pared with its intensity? How is it explicable, that, in the elec-
trotype process, a single pair of plates will reduce many ounces
of copper from its solution in a few days, the intensity of any
electricity in operation being so feeble as to be inappreciable ;
while the utmost power of the largest electrical machine would
absolutely never effect the same object? Why isthe most feeble
intensity of voltaic electricity so effective, when the intensity of
frictional electricity, perhaps a hundred times more energetic, is
comparatively powerless, and required the ingenuity of a Wol-
laston or a Faraday to make it act at all? In this argument the
consideration of quantity may be omitted; we do not recognise
quantity of affinity; all we are acquainted with is strength or
intensity of affinity. Were it granted that the affinity which
holds together the elements of a grain of water is electricity
amounting to a flash of lightning, as supposed by Faraday, then
indeed the attraction might be understood to be so intense as to
resist decomposition by frictional electricity; for in that case a
vast quantity would be concentrated within a small bulk. But
were this true, how could frictional electricity, under any circum-
stances, decompose water ?
In this view of the subject, it is most strange that, although
a wire of zinc and a wire of platinum joined can decom-
pose acidulated water voltaically, the utmost power of a large
electrical machine, acting through the same wires connected with
both conductors, will prove ineffectual, unless some devices be
made use of which altogether change the character of the pro-
ceeding; and even then the effects are trifling. The enor-.
mous power of a hydro-electric machine is necessary to procure
the decomposition, with voltaic arrangement of the elements.
Here, then, Faraday’s law fails, namely, that “the chemical
power of a current is in direct proportion of the absolute quan-
tity of electricity which passes¥.” It is true that he makes the
case of water when acted on by common electricity an exception
* Researches, par. 821,
136 Mr. M. Donovan on the supposed Identity of the Agent
to his law*. The essence of a law of nature is its universality ;
if there be an exception, the alleged law is not a constituent
ordination im the organization of the universe. Should we not
confine the application. of this law, if it be really a law, to the
operations of the voltaic agent, whatever it may be, and with-
draw the decomposition of water by frictional electricity alto-
gether from its comprehension, claiming its refractory comport-
ment as a proof of difference rather than of identity ?
The decomposition of water, accompanied by voltaic arrange-
ment of the elements which the hydro-electric machine is known
to effect, offers no objection to the foregoing reasoning ;. the fact
only proves, what is nowhere denied in this essay, that in all
electricity there is an admixture of the constituent element which
imparts tovoltaic phenomena their characteristic chemical powers.
Nay, the necessity of such an enormous quantity and intensity
of frictional electricity for the decomposition of water is in itself
a presumption that the real agent is not the electricity proper,
but some other constituent, of which the former is but the
vehicle. If the electric fluid, amongst its other elementary con-
stituents, contain even the most minute portion of that chemical
agent which in voltaic phenomena produces the chief part, a
continued torrent of sparks ought to produce just the small evi-
dences of chemical’ action which we observe. Perhaps the small
degree of chemical action which large quantities of frictional
electricity exercise, affords us the best measure of the real de-
composing agent present. Instances will be given in a subse-
quent part of this essay, where the ratio of the chemical consti-
tuent appears to predominate over what I have called the elec-
tricity proper, as much as, in frictional electricity, the latter does
over the former.
There is a point of view in which the relation of electricity to
affinity must be considered with the object of questioning whether
decompositions effected either by ordinary or voltaic electricity
are explicable by, and compatible with the doctrine of electro-
chemical equivalents, viz. that. “the equivalent weights of bodies
are simply those quantities of them, which contaim equal quan-
tities of electricity, or have naturally equal electric powers ;
it being electricity which determines the equivalent number,
because it determines the combining force. Or if we adopt the
atomic theory or phraseology, then ‘the atoms of bodies which
are equivalents to each other in their ordinary chemical action
have equal quantities of electricity naturally associated with
them+.” Hence we learn, that, according to this view, the atoms
of matter are all endued with, equal quantities of electricity,
* Researches, par. 329, + Ibid. par, 869,
concerned in the Phenomena of ordinary Electricity, &e. 137
and that these quantities constitute thew affinity for each
other*.
Although Professor Faraday has not expressed himself fully
on this subject, I understand him to mean, that of combining
atoms some are naturally in the positive state (2. e. naturally
associated with a positive electricity or affinity), and some in the
negative state; and indeed he expresses himself elsewhere+ to
this precise effect. An atom of each of the different kinds of
matter will contain an equal quantity or degree of a different
state or kind of electricity ; that is, will have an electric attrac-
tion equal with that of every other atom in the same electric
state, for every atom that is naturally in a differently electric
state. But if all the atoms of matter are endued with equal
forces of electrical attraction, then they are all endued with equal
forces of affinity ; and if all atoms, that is all matter, be endued
with equal force of affinity, then there can be no superior or
inferior forces of affinity, and therefore chemical decomposition
due to this cause can never take place. Mixtures of incompa-
tible substances may therefore be made without exchange of
principles ; all the affinities will be quiescent, because not any
one of the elements concerned will possess stronger powers of
affinity than another.
How, then, can the decomposing powers of electricity, whether
frictional or voltaic, be reconciled to the doctrine of electro-
chemical affinity and electro-chemical equivalents? Ifthe atoms
of all bodies be associated with equal quantities of electricity or
affinity, and if during decomposition “the quantity (of electricity)
which passes is the equivalent of, and therefore equal to that of
the particles separated,” it is not easy to understand why the
equal quantity of electricity that is supposed to act should pro-
duce separation of the elements previously united by a force ex-
actly similar.
On this subject Baron Berzelius observes, that “according to
this hypothesis, the same electric current which is adequate to
the separation of an atom of silver from an atom of oxygen
would also separate an atom of potassium from an atom of
* This idea, in a somewhat different form, had occurred to Sir H. Davy
in 1826, but he did not follow it up. That philosopher says, “in assuming
the idea of two «ethereal, subtile, elastic fluids, attractive of the particles of
each other, and repulsive as to their own particles, capable of combining in
different proportions with bodies, and according to their proportions giving
them their specific qualities, and rendering them equivalent masses, it would
be natural to refer the action of the poles to the repulsions of the sub-
stances combined with the excess of one fluid, and the attractions of those
united to the excess of the other fluid, and a history of the phanomena
not unsatisfactory to the reason might in this way be made out.”—Philo-
sophical Transactions, 1826.
+ Researches, par. 961. { Ibid. par. 855,
138 Mr. J. J. Sylvester on
oxygen, although the former combination is one of the weakest,
and the latter one of the strongest with which we are acquainted*.”*
If Faraday’s electro-chemical equivalent numbers represent
neutralizing quantities of electricity, as atomic numbers repre-
sent saturating ratios of combinable bodies, it should happen
that combination of different kinds of matter, in atomic ratios,
should take place without development of free electricity, the
two states having been in all cases exactly sufficient to neutralize
each other. But the contrary condition of chemical combination
is notorious ; for there are few instances of chemical action which
are not accompanied by the evolution of electricity, and such
evolution is easily recognizable, provided the bodies concerned
are conductors. Instances in abundance are furnished by the
experiments of Lavoisier, Laplace, Becquerel, Pouillet and others.
[To be continued. |
XIX. A Demonstration of the Theorem that every Homogeneous
Quadratic Polynomial is reducible by real orthogonal substitu-
tions to the form of a sum of Positive and Negative Squares.
By J. J. Syvuvester, Barrister-at-Law+.
T is well known that the reduction of any quadratic polynomial
(1, 1)a?+2(1, 2)xy + (2, 2)y?+&e.... +(n, n).2?
to the form a,.&?+a,.7?+...+a,.67, where & 7,...6 are
linear functions of 2, y,...¢, such that 2?+7?+...+@ re-
mains identical with €?+?+ ...6? (which identity is the cha-
racteristic test of orthogonal transformation), depends upon the
solution of the equation
(1,142 (1,2)... (yn)
(2, 2) (2, 2) +2... (2, m) =0.
(n, 1) (n, 2) ... (n,n)+r
The roots of this equation give a, d,,...a,; and if they are
real, it is easily shown that the connexions between 2, y,...¢;
, 7,.-.0, are also real. M. Cauchy has somewhere given a
proof of the theorem}, that the roots of X in the above equation
must necessarily always be real; but the annexed demonstration
* Traité de Chimie. Paris edition, 1845, p. 100.
+ Communicated by the Author.
{ Jacobi and M. Borchardt have also given demonstrations; that of the
latter consists in showing that Sturm’s functions for ascertaining the total
number of real roots expressed by my formule (many years ago given in
this Magazine) are all, in the case of f(A), representable as the sums of
squares, and are therefore essentially positive.
—_—
/
Homogeneous Quadratic Polynomials. 139
is, I believe, new; and being very simple, and reposing upon a
theorem of interest in itself, and capable no doubt of many other
applications, will, I think be interesting to the mathematical
readers of the Magazine.
Let
fA)= | (1, 1) +2 (1, 2) Phcan (1, 2)
(2, 1) (2; 2) +0 > 22. (2; 0)
(3, 1) (3, 2) (3, 3) +A.(3, n)
(n, 1) (5:2); ostidies (n, n) +r
it is easily proved that f(A) x f(—»)
= ft) Tn? 1, 2] ee Ea]
[2, 1] [2, 2] —A?.. | [2, n]
[n, 1] [n, 2] ake, ¥ [n, n| =,
where
[y e]=(4 1) x (1, 6) + (42) x (2) + -.. + (4) x(n, €).
If, now, for all values of 7 and s (r, s)=(s, 7), 2. e. if f(0) be-
comes the complete determinant to a symmetrical matrix, then
every term [7, s] in the derived matrix becomes a sum of squares,
and is essentially positive, and (—1)”. f(A) x f(—2) assumes the
form
OF + GO 4 +L,
where F, G,... L will evidently be all positive; for it may be
shown that F will be the sum of the squares of the separate terms,
i. e. of the last minor determinants of the given matrix, G the
sum of the squares of the last but one minors, and so on, L being
the square of the complete determinant. For instance, if
SM=[4tr ¥ B
Yy b4+-2Xr «
B a c+xX
—f(r) x f(—r) =r\°— Fat + GA? —-H,
where
F=a? + b? + c? 4 2a? 4 28? + 2r/?
G= (ab—v+’)? + (be— a”)? + (8? —ac)?
+ 2(aa— By)? + 2(bB —ya)? +2 (cy—a 8)?
= a ey Gaal
y b «@
|: Cait hae
,
140 Mr. J. J. Sylvester on
Hence it follows immediately that f(A) =O cannot have imagi-
nary roots ; for, if possible, let A=p+g “—1, and write
at+tp=a) b+p=0') c+ psc A+p=N,
f(A) becomes
ad+M oy B
Y B+N oo «
B a cd +n
or say P(X’), and the equation $(X) x 6(—!) =0 will be of the
form —F’. x44 G'?— H’=0, where F’, G’, H! are all essen-
tially positive. Hence, by Descartes’ rule, no value of \/? can be
negative, i. e. (\—p)? cannot be of the form —g?*; that is to
say, it is impossible for any of the roots of f(X) =O to be impos-
sible, or, as was to be demonstrated, all the roots are real.
I may take this occasion to remark, that by whatever linear
substitutions, orthogonal or otherwise, a given polynomial be
reduced to the form }A,¢?, the number of positive and negative
coefficients is invariable: this is easily proved. If now we pro-
ceed to reduce the form (expressed under the umbral notation)
(a,%,+Qo%o+ ... +a,.x,)? to the form
AG P+ Agks?-+ ss + Any G2) +A, . 23,
by first driving out the mixed terms in which 2, enters, then
those in which wz, enters, and so forth until eventually only z, of
the original variables is left, it may readily be shown that
Ay Agee Gy, Ay Age Mp)
Tae eB. wh, SUS
It follows, therefore, that in whatever order we arrange the
umbre a, d,...4,, the number of variations and of continua-
tions of sign in the series
1, Th Mite an Og =
af aya, * a, ag. id,
will be invariable, and in fact will be the same as the number
of positive and negative roots in the generating function in X
above treated of, 2. e. since all the roots are real, will be the same
as the number of variations and continuations in the series formed
by the coefficients of the several powers of A, 7. e.
tS See ee
Ay Ayg? AyAg + Un
The first part of this theorem admits of an easy direct demon-
stration ; for by my theory of compound determinants, given in
Homogeneous Quadratic Polynomials. 141
this Magazine, we know that
a Ags «+ M;—) 4,\ ay Ag so Apa + Op 41 |
Ay Og ive Qype Ay Ages Opry + Oper
=) asi. | s i Gg). » Api 99 a
Aj} sss pai By bt Opa Op. Opt
The first member of this equation is equivalent to
(“ gs ole Of4 “n) . (ie Os: aot Ope ee)
a asx 4 te ipas Ay Ag ie pny Opi
—(% Up «ys Op Oy )
Ba “Gata ofr ot lead oc
Hence it follows, that if the two factors on the right-hand side
of the equation have the same sign,
a a3 eee Ay—~} a, and a, Ag eee Ayp—~} y+)
a Ue) eee a,—) a, ay, Ag eee Q;-1 yl
haye also the same sign. néer se, and consequently the two triads
& a. otal ere) “| Be Ayeeey—1 Oy ae
@y Age + + Apart La, dg.+. G1 4, Ay AgeeeAy—1 Up Up 41
and
fe Ga wriie oe | by Gg one Oy eal be Agee. Dp—y Up+1 “|
Ay Ogee Apap) Ly dg eee Ayn) Apri LG, Ages Opi G41 4,
will in all cases present the same number of changes and conti-
nuations, which proves that the contiguous umbre, @,, @,,,, may
be interchanged without affecting the number of variations and
continuations in the entire series; but, as is well known, any
one order of elements is always convertible into any other order
by means of successive interchanges of contiguous elements,
which demonstrates that, in whatever order the elements @, a,...a@,
be arranged, the number of continuations and variations in
1, 2 My | nh 0 a,
Di Olney AiR ole Ge
is invariable. But that the same thing is true (as we knowit to
be), for the rclation between any one of these unsymmetrical
series and the symmetrical series (resulting from the method of
orthogonal transformation)
ay; 4,0 AyAg+.-
1, ae ae Be. are > re "
1
is by no means so easily demonstrable im the general case by a
direct method, and the attention of algebraists is imyited to sup-
ply such direct method of demonstration. My knowledge of the
142 Mr. J. D. Smith on Harly Egyptian Chemistry.
fact of this equivalence is, as I have stated, deduced from that
remarkable but simple law to which I have adverted, which
affirms the invariability of the number of the positive and nega-
tive signs between all linearly equivalent functions of the form
L+e,. 2" (subject, of course, to the condition that the equivalence
is expressible by means of equations into which only real quan-
tities enter) ; a law to which my view of the physical meaning
of quantity of matter inclines me, upon the ground of analogy,
to give the name of the Law of Inertia for Quadratic Forms, as
expressing the fact of the existence of an invariable number in-
separably attached to such forms.
26 Lincoln’s-Inn-Fields,
July 12, 1852.
XX. Early Egyptian Chemistry. By J. Dennam Smita.
To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,
jE igen a me to occupy a small space in your Journal with a
few observations on Mr. Herapath’s paper with the above
title, published in your Supplement Number for July.
Mr. Herapath’s fact of a solution of silver having been used
some three thousand years since as “ markimg-ink,” is in every
way interesting, being excellent additional evidence of the fami-
liarity of the ancient Egyptians with a somewhat advanced stage
of the chemical arts; but dissenting as I do from all the deduc-
tions Mr. Herapath has arrived at from this fact, and thinking
it probable that they may take deep root and become widely
spread as received opinions, if unremarked upon, I have ventured
to allege a few reasons in refutation of the inferences of your
correspondent.
The first conclusion necessarily involved in the views of Mr.
Herapath is, that the ancient Egyptians must have been ac-
quainted with nitric acid; the second is, that they were familiar
with the use of sulphuric and hydrochloric acids; the third,
that the Great Lawgiver travelled with what must be considered
a well-appointed laboratory, or, which is still less probable, was
able to construct an umpromptu one (both materials and appa-
ratus) in the Desert ; and the fourth, that the golden calf was
dissolved in aqua regia; all of which conclusions are founded
and built up on the single fact of the existence on mummy linen
of marks which must have been produced by a solution of silver.
To the two first, (the third I need not notice) I would object
that there is no nation of antiquity, with whose every-day exist-
ence, their manners, customs and arts, we are so well acquainted
as with those of the ancient Egyptians; and that, whilst we
Mr. J. D. Smith on Early Egyptian Chemistry. 143
haye abundant evidence of their familiar and skilful practice of
many metallurgic arts, there is no representation nor evidence
whatever,—I speak under correction,—of their acquaintance
with the art of distillation; and I hold that, in this instance, the
absence of such evidence amounts to a primd facie proof that they
were ignorant of it. How these acids were to be obtained without
distillation, Mr. Herapath does not inform us. I have here
taken the most favourable supposition, that the presumed Egyp-
tian sulphuric acid was obtained by distillation, like the Nord-
hausen acid, rather than by any complicated processes similar to
those employed in the present day.
Again, if it can be shown that the Egyptians of those times
were acquainted with substances capable of producing a solution
of silver, it is surely advisable to pause before adopting a theory
involving the employment of various materials and several com-
plicated processes, of which, excepting silver and common salt,
there is no evidence whatever they knew of, and take Horace’s
-counsel—
“Never presume to make a god appear,
But for a business worthy of a god.”
With silver, and consequently with its ores, with common salt,
and with lime, it will at once be admitted that this nation was
familiar; and although it is probably incapable of proof that
ammonia was known to them, yet if we consider that sal-ammoniac
was for ages derived exclusively from Egypt, being procured
from the soot of camel’s-dung used as fuel, a necessity, and con-
sequently a practice, which must have existed in the Mosaic
epoch as well as now, since no other fuel is procurable in the
Desert, together with the unchangeableness of eastern habits, and
the fact that this salt was known to the writer of the earliest
authentic chemical treatise extant, it is scarcely assuming too
much to believe that sal-ammoniac was employed in the arts in
ancient Egypt; and with these four substances, as every chemist
knows, a solution of silver may readily be procured without the
intervention of nitric, or indeed of any acid whatever; which
solution is decomposed by exposure to air and light, particularly
if in contact with an organic body, with the production of dark
purple-black stains. It must not be supposed, because an ar-
gentine solution might have been procured in this way at the
period we are considering, that I therefore hold such must have
been the solution employed in Egypt; but that I merely suggest
it as more probable and consistent with existing evidence, than
the wholly gratuitous supposition that the marking-ink of ancient
Egypt had nitrate of silver for its basis.
How the notion first arose, that the Israelitish idol was dis-
solved, I cannot comprehend, save that the text was never read
144, Mr. J. D. Smith on Early Egyptian Chemistry.
by a “solutionist,” seeing that it is directly opposed to the plain
meaning of the sacred narrative, which tells its tale in as clear,
simple, and concise language as could be employed in the pre-
sent day, were we desirous of relating the same facts in the most
condensed form. These are the words :—“ And he took the calf
which they had made, and burnt it im the fire, and ground it to
powder, and strawed it upon the water, and made the children
of Israel drink of it.””? (Exodus, xxxu. 20.) The other version of
the translation closely resembles the foregoing :— And I took
your sin, the calf which ye had made, and burnt it with fire, and
stamped it, and ground it very small, even until it was as small
as dust ; and I cast the dust thereof into the brook that descended
out of the mount.” (Deut. ix. 21.) Can anything be more evi-
dent than that the golden calf was reduced to an impalpable
powder, and thus rendered potable when mixed with water? Yet
Mr. Herapath, like many before him, writes,—“ A probable spe-
culation might be raised upon this” (the assumed knowledge of
the uses of nitric acid by the Egyptians) “to account for the.
solution of the golden calf by Moses ;” and then, after destroymg
the Chimera of the solution of the calf in sulphuret of potassium,
tumbles himself into this Charybdis,—“ It is therefore more pro-
bable that the priests had taught Moses the use of the mixed
nitric and hydrochloric acids with which he could dissolve the
statue, rather than a sulphuret, which we have no evidence of
their being acquainted with,” an observation which I have en-
deavoured to show is equally applicable to these two acids.
If it be asked, How did Moses grind this malleable idol “as
fine as dust?” the answer seems to me very easy; im the words
of the text, “he burnt it with fire ;” that is, he fused and alloyed
it with a substance capable of rendering gold brittle. What this
was I pretend not to say, but many bodies possess this property ;
it might have been arsenic, more probably antimony, but still
more probably it was lead ; I say, still more probably, as, although
we know the antiquity of the use of sulphuret of antimony for
painting the eyes and eyebrows in the Hast, yet I am unaware
of any positive evidence that it was known to the ancient Egyp-
tians; whilst with regard to lead, we have both material evidence
and written testimony,—“ Only the gold, and the silver, the
brass, the iron, the tin, and the /ead” (Numbers, xxxi. 12),—that
lead was then a common metal; whilst with respect to the pro-
perties of this alloy, L. Gmelin, vi. p. 245 (Cavendish Soc.), thus
describes an “Alloy of gold and lead :—11 parts of gold and
1 part of lead form a pale yellow alloy, as brittle as glass. The
ductility of gold is destroyed by admixture of z5'75 of lead.”
Now without presuming to say that lead was actually the mate-
rial used by Moses to render the golden calf so brittle as to
|
:
On the Daily Motion of the Magnetic Needle. 145
enable him to grind it “as fine as dust,” yet I would submit, as
this metal completely fulfills every condition required by the
history, and as dokimasy was then sufficiently advanced to allow
of such an alloy being made, that it assumes a very high degree
of probability, being in complete and exact accordance both with
the sacred narrative and also with the ascertained state of the
metallurgic art at the time, that the golden calf was alloyed with
lead; that this brittle alloy, when stamped and ground as fine
as dust, was “strawed” on the water from the mount, of which
the Israelites drank, and that a solution of the idol was neither
effected nor even thought of.
; I am, Gentlemen, yours, &e.
Putney, July 19, 1852. J. Denna Smiru.
XXI. Addenda to the Investigation on the Decennial Period in the
Magnitude of the Daily Motion of the Magnetic Needle. By
Dr. Lamont*.
N the June Number of this Magazine a paper from me will
be found, in which I have endeavoured to show that a de-
cennial period exists im the daily motion of declination; at the
conclusion of the said paper it is hinted, that in the horizontal
intensity also a similar period probably exists. At that time the
observations of our magnetic observatory were not so completely
calculated as to permit of a closer discussion of the subject. At
present, the calculations, at least so far as is necessary for a pre-
liminary investigation, are carried out, and [ will not neglect
communicating the results.
As magnitude of the daily motion of the horizontal intensity,
I assume, approximately, the difference between the position at
11 o’clock in the morning and 6 o’clock in the evening, and
thereby obtain the following means for the years specified (ex-
pressed in ten-thousandths of the horizontal mtensity) :—
Mae ep Da dr GAR
ee ae Mie
Res Oe Oe a ee
fades 2) Or ae
eae tres. eee
a fe, ee ee ee
eae 8 ee ae
a ee ee ee eee
Lo Abt amegor ete Pane: 2
Although no regular transition, as in the case of the declina-
tion, is to be observed here, still the existence of a period is very
* From Poggendorff’s Annalen, vol. Ixxxvi. p 88.
Phil. Mag. 8. 4. Vol. 4. No. 28, Aug, 1852. L
146 On the Daily Motion of the Magnetic Needle.
plainly indicated. As the series embraces too few years to en-
able us to pronounce with certainty upon the duration and point
of turning of the period, I will assume these to be the same as
were found in the case of the declination. The magnitude of
the motion will then be expressed by the formula
9°82 + 3:06 sin (72°58 + 34°-84n),
where n expresses the number of years reckoned from 1848.
From a comparison of the formula with the results of obser-
vation given above, the following differences are obtained :—
Difference.
Year. Calculation—Observation.
1848. leat, Sob racra di
1644e? blew ties OE
1S4 571. ow Sree AG
1846s HieieR sia lA
1847, . . . . =—0°4
TR46 2 |. EG
g iter! AO Mba wing! WES oat tL lg
TS5O, ao ope tO
Lee ae ae we SEU
The differences here are greater than in the case of the decli-
nation ; but I must remark in connexion with this, that I have
not excluded the days of disturbance. These days exercise, how-
ever, an important influence, inasmuch as the causes of disturb-
ance always operate in ¢he same sense, and hence do not annul
each other when the mean values are taken.
For the further establishment of the period of intensity, we
shall look in vain to the observations of earlier times, some of
which, in the ease of the declination, we have found applicable,
and nothing remains but to await the results of future observa-
tions.
For the present, the simple fact that the magnitude of the
magnetic motions is subjected to a regular and very consider-
able increase and decrease, appears to me to imply consequences
worthy of consideration ; for if, in the effect, a period be shown
to exist, it must be the result of a corresponding period in the
influencing cause. It is, however, quite certain, that in the tem-
perature of the atmosphere—to which at present it is customary
to refer the magnetic variations—no such period exists ; and for
this reason I hold it to be absolutely necessary, either to give up
totally the assumed influence of atmospheric temperature, or to
modify it essentially by the introduction of a second coordinate
cause.
Py dAte |
XXII. Proceedings of Learned Societies.
ROYAL SOCIETY.
(Continued from vol. iii. p. 473.) —-
March 11, yy the Lunar Atmospheric Tide at Singapore.” By
1852. Captain C. M. Elliot, M.E., F.R.S.
The discussion of the barometric observations at St. Helena by
Colonel Sabine having clearly and decidedly shown the moon’s in-
fluence on the atmosphere, the author determined to discuss in a
similar manner the barometric observations at Singapore. The re-
sults of this discussion are given in the present communication.
In order that a comparison might be made between the results at
Singapore and at St. Helena, he copied to a considerable extent the
form of the different lunar tables drawn up by Colonel Sabine in his
paper published in the Philosophical Transactions.
The observatory at Singapore was in latitude 1°18! 32! N. and
longitude 103° 56! 30" E. of Greenwich. The cistern of the baro-
meter, one of Newman’s, having a tube 0°532 inch in diameter, was
a few feet above high-water mark. The observations, during the
whole of 1841 and the early part of 1842 and that of 1843, were
made at every two hours; during the remainder of the time, to the
close of 1845, at every hour.
The diurnal variation of the barometer having been eliminated, by
deducting the mean monthly height at each hour, from the height
given by observation, the residual quantities were arranged in tables ;
and the observation corresponding the nearest in time to the moon’s
superior culmination for each day being marked as O hour of lunar
time, the whole were again rearranged in tables according to lunar
hours. The variation or range of the mean of the sums of the dif-
ferences thus arranged is exhibited in a table, in the last column of
which are given the means of all the hours for each period of six
months. In a second table are given the differences between these
mean results in the last column of the preceding table and the num-
bers corresponding to the several hours in the other columns.
The means of the complete years of observation, 1841, 1844,
1845, are shown in a third table, in which are also given the means
of the first six months of 1842 and 18438, during which two-hourly
observations were made, and the means of the latter halves of these
years, during which the observations were made hourly.
The means of the twenty-four months of the two-hourly observa-
tions, and of the thirty-six months of the hourly observations, are
given in Table IV. Finally, Table V. exhibits the results of the
observations of three years, so combined as to show the effect on
the barometer, of the moon when similarly situated with reference
both to its superior and inferior passage. In a column of this table
are given the results of two years’ observations at St. Helena, ex-
tracted from Colonel Sabine’s paper. From a comparison, it appears
that the effect produced by the moon on the barometer at Singapore,
nearly on the equator, is slightly greater than at St. Helena, more
distant from it by 144° of latitude.
L2
148 Royal Society.
March 18.—A paper was read, entitled, “On the Blood-proper
and Chylo-aqueous Fluid of Invertebrate Animals.” By Thomas
Williams, M.D.
In this paper the author has accumulated numerous observations,
founded upon dissection and microscopic inquiry, to prove that there
exist in invertebrate animals two distinct kinds of nutrient fluids ;
that in some classes of this sub-kingdom these two fluids coexist in
the same organism, though contained in distinct systems of con-
duits, while in others they become united into one. The author
proposes to distinguish these two orders of fluids under the denomi-
nations of the blood-proper and chylo-aqueous fluid. The former is
always contained in definitively organized (walled) blood-vessels,
and having a determinate circulatory movement; the latter, with equal
constancy, inchambers and irregularcavities and cells, communicating
invariably with the peritoneal space, having not a determinate cir-
culation, but a to-and-fro movement, maintained by muscular and
ciliary agency. He then adduces evidence, derived from dissection,
in proof of the statement that the system of the blood-proper does
not exist under any form, the most rudimentary, below the Echino-
dermata; that, in other words, the system of the true blood, or of
the blood-proper, begins at the Echinodermata. ‘The author then
shows that below the Echinodermata, namely in the families of Polypes
and Acalephez, the digestive and circulatory systems are identified,
and that consequently the external medium is admitted directly into
the nutrient fluids. He considers that this circumstance constitutes
a fundamental distinction between the chylo-aqueous system and
that of the blood-proper, into which, under no conditions, is the ex-
ternal inorganic element directly introduced.
He conceives that his observations suffice to establish the law,
with reference to the chylo-aqueous fluid, that in every class in
which it exists, it is charged more or less abundantly with organized
corpuscles. ‘This is an invariable fact in the history of this fluid.
His inquiries show that these corpuscles are marked by distinctive
microscopic characters, not in different classes and genera only, but
in different species, entitling these bodies to great consideration in
the establishment of species.
The paper then proceeds to demonstrate the proposition, that in
those classes, as in the Echinodermata, Entozoa and Annelida, in
which, in the adult animal, these two orders of fluids coexist, though
distinct, in the same individual, there prevails between them, as
respects their magnitude or development, an inverse proportion ; that
while, as instanced in the Echinoderms, the chylo-aqueous fluid
filling the ciliated space between the stomach and integument is
considerable in volume, the blood-proper and its system are Jittle
evolved; that while, as in the Entozoa, the chylo-aqueous fluid is
still the most important fluid element in the organism, the blood
system is proportionally rudimentary; that in the Annelida, espe-
cially the higher species of that class, the chylo-aqueous fluid almost
disappears, while the system of the true blood acquires, illustrating
the law of inverse proportion, a correspondingly-augmented develop-
Royal Society. 149
ment. The author then states, that the system of the chylo-aqueous
fluid does not exist in the adult, but only in the darva state of the
higher members of the articulated series, such as the Myriapoda,
Insecta and Crustacea.
In Myriapods and Insects, he has observed that the peritoneal
space is occupied by a fluid which does not communicate with, and
is distinct in composition from, the contents of the true biood-vessels.
This peritoneal fluid, however, in these classes disappears at a
subsequent stage of growth. Thus the author thinks that a con-
tinuous chain, through the medium of the fluids, is established be-
tween the Echinoderms at one extreme and the Crustacea at the
other. These classes he proposes to connect together under the
designation of the double fluid series, corresponding to the radiate
and articulate series of systematic zoologists.
Returning to the standard of the Echinoderms, where the system
of the blood-proper first appears in the zoological scale, he shows
that at this point the Molluscan chain diverges from the radiate and
articulate chain, and may be indicated, in contradistincticn from
the latter, as the single-fluid series. The author’s observations lead
him to believe, with Professor Milne-Edwards, that in all Molluscs,
from the Tunicata to the Cephalopods, the chamber of the perito-
neal is continuous with the channels of the circulation, and that
consequently the fluids observed in these parts are one and the same
fluid, establishing the singleness of the fluid system of the body; and
this conclusion is corroborated by additional evidence drawn from
microscopic examinations.
He then recapitulates the results of his researches, and maintains
that the base of the invertebrated kingdom of animals is formed of
all those inferior series which rank below the Echinoderms; and
that this series is distinguished from the Molluscan, in which also
the fluid system is single, by the important circumstance that in the
former, unlike the Mollusca, the digestive and circulatory system
are identified, or confounded into a single system ; that at the Echino-
derms the series divaricates into the double-fluid series and single-
fluid series, the former coinciding with the radiate and articulate
class, and joining the Vertebrata through the Crustacea; the latter
running parallel with the Molluscan order, and connecting itself to
the Vertebrata through the Cephalopods.
The fluids of the zoophytic series are invariably corpusculated,
but the corpuscles cannot yet be reduced to any definite type of
conformation. In the Medusan series these bodies become more
definitively organized. The author then demonstrates, that through-
out the whole radiate and articulate classes, wherever it is found,
the chylo-aqueous fluid is richly corpusculated, or in other words,
charged with floating morphotic elements, which, from the constancy
of their characters in different species, become grounds for specific
distinctions. It is stated, that, throughout the Echinoderms, En-
tozoa and Annelida, in which, even in the adult animal, the blood-
proper and the chylo-aqueous fluid, though separate, coexist, the
latter fluid only is corpusculated, the true blood being invariably
150 Royal Society.
limpid and perfectly fluid (incorpusculated), and almost always the
seat of the colour; the latter existing as a substance dissolved in
the fluid, while in no instance does colour develope itself in the
chylo-aqueous fluid.
The paper then shows, that at the point where the chylo-aqueous
system disappears, namely at the Myriapods, the true blood becomes
the vehicle of the corpuscles.
And lastly, the author adduces a great variety of observations in
confirmation of the statement, that throughout the whole Molluscan
series without exception, coinciding with his ‘‘ single-fluid series,”
the fluids are richly charged with corpuscles.
The paper is accompanied by numerous illustrations, displaying
the characters of the morphotic elements of the circulating fluids of
the Invertebrata.
April 1.—A paper was also read, entitled, ‘‘ On the Electro-che-
mical Polarity of Gases.”” By W.R. Grove, Esq., M.A., F.R.S., &c-
The author refers to the experiments of Faraday on dielectric
induction, to those of Gassiot on the increase of electrical effects of
tension, according as the chemical intensities of a voltaic battery
are increased, and to other results, which, though supporting the
view of a physico-polar state of gaseous substances intervening be-
tween oppositely electrified surfaces, have not hitherto shown any
change in the arrangement of the gaseous particles dependent upon
their chemical characteristics.
The electric or voltaic disruptive discharge has hitherto presented
only one phenomenon which offers any analogy to electrolysis, viz.
that observed by Mr. Gassiot and others, of the positive terminal
being more intensely heated than the negative, when the voltaic
discharge passes between metals. With the voltaic arc the effects
of heat and the destruction of the terminals so interfere with any
effects properly due to the transmission of the electric current, that
it is next to impossible to eliminate the latter; on the other hand,
with the electric spark from an ordinary machine, the quantity of
matter acted on is too minute to give satisfactory evidence of the
changes taking place. Mr. Grove sought an intermediate degree
of electrical action, and by the aid of an apparatus of Ruhmkorf for
producing a powerful secondary current, the results detailed in this
paper were mainly obtained.
A polished silver plate is laid on the pump plate of a good air-
pump, and a metallic point is attached to the rod passing through a
collar of leathers at the top of the receiver, the point being adjusted
at from one-eighth to one-fourth of an inch distance from the plate.
Caustic potash is kept suspended in the receiver, and a mixture of
oxygen and hydrogen, or atmospheric air and hydrogen, allowed to
enter it, and then attenuated until the barometer stands at half an
inch; the discharges from the secondary coil are now made to pass
between the point and the plate, when if the latter be positive it is
oxidated, if negative the spot of oxide is reduced. :
If there be excess of oxygen and little or no hydrogen, oxidation
takes place, whether the plate be positive or negative, though in
Royal Society. 151
different degrees; and if the gas be wholly or mainly hydrogen,
reduction takes place whether the plate be positive or negative.
At certain intermediate states of mixture rings or zones of alter-
nate oxidation and reduction are shown, quite distinguishable from
the ordinary succession of colours of thin plates, and showing
alternations or periods of interference of electrical action.
The author then gives the results of experiments with several
other metals, of which bismuth was the only one he found to produce
effects anything like equal to the silver, though other metals showed
them in some degree.
He also varied the gas or gases employed, and details the results
obtained with several gases; among them carbonic oxide is the
most worthy of note, as with it effects are produced similar to those
with the mixture of oxygen and hydrogen, viz. oxidation when the
plate was positive, and reduction when it was negative.
The author's theory or mode of explaining the results is as follows.
The discharges are successive, not continuous, and antecedent to
each discharge the intervening gas is thrown into a state of chemical
polarity, similar to that which takes place in an electrolyte anterior
to electrolysis; by this means the positive terminal has in juxta-
position with it oxygen or an electro-negative gas; the discharge
takes place, and by the superficial ignition the layer of oxygen com-
pines with the metal in contact with it.
Conversely, when the oxidated surface is negative and in contact
with an electro-positive gas, the heat of the discharge produces re-
duction. The fact of oxidation only taking place when air or oxygen
alone are present, and reduction only when hydrogen is present, he
considers irreconcilable with the effects being attributable to the dis-
charge itself, or to their being regarded as analogous to electrolysis ;
while these phenomena are corroborative of the view he puts forth.
The author refers to the experiments of Priestley, Karsten and
others, in which spots or marks have been shown to be produced by
electrical discharge, but which do not otherwise bear upon the ob-
jects sought to be elucidated by this paper.
April 22.—The following papers were read :-—
1. “‘Onthe Structure of the Stem of Victoria regia.” By Arthur
Henfrey, F.L.S. &c. Communicated by Professor Edward Forbes,
F.R.S.
The investigation of the anatomy of Victoria regia acquires its
interest from the fact of the relations which have been pointed out
to exist between the Nymphzaceze and some of the undoubted
Monocotyledonous families, especially also from the researches of
M. Trécul on the anatomy of Nuphar lutea, which plant that author
describes as having a stem of the Monocotyledonous type of struc-
ture. Through the unfortunate death of the plant of Victoria regia,
which had flowered for some time in the gardens of the Royal
Botanic Society of London, the author had an opportunity of ex-
amining the anatomy of its stem. It is an upright rhizome, with
undeveloped internodes, growing by a single terminal bud, appa-
rently perennially, and attaining considerable thickness; on the out-
side it bears the remains of the petioles and flower-stalks, which
152 Royal Society.
separate by disarticulation, and their remains are found arranged in
spiral lines upon the outside, so as to give the short, thick rhizome
the aspect of a piece of a palm stem. As in Nuphar, the roots are
produced in bundles at the bases of the petioles, and fall off suc-
cessively upwards as the new ones are developed, leaving very con-
spicuous scars. The internal structure of the stem is quite Mono-
cotyledonous in its character, presenting no trace of the arrange-
ment of the vascular bundles into rings of wood, no true woody
fibres, and no cambium layer. The vascular bundles, which are.
composed exclusively of spiral, annular and reticulated ducts sur-
rounded by elongated parenchymatous cellular tissue, are isolated
and arranged just as in Monocotyledons, such as the Palms; and the
outer part of the stem exhibits a cortical parenchyma, much more
like that of the herbaceous rhizomes of the rush-like plants, than
any other known structure ; it bears not the least resemblance to
the bark of Dicotyledons. The results of the investigation show.
that Victoria, like Nuphar, has a stem of essentially Monocotyle-
donous structure. The paper was accompanied by drawings illus-
trating the general and microscopic anatomy of the stem.
2. “On the Meteorology of the English Lake District, including
the results of Observations on the Fall of Rain at various heights,
up to 3166 feet above the Sea-Level :” Fifth paper, for the year 1851.
By John Fletcher Miller, Esq., F.R.S. &c.
The author states that the results for the past year do not seem to
call for any particular remarks, and as it appears desirable, as a
general rule, to defer all attempts at deduction until after the com-
pletion of the observations, the Tables for 1851 are presented, with-
out many notes or comments, in continuation of the series which
have previously appeared in the Transactions of the Society. The
table for January, 1851, is given as an example of the daily fall of
rain in the district during an excessively wet month, and also as
showing the form of permanently registering the returns from the
various stations, when sent in at the close of each month. He re-
marks that the quantity of 38°86 inches precipitated on ‘‘ The Stye”
in January 1851, is, he believes, without a parallel in the temperate
zone.
3. ‘“‘Formulization of Horary Observations presumed d priori to
be nearly of a Periodic nature.” By S. M. Drach, Esq., F.R.A.S.,
F.R.G.S. Communicated by Colonel Sabine,R.A.,Treas.,V.P.R.S.&c,
Referring to his former publications on the subject (Proceed. Roy.
Soc. March 1842, Phil. Mag. 1842-51), the author empirically re-
solves the formula
ht=H+2A; sin tt + 2a; cos it =H+ SR; sin (it+ 4),
h being the effect observed at the hour-angle ¢, thus obtaining from
the 24 hourly observations all values up toi=12. This method
giving the values of A, a» R for the different months, he believes
that by it the law of change connected with the sun’s motion in
longitude and declination will be most readily deduced. The for-
mula is exemplified by calculations and results of the diurnal varia-
tion of magnetic declination for each month at the various Colonial
Intelligence and Miscellaneous Articles. 153
Observatories, and also of the temperature at the Cape, St. Helena,
Hobarton, Toronto, Greenwich, Leith, and Melville Island. The
author infers that the temperatures taken at six-hourly intervals give
Sor their sum four times the mean temperature of the day, whatever be
the commencing hour ; and thus travellers and voyagers observing at
5*, 11", 17" and 23", will get the mean temperature of their position at
2r.m. Hence, from the communications of the captains of Merchant-
men, the Atlantic oceanic temperatures might be mapped in the
course of a year, and the isothermal curves on this broad level sur-
face be accurately laid down (see Journ. R. Geograph. Soc. ix.
p.369). Excepting at Melville Island, R, is the greatest coefficient,
iy, is nearly constant, and
H+ )R,sin (i¢+y,) + cos St cos 2¢(F sin ¢+ G cost)
will give the yearly formula: the homonymous hours are expressed
by H+ = R; sin (i¢+;) as in the oceanic tides nearly. At Melville
Island, ,=45° nearly and R, is the greatest. The semester from
midwinter to midsummer is also nearly expressed by
P+Qsin © long. for R,.
Having obtained the empirical R and y, or A and a, any theoretic
formula can be tested by the results.
XXIII. Intelligence and Miscellaneous Articles.
RESEARCHES ON THE SULPHURETS WHICH ARE DECOMPOSABLE
BY WATER. BY E. FREMY.
pore object of this paper is to make known the production and
principal properties of a class of sulphurets hitherto little ex-
amined, and the study of which is alike interesting to chemists and
geologists, from the light which it throws on the formation of
mineral waters.
When we consider the action of water on the sulphurets. we find
that these compounds may be divided into three classes: the first
comprises the sulphurets of the alkalies and of the alkaline earths
which dissolve in water ; the second is formed of the insoluble sul-
phurets; the third consists of the sulphurets of boron, silicon, mag-
nesium and aluminium, which are decomposed by water : these latter
are scarcely known, owing to their preparation having hitherto been
accompanied with great difficulties. In order to a thorough inves-
tigation of all the questions which are connected with the decom-
position of the sulphurets by water, i first sought for a method by
which they might be easily prepared. This method I will now describe.
It is well known that sulphur exerts no action upon silica, boracic
acid, magnesia and alumina. I imagined it might be possible to
replace the oxygen in these substances by sulphur by the interven-
tion of a second affinity, as that of carbon for oxygen. Such decom-
positions, produced by two affinities, are not rare in chemistry ; and
in some yet unpublished experiments on the fluorides, I had observed
that the sulphuret of carbon completely decomposed the fluoride of
calcium mixed with gilica, producing sulphuret of calcium. I was
therefore led to presume that the sulphuret of carbon, acting by its
two elements upon the preceding oxides, would remove the oxygen
154. Intelligence and Miscellaneous Articles.
by means of the carbon which it contains, and would at the same
time form sulphurets: this supposition I found confirmed by experi-
ment. In fact, I have cbtained the sulphurets of boron, silicon,
magnesium and aluminium, by submitting boracic acid, silica, mag-
nesia and alumina, to the action of sulphuret of carbon at a high
temperature. ‘To facilitate the reaction, and remove the sulphuret
from the decomposing action of the alkalies contained in the por-
celain tubes, it is sometimes useful to mix the oxides to be reduced
with charcoal, and to form them into little balls similar to those
which are used in the preparation of chloride of silicon.
I have ascertained by analysis that these sulphurets correspond to
the oxides from which they have been derived.
I will now say afew words of the sulphurets obtained by the above
method. The sulphuret of silicon had been obtained in small quan-
tity by Berzelius in the reaction of sulphur upon silicon, and by
M. Pierre in the decomposition of chloride of silicon by hydrosul-
phuric acid. I have obtained this substance with the greatest ease,
by passing the vapour of sulphuret of carbon over pellets of charcoal
and gelatinous silica placed in a porcelain tube heated to bright red.
The sulphuret of silicon condenses in the tube in beautiful white
silky needles, which are not very volatile, but are readily carried
along by the vapour.
To show the interest which attaches to the examination of this
substance, it will suffice to mention here two of its reactions. When
sulphuret of silicon is heated in a current of moist air, it is decom-
posed, and furnishes silky crystals of anhydrous silica; it is evident
that we may explain by means of this experiment the natural pro-
duction of certain filamentose crystals of silica. The sulphuret of
silicon in the presence of water is decomposed with a brisk evolution
of hydrosulphuric acid into silica, which remains entirely dissolved
in the water, and is not deposited until the liquid is evaporated. It
is impossible not to connect this curious property with those natural
conditions under which certain mineral waters and siliceous incrus-
tations are formed.
As the sulphuret of silicon is probably produced in all those cases
where silica is submitted to the double action of a binary compound
which cedes sulphur to it, and at the same time appropriates its
oxygen, this sulphuret is probably not so rare as has been hitherto
thought; and by admitting its presence in those rocks in which
sulphurous springs occur, we might explain the simultaneous exist-
ence of silica and sulphureted hydrogen in the principal sulphurous
waters. his hypothesis is in some measure confirmed by the inter-
esting observations of M. Descloizeaux, which show that the sili-
ceous springs of the Geysers of Iceland contain a large quantity of
sulphureted hydrogen. '
I content myself with submitting these considerations to geolo-
gists, merely observing that, in explaining the formation of sulphu-
rous and siliceous waters by the decomposition of the sulphuret of
silicon, I am only extending the ingenious theory proposed by
M. Dumas to explain the formation of boracic acid.
The sulphurets of boron and aluminium were prepared like the sul-
phuret of silicon, and are likewise decomposed by water.
Intelligence and Miscellaneous Articles. 155
The sulphuret of magnesium I obtained by passing sulphuret of
carbon over pure magnesia; in this case the presence of charcoal
does not appear to be of any use. ‘This sulphuret crystallizes, and
is soluble in cold water ; when its solution is kept at the ordinary
temperature, there is but a feeble disengagement of sulphureted
hydrogen; but when heated to ebullition, a lively effervescence of
sulphureted {hydrogen takes place, and there is an immediate depo-
sition of magnesia.—Comptes Rendus, July 5, 1852.
ON THE EXISTENCE OF ORGANIC MATTER IN STALACTITES AND
STALAGMITES, FORMING CRYSTALLIZED AND AMORPHOUS CRE-
NATE OF LIME. BY DAVID A. WELLS.
In the eighth chapter of Liebig’s Agricultural Chemistry, edited
by Playfair, there is given the result of some examinations of sta-
lactites from caverns in Germany, and from the vaults of old castles
upon the Rhine, made with the view of ascertaining the fact of the
presence or absence of organic matter in these bodies, either com-
bined or uncombined.
The result may be stated in the words of the author, Prof. Liebig.
The stalactites from the caverns “contain no trace of vegetable
matter, and no humic acid, and may be heated to redness without
becoming black.” In the stalactites from the vaults and cellars of
old castles, he says, “we could not detect the smallest traces” of
humic acid. “There could scarcely be found a more clear and
convincing proof of the absencé of the humic acid of chemists in
common vegetable mould.” Under the term humic acid, Prof.
Liebig undoubtedly means to include all those organic acids arising
from the decomposition of vegetable matter, and which have re-
ceived the names of crenic, apocrenic, geic and humic acids.
Having been informed by Dr. A. A. Hayes of Boston, that he
had in numerous examinations arrived at results directly opposed to
those of Prof. Liebig, I was induced at his suggestion to make an
examination of a large number of stalactites and stalagmites obtained
from various localities, with reference solely to the presence or
absence of organic matter in these bodies.
The specimens examined were all from caverns, or rock forma-
tions, and were obtained from various parts of the United States,
from Trieste in Austria, Malta and the Sandwich Islands. In colour
they varied from an almost pure white to red, yellow, and brown of
different shades; and in crystalline character, from a structure re-
sembling arragonite to a variety entirely wanting in symmetrical
arrangement, or a mere incristation. The specimens were dissolved
in dilute hydrochloric acid, the floceulent matter separated, collected
and washed, boiled in caustic potash, carbonate of ammonia or car-
bonate of soda, and then tested in the usual way for crenic and apo-
erenic acids by acetate of copper and carbonate of ammonia. In
all the varieties, with one exception, abundant flocculent organic
matter was separated, which on testing gave evidence of crenic acid
in considerable quantities, with doubtful traces of apocrenic acid.
The exception alluded to was the specimen examined from Trieste,
which did not afford any appreciable flocculent matter on dissolving
156 Intelligence and Miscellaneous Articles.
in acid. The greatest quantity of organic matter was found in sta-
lactites of a deep yellow colour, highly crystalline and uniform in
character, and in the portions examined perfectly homogeneous and
free from Jayers, or intervening bands indicating different periods
and changes in deposition. As the presence of iron could not be
found in the acid solution, it is inferred that the colour of these
yellow stalactites must be owing in great part to combined organic
matter, existing as crenate of lime. In specimens like the spar or-
naments from the Rock of Gibraltar, with which all are familiar,
the colouring and delicate shading is also probably due to organic
matter.
Dr. Hayes informs me, that he has also found organic matter in
arragonite in sufficient quantity to separate in flakes, while the spe-
cimen was dissolving in acid.
From these statements, it must, I think, be inferred, contrary to
the view of Liebig, that organic matter does exist in stalactites
generally, as an acid combined with the lime, and imparting to them
their various colours. [I would by no means call in question the
accuracy of the experiments of Prof. Liebig, further than that, as
far as my observations extend, crenic acid in the presence of lime,
and combined with it, passes over like oxalates, upon heating, into
carbonates, without perceptible blackening.
It may here be added, that Prof. Johnston of England describes
a compound of alumina with crenic acid, occurring in caves of
granite upon the coast of Cornwall. This mineral has received the
name of Pigotite, and is observed in places where the surface-water
trickles down over the granite rocks. From this it may not be in-
appropriate to apply the term ecrenite to those lime formations in
which crenic acid occurs in considerable quantities.
Results similar to those announced above have been obtained by
Dr. C. T. Jackson, as well as by Dr. Hayes of Boston. Dr. J.
Lawrence Smith informs me, that he has frequently met with crenic
acid in lime concretions from Asia Minor, and its existence in sta-
lactites was also announced by Dr. Emmons of Albany some years
since. My results can therefore be considered but as the verifica-
tion of those obtained by others.—Silliman’s Journal, Jan. 1852.
ON THE NEW METAL DONARIUM.
A few months ago M. Bergemann discovered an oxide in a mineral
from Langesundfiord, near Brevig in Norway, which he considered to
be new. He gave the name Donarium to the metal, and that of
Orangite to the mineral*.
Damour has since examined a specitnen of orangite. Its specific
gravity was 5°19; Bergemann found 5°39. On comparing his ana-
lysis with that of Bergemann, and also the properties of the supposed
new oxide, M. Damour concludes that the oxide of donarium is
nothing Jess than impure thorina. Bergemann’s analysis does not
enumerate oxide of lead and oxide of uranium among the constitu-
ents. M. Berlin of Lund has also found that the oxide of donarium
is thorina mixed with minute traces of oxide of uranium, oxide of
* See pp. 583 and 390 of vols. i. and ii. of the present Series.
Intelligence and Miscellaneous Articles. 157
iron, vanadic acid, tin, and perhaps a little molybdic acid. The
following are the analyses :—
Damour. Berlin.
Siticars UqstA eRe, P52 SER TS, FO eT aT 17°78
Prova ey eee 71°65 ‘Titorint eee: 73°29
Mme 72, FAO O0 018 1°59 Litie 10 08 D108 Shs OOD
Oxide of lead ........ 0°88 Oxide of uranium ..
Oxide of uranium .... 1°18 Peroxide of iron,... 0:96
Oxide of manganese .. 0°28 ‘Tin ag
Peroxide of iron ...... 0°31 Vanadium....
Magnesia...) 5. ..-: brace "Water at se acre o's 712
Avnimina’s; Qtek Fe eke 0°17 T00-00
Potash . . 0°14 40:00
STi i ean 0°33
Water, with trace of
carbonic acid ....
100-14
Damour deduces from his analysis the formula3ThO + SiO’ + 2HO.
Berzelius assumed that thorite consisted of several silicates, but prin-
cipally of a silicate of thorina of the formula 3ThO+Si03+2HO.
Damour is of opinion that Berzelius’s analyses do not lead to any
definite proportion; but they prove that orangite and thorite are
identical, and that the metal donarium must be struck from the list
of simple bodies.
Berlin also calculates from his analysis the formula
3ThO + SiO’ + 2HO,
and is likewise of opinion that orangite is only a purer thorite. He
also draws attention to a peculiar property of thorina, It is stated
that calcined thorina is insoluble in acids. ‘This is correct as far as
regards the earth obtained by calcining the hydrate, but not for that
obtained by igniting the oxalate, which dissolves slowly in hydro-
chloric acid.—Central Blatt, June 23, 1852.
ON A NEW MODE OF MEASURING HIGH TEMPERATURES,
BY MR. JOHN WILSON.
After referring to, and describing briefly the pyrometers at
present in use, the paper explained the method employed by the
author to measure high temperatures. According to his plan, a
given weight of platinum is exposed for a few minutes to the fire,
the temperature of which is required to be measured, and then
plunged into a vessel containing water of a determined weight and
temperature. After the heat of the platinum has been communi-
cated to the water, the temperature of the water is ascertained ; and
from this is estimated the temperature to which the platinum was
subjected. hus, if the piece of platinum employed be 1000 grains,
and the water into which it is plunged be 2000 grains, and its tem-
perature 60°, should the heated platinum when dropped into the
water raise its temperature to 90°, then 90°—60°=30°; which,
multiplied by 2 (because the water is twice the weight of the pla-
tinum), gives 60°, that an equal weight of water would have been
raised. Again; should the water in another case gain 40°, then
158 Intelligence and Miscellaneous Articles.
40° x 2=80°, the temperature measured by the pyrometer. To
convert the degrees of this instrument into degrees of Fahrenheit,
we must multiply by 31°25, or 314. Thus, 80° x31} would give
2500° of Fahrenheit. And 60° x 314=1875°. The multiplier 31°25
is the number expressing the specific heat of water as compared with
that of platinum, the latter being regarded as 1.
In order to attain very accurate results by this method, precau-
tions similar to those required in determining the specific heat of
bodies must be taken ; that is, it is necessary to guard against the
dissipation of heat by conduction and radiation. The apparatus
used by the author consists of a polished tinned iron vessel, of a
cylindrical form, 3 inches deep and 2 inches in diameter; this is
placed within a concentric cylinder, separated from the enclosed
vessel about J inch. By this means there is but little heat lost during
the experiment, either by radiation or conduction.
At the commencement of the experiments, the author imagined it
would be necessary to employ a considerable proportion of water,
and therefore took twenty-five times the weight of the platinum ;
but he found that the temperature gained by the water, even in
cases of very high heats, did not exceed 4° or 5°; and an error of
1°, when converted into.degrees of Fahrenheit, amounted to 400°.
To obtain results within much narrower limits of error, it became
obvious, a much smaller proportion of water should be employed ;
and ultimately it was found that double the weight of the platinum
was in all cases sufficient.
There is no appreciable loss of heat from the evaporation of steam
when the hot platinum is plunged into the water ;—there is probably
no actual contact with the water until the platinum is fairly at the
bottom of the water. It is in fact the converse of dropping water
on a plate of platinum or iron strongly heated ; in which case the
water, instead of being suddenly dissipated as steam, assumes the
spheroidal form, and runs about over the plate without coming in
contact with the heated surfacé. It is only when the temperature
of the metal becomes much reduced that the water is rapidly con-
verted into vapour.
In ascertaining temperatures by this pyrometer, a correction has
to be made for the portion of the total heat that is absorbed by
lst, the mercury of the thermometer in the water ;
2nd, the glass bulb and stem of the thermometer ;
3rd, the iron vessel containing the water ;
4th, the heat retained by the piece of platinum.
The portion of the total heat that is absorbed by these several
bodies, compared to the portion received by the water, will be in
proportion to their several weights, and the specific heat of each com-
pared with water.
Equivalent grs.
of water.
Mercury ... 200 grains x 34th specific heat= 7
Glass. tect 35, x 4th x 6
Frome33 0228.2 658 ,, % $th is 73
Platinum... 1000 ,, xggnd % 31
POUL 22, toeeeeticdse EE?
Meteorological Observations. 159
Therefore the effect of these bodies is equivalent to the addition
of 117 grains to the 2000 grains of water, or ;i;th has to be added
as a correction to all the temperatures obtained by this instrument ;
or, in other words, the multiplier must be increased from 31} to 33
in this instrument, and in all similar ones where the weights of the
mercury and glass of the thermometer, and of the iron vessel, are
the same as stated above.
As the piece of platinum is the most expensive part of the appa-
ratus, it is proposed to use a small piece of baked Stourbridge clay
as a substitute for the platinum. The author has found, by experi-
ment, that a piece of Stourbridge clay, 200 grains in weight, when
heated to the melting-point of silver, and plunged into the tinned
vessel containing 2000 grains of water, raises the temperature of
the water 41°.
Now, if 1890° Fahrenheit (the melting-point of silver) be divided
by 41, we obtain 46° as the number corresponding to 1° of this
pyrometer; and 46 will therefore be the correct multiplier ; and no
corrections are required for any heat abstracted by the thermometer,
the tinned vessel, or the piece of clay.
The temperature of all sorts of furnaces and flues of steam-
engines, &c., may be readily ascertained by means of the piece of
Stourbridge clay.—Proceedings of the Institution of Mechanical En-
gineers, Birmingham.
—
METEOROLOGICAL OBSERVATIONS FOR JUNE 1852.
Chiswick.—June 1. Clear and fine. 2. Cloudy: fine: rain. 3. Cloudy. 4.
Overcast: fine: clear. 5. Very fine: slight rain. 6. Rain: clear at night.
7. Constant rain. 8. Thick whitish haze: low fog in the evening: heavy rain.
9. Excessively heavy rain throughout. 10. Rain: cloudy: clear. 11. Overcast.
12. Slight rain: overcast. 13. Fine: rain at night. 14. Showery. 15. Fine:
showery: clear. 16. Rain: uniformly overcast. 17. Cloudy throughout. 18.
Rain: showery: heavy rain. 19. Heavy clouds: clear and fine. 20. Overcast :
rain. 21. Rain: cloudy. 22—24. Fine. 29. Uniformly overcast : fine : rain at
night. 26. Rain: heavy showers. 27. Overcast: heavy showers. 28. Fine:
densely overcast. 29. Overcast : cloudy: clear. 30. Fine: rather windy : clear
at night—More rain fell on the 7th, 8th, and 9th, than on any three consecutive
days for at least twenty-six years near T.ondon.
Mean temperature of the month ....++.-cseessesereeeeeseeereters 58°01
Mean temperature of June 1851 .....sseeeeeseesereeererene ste 59°21
Mean temperature of June for the last twenty-six years ... 60°61
Average amount of rain in Jue — seeeeesesessseseeetercestee se 1°77 inch.
Boston.—June 1. Fine. 2. Fine: rain p.m. 3. Cloudy: rain A.M. 4, Fine:
rain aM. 5. Fine. 6. Rain: raina.M. 7,8. Cloudy. 9. Cloudy: rain A.M:
10, 11. Cloudy: rain a.m.andp.m. 12. Clondy: rain a.m. 13. Cloudy :-rain P.M.
14, 15. Cloudy: rain a.m. and P.M. 16. Rain: rain A.M. and p.m, 17. Fine.
rain A.M. andp.M. 18,19. Cloudy: rain a.M. 20. Cloudy: rainp.M. 21. Rain:
rain A.M. 22. Cloudy: rain a.m. and p.m, 23—29. Fine. 26. Cloudy: rain A.M.:
27. Cloudy. 28. Cloudy: rain p.m. 29, 30. Cloudy.
Sandwick Manse, Orkney—June 1, 2. Showers. 3. Rain: showers. 4, 5.
Bright: clear: fine. 6. Hazy. 7. Hazy: clear: fine. 8. Bright: fine. 9. Cloudy :
damp. 10. Drizzle. 11. Drizzle: showers. 12. Damp: bright. 13. Clear:
fine: cloudy. 14. Showers: cloudy: fine. 1. Bright: fine : clear: fine. 16.
Bright : fine: cloudy. 17. Clear: fine: cloudy. 18. Damp: fog. 19. Bright :
clear: fine. 20. Damp. 21. Damp: fog. 22,23. Rain. 24, 25. Bright: showers.
26. Bright: rain. 27. Bright: showers: fine. 28. Clear: fine: drops: fine.
29. Clear: fine: cloudy: fine. 30, Rain.
—— TEE
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THE
LONDON, EDINBURGH anv DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
[FOURTH SERIES.]
SEPTEMBER 1852.
XXIV. On some Salts and Products of Decomposition of Pyro-
meconic Acid. By Mr. James F. Brown*.
= fl acid was discovered by Sertuerner, and long viewed as
sublimed meconic acid, till Robiquet in 1832 obtained the
meconic acid from which it is produced, and showed that the
acid existing in opium differed in its properties from the sub-
limed acid: he also prepared and analysed its lead salt, from
which he deduced the formula PbO, C!°H?0*. Liebig has ob-
served that its composition is the same as that of pyromucic
acid, and thought it probable these acids might prove identical.
This assertion, however, has been refuted by Dr. Stenhouse in
his paper on the subject, to some of the details in which I shall
have occasion to refer.
The pyromeconic acid employed in the following experiments
was obtained by distilling, at a temperature of about 500° and
600° F., the impure meconie acid got by treating the crude
meconate of lime twice with hydrochloric acid, which, though
much coloured, answered sufficiently well. For the purification
of the acid, which when first sublimed is in the form of an oily
semifused mass, Stenhouse recommends pressure between folds
of filtering paper, redistillation, and frequent crystallization from
boiling alcohol. I found, however, that simple pressure, and
sublimation at a comparatively low temperature in a cylindrical
glass vessel provided with a number of diaphragms of filtering
paper, rendered the acid perfectly colourless, and pure enough
for the preparation of all its salts and products of decomposition.
As thus obtained, it is in beautiful large transparent plates, of
ready solubility in water and alcohol, both hot and cold, from
* Communicated by the Author, having been read before the Royal
Society of Edinburgh, March 1, 1852.
Phil. Mag. 8, 4, Vol, 4. No. 24. Sept, 1852. M
162 Mr. J. F. Brown on some Salts and Products of
which it crystallizes in four-sided prisms of considerable size. It
is slightly acid to litmus, and even after three crystallizations
from boiling water it retained its acidity. _ It is completely volatile
at 212°. A quantity having been exposed to that temperature for
about fourteen hours, was found to have entirely disappeared.
This property may serve as a test of its purity from paracomenic
acid, with which pyromeconic, as first sublimed, is always conta-
minated, that acid requiring a much higher heat to volatilize it. It
gives, as is well known, a deep red colour with persalts of iron,
and does not precipitate chloride of calcium, barium, manganese,
nor sulphate of magnesia, either hot or cold, even on the addition
of a small quantity of ammonia. Bichloride of mercury gives
after some time a white amorphous precipitate, soluble on boiling
the fluid. When a hot aqueous solution of pyromeconic acid is
treated with strong caustic potash in excess, and allowed to stand
some hours, crystals soon begin to form, which upon examina-
tion proved to be the acid unaltered ; a similar experiment was
made with ammonia, but with the same result, the fluids in both
cases becoming nearly black.
To ascertain the purity of the acid, the following analysis was
made of it, dried in vacuo, after one sublimation.
5:74 grains substance gave 11°133 carbonic acid and 1:905
water,
Caleulation.
Experiment. _
Carbon . . 5a'23 53°57 C! 60
Hydrogen . 3°71 By AR ra |
Oxygen . . 43°06 42:86 Of 48
100:00 100-00 112
The formula of the acid is therefore represented by
C10 H? O° + HO.
Pyromeconate of Baryta—This salt may be obtamed by
mixing a warm ammoniacal solution of pyromeconic acid with
acetate of baryta, when it makes its appearance after a short time
in small colourless silky needles. In dilute solutions they do
not appear immediately, but after standing some time they com-
mence forming and rapidly increase. It is the most soluble in
water of all the earthy salts of this acid,—181°90 grains of a
saturated solution at 60° F. gave on evaporation at 212° a residue
of 4°50 grains = 2°50 per cent. It is of sparing solubility in
alcohol. Like the other pyromeconates, it reacts strongly alka-
line, and gives a slight red colour with chloride of iron, which
may be made much more apparent if the crystals be employed
instead of a solution of the salt, By evaporation im vacuo it
deposits itself in short prisms of a yellowish colour. When ex-
Decomposition of Pyromeconic Acid. 163
posed to a temperature of 212°, it loses no weight ; but heated
to a higher temperature, it burns with a shght deflagration
without previous fusion. The following are the results of ana-
lysis after the salt had been thoroughly washed with alcohol,
and dried at 212°. The other salts of this acid were also dried
at 212° previous to analysis.
4°81 grains substance gave 5°55 carbonic acid and 1-06 water.
4°33 grains substance gave 2°24 carbonate of baryta.
Calculation.
Experiment. — A—_——_—~,
Carbon . . 81:46 31:82 Cl 60:00
Hydrogen . 2°48 8 i é i 4°00
Oxygen . . 25°56 25°47 O08 48°00
Baryta . . 40°55 40°59 BaO 76°55
100:00 100-00 188°55
The composition of the salt is therefore represented by the
formula BaO, C!° H? 0°+ HO.
Pyromeconate of Strontia.—When alcoholic solutions of ni-
trate of strontia and pyromeconic acid, made ammoniacal, are
mixed, there immediately ensues a precipitate of minute silky
needles, which by solution in water are obtained in stellar groups
of a yellowish colour. As precipitated, it is colourless, sparmgly
soluble in cold water and alcohol, more so in hot, and reacts
strongly alkaline. 224 grains aqueous solution at 68° gave 3-00
grains on evaporation at 212° = 1°3 per cent. It loses nothing
at 212°, and at a higher temperature is infusible, but burns with
a slight explosion.
The well-washed substance gave the following results on ana-
lysis, the strontia being determined as carbonate.
5'875 grains substance gave 7°79 carbonic acid and 1°35 water.
7°97 grains substance gave 3°58 carbonate of strontia.
Calculation.
Experiment. ——_—_
Carbon . . 36:16 36°63 C!®? 60
Hydrogen. 2°74 2°44 H* 4
Oxygen . . 29°61 29:31 Of 48
Strontia . . 31°49 31:62 SrO 51:78
100-00 100-00 163°78
The formula of the salt is therefore SrO, C!° H? 0° + HO.
Pyromeconate of Lime.—This salt is obtained in the form of
small colourless silky needles when a warm ammoniacal solution
of pyromeconic acid is added to acetate of lime in excess. It is
slightly soluble in boiling alcohol, but rather more so in water,
from which it deposits itself by gradual cooling of the solution
M2
164 Mr. J. F. Brown on some Salis and Products of
in crystals of considerable size. 8°41 grains aqueous solution of
this salt at 60° gave 1:08 grain of residue at 212°=0°31 per
cent.
6:15 grains substance gave 10°26 carbonic acid and 1°56 water.
6-34 grains substance gave 2:34 carbonate of lime.
Calculation.
Experiment. —
Carbon . . 42°94 42°85 C 60
Hydrogen . 2°60 ano i" 4
Oxygen . . 384-02 34°30 Of 48
Lime . . . 20°44 20:00 CaO 28
100-00 100°00 140-00
Hence the composition of the salt is represented by the for-
mula CaO, C!° H3 0°+ HO.
Pyromeconate of Magnesia.-—A warm aqueous solution of py-
romeconic acid gives with acetate of magnesia a white amorphous
precipitate, insoluble in water and alcohol. In its properties it
closely resembles the other pyromeconates. The following is
the analysis of the salt, the magnesia being determined by igni-
tion of it, and weighing the residue. It loses nothing at 212°.
4-925 grains substance gave 8°735 carbonic acid and 1:235
water, 4595 graims substance gave ‘76 magnesia.
Calculation.
Experiment.
Carbon . . 48:37 48:51 C!° 60
Hydrogen . 2°76 241 He 3
Oxygen . . 82°34 32°37. O° 40
Magnesia . 16°53 16-71 MgO 20°67
100-00 100-00 123°67
From which it appears that this is the only earthy salt of py-
romeconie acid which is anhydrous, the composition of it bemg
expressed by the formula MgO, C10 H3 0°.
Pyromeconate of Lead.—When a warm concentrated solution
of pyromeconic acid, made ammoniacal, is added to acetate of
lead, it causes an immediate precipitate of a dense crystalline
powder, which rapidly increases upon violent agitation of the
fluid. This salt, as has already been mentioned, was prepared
and analysed by Robiquet, who formed it by adding hydrated
oxide of lead to a hot solution of pyromeconie acid; he found it
to be anhydrous, and to consist of PbO, CH? O°.
The crystals require a considerable quantity of hot water for
their solution ; they are not so soluble in alcohol either hot or
cold. It is colourless when thrown down, but rapidly becomes
yellow by exposure for any length of time to bright daylight.
Decomposition of Pyromeconic Acid. 165
It loses nothing at 212°, even after being kept for three or four
hours at that temperature.
The following is the result of analysis, the lead being deter-
mined as sulphate by ignition of the salt with a few drops of
strong sulphuric acid.
5:48 grains substance gave 5°65 carbonic acid and 0°815
water. 5°29 grains substance gave 3°74 sulphate of lead.
Calculation.
Experiment. |
Carbon. . .» 28:12 27:94. Cl 60
Hydrogen . . = 1°65 1:39 H?® 3
Oxygen . . . 18°21 18:72, O°.) 40
Oxide of lead . 52:02 51:90 PbO 111°56
100-00 100:00 21456
The formula is therefore represented by PbO, C!° H? O°.
Pyromeconate of Copper.—The ammonio-sulphate of copper
mixed with a warm aqueous solution of pyromeconic acid causes
an immediate precipitate of this salt in bright green crystalline
needles, which are extremely brittle and easily pulverized. This
salt has also been examined by Stenhouse*, who prepared it by
boiling the acid with hydrated oxide of copper, and allowing the
filtered solution to cool. The crystals require a considerable
amount of hot water for their solution, and are very slightly
soluble in cold water or alcohol.
The copper was determined as oxide by heating the salt to
redness, and then igniting the residue with nitric acid. It loses
nothing at 212°.
6:00 grains substance gave 1-66 oxide of copper, which calcu-
lated per-centage gives 27°66 of oxide of copper, the number
27°79 being that corresponding with the formula
CuO, C!° H3 O°.
Pyromeconate of Iron.—Dr. Stenhouse has observed in the
aper before mentioned, that when pyromeconic acid is boiled
with hydrated peroxide of iron, and also with the persulphate,
it combines with the oxide and forms a brownish-red powder,
which when neutral is very little soluble in cold water. It may
also be obtained, and perhaps more conveniently, by adding
perchloride of iron to a hot concentrated solution of the acid in
water, when the cinnabar-red crystals begin to make their ap-
pearance, adhering firmly to the sides and bottom of the vessel.
Its properties have been so fully described by Stenhouse, that
further remark is unnecessary.
The crystals were well washed with cold water, until the fluid
* Mem. and Proc, Chem, Soe. vol. ii. [Phil. Mag. S. 3. vol. xxiv. p. 128.]
166 Mr. J. F. Brown on some Salts and Products of
which passed through ceased to precipitate nitrate of silver, and
then subjected to analysis in the usual way.
6°53 grains substance gave 1°32 peroxide of iron.
The per-centage calculated from the number is 20°21, while
20:56 is that corresponding to the formula Fe? 0%, 301° H? O°.
Produets of decomposition of Pyromeconic Acid.—If some
crystals of the acid be moistened with strong nitric acid in the
cold, they immediately assume a white gelatinous appearance,
and bubbles of nitrous acid are soon evolved ; by the application
of a gentle heat the action becomes excessively violent, and con-
tinues so even though the heat be withdrawn, with the produc-
tion of oxalic and hydrocyanic acids. Sulphuric acid in the cold
has no action on pyromeconic acid; but when gently warmed, it
dissolves it to a colourless fluid, which upon cooling deposits the
pyromeconic acid again.
Several experiments were made by passing chlorine into a
solution of pyromeconic acid with the view of obtaining a chlo-
rine substitution compound, but without success, that reagent
acting too powerfully on it. Complete decomposition always
ensued, and oxalic acid was detected in the fluid, but not m
large quantity. I may here mention that I failed in obtaining
an ether of pyromeconic acid by passing dry hydrochloric acid
gas into a solution of the acid in absolute alcohol, the crystals
which deposited from the fluid proving on analysis to be the acid
unaltered.
Action of Bromine on Pyromeconic Acid—When bromine
water is added to a strong aqueous solution of pyromeconic acid,
leaving the latter in excess, it is rapidly absorbed, yielding a
colourless fluid, which after standing for an hour or even less,
deposits the new acid in beautiful small colourless prisms. In
one experiment a large excess of bromine failed to yield any of
the new acid, even after standing a considerable time; more
bromine was then added, but no crystals made their appearance.
The solution, which had acquired a yellowish colour, was evapo-
rated to a small bulk, still without the formation of any bromo-
pyromeconic acid. It had now become perfectly black, and
oxalic acid was found in fluid.
The crystals obtained by the action of a limited quantity of
bromine, after thorough washing with cold water, gave the fol-
lowing results on analysis :—
4:97 grains substance gave 5°82 carbonic acid and 0°925 water.
4°845 grains substance gaye, when burned with lime, 4°71 grs.
bromide of silver,
Decomposition of Pyromeconic Acid. 167
Calculation.
Experiment. §£§_, —————-*~—_
Carbon . . 31°93 31:70 CC? 60
Hydrogen . 2°05 158 ts Borin
Oxygen . . 24°68 25°65 OF 48
Bromine. . 41°34 41:07. Br 78:26
100:00 100:00 189°26
Which show that they consist of an acid produced by the sub-
stitution of an equivalent of hydrogen in pyromeconic acid by an
equivalent of bromine.
This acid is of sparing solubility in cold water, more so in hot,
and reddens litmus slightly. Boiling alcohol dissolves it readily,
from which it crystallizes in beautiful fibrous plates ; and if the
cooling be carefully effected, in short prisms. It imparts to
persalts of iron a deep purple colour, quite distinct from the red
produced by the original acid. Nitric acid decomposes it with
effervescence, but sulphuric dissolves it without any apparent
decomposition. Submitted to destructive distillation, it fuses
and then blackens, hydrobromic acid being evolved in large
quantity ; after the continuation of the heat, a white crystalline
substance begins to collect on the cool part of the tube, but in
quantity too small to admit of examination.
It gives no precipitate with nitrate of silver, neither when
~ boiled does it reduce the oxide to the metallic state. It causes
no precipitate in solutions of chloride of barium, calcium, or sul-
phate of magnesia, even in the presence of ammonia. Ammonio-
sulphate of copper, though producing no effect in the cold, gives
when heated a precipitate of a bluish tint.
Bromo-pyromeconic acid, like pyromeconic, is monobasic,
forming only one series of salts. The salt employed for con-
trolling the analysis and establishing the saturatmmg power of the
acid was that of lead.
Bromo-pyromeconate of Lead.—A warm alcoholic solution of
the acid gives with acetate of lead, also dissolved in alcohol, a
white precipitate of small dense crystalline needles which rapidly
fall to the bottom of the vessel. From its insolubilty in water
and alcohol, recrystallization of the salt was impossible ; thorough
washing with alcohol was therefore resorted to. This salt may
also be obtained by using aqueous solutions of the acid and salt
of lead with the addition of ammonia, but the product is in this
case very much coloured.
The lead in the following analysis was determined as sulphate
by ignition of the salt with Tacha acid. It loses nothing
at 212°.
168 Prof. Thomson on the Dynamical Theory of Heat.
7:34. evains substance gave 5:54 carbonic acid and 0:56 water.
4°68 grams substance gaye 2°29 sulphate of lead.
Calculation.
Experiment. ——_—_———
Garbon. iss) sidkueie ion 19:91 Cle 60
Hydrogen . . 00°85 00:99 H® 3
Oxygen os psn tee 16:19 O& 48
Bromine. 2.0 dunes . a RG OL. Br 78°26
Oxide of lead . 36°48 86:90 PbO 111°56
100:00 100:00 300°82
The composition of this salt is therefore expressed by the for-
mula PbO, C!° H? Br 0°+ HO.
I have also obtained a substitution product of iodine, by ope-
rating in a particular manner, which I shall describe in detail in
a future paper. I shall conclude this communication with a list
of the substances described in it along with their formule.
These experiments were performed in the laboratory of Dr.
Anderson, to whom I am much indebted for assistance.
Pyromeconic acid . . . C0 He 0O°+ HO.
Pyromeconate of baryta_ . _ BaO, C!° H3 0° + HO.
Pyromeconate of strontia . SrO, C!° H? 0° + HO.
Pyromeconate of lime ~ . CaO, C!° H? 0°+ HO.
Pyromeconate of magnesia MgO, C!° H? O°.
Pyromeconate of lead . . PbO, C?° H3 O°.
Pyromeconate of copper . CuO, C?° H3 O°.
Pyromeconate of iron . . Fe? 03,3010 H3 O°.
Bromo-pyromeconiec acid . C!0 H? Br O° + HO.
Dibed' Salt en Oe PbO, ClCH Br e-file
Edinburgh, July 1, 1852.
XXV. On the Dynamical Theory of Heat, with numerical results
deduced from Mr. Joule’s equivalent of a Thermal Unit, and
M. Regnault’s Observations on Steam. By W1t11\M THomson,
M.A., Fellow of St. Peter’s College, Cambridge, and Professor
of Natural Philosophy in the University of Glasgow.
[Concluded from p. 117.]
Parr II1.—Applications of the Dynamical Theory to establish
Relations between the Physical Properties of all Substances.
AA. HE two fundamental equations of the dynamical theory
of heat, investigated above, express relations between
quantities of heat required to produce changes of volume and tem-
perature in any material medium whatever, subjected to a uniform
pressure in all directions, which lead to various remarkable conclu-
Prof. Thomson on the Dynamical Theory of Heat. 169
sions. Such of these as are independent of Joule’s principle
(expressed by equation (2) of § 20), being also independent of
the truth or falseness of Carnot’s contrary assumption regarding
the permanence of heat, are common to his theory and to the
dynamical theory; and some of the most important of them*
have been given by Carnot himself, and other writers who
adopted his principles and mode of reasoning without modifica-
tion. Other remarkable conclusions on the same subject might
have been drawn from the equation ap Verte expressing
Carnot’s assumption (of the truth of which experimental tests
might have been thus suggested) ; but I am not aware that any
conclusion deducible from it, not included in Carnot’s expres-
sion for the motive power of heat through finite ranges of tem-
perature, has yet been actually obtained and published.
45. The recent writings of Rankine and Clausius contain
some of the consequences of the fundamental principle of the
dynamical theory (expressed in the first fundamental proposition
above) regarding physical properties of various substances;
among which may be mentioned especially a very remarkable
discovery regarding the specific heat of saturated steam (inves-
tigated also in this paper in § 58 below), made independently
by the two authors, and a property of water at its freezing-point,
deduced from the corresponding investigation regarding ice and
water under pressure by Clausius; according to which he finds
that, for each 15° Cent. that the solidifymg point of water is
lowered by pressure, its latent heat, which under atmospheric
pressure is 79, is diminished by ‘081. The investigations of
both these writers involve fundamentally various hypotheses
which may be gr may not be found by experiment to be ap-
proximately true ; and which render it difficult to gather from
their writings what part of their conclusions, especially with
reference to air and gases, depend merely on the necessary prin-
ciples of the dynamical theory,
46. In the remainder of this paper, the two fundamental pro-
positions, expressed by the equations
dM _dN_1dp
ae hee eet el
and rl. a
Me ern tak Sen SRE;
ave applied to establish properties of the specific heats of any
substance whatever; and then special conclusions are deduced
for the case of a fluid following strictly the “gaseous laws” of
* See above, § 22,
170 Prof. Thomson on the Dynamical Theory of Heat.
density, and for the case of a medium consisting of parts in dif-
ferent states at the same temperature, as water and saturated
steam, or ice and water.
47. In the first place it may be remarked, that by the defi-
nition of M and N in § 20, N must be what is commonly called
the “ specific heat at constant volume” of the substance, pro-
vided the quantity of the medium be the standard quantity
adopted for specific heats, which, in all that follows, I shall take
as the unit of weight. Hence the fundamental equation of the
dynamical theory, (2) of § 20, expresses a relation between this
specific heat and the quantities for the particular substance de-
noted by Mand p. If we elimmate M from this equation, by
means of equation (3) of § 21, derived from the expression of
the second fundamental principle of the theory of the motive
power of heat, we find
Nos
aN _ _\udi/ lap (14)
dv-~ ait PEO VERON SS ;
which expresses a relation between the variation in the specific
heat at constant volume, of any substance, produced by an altera-
tion of its volume at a constant temperature, and the variation
‘of its pressure with its temperature when the volume is constant ;
involving a function, «, of the temperature, which is the same
for all substances.
48. Again, let K denote the specific heat of the substance
under constant pressure. Then, if dv and dt be so related that
the pressure of the medium, when its volume and temperature
are v+dv and ¢+dt respectively, is the same as when they are
v and ¢, that is, if
O= P ty Dy
d dt
we have
Kdt= Mdv + Ndé.
Hence we find
M=——(K—N) .... . (15),
which merely shows the meaning in terms of the two specific
heats, of what I aave denoted by M. Using in this for M its
value given by (3) of § 21, we find
(i)
dp
naan
K—N=
(16),
Prof. Thomson on the Dynamical Theory of Heat. 171
an expression for the difference between the two specific heats,
derived without hypothesis from the second fundamental prin-
ciple of the theory of the motive power of heat.
49. These results may be put into forms more convenient for
use, in applications to liquid and solid media, by introducing
the notation :—
is (17),
1 dp |
e= ——
Kdt }
where « will be the reciprocal of the compressibility, and e the
coefficient of expansion with heat.
Equations (14), (16) and (3), thus become
Ke
dN a) ke
dv ae Ge),
2
K-N=o~- at cong 247s ergy
Mi tet (20);
the third of these equations being annexed to show explicitly the
quantity of heat developed by the compression of the substance
kept at a constant temperature. Lastly, if @ denote the rise in
temperature produced by a compression from v+dv to v before
any heat is emitted, we have
is ALY.
50. The first of these expressions for 0 shows that, when the
substance contracts as its temperature rises (as is the case, for
instance, with water between its freezing-poimt and its point of
maximum density), its temperature would become lowered by a
sudden compression. The second, which shows in terms of its
compressibility and expansibility exactly how much the tempe-
rature of any substance is altered by an infinitely small alteration
of its volume, leads to the approximate expression
ke
d= pK’
if, as is probably the case, for all known solids and liquids, e be
so small that e.v«e is very small compared with wK.
51. If, now, we suppose the substance to be a gas, and introduce
172 ~—— Prof. Thomson on the Dynamical Theory of Heat.
the hypothesis that its density is strictly subject to the “ gaseous
laws,’ we should have, by Boyle and Maniotte’s law of com-
pression,
GD, ePiiihio eaninlsy Sif ody bn gapyi
dv v
and by Dalton and Gay-Lussac’s law of expansion,
dv Ev
Roo Ta dt ctonatvsl dob senihBe)is
from which we deduce
dp _ Ep
di, A 4RE
Equation (14) will consequently become
d wx “mm Ep
eee PO a }
a result peculiar to the eae ae and equation (16),
(24),
(25),
which agrees with the result of § 53 of my former paper.
If V be taken to denote the volume of the gas at the tempe-
rature 0° under unity of pressure, (25) becomes
K—N= Hy (26)
aia grr ieee :
52. All the conclusions obtained by Clausius, with reference
to air or gases, are obtained immediately from these equations
by taking
E
eI
which will make es =0, and by assuming, as he does, that N,
dv
thus found to be independent of the density of the gas, is also
independent of its temperature.
53. As a last application of the two fundamental equations of
the theory, let the medium with reference to which M and N
are defined consist of a weight 1—w of a certain substance in
one state, and a weight x in another state at the same tempera-
ture, containing more latent heat. To avoid cireumlocution and
to fix the ideas, in what follows we may suppose the former state
to be liquid and the latter gaseous; but the investigation, as
will be seen, is equally applicable to the case of a solid in con-
tact with the same substance in the liquid or gaseous form.
54, The volume and temperature of the whole medium being,
Prof, Thomson on the Dynamical Theory of Heat. 173
as before, denoted respectively by v and ¢, we shall have
Ml—2) + yr... |S ord,
if X and y be the volumes of unity of weight of the substance in
the liquid and the gaseous states respectively: and p, the pres-
sure, may be considered as a function of ¢, depending solely on
the nature of the substance. To express M and N for this mixed
medium, let L denote the latent heat of a unit of weight of the
vapour, ¢ the specific heat of the liquid, and / the specific heat
of the vapour when kept in a state of saturation. We shall have
Mdv=L el dv
dv
Ndt=c(1—z)dt 4-hadt +L oat
Now, by (27), we have
d:
(yr) S = (28),
and dz dr dy _ e
(Y-d) FF +2) FF +257 =0 (29)
Hence cig!
TN eRe Sa NGHALT WN Gosia MEF Wee
a) 424
N=c(l—a2)+he—L may (81).
55. The expression of the second fundamental proposition in
this case becomes, consequently,
dp
(7-1) =
ARES WCE (32),
which agrees with Carnot’s original result, and is the formula
that has been used (referred to above in § 31) for determining
» by means of Regnault’s observations on steam.
56. To express the conclusion derivable from the first funda-
mental proposition, we haye, by differentiating the preceding
expressions for M and N with reference to ¢ and v respectively,
aM. 1. du L = d(y—2)
By Gh
ie (ae i)
y- dw
_fh-—e L od)
~ yan ap de
174 Prof. Thomson on the Dynamical Theory of Heat.
Hence equation (2) of § 20 becomes
du +e—h
BE ein
y—nN SS dt
Combining this with the conclusion (32) derived from the
second fundamental proposition, we obtain
dL Ie
We +e— h= -% . BY pers oe i
The former of these equations agrees precisely with one which
was first given by Clausius, and the preceding investigation
is substantially the same as the investigation by which he arrived
at it. The second differs from another given by Clausius only in
not implying any hypothesis as to the form of Carnot’s function p.
57. If we suppose » and L to be known for any temperature,
(33).
(34).
equation (32) enables us to determine the value of for that
temperature ; and thence-deducing a value of dt, we have
—Xr
TL Mee hokey saote Neiaeme
which shows the effect of pressure in altermg the “ boiling-
point ” if the mixed medium be a liquid and its vapour, or the
melting-point if it be a solid in contact with the same substance
in the liquid state. This agrees with the conclusion arrived at
by my elder brother in his Theoretical Investigation of the Effect
of Pressure in Lowermg the Freezing-Pomt of Water*. His
result, obtained by taking as the value for w that derived from
Table I. of my former paper for the temperature 0°, is that the
freezing-point is lowered by :0075° Cent. by an additional atmo-
sphere of pressure. Clausius, with the other data the same,
obtains ‘00733° as the lowering of temperature by the same ad-
ditional pressure, which differs from my brother’s result only
from having been calculated from a formula which implies the
ae
hypothetical expression J ia for w. It was by applying
Raat 20: :
equation (33) to determine = for the same case that Clausius
arrived at the curious result regarding the latent heat of water
under pressure mentioned above (§ 45).
58. Lastly, it may be remarked that every quantity which ap-
* Transactions, yol. xvi. part 5. His paper was republished, with some
slight modifications, in the Cambridge and Dublin Mathematical Journal,
new series, vol. vy.— Noy. 1850.
Prof. Thomson on the Dynamical Theory of Heat. 175
pears in equation (33), except 4, is known with tolerable accuracy
for saturated steam through a wide range of temperature; and
we may therefore use this equation to find h, which has never
yet been made an object of experimental research. Thus we have
et Be (Ne
ey aN ere:
For the value of y the best data regarding the density of satu-
rated steam that can be had must be taken. If for different
temperatures we use the same values for the density of saturated
steam (calculated according to the gaseous laws, and Regnault’s
observed pressure from maT taken as the density at 100°), the
values obtained for the first term of the second member of the
preceding equation are the same as if we take the form
_ Tp (db )
— het (Fe
derived from (34), and use the values of » shown in Table I. of
my former paper. The values of —/ in the second column in
the following table have been so calculated, with, besides, the
following data afforded by Regnault from his observations on
the total heat of steam, and the specific heat of water
di
Fa +-e='305.
L= 606-5 + -305t— (-00002/2 + 00000037).
The values of —f shown in the third column are those derived
by Clausius from an equation which is the same as what (34)
: E .
would become if J Ta he Were substituted for p.
—h according to
t. Table I. of “ Account| ~— According to
of Carnot’s Theory.’? Clausins,
0 1/863 1916
50 1479 1:465
100 1174 1-133
150 0951 0879
200 0-780 0676
59. From these results it appears, that through the whole
range of temperatures at which observations have been made,
the value of / is negative; and, therefore, if a quantity of satu-
rated yapour be compressed in a vessel containing no liquid
water, heat must be continuously abstracted from it in order
176 Prof. Thomson on the Dynamical Theory of Heat.
that it may remain saturated as its temperature rises; and con-
versely, if a quantity of saturated vapour be allowed to expand
in a closed vessel, heat must be supplied to it to prevent any
part of it from becoming condensed into the liquid form as the
temperature of the whole sinks. This very remarkable conclu-
sion was first announced by Mr. Rankine, m his paper commu-
nicated to this Society on the 4th of February last year. It was
discovered independently by Clausius, and published in his paper
in Poggendorft’s Annalen in the months of April and May of the
same year.
60. It might appear at first sight, that the well-known fact
that steam rushing from a high-pressure boiler through a small
orifice into the open air does not scald a hand exposed to it*, is
inconsistent with the proposition, that steam expanding from a
state of saturation must have heat given to it to prevent any part
from becoming condensed ; since the steam would scald the hand
unless it were dry, and consequently above the boiling-point in
temperature. The explanation of this apparent difficulty, given
in a letter which I wrote to Mr. Joule last October, and which
has since been published in the Philosophical Magazine, is,
that the steam in rushing through the orifice produces mecha-
nical effect which is immediately wasted in fluid friction, and
consequently reconverted into heat; so that the issuing steam
at the atmospheric pressure would have to part with as much
heat to convert it into water at the temperature 100° as it would
have had to part with to have been condensed at the high pres-
sure and then cooled down to 100°, which for a pound of steam
initially saturated at the temperature 7 is, by Regnault’s modi-
fication of Watt’s law, 805 (¢— 100°) more heat than a pound
of saturated steam at 100° would have to part with to be re-
duced to the same state; and the issuing steam must therefore
be above 100° in temperature, and dry.
[* Note added June 26, 1852,—At present I am inclined to believe that
the rapidity of the current exercises a great influence on the sensation
experienced in the circumstances, by causing the steam to mix with the
surrounding air; for I have found that the hand suffers pain when exposed
to the steam issuing from a common kettle, and dried by passing through
a copper tube surrounded by red-hot coals or heated by lamps. But
although there may be uncertainty regarding the causes of the different
sensations in the different circumstances, I believe there is no reason for
doubting either the fact of the dryness of the steam issuing from a high-
pressure » boiler (except when there is “priming” toa considerable extent),
or the correctness of the explanation of this fact Which I have given in the
letter referred to. |
———_-
wipe
2 vised,
feet]
XXVI. Renewed Inquiries concerning the Spiral Structure of
Muscle, with Observations on the Muscularity of Cilia. By
Martin Barry, M.D., F.R.S.
[Concluded from p. 98.]
On the Muscularity of Cilia.
AS’ his previous observations had led him to expect, cilia were
found to be no other than his twin or double spirals. No
man, he thinks, will do him the injustice to suppose he maintains
the possibility of discerning a double spiral in the minutest cilium.
He is as far from maintaining this as he is from asserting the
possibility of seeing a double spiral in the minutest muscular
fibril. But he does maintain that those who undertake the
examination of cilia in the way in which they should set about
the examination of all organic tissues, 7. e. with a desire to know
how they originate, what is the history of their development,
will certainly find that the double spiral is the fundamental form
of all cilia the structure of which can be reached with the micro-
scope, and therefore probably of the most mmute. Indeed under
favourable circumstances, traces thereof are not so very rarely to
be discerned, by the accustomed eye, even in the latter.
In the author’s observations he used several bivalve moilusca,
including the Oyster, Ostrea edulis, and the common Sea Mussel,
Mytilus edulis, The one last mentioned is to be preferred,
because of the bars of its branchial lamin being most easy of
separation. And this mussel is further recommended to those
disposed to repeat the author’s observations, on account of the
excellent description of its gills given by Dr. Sharpey in his
Article “ Cilia” mm Todd’s Cyclopedia of Anatomy and Physio-
logy. He recommends the examination of this Mussel when
small, because of the branchial laminz being more transparent
than in the larger specimens. He examined some in which the
shell measured scarcely two lines in length, they being the small-
est he could obtain. The most convenient size, however, he
found to be that in which the shell measured in length from 4
to $ of an inch. Still an examination of the largest should not
be omitted.
Convinced by his earlier microscopic labours that it is best to
direct the eye for a considerable time exclusively to the same
part or set of objects in order to enable it to detect minute dif-
ferences in the same or in different individuals, the author
directed his solely to the branchial lamin, and here to little
more than the sides of those parallel bars of which the branchial
laminze are composed. In this way it was that he became ac-
quainted with the fact, that, as the ever-acting heart requires a
continued renewal of its fibrils, so are new generations continu-
ally preparing to succeed the indefatigably vibrating cilia.
Phil, Mag, 8, 4, Vol, 4, No, 24, Sept, 1852, N
178 Dr. Barry’s renewed Inquiries concerning the
Before detailing his observations, the author states what others
should do who may be disposed to repeat the examinations. A
small piece, about a square line, having been cut from the mar-
ginal edge of the gill and placed upon glass, he adds to it a drop
of the fluid, which, on the mussel being opened, collects mm the
shell, gently and to a small extent separates the bars from one
another with fine needles, and places them under the microscope
without the addition of any covering such as glass or mica. It
is soon seen that some of the bars, wedge-like in their transverse
sections, present the thicker of their edges to the eye, fig. 37,
while others are lying on their sides, figs. 41, 36. Both should
be examined with especial reference to the cilia on the two sides
of the bar. Of these cilia there are three sets, and not two only,
as hitherto supposed; one set uppermost when the thicker edge
of the bar is directed towards the eye, and marked m in the
figures just referred to; the second occupying a middle place,
and marked 7 in the same figures ; the third lowest, and marked o.
Concerning these cilia, the author states the following as new
facts :—In the first place, these cilia, and from analogy probably
all cilia, consist of double spiral threads, and thus have a struc-
ture like that of the muscular fibril; secondly, the cilia m, fig. 36,
&c., present merely stages in the development of the cilia x ;
thirdly, the cilia o, in the same figures, hitherto either overlooked
or held to be identical with the cilia n, are really not so,—they
are the counterpart thereof. And he then proceeds to establish
these three positions in the order here laid down, as follows :—
Separated from their localities by manipulation, and strewn
through the field of view among the fragments of the gill, are
seen simple cells, several of which are represented in outline in
fig. 27. In the interior of such cells the young cilia are indi-
cated. They push before them the membrane of the cell, so
that it appears pointed; and afterwards present themselves, as
in fig. 28, of a club-like form*. Sometimes this club-like form
appears referrible to a provision of plastic substance at the ex-
tremity for the lengthening of the cilium, and sometimes to a
bending down of the extremity hook-like upon itself. Up to
this time the membrane of the cell appears in some instances to
continue entire,—the young cilium, though coming into view,
being as it were still unborn. At length the membrane is rup-
tured, and the bent down extremity of the cilium gradually de-
velopes and unrolls itself like a young fern, fig. 29. This figure,
fig. 29, represents part of a large fragment, several of which
were found in substance scraped from the gill of the Oyster.
* Probably Valentin saw the same stage of development in Unio pictorum,
where he mentions it (the “ club-like form”) as an unusual shape’ (“ aus-
nahmsweiser Gestalt ”).—R. Wagner’s Handwérterbuch der Physiologie,
p. 500
Spiral Structure of Muscle. 179
They contained at the margin numerous cells. The middle
space presented none. On the nature of these large fragments
the author has for the present nothing further to remark, than
that they afforded him an invaluable contribution towards the
history of development of cilia; for of that development they
presented with distinctness a very early stage. The minute cells
in their interior seemed destined to give origin to cilia, which
here and there, fig. 29, were seen to have been already formed
and to have burst through the membrane of their cells. One of
these, the interior of which was seen with rare distinctness, 1s
represented on a larger scale in fig. 30. The young cilium here
drawn consisted of two spirals, within the winds of which was a
pellucid substance corresponding to that which the author above
and elsewhere has termed hyaline. At the extremity the two
spirals passed into one another, and were bent over hook-like
towards one side. At the base they separated, to bestride, as it
were, the contents of the cell in which the cilium had been
formed*. Perhaps these two separate threads may be considered
as the radical ends of the cilium, in which growth first of all
takes place somewhat in the following manner :—The extremity
of each of these two threads draws into itself new substance from
the nucleus of the cell. And now as the cilium is alternately in
the states of twisting and untwisting, it gradually spins up into
its substance those after-threads, and in this manner elongates.
Drawings are then given of stages following those just de-
scribed, of which figs. 831, 32, 33, and 34 present a selection.
These different appearances evidently denote different degrees of
development. [Corresponding differences were noticed in their
movements. None of them, however, were in a perfect state.
For the movements of even the most advanced were awkward,
showing them to be, as it were, still in their apprenticeship. ]
Now to all of these cilia, making allowance for differences in the
degree of development, may be applied the description just given
of fig. 30 ; though it is only here and there that a trace of con-
nexion with the cell, such as that in fig. 30, can be distinctly
seen. The author thinks that no observer can attentively examine
such cilia without seeing, as he did, that each of them consists of
a double spiral thread, having therefore a structure like that of
the muscular fibril, and thus establishing his position No. 1.
The broad cilia of which examples have been given in Beroé
and other ciliograde Mollusea,—where, instead of cilia of usual
form and arrangement, there are found rows of broad flat flaps
each of which is said to consist of a row of single cilia,—appear to
atl will be observed, that each of these separate threads is twisted on
itself.
N 2
180 Dr. Barry’s renewed Inquiries concerning the
the author to consist of fasciculi of cilia; and if this be the case,
their mode of reproduction is probably the same as that of other
muscle. He found the bulb at the base of some cilia much
smaller than at that of others. This may have arisen from
division,—a larger bulb together with its cilium dividing into two ;
or it may have arisen from consumption of the bulb, through
nourishment and growth of the cilium. In other cases the bulb
had entirely disappeared, and the cilia arose from a common
ground, fig. 35. Here it is possible that after the bulbs had
been entirely spent from the growth of the cilia, all trace thereof
had disappeared.
Notwithstanding all that he has said, both in this treatise and
in former ones, on the necessity in all researches on the struc-
ture of tissues of attending to the history of their development,
the author adds that he feels called upon candidly to acknow-
ledge cilia to present in this respect a difficulty such as perhaps
is scarcely to be found elsewhere. Here the observer has it not
in his power to begin with the history of development ; for after
what has been above stated of a continued renewal of the cilia,
and of several stages in their development being sometimes met
with even in the same bar, it cannot be expected that the younger
cilia will necessarily be found in the younger mussels. The few
facts in their development recorded in this memoir, were not
fully ascertained until after a long series of measurements and
observations on movements, and on forms of cilia met with quite
at random. The author trusts his descriptions and drawings of
the several stages may be useful to others in following out the
history of development; b t it is a misfortune for him not to
have it in his power to say just where the younger and most
convincing stages are to be found, such as would enable others
so easily to confirm his observations on their spiral structure.
It is added: “ You may open a very large number of mussels,
and devote whole days to the examination, before you find an
example for demonstration. If, however, you are so fortunate
as to meet with a stage such as that in fig. 30, you feel richly
rewarded for all the labour.”
The author then proceeds to establish his position No. 2, that
the cilia marked m in fig. 36, &c. are merely different stages in
development of the cilia n in the same figures. To this unex-
pected observation he was led by the following facts.
In the first place, the cilia m and n, see fig. 36, have a common
place of origin, their roots arising mixed together in the same
field. Secondly. You here and there see one of the cilia m flexed
at its base, by which its extremity is made to approach the ex-
Spiral Structure of Muscle. 181
tremities of the cilia x; but it instantly returns to its previous
state, to be immediately afterwards depressed again as before ;
and so on*. Thirdly. You sometimes meet with states in which
this depression of some of the cilia m is permanent. See ml
in the same figure. Fourthly. As already mentioned, the cilia m
in different individuals present very different states, figs. 31, 32,
33, 34, 39,40. Their lengths differ, some being very short ;
sometimes they are straight, sometimes curved ; sometimes they
are found moving, sometimes motionless. The movements are
generally quite irregular. There is nothing like a common pur-
pose in them ; certainly no combination for the production of a
current. In some they are such as to suggest the idea of efforts
to become unbent at their extremities, fig. 32; and in others no
longer bent at their extremities, the movements seem made for
the purpose of becoming elongated, fig. 40. You sometimes
meet with the two last-mentioned states in the same bar, fig. 39.
In short, these different appearances and movements evidently
denote different degrees of development. Not until they reach
the state in fig. 36 can the cilia m be said to have attained ma-
turity, and to exhibit a common purpose in their movements.
But even then their movements are not so vehement as to be
likely soon to wear them out. Why, then, are they so constantly
renewed? The fact is, that by flexion at the base, the cilia m
(see fig. 36) pass, one after another, into the vehemently vibrating
cilia n, which they succeed as a later generation. For this pur-
pose they are formed, and then for the first time do they perform
really efficient action. Thus it was that the author was led to
his position No. 2.
In his third conclusion, he stated that the cilia o in fig. 86,
&c., hitherto either overlooked or held to be identical with the
cilia n, are really not so,—they are the counterpart thereof. This
will be immediately made clear if attention be paid to their origin
and the function they perform.
The roots of these two lines of cilia are separated by a broad
pellucid space, fig. 36 h, in which are no cells such as those (p)
giving origin to the cilia in question. The cilia of the two lines,
proceeding from opposite sides of the pellucid space, arch over it,
their extremities meeting in the middle line, where they, alter-
nating with one another, like the fingers of the two hands, form
* The movements of the cilia m are described by Sharpey merely as
follows :—“ The more opake cilia, or those of the exterior range, appear
and disappear by turns, as if they were continually changing from a hori-
zontal to a vertical direction and back again.”—L. c. p. 622. And the
author says, he is not aware that any other author has given more exact
information concerning them.
182 Dr. Barry’s renewed Inquiries concerning the
a sort of tunnel, through which water is driven by their vehe-
ment movements. So much for conclusion No. 3*.
On the subject of functions it is also to be remarked, that the
pellucid space, fig. 36 A, over which these two lines of cilia, n
and 0, move so vehemently, belongs to the membrane of the bar
(known to be considered as a vessel of the gill), which membrane
is probably destined to absorb oxygen from the water and com-
municate it to the blood. This would be materially assisted
were the stream of water accelerated, and a fresh supply of
oxygen constantly afforded.
It must further be remembered, that, as is known, the direc-
tion of the current in neighbouring bars is different. If in one
it is from the base of the gill towards its margin, in the next it
is from the margin towards the base; in the one case appearing
to end at a round projection covered with vibrating cilia,
fig. 41 gg,—in the other appearing to begin there. The direction
of the currents now mentioned as opposite in neighbouring bars,
is also opposite on the two sides of the same bar, figs. 37, 88.
The round projection, fig. 41 gq, just referred to, Sharpey has
not particularly mentioned. It seems to be of the same nature
as his “round projections,” g in the same figure, with this dif-
ference, that where the two bars pass into one another at their
ends, two round projections pass into one. Hence the larger
size of that at gq, fig. 41.
The marvellously complicated movements of the cilia n and o,
figs. 36, 37, 38, 41, the author says he has very often observed,
continuing to watch them until they became slower, and at length
ceased. At last only groups of them are seen thus moving, then
not more than two or three together, and finally single ones.
* The cilia 0, as an independent line, Sharpey appears not to have ob-
served; he mentions and figures merely the cilia n, as is evident from the
following :—‘ The motion of the other set consists in a succession of un-
dulations, which proceed in a uniform manner along the sides of the bar
from one end to the other. It might be very easily mistaken for the cir-
culation of globules of a fluid within a canal, more especially as the course
of the undulations is different on the twe sides of the bar, being directed
on one side towards the edge of the gill, and on the other towards the base.
But besides that the undulations continue for some time in small pieces cut
off from the gill, which is inconsistent with the progression of fluid in a
canal, the cilia are easily distinguished when the undulatory motion becomes
languid. When it has entirely ceased, they remain in contact with each
other, so as to present the appearance of a membrane (d, d, fig. F).”—
Sharpey, /. c. p. 623.
So far Dr. Sharpey. And the author adds, that he is not aware of any
other observer having made any mention of them,—the cilia 0.
+ [This fact also is already known. ]
Spiral Structure of Muscle. 183
When the movements have entirely ceased, the two lines of cilia
lie nearly parallel, fig. 36, n, 0, and somewhat bent, with the
convexity almost always in the same direction as the current
their movements had occasioned.
It remains to be added respecting the cilia n and 0, that when
their movements have terminated, and the cilia are left in a state
of relaxation, they often in a short time entirely disappear. Pro-
bably most of them break off at their roots, as mdeed may con-
stantly happen during life, when the old ones become replaced
by new, the former going off when worn out, being carried away
by the stream, and thrown out at the excretory orifice.
As nothing until now was known regarding the structure of
cilia, everything brought forward as to the cause of their move-
ments has been conjecture only. Having found in them a struc-
ture adapted for contraction and relaxation, the author has much
pleasure in thus showing that his fellow-countryman, Professor
Sharpey, was right when in the year 1836 he thought it probable
that the moving power of cilia lay in the cilia themselves, and
was referrible to a substance contained in more or less of their
length, like that of muscle.
The undulatory movements of cilia,—compared by Sharpey,
when many were seen together, to those produced by the wind
on a field of corn,—the author on two occasions witnessed when
performed by cilia in a single line, and when most perfect; on
one of which occasions he had the pleasure of showing the rare
spectacle to Purkinje. In both instances this living mechanism
was seen at the marginal end of the bar, and in the line of cilia
m, fig. 41; im one instance at the point 7, in the other at the
point marked s. The rough diagram, fig. 42, will scarcely serve
to convey an idea of these undulatory movements, for the ap-
pearance was exceedingly delicate and beautiful. The undula-
ting cilia in the two instances were in different conditions. In
the one instance they had their spirals in a twine-like state, as
in fig. 40, and were permanently contracted at no part; in the
other instance they were permanently contracted at the base, as
at m in fig, 36. In the first case the movements may have con-
sisted merely of a shortening and lengthening in the axis of the
cilia ; in the second, of flexion at the base. Further, the cilia
in the two instances in question were of different forms ; in one
instance being straight, as in fig, 40,—in the other curved, as in
fig. 36m. As now the contraction of a double spiral implies a
twisting of the same, the extremity when bent must describe a
course spirally infundibular, not represented in the diagram.
[The author observed very young hives fig. 43, which evidently
184: Dr. Barry’s renewed Inquiries concerning the
showed in their movements a shortening and lengthening. No
definite order, however, such as that implied by undulation, was
observed. Perhaps a disturbance had occurred through mani-
pulation. ]
It is important, the author thinks, to have seen these undu-
latory movements performed by the cilia m, fig. 36; for, as suc-
cessors to the cilia n, the cilia thus undulating were about to
arrange themselves in one of the two lines above mentioned as
combining to form a sort of tunnel, through which by their ex-
tremely vehement movements to drive a rapid current. And
the following occurred to him as possibly sufficient to explain
the appearance presented by these movements,—which have been
aptly compared to the rapid flow of globules of a fluid. The
cilia n, fig. 36, are all bent in the same direction; they are
arranged in a line, and perform their swinging or lashing move-
ments in an undulatory manner according to the order of their
positions in that line. Like movements, and in the like order,
are performed by the cilia o in the opposite Ime; their extremi-
ties alternating with the extremities of the cilia in the first line,
like the fingers of the two hands, and moving without the slight-
est mutual interference. Now were the movements throughout
the whole phalanx of cilia contemporaneous, there would be pre-
sented to the eye a permanent line of swinging movements. As,
however, those swinging moyements are performed by the cilia
one after another in the order of their positions in the line, they
assume the appearance of a row of roundish waves, following, or
as it were chasing, and uninterruptedly passing into one another ;
not rarely appearing to the eye like a long revolving screw.
The difference between rows of globules (the appearance most
frequently presented by the movements in question) and screw-
cylinders, may be supposed to arise as follows:—When the
swinging movements are of different extent at different parts, we
have the appearance comparable to a row of globules; when
those movements pass uniformly into one another, there is seen
the long-revolving screw*.
Having found the cilia on the branchial laminz of Mussels to
consist of double spirals, the author deems it scarcely needful to
remark, that he infers a like structure in other cilia, exist where
they may. As, however, in the course of these researches he
has very often had the opportunity of examining cilia of Infu-
soria, several species of which are met with in the fluid of the
Mussel’s shell, he cannot refram from making known the fact,
that in these cilia also he finds his double spiral. Often did he
* [The screw probably exhibiting the normal, and the row of globules a
disturbed state. |
4 So 6 eee eee
gt eee ee Be eg ed
Spiral Structure of Muscle. 185
see in them the spiral structure with such distinctness, as to
feel astonished at its not having been long since observed. As
the tails of spermatozoa of course correspond to cilia, their struc-
ture must be essentially the same. He states it to be now nine
years since he published his observation of the spiral structure
of the tail of the mammiferous spermatozoon (Phil. Trans. 1842,
p. 107). It is probably owing to a like refractive power in the
spirals and in the hyaline which lies between them, that the
spirals are so difficult to distinguish in the tails of spermatozoa ;
and hence it no doubt is that they were not observed before.
The subject of the present paper being the structure of muscle,
the author has avoided the special mention of other tissues.
Lest, however, from this omission it should be supposed that he
has abandoned his views,—that the structure of all the element-
ary fibres, as well of plants as of animals, is originally spiral,—
he thinks it right before concluding briefly to declare that those
views remain unchanged. Bowman says: “ Dr. Barry might
as well have entitled his paper ‘On the Spiral Structure of the
Organic World*.’ ” To this title, satirically proposed by Bow-
man, the author remarks that he has not the least objection ; so
far, indeed, is he from being thereby annoyed, that he thanks
him for it. He thanks Prof. Bowman for having thus recorded
in the Cyclopedia of Anatomy and Physiology, as far back as in
the year 1842, that his (Dr. Barry’s) views in regard to the
spiral structure of organic fibre were universal in their character ;
“and I am convinced,” it is added, “that the day will come
when my views will be as universally adopted by physiologists,
as I myself am convinced that the spiral structure is universal.
Let it only be fully understood what those views are. What I
maintain is, that the spiral form of fibre everywhere is the ori-
ginal and incipient form; and that if this form be lost in many
tissues in the course of their special development, it remains
permanent in the fibre of muscle as a necessary attribute of its
function.”
In a postscript it is added, that in the contractile stem of the
Bell polype (Vorticella convallaria), of which several specimens
were examined, the author found his double spiral. In relaxa-
tion, this double spiral lay in its extended cylindrical gelatinous
sheath, (which he regards as its elastic sarcolemma) in [elon-
gated] spiral winds. In contraction, it presented itself in a
manner about the same as that in fig. 18; with this difference,
that the double spiral in the polype was enclosed in its gelati-
nous sarcolemma, which that figure, representing quite another
object, does not show.
i i uma of Anat. and Phys., art. ‘‘ Muscle and Muscular Motion,”
p. 511.
[ 186 ]
XXVII. On the Chemical Constitution and Atomic Weight of the
new Polarizing Crystals produced from Quinine. By WiLL1aM
Birp Herapraru, M.D.*
N the March Number of this Journal the author announced
the discovery of a peculiar salt of quinine, which possessed
the power of polarizing a ray of hght with even greater inten-
sity than the tourmaline ; and at certain angles of rotation it also
depolarized light, and acted as selenite would do under similar
circumstances.
He then stated that the qualitative analysis showed this salt
to be a compound of quinine, iodine, and sulphuric acid; and
although the relative quantities of these constituents had not at
that time been estimated, he gave it the name of iodide of di-
sulphate of quinine. In the present communication, the results
of the quantitative chemical analysis of this compound will be
detailed ; and it will be evident that a new idea of its constitu-
tion will be elicited, which will render another name necessary,
and more in accordance with the results specified.
Before attempting the analysis, it was of course necessary to
invent a process which would furnish a large quantity of this
substance at one operation; after several attempts, with more or
less success, the following method was adopted, which at the
same time served as a means of corroborating the results of the
future analysis, as it enabled the experimenter to account for all
the iodine used in the operation.
A tubulated retort was adapted to a receiver by careful con-
nections, and the latter adjusted to a second receiver, somewhat
in the manner of a Wolff’s apparatus ; the condensers were then
surrounded by a freezing mixture of nitre and hydrochlorate of
ammonia. Into the retort were placed 100 grs. of pure disul-
hate of quinine, 3 fluid ounces of pyroligneous acid, 2 drms,
of diluted sulphuric acid (containing about 12 grs. of dry acid) ;
when this mixture had been raised to about 180° Fahr., the al-
coholic solution of iodine was gradually added through a bent
glass funnel adapted to the tubule of the retort. In this man-
ner 30 grs. of iodine dissolved in 1150 grs. of alcohol were em-
ployed; the whole operation occupied about half an hour, during
which period a reddish-coloured fluid was collected in the re-
ceivers, about 4 fluid drachms in quantity; this of course was
carefully set aside for examination.
The whole was allowed to grow cold, still in connection; an
abundant crop of crystals formed in the retort, which, having
been kept during twenty-four hours at a temperature of 40°
Fahr. to deposit, were collected on a filter, and washed several
* Communicated by the Author.
{fies
On the new Polarizing Crystals produced from Quinine. 187
times with acetic acid at 40° Fahr., which had been previously
found to have little solvent power on this compound at that
temperature. The crystals having been well washed, were dis-
solved in boiling alcohol, spec. gray. ‘838, and on cooling they
recrystallized ; this operation having been repeated, they were at
length obtained pure from any admixture of disulphate of quinine.
Having been drained on a filter and washed with cold spirit,
they were dried at 90° Fahr., then over sulphuric acid, and
weighed : 66°6 grs. were obtained by this operation.
The acid mother-liquid, together with the first washings, were
then examined for iodine; upon allowing a few drops to evapo-
rate spontaneously on a slip of glass, polarizing crystals formed
around the edge of the liquid; consequently the compound is
slightly soluble in cold acid. The acetic acid having been nearly
neutralized by ammonia, nitrate of silver was dropped into the
solution as long as any iodide of silver was deposited; this was
then carefully collected on a filter, washed repeatedly with di-
stilled water, then with ammonia to remove any chloride, again
with distilled water, dried and ignited; it weighed 2:00 grs.=
iodine 1°08.
The alcoholic mother-liquids and washings were then examined
for iodine, and crystals were similarly obtained upon sponta-
neous evaporation. In order to precipitate the iodine, a silver
salt was used, and dropped into the solution as long as any
cloudiness was produced ; the whole thrown on a filter, and the
precipitated iodide of silver, washed with diluted nitric acid to
remove any quinine, and subsequently with ammonia to take
up any chloride, and then with distilled water ; dried and ignited,
it weighed 3°63 grs.=iodine 1-951.
It now remained to examine the distilled liquids for iodine,
as it existed in these in the free state dissolved in alcohol; they
were mixed together, and placed in a counterpoised matrass
with metallic zinc. After prolonged digestion, a little water
added to facilitate the operation, the iodine was converted into
iodide of zinc; the fluids were then distilled off, the iodide of
zine dried at 212° and weighed; 3°35 grs.=iodine 26715 ers,
were obtained.
Now, if any substitution compound had been formed by the
action of the iodine on the quinine, it was probable that hydriodie
wether would be produced ; if so, it wouldbe found in the distilled
fluid; this was carefully examined for this substance, but none
detected. Subsequent experiments showed that none could have
been produced, or if any, so small a quantity, that its presence
would be immaterial, for all the iodine used, with the exception
of 2°56 grs., can be accounted for thus :;—
188 Dr. Herapath on the Chemical Constitution of the
217375 iodine in the 66°6 grs. of crystals at 32°63 per cent.
1-0800 iodine in the acid mother-liquids (as crystals).
1:9510 iodine im the alcoholic mother-liquids (as crystals).
26715 iodine in the distilled fluids as free iodine.
27°4400
2°56 — grs. iodine lost in drying the crystals by expression
between folds of bibulous paper.
Had a substitution compound been formed, one-half the iodine
should have formed hydriodic acid, the other half should have
been in the crystalline compound ; therefore it is evident to me
that no such substitution base can be the result.
One other question arises, Does the iodine exist in the com-
pound as hydriodic acid? Some of the crystals were dissolved
in diluted alcohol boiling, and starch was added to the hot liquid ;
instantly an abundant precipitation of the blue iodide of amidine
occurred ; starch was added in excess, and until no further indi-
cations of iodine were evident ; the fluid was then separated by
decantation, and tested with nitrate of silver; not the least trace
of hydriodie acid or any soluble iodide was apparent ; similar
results were obtained when the crystals were dissolved in hot
acetic acid and tested with starch ; but if they were dissolved in
hot rectified spirit of wine, ‘838 spec. gray., there was no evi-
dence of iodine ; on cooling, the crystals again formed, the rea-
son being that the chemical attraction of alcohol for iodine was
greater than that of iodine for starch, whereas it was less than
that of the iodine in the compound. It has therefore been
proved satisfactorily that the iodine cannot exist in the com-
pound as a substitution base or even as hydriodic acid.
The iodine separating in the free state so readily upon dissol-
ving the crystals in alcohol or in acetic acid, rendered it a some-
what difficult matter to estimate it correctly. Starch was first
used as the precipitant ; the resulting iodide of amidine was de-
composed by sulphuretted hydrogen, the hydriodic acid produced
neutralized by ammonia, then precipitated by nitrate of silver,
and the resulting iodide of silver estimated; but accuracy was
very far from being attained by this method, in consequence of
iodine distilling during the heating of the fluid and solution of
the crystals.
At length it was found, that by passing a current of washed
and pure sulphuretted hydrogen through acetic acid, in which
a known weight of crystals had been placed, and applying heat
to the mixture, as soon as gas commenced being evolved, the
iodine was converted into hydriodie acid upon its being liberated
from the crystals ; the decomposition being perfect and the ope-
new Polarizing Crystals produced from Quinine. 189
ration finished, the excess of sulphuretted hydrogen was expelled
by boiling, testing with acetate of lead paper occasionally, the
precipitated sulphur removed by filtering, washed well with di- °
stilled water, and to the filtrate ammonia added, nearly to neu-
tralization, but short of precipitating the quinine ; then the so-
lution boiled and the iodine precipitated by nitrate of silver,
collected on a filter, washed with distilled water, then with
diluted nitric acid to remove any quinine (which falls with iodide
of silver even from an acid solution), and lastly dried and fused
by ignition in a platina capsule; 25 grs. of crystals gave by this
method 15°14 grs. of iodide of silver =8:1523 grs. of iodine
= 32°6092 per cent.
The solution after the separation of iodine was then, together
with the washings, treated with acetate of baryta until no further
deposition of sulphate occurred:; it was boiled to hasten the sepa-
ration, filtered, washed, dried, ignited and weighed ; it gave 7°76
grs. BaO + SO0®=2-653 SO?=sulphuric acid per cent. 10-612.
The liquid after the separation of iodine and sulphuric acid
was then acted on, first by sulphate of ammonia to remove ex-
cess of baryta, then with hydrochlorate of ammonia to remove
the excess of silver.
To this fluid, concentrated by evaporation to about 3 fluid
ounces, was added ammonia in excess; an immediate deposition
of alkaloid was the consequence. Alther was now added in suf-
ficient quantity to dissolve the alkaloid, the supernatant ethe-
rial fluid was decanted into a counterpoised flask, the operation
being repeated as often as necessary; the ztherial fluids mixed
were then distilled; the residue, dried at 212° Fahr., weighed
7533 grs.
The aqueous and ammoniacal solution, upon evaporation to
dryness in a water-bath, again treating with ether as long as
necessary, and distilling as before, furnished a second quantity
of alkaloid, weighing, after drying as before, 3°14 ers.
Then 7°533 +3:14=10:673 alkaloid equal to 42-692 per cent.
This analysis, therefore, accounts for—
Per cent.
DBOIG o a: oy ll wchecec ce, pawn, OO?
Sulphuric acid . . . . 10°612
Alicalow, “..hels< tie ve -4.< 42°692
85°9132
The loss of 14-0868 was probably water of crystallization,
but it now became necessary to perform an analysis to make
this point certain; after several attempts, the following process
was adopted, and furnished correct results.
Having arranged an apparatus for preparing a current of dry
hydrogen gas, the stream was passed through a flask containing
190 Dr. Herapath on the Chemical Constitution of the
iron filings; these were then heated red-hot, the organic mat-
ters were decomposed and reduced to pure carbon, and the oxide
of iron was reduced to the metallic state ; when the gas issuing
from the exit-tube of the apparatus burnt with a steady, yellow
flame, the operation was discontinued; at least the spirit-lamp
was removed and the iron allowed to cool, still in an atmo-
sphere of dry hydrogen gas, and when cold, removed and well
secured in a small stoppered bottle.
To the same apparatus for generating the dry hydrogen was
adapted a counterpoised test-tube (a), and to the exit-pipe from
this was connected a tube contaiming chloride of calcium, this
tube, with its contents, being accurately counterpoised. Into
the counterpoised test-tube (a) was placed a mixture of 10:2
grs. of the crystals previously dried at 212°, rubbed up in a
mortar with 50 grs. of the purified iron filings; the mortar was
wiped out carefully by 20 grs. of the same iron, and this also
inserted in the tube, a layer of pure iron filings placed over the
whole, and the tube, with its fittings, again weighed.
This part of the apparatus was then placed in a flask contain-
ing a solution of chloride of zine—destined to act as a bath:
the whole apparatus having been satisfactorily adjusted, heat was
applied to the bath, and gradually raised until the chloride of
zinc ceased to give off any water, and of course fused; this must
have been 420° Fahr. or more.
In this operation the crystals were decomposed ; the iron seized
the iodine as fast as it was liberated; the quinine retained the
sulphuric acid ; and the current of dry hydrogen gas carried over
the aqueous vapour to the chloride of calcium tube, where it was
retained: the mcrease in weight was 1:44 ers.: then as 10°2
> 1:44::: 100: 14°1764 of water.
This method was also adopted as a means of estimating the
iodine, but for this purpose the chloride of zine bath was not em-
ployed, as a more perfect decomposition was then necessary ; the
mass in the test-tube (a) was lixiviated repeatedly, as long as any
iodide of iron was dissolved ; this was at once filtered into a solu-
tion of nitrate of silver, iron filings being kept in the filter to avoid
decomposition ; the filter was repeatedly washed with boiling di-
stilled water, and of course the washings added to the previous
liquid; the resulting mixture of iodide of silver with the oxides
of iron was thrown on a filter, washed with hot diluted hydro-
chloric acid as long as any iron was removed, then with ammo-
nia to remove any chloride, and then with distilled water; dried
and ignited, it weighed 6:00 grs.=iodine 3°1453 =per cent.
31°453, corresponding very closely with that previously ob-
tained. A second analysis, specially directed to the estimation
of the sulphuric acid, gave 10°844: per cent. as the result,
new Polarizing Crystals produced from Quinine. 19]
Therefore we now have found—
Aa B. Calculated. Per cent. At.
Iodine. . 82°6092 3)°453 124 Jodine. . 32°63 1
Sulph. acid 10°612 10°844 40 Sulph. acid 1052 1
Alkaloid . 42:692 162 Quinine . 42°63. 1
Water . . 141764 D4 Water. . 142152 6
- 100°:0896 380 99-9952
These results correspond very closely with the formula
(C* H’ NO?+1)+S0%+6HO; and as it has been previously
proved that the base is not a substitution compound, it only re-
mains to consider it as a salt in which iodine is superadded to the
base quinine without interfermg with its basic properties, how-
ever much it may alter its chemical characters. Experiments
have been instituted to produce this iodo-quinine in an isolated
state, but hitherto without success,—the nearest approach hi-
therto made is by the action of ammonia at 60° Fahr.,—by care-
fully triturating the polarizing crystals in the strongest Liquor
Ammoniz during half an hour, separating on a filter, washing
with cold distilled water, and carefully drying the reddish-yellow
mass produced : this contained nearly all the iodine and quinine,
but the ammoniacal solution contaimed sulphate of ammonia;
some of the resinous compound dissolved in it, together with
about 11-0 per cent. of hydriodate ammonia. The resinous mass
was treated with diluted sulphuric acid, in order to attempt to
produce the polarizing crystals again; they certainly were re-
produced, but not in a satisfactory manner; some other com-
pounds were also produced, the formation of which cannot be
accounted for in the present condition of the question.
The alkaloid separated by the previously detailed analysis was
then examined. From it was first made the disulphate; this
differed materially from disulphate of quinine, both in its cry-
stalline form and its solubility ; it would dissolve in about three
times its weight of water at 212°, crystallizing in radiating plu-
mose tufts, very similar to acetate of morphia in appearance.
From this disulphate were reproduced the polarizing crystals
very readily upon submitting it to the same operation as was
originally used, namely, solution in acetic acid, and then adding
an alcoholic solution of iodine to the heated fluid; on cooling,
the green crystals deposited, having their original extraordi-
nary properties. The disulphate of the alkaloid differed as
much in its optical as in its chemical characters from quinine ;
assimilating itself in the former to the disulphate of quini-
dine (8-quinine), whereas the pure alkaloid much more re-
sembled quinine in its chemical characters, as it is soluble both
in alcohol and in ether, but crystallizes from neither with faci-
lity; some slight appearance of crystallization is obtained by
192 Mr. J. Napier on Copper Smelting.
exposing an alcoholic solution to spontaneous evaporation in a
test-tube; around the edge of the liquid a thin radiating plu-
mose crop is produced, being more distinctly acicular than the
disulphate. It is therefore not quinidine (@-quinine), but as-
similates probably to that variety of quinine recently called
y-quinine, a monohydrate of the organic radicle C* H'!? NO®, of
which «-quinine is the tri-hydrate, and 8-quinine the bi-hydrate.
However, further researches are necessary to establish this fact ;
for the present we are justified, from the reproduction of the
polarizing crystals from the alkaloid separated from the green
polarizing compound, in considering that the alkaloid quinine
enters into the composition of the crystals, but in the character of
an iodo-base; not a substitution base, as has been previously shown,
but a compound analogous in its constitution to iodo-codeme,
dicyano-codeine, cyaniline, cyano-toluidine and cyano-cumidine,
all of which are compounds not belonging to the series of sub-
stitution products: this, if correct, is a remarkable fact, and
worthy of verification by a more elaborate investigation.
It is necessary to correct an error into which I inadvertently
fell in my last communication, in reference to the optical pro-
perties of the disulphate of cinchonine, fig. 11. Pl. IV.; this
should have been disulphate of the alkaloid quinidine (6-quinine).
Since the publication of my last communication, I have suc-
ceeded in producing and mounting an artificial tourmaline, large
enough to surmount the eye-piece of the microscope, so that at
the present moment I am perfectly independent of the tourma-
line or Nichol’s prism in all my experiments upon polarized
light; and the brilliancy of the colours is much more intense
with the artificial crystals than when employing the natural
tourmaline; as an analyser above the eye-piece, it offers some
advantages over the Nichol’s prism employed in the same posi-
tion, for it gives a perfectly uniform tint of colour over a much
more extensive field than can be had with the prism.
32 Old Market Street, Bristol.
June 11, 1852.
XXVIII. On Copper Smelting. By Jamus Napinr, F.C.S,*
[Continued from p. 59. ]
Assaying of the Ores.
v Pte first object of the assayer, like that of the smelter, is to
separate the earthy matters contained in the ore from the
metallic portion. But experience has taught, that if the copper
* Communicated by the Author, who reserves to himself the copyright,
any infringement whereof will invoke legal proceedings.—Eps.
—
Mr. J. Napier on Copper Smelting. 193
in the metallic portion or mat exceeds 50 per cent., the slag or
scoria obtained will contain some copper, and there will therefore
be a loss. The mat should not contain more than 40 per cent.
of copper in order to get clean slag. The assayer therefore
arranges his samples according to their quality as determined
by the eye. Those full of mwndic, having much sulphur and
iron, and containing arsenic, are kept apart, in order to be sub-
jected to a dull red heat for a short time to expel a portion of
these impurities before adding flux.
A portion of the sample to be assayed is weighed off. The
assayers have special weights divided into 100 parts, termed cents
or centners, with 3, 4, 4, sth ; 100 parts or cents are generally
taken ; and if no excess of sulphur or arsenic be present to re-
quire a slight roasting previously, the ore is mixed with a quan-
tity of flux composed of lime, borax, fluor-spar, a little salt and
nitre; occasionally a little soda or potash is used, and ground
window-glass. The nitre is termed the operating flux, as it
purifies the ore by supplying oxygen to the arsenic and other
impurities present ; the quantity of the flux added is not very
precise, generally about twice the weight of the ore used, but
sufficient to cause the perfect fusion of all the silica present.
The flux and ore are intimately mixed and put into a clay cru-
cible having a clay cover, then placed im a furnace and brought
to complete fusion, in which state the mass is kept for about
ten minutes; the whole should be perfectly liquid, and should
exhibit no effervescence. The crucible is then removed from the
fire, and the contents poured into an iron ladle and allowed to
cool: some operators immerse the ladle and contents into cold
water. When taken from the ladle, the metallic portion forming
the mat is found as a button at the bottom, the slag or scoria
on the top; they are separated, and the slag carefully examined
for any metallic particles before being thrown away ; but, as
above observed, if the mat contain less than 40 per cent. of
copper, the slags are generally free. The contents of the cru-
cible, instead of being poured into a ladle, may be allowed to
cool in the crucible, which is afterwards broken andthe slag and
mat separated. The crucible being seldom fit to use again, no
loss is occasioned ; however, it is seldom practised by the Cornish
assayers.
The regulus or mat, when separated from the slag, is finely
ground and put into a clean crucible, taking great care that none
of it is lost; it is then placed in a slow fire, and gradually brought
to a dull red, the powder being stirred constantly with an iron
rod to prevent it caking; the point of the rod is examined from
time to time to see whether there is the slightest tendency to
cake, which is evinced from the particles adhering to the rod, in
Phil. Mag. 8, 4, Vol, 4. No, 24, Sept. 1852. O
194 Mr. J. Napier on Copper Smelting.
which case the crucible must be instantly removed from the fire
and the heat lowered. After a great quantity of the sulphur is
volatilized, there is less tendency to cake ; the heat may then be
increased gradually to a bright red, and continued until all the
sulphur is expelled, which is ascertained by taking out the cru-
cible and holding the head cautiously over it. The success of
the operation depends upon the perfect calcination of the regulus ;
should any sulphur be left in the powder, there is great risk of
the copper not being all got in the fusion. When calemation is
complete, the crucible is allowed to cool, and the contents mixed
with from one to two times its weight of black flux (according
to its richness in copper), and its weight of ground crown-glass
and borax mixed in about equal parts. The whole is put into
the same crucible as used for calcining, and a layer of borax
spread over the surface; the crucible is placed in a furnace, and
the heat raised until the whole fuses: the more intense the heat
in this operation the better. It is kept in fusion for about ten
minutes. The mass should not only be fluid, but there should
be no effervescence or ebullition. When removed from the fire,
the contents are either rapidly transferred to an iron ladle, or
allowed to cool in the crucible, which is then broken; in either
case a button of metallic copper is found at the bottom. The
scoria from this operation is ground fine, and carefully examined
for metal; and if any particles are seen, it has to be re-fused
with a little more flux, and the small button or prill obtained
added to the first.
The copper obtained is often brittle and hard, and has conse-
quently to be refined; this is an operation requiring some little
experience to perform properly. The metal is put into a clean
crucible with a very small portion of black flux, or borax, and
brought to fusion; the fused button should not be covered with
the flux; there is then thrown upon the fused metal from time
to time small portions of refining flux, made by mixing together
3 parts nitre,
2 parts argal,
1 part common salt,
and igniting them in the same way as in preparing black flux.
When the metal is very impure, a little more common salt is
added. The addition of this flux is made until the button
appears to clear easily from a red skin over it: this operation
requires time; a little borax is added just previous to taking
from the fire. The metal thus refined should be ductile,
capable of being hammered thin without cracking on the edge,
and when broken, the fracture should be fine-grained, and have
a silky lustre. The scoria from this refining operation generally
Mr. J. Napier on Copper Smelting. 195
contains a little copper, and is ground up and fused. This is
generally done along with that from the reducing operation, and
the prill from the two added to the assay.
When the ores to be assayed are rich in copper, such as sub-
sulphurets, oxides, and carbonates, there is generally added to
the first fusion, when separating the gangue from the metallic
portion, a quantity of sulphur, in order to form a regulus or mat
of the desired quality, as stated above, which is proceeded with
as already described. ‘To fuse carbonates and oxides with sul-
phur, and then be at the labour and cost of calcining to get quit
of the sulphur again, seems ridiculous. And when these ores
have little earthy matters in them, it is unnecessary; but when,
as in many cases, there are upwards of 50 per cent. of earth
matters present, in fusing these with a reducing flux, the liability
of the oxide of copper to combine with the silica and remain in
the slag is so great, that it is found better in practice to take
the apparently longest method in order to obtain the most correct
results.
The above is a mere outline of the general method by which
the ores of copper are assayed. The following may be said to be
a general rule followed in suiting the fluxes, &c. to the kind of
ore after assorting.
Fluxes for different Ores.
(1st heating with a little nitre, quantity
depending upon the sulphur and
arsenic in the ore.
Yellow sulphurets . < 2nd fusing. Fluor-spar, lime, borax,
, salt, a little argal, quantities accord-
ing to the earths.
lst heating. Nitre, small proportion.
Gray sulphurets. 2nd fusing. Borax, lime, salt, fluor-
spar, and a little argal.
Black sulphurets . . Same as above.
Ist fusion. Lime, fluor-spar, and sul-
Red and black oxides phur.
and carbonates . . | 2nd fusion. Borax, salt, lime and argal,
or black flux.
Native copper . . . Only refined.
Ground tartar or argal is often used instead of black flux.
The black flux is prepared by mixing intimately—
2 parts nitre, and
3 parts tartar or argal
in an iron mortar or other vessel that will stand heat, and insert-
ing into the mixture a red-hot iron or red cinder, When rapid
02
196 Mr. J. Napier on Copper Smelting.
conflagration takes place, cover with a tile or any convenient
article till the burning ceases ; then grind what is left, and keep
in a stoppered bottle as it is liable to deliquesce.
By the results of the assays both the buyer and seller of the
ores are guided, and the regular agreement of the various assay-
ers in their results is a proof of general accuracy. When, week
after week, not less than a dozen assayers, every one separately
assaying the same sample of ore two or three times over, are all
found to agree within ;!,th of a per cent., it must be a source of
confidence to all parties. Nevertheless many of the assayers know
as little of the principles of their operation as the miner or seller ;
consequently the whole process, as it is practised, is a mecha-
nical operation, and one that has undergone little or no change
these two centuries, as will be evident by a few extracts from.
the works of the celebrated Lazarus Erckern, published in this
country in 1683. Indeed so accurate are his processes and de-
scriptions, that an edition of his works, with our improved no-
menclature and apparatus, would be a valuable addition to the
library of every chemist and metallurgist.
“ To make Flux to prove Copper Ores.
“Take two parts of argal and one part nitre, grind them small
and mingle them, and put the whole into an unglazed pot, and
put a little live coals in it, when it will begin to burn; when the
burning gives over, put away the coals, and grind the flux and
keep it in a warm place; if set in a cool or moist place it deli-
quesces. This flux is to be used to good copper ore ; but for
flinty or other ores hard to melt, this flux is too weak of itself ;
there must be something additional added.”
“ How to prove easily flowing (melting) ores.
“Rich good copper ores (not flinty and speiry) are proved
thus: grind the ore small, and weigh two centners (200 parts),
and put them in a crucible with three times as much of the
before-mentioned flux well mixed ; then cover this with a layer
of common salt a full finger thick, press it down, cover the cru-
cible luted with clay to prevent coals falling in or the contents
flowing over; place the crucible in the fire or oven, then cover
with coals about an handbreadth high, and blow through the
hole under the grate that the wind may go alike round the eru-
cible until in perfect fusion ; let it stand awhile in the fusion,
then take the upper fire off and lift out the crucible, and set it
on a plain tile that the grains of copper may settle. When cool,
the crucible is broke, and a button of copper is found at bottom.
You must observe in proving, the heat be not too high, for the
copper will burn and drive itself into the slack (slag). If the
Mr. J. Napier on Copper Smelting. 197
slacks are red, the heat has been too high ; but if brown, the proof
is good.”
“ How hard-flowing Copper Ores are proved.
“ Hard-flowing ores are not to be proved as the smooth, but
in another manner. Thus, take the ore, beat it as small as the
seeds of hemp, weigh two centners and put into a crucible, and
give it a very gentle heat that it begin to roast itself, stirring it
with an iron rod, else the ore will turn to ashes (cake) and not
roast. When it is stirred the first time, give it a little stronger
fire that it may glow well, then lift out the crucible and let it
cool ; it is then put back into the fire, and kept there until it
has done smoking and smells not of sulphur. It is now ground
a little finer, but not so fine as flour; roast it again until it
stinks no more of sulphur, stirring it with the iron rod to pre-
vent caking. When cool, it is again ground as fine as can be,
and roast once more until quite dead, that is, till it has no sul-
phurous smell, when it is ready for the proof. Divide the whole
into two parts, so that should the first fail, another can be done,
or two may be done to haye a surer proof. One part is put into
a crucible, with three times as much of the before-mentioned
flux and some flowing glass gall (a flux mostly oxide of iron)
well mixed, and cover it with common salt, as before mentioned ;
lute it over with clay, and fuse for a considerable time ; take out
the crucible and break it, when a button of copper of quality
according to the nature of the ore will be got, from which a
right proof of the ore will be obtained.”
These short extracts upon copper ores will verify the above
remarks,
From the fact of the manufacturers of copper obtaining a
greater quantity of copper from the ore on the large scale than is
indicated by the assay, the source of this has been sought for in
the above method of assaying not giving accurate results. We
have tested the slag of the Cornish assayer, and have almost
invariably found it to contain copper, but not more than the
slag obtained from the smelting operations; the cause of the
discrepancy between the assayer and smelter will be noticed in
another paper. In the mean time it has been suggested to be
owing to the assayers using fluor-spar as a flux; but this sub-
stance the smelters also use as a flux.
The flux we use for fusing, when assaying sulphurets, and
which gives us slags without a trace of copper, is composed of—
1 part dried borax.
1 part slaked lime.
1 part oxide of iron.
i part nitre.
% part common salt.
zg part of charcoal dust.
198 Mr. J. Napier on Copper Smelting.
Mix intimately 400 grains of the ore with twice its weight of
the above flux, and fuse ina crucible for ten mimutes; if the ore
is very siliceous, a little more of the flux is used. When the
crucible is cold, break it, and the mat or regulus is found at the
bottom; the slag is a glassy homogeneous mass. The regulus
is calcined and proceeded with as before described.
Besides these methods of assaying by the dry way, or fire,
there are various methods practised by acids, or what is termed
the wet way. The first is the precipitation of the copper by
caustic potash: take 25 grains of the ore, and digest or boil for an
hour in a mixture of two parts nitric acid and one hydrochloric
slightly diluted with water; to this add ammonia till the whole
smells strongly of that alkali, then pour the whole upon a paper
filter, and when the liquid has passed through, wash the contents
of the filter by pouring over it water containing a little ammonia ;
this washing is continued until the water passing through is
colourless. The whole liquid obtained is put into a flask or beaker
and boiled; when boiling, add some caustic potash or soda, and
continue the boiling until the blue colour disappears, and there
remains no smell of ammonia; the copper then forms a black
precipitate, This solution with precipitate is now put upon a
paper filter, and the precipitate washed with hot water until the
water passing through the filter ceases to turn red litmus paper
blue ; the filter is then dried, and the precipitate scraped off the
filter into a porcelain crucible ; the paper is burned on the cover
of the crucible exposed to the air, and the ashes laid on the top
of the precipitate; the crucible with contents is then brought to
a dull red, and afterwards weighed. The substance thus ob-
tained is oxide of copper, every 40 parts of which are equal to 32
of copper; the result is thus calculated by the common rule of
proportion, and the quantity of copper in the 25 grains ascer-
tamed. This method is tedious, and requires great care to obtain
accurate results ; and the results are always higher than can be
obtained by furnace operations.
Another method often practised is by digesting in acids as
stated above, and, after filtering the blue solution obtained by am-
monia, evaporating to dryness, redissolying the dry residue in a
little hydrochloric acid, and then diluting with water and adding
a piece of iron or zinc, when the copper precipitates in a metallic
state upon either of these metals. When the whole is precipi-
tated, the zine or iron is washed and the precipitate collected
upon a weighed filter, washed, dried and weighed: the first
washing-water should have a little sulphuric acid added to it,
and the washing afterwards continued till no trace of acid is left.
With care, very accurate results may be obtained by this method,
but it is tedious.
Another and very simple plan is by colour, The operator
Mr. J. Napier on Copper Smelting. 199
provides himself with three bottles or glass tubes of equal di-
mensions, and a measure graduated into 10 or 100 divisions; a
common alkalimeter answers the purpose: 2 grains of pure
copper are weighed off and dissolved in nitromuriatic acid, then
excess of ammonia added. This solution is made up to two
measures exactly of the graduated glass or alkalimeter. Two of
the bottles or tubes are filled with the solution, and well-stopped
and placed upon a frame. To test an ore by this method, 20
or more grains are digested in nitromuriatic acid, as previously
described, ammonia added and then filtered; the blue solution
is now tried by filling with it the remaining third tube, or bottle,
and placing it between the other two in the frame and comparing
the colour; it is diluted carefully until the tint is exactly the
same as the tubes outside ; the whole is then measured in the
alkalimeter, every measure of which being equal to one grain of
copper, the per-centage is soon ascertained. A little practice in
this method gives tolerably accurate results with expedition ;
however, they are generally too high to serve as a guide in pur-
chasing the ore. By making up test-bottles of different strengths,
such as 3, 4, , 4; of a grain, the process is well adapted for test-
ing slag and refuse of furnaces or other products, and should
form a part of the operations in every assaying-room or smelting-
works, a subject we may have occasion to refer to again.
Similar methods have been recommended, but in which,
instead of judging by the colour, a solution of another salt is used
that destroys the colour, such as the sulphurets of sodium and
potassium ; solutions of these salts of such strength are employed,
that a given measure is equivalent toa givenweight of copper. Mr.
H. Parkes has recommended a solution of cyanide of potassium as
follows: —“Take a given quantity of pure copper (say, for instance,
10 grains), place it in a flask, and dissolve in nitric acid; add
ammonia in excess, and then make it into a bulk of about 2500
grains by measure by the addition of water, although this is not
absolutely necessary. Dissolve 1 oz. (avoirdupois) pure cyanide
of potassium, free from ferrocyanide or sulphuret of potassium,
in 5 oz. by measure of water ; filter, if necessary, and place the
solution in a well-stoppered bottle till required for use. I then
ascertain the quantity of this solution of cyanide of potassium
required to decolorize the solution of copper, by taking a given
panty in any graduated vessel, as a burette, and pour it by
egrees into the solution of copper, adding the last quantity drop
by drop till decolorized. This is very easily perceived, as there is
no precipitate to interfere ; and the operation is conducted at the
ordinary atmospheric temperature. Mark down the quantity
required (say 500 grains) by volume, After having established
these data, it is very easy to estimate the quantity of copper con-
200 Mr. J. Napier on Copper Smelting.
tained in any ore or cupriferous product, by simply dissolving a
certain quantity (say 20 grains in nitric or nitromuriatic acid),
with the assistance of heat, if required, as in the case of some
sulphurets, the addition of ammonia in excess is necessary ; and
if any considerable quantity of iron or alumina was present in
the sample, it should be allowed to digest at a gentle heat, under
ebullition, to make sure that all the copper is taken up by the
ammonia ; filter into a flask, wash the precipitate with water,
and make into a bulk of 2500 grains, as when taking the stand-
ard of the solution of pure copper. All that now remains to be
done is to allow it to get cold, and add the cyanide of potassium
until decolorized, noticing the quantity taken. Suppose it
required 400 grains by volume of the cyanide solution; then
from the proportion—500 ers. K Cy: 10 Cu:: K Cy 400 : Cu8
—the quantity of copper contained in the 20 grains of material
taken for analysis, or 40 per cent. If the ore taken was a sul-
phuret, it is sometimes advisable to filter, in order to separate
the sulphur before adding the ammonia, or else to use a dilute
solution of ammonia, and a gentle heat when digesting, or small
particles of sulphuret of copper might be reproduced, especiall
when the precipitate produced by the ammonia is a bulky one.”
These processes are complicated, and liable to many sources
of error, and require an experienced chemist for their perform-
ance; while any process to be generally useful to the assayer
or smelter, should be easily performed, and the liability to
errors few.
Depositing the copper from solutions by means of electricity
has also been recommended as a process for assaying. The
process is simply to get the copper into solution by digesting
the ore im acids, diluting and filtering, as already described ;
in the filtered solution is placed a porous vessel of unglazed
earthenware filled with a solution of common salt or weak sul-
phuric acid, in which is immersed a piece of amalgamated zinc
or a piece of iron, connected by a copper wire with a small
piece of copper previously weighed, which is put into the copper
solution. The porous cell should be so placed that the piece of
copper be under it. Galvanic action begins between the copper
and zine, and the copper held in solution is deposited in the
metallic state upon the slip of copper; the action is allowed to go
on until all the copper is extracted from the solution, which may
be known by taking out a drop and touching it with ammonia,
which if copper be present gives a blue colour ; or by dipping
into the solution a blade of a knife, which will take a copper
colour if any of that metal remain in solution. When the opera-
tion is finished, the piece of copper is again weighed; the in-
crease of weight is due to the copper that was in the solution.
On Mr. T. S. Davies’s Notes on Geometry and Geometers. 201
This process may be variously modified; and when care is
taken, gives accurate results, but far too complicated for ordinary
use. We shall have occasion to allude to this process again in
reference to large operations.
A variety of other methods for determing the quantity of
copper in copper ores have been recommended by different
parties, all more or less depending upon careful manipulation.
We have contented ourselves with describing briefly the leading
features of a few of the modifications and new processes which
have been advocated.
The next paper will be on the kind of fuel suitable for smelt-
ing copper ores.
[To be continued. |
XXIX. Additions to the late Mr. T. 8. Davies’s Notes on Geo-
metry and Geometers. The Swale Manuscripts. By T. T.
Wixinson, Esq., F.R.A.S.
[Continued from p. 33.]
HE first and second volumes of Mr. Swale’s MSS., though
of different sizes of paper, are continuations of each other,
and comprise in the whole 425 quarto pages of densely crowded
matter, entitled ‘“A Miscellaneous Collection of Geometrical
Questions ; those not original being proposed for the purpose of
generalizing and receiving improved and original solutions.” In
addition to numerous original theorems and problems, these
volumes contain diversified coustructions, with occasional ana-
lyses and demonstrations, to all the principal geometrical ques-
tions which had been proposed in the Lady’s Diary, Gentle-
man’s Diary, Mathematician, Burrow’s Diary, Hutton’s Mis-
cellany, The Mathematical Repository, Student, Mathematical
Companion, Enquirer, Leeds Correspondent, Playfair’ s Euclid,
Bonnycastle’s Trigonometry, Apollonius, and Simpson’s Algebra,
Geometry, and Select Exercises; illustrated by upwards of one
thousand carefully constructed diagrams. Each day’s work is
generally pointed out ‘by having its respective date affixed; and
not a few imcidental notices occur which show that he sustained
a long and active correspondence with his friends Messrs. Whit-
ley, Nicholson, Shepherd, Leybourn, Davis, Ryley and Lockwood.
“Mr. Crakelt, of Northfleet, Kent,” is designated as “an ex-
cellent Geometrician ” in page 12, when engaged upon one of
his problems from Burrow’s Diary ;—“ four curious 'Theorems ”
and a statical problem are pointed out on page 90 as having
been “sent to Mr. Leybourn, 6th Dec. 1830 ;” and a printed
sheet containing them is inserted as having been received “ from
Mr. Leybourn, 14th May 1833,” who had arranged them as
202 My. T. T. Wilkinson’s Additions to the late
Questions 553 and 558 of the Repository. By the time he
arrives at page 129 his worldly prospects had been blighted by
the “dishonest relative” alluded to by Professor Davies ; for at
the foot of the page he remarks, “these are trifles, but they
divert my attention from the dark clouds of my calamitous cir-
cumstances ;” and a fortnight later, “5th May 1828,” he adds,
“TI do very little now ;—the poverty to which I and my children
are reduced by plundering villains has prostrated all my enjoy-
ments and hopes. I have slaved for 33 years, and at 53 I am
destitute.” With how many of our ablest geometers such has
been the case we need not here inquire :—poverty and mathe-
matics seem to be inseparable adjuncts to those of the Lanca-
shire and Yorkshire schools ; for amongst them, wherever a genius
for the latter has existed in an unwonted degree, the withermg
influences of the former have almost invariably been more than
ordinarily present. It was ever the case with Wolfenden and
Butterworth, and fortune has not been more favourable to some
of their illustrious contemporaries who still survive.
In page 160 Mr. Swale notices with commendation a solution
by Mr. Jeremiah Ainsworth (the grandfather of the gifted novel-
ist, William Harrison Ainsworth), who was long the ablest and
favourite contributor to Burrow’s Diary; and in a subsequent
page, Mr. Richard Nicholson is alluded to with much tenderness
of feeling as his “ early mathematical associate and an excellent
geometrician,” who used to meet him “at Mr. Ryley’s house in
Leeds to converse on mathematics.” “TI linger,’ he adds sub-
sequently, “‘ among these problems and sketches as the pleasing
though melancholy reminiscences of days for ever gone and of
early acquaintances now silent and mouldering in the tomb.”
Pages 197, 198 are occupied with the demonstrations of several
theorems which he afterwards applies (pp. 227-2380) to the de-
termination of the general problem on “ Inclinations ;” but as:
these were afterwards corrected and extended in a separate manu-
script, they need not at present be more particularly described,
The subject of Inclinations is again resumed in pp, 2383-235,
after another method, and two or three different constructions
are given to each case; but agreeably to Mr. Swale’s usual prac-
tice, no demonstrations are added, which is the more to be re-
gretted since the methods are generally different from those in
common use. The Maxima and Minima of geometrical quan-
tities oceupy pp. 251-257, which are treated with his usual ele-
gance :—from internal evidence I am led to think that a portion
of these were intended to follow those in No, II. of the Apollo-
nius, especially since page 252 supplies a correction to Mr. Wil-
liam Smith’s elaborate solution to Question 69, No, X. of the
Mathematical Companion. Several of these investigations are
ln ee eh
Mr. T. 8. Davies’s Notes on Geometry and Geometers. 2038
well worthy of transcription ; but the complexity of the requisite
diagrams renders it impossible, whilst the enunciations would be
unintelligible without them. Indeed one of the peculiarities of
Swale’s geometry is the complexity of his diagrams: he almost
invariably uses more lines than any other investigator ; but this
disadvantage is more than counterbalanced by the elegant sim-
plicity of his reasonings, and the vast number of collateral pro-
perties which he developes in his processes. In these respects
I know of no geometer who has so nearly equalled him as the
late Professor Davies, whose diagrams have frequently presented
such a similarity to those used by Mr. Swale as to lead some of
the friends of the latter to suppose that Mr. Davies had access
to these MSS. long before he even knew of their existence. The
Swale MSS. were not seen by Professor Davies until ‘‘ October 5,
1850,” and he had only time to write the few notes respecting
them contained in No. VII. of this series of papers before his
progress was arrested by the hand of death.
“ A Collection of Problems by the Compasses alone” occupies
pages 292-332; but since they are principally of an elementary
character, they need not be further particularized. His son
appears to have been very expert in such constructions; for on
page 296, after giving an elegant determination of “the centre
of a given circle,” he adds, “this method, which is more simple
and elegant than Mascheroni’s, was discovered by J. H. Swale,
junior, 19th February 1829.” The solution of isolated problems
by ordinary geometry is again resumed at page 382, and is con-
tinued throughout the remainder of the two volumes. In the
page just cited, a theorem occurs which appears to have been
“sent to Professor Leybourn, 6th Dec. 1830,” but did not find
its way into the Repository; it furnishes a ready proof of the
methods of finding the centre of a given circle already instanced.
in No, VII. by Professor Davies, and has recently been published
as Question 878 of the Educational Times. ;
The problems on “ Tangencies,” already mentioned, occur in
pp. 383-386 ; the fifth and sivth cases heimg first constructed
from the principles of the poles of similitude, and afterwards
reduced to Simpson’s principle before stated. The last portion
of the volume appears to have been formed from an earlier ma-
nuscript, since « portion of its pages is occupied with the demon-
stration of several problems relating to poles of similitude appa-
rently deduced from Lawson’s translation of Vieta’s Tangencies,
the intervening spaces being filled up with later speculations.
In volume III. a few isolated problems from the Diary occur,
but the principal portion is occupied with the extension and ap-
plication of the problems already alluded to as preparatory to
the solution of the problems on Inclinations. He here treats
204 Mr. T. T. Wilkinson’s Additions to the late
them under the name of “ Original Theorems on the Circle,”
and appears to have taken more than ordinary pains to complete
the demonstrations, and apply the properties deduced to pro-
blems corresponding to the theorems and others related to them.
The latter portion of this MS. is fully prepared for the press :—
five theorems are distinctly enunciated, demonstrated, and applied
to the solution of ¢en collateral problems under the extended
title of “ Original Theorems on the Circle, with their use in the
determination of some Geometrical Problems.” Mr. Davies’s
attention had evidently been drawn to this remarkable portion
of the MSS., for his pencilled autograph occurs at the head
of the page, indicating that what follows is a repetition of
the preceding theorems and problems. An earlier manuscript
appears to have been destroyed in order to form this; and as
such is the case with several of the remaining ones, we may
reasonably account for the absence of those of earlier dates :—no
doubt the contents of those destroyed had already found their
way into periodical works and his own Geometrical Amusements,
and hence could readily be dispensed with after transferring what
was considered worthy of preservation to the manuscripts still
remaining. Volume IV., which is endorsed “Geometry and
Algebra,” commences with a few problems on Loci, which he
notes as having been “sent to Mr. Shepherd, 12th Nov. 1830.”
The general problem of Inclinations occupies pages 2, 89, 91, 93,
of which a “General Analysis and Construction” are given ;
other portions of the volume are devoted to the consideration of
isolated geometrical problems from various sources, some of which
are noticed as sent to him by Messrs. Whitley and Shepherd ;
pages 101 to 132 contain a connected series of forty-two geome-
trical exercises originally compiled as “ Lessons” for his son ;
and amongst these are interspersed solutions of some difficult
Diophantine problems, one of which is Question 310 of the Ma-
thematical Repository, where the “Prize Medal” is awarded to
“A Lady” (Mrs. Somerville) for her solution. An obituary
notice of Mr. William Hilton, editor of the Liverpool Student,
justly designated by Professor Davies as “a work of rare merit,”
occurs in page 102, where he is stated to have died ‘‘ of Apoplexy,
at Liverpool, on the 8th of May 1826.”
The fifth manuscript volume is entitled ‘“ Mathematical
Seraps,” and commences with a variety of methods for drawing
tangents to a given circle, so as to be divided by a line given in
position and the point of contact into parts having a given ratio.
Pages 20 and 21 contain no fewer than eight methods of drawing
“through a given point P, a line that shall tend to the pomt of
concourse of two other lines AB and CD given in position ;” a
problem, for whose ready solution, by draughtsmen, the “ Centro-
Mr. T. S. Davies’s Notes on Geometry and Geometers. 205
linead ” was expressly invented. The eighth method being re-
markably simple is here transcribed :—
“Draw PH, PK, parallel to AB and CD; and the required
line PQ will pass through L the point of bisection of HK.”
“Some problems (19) on the Maxima ” and their application
occupy pages 32-45, one of which is noted as “sent to Whitley,”
and another difficult theorem “to puzzle Shepherd ;”—a “new
Theorem from Mr. Whitley ” anda “ Locus from Mr. Shepherd”
are merely enunciated whilst the rest are constructed only. The
latter portion of the MS. contains solutions to some of the most
difficult equations in Bland’s algebraical problems, several of
which exhibit a ready command of algebraical artifice, and the
remainder is filled up with extracts from works having no relation
to mathematical subjects.
The title of volume VI. almost sufficiently explains its con-
tents:—it is “ Memorandums, Scraps, Mathematical, Poetical,
Biographical, Satirical, &c. &e. &c.;” and a slight inspection
proves that its designation is not unaptly chosen. A letter to a
friend occurs at page 42, in which he complains that “ scientific
matters are with [him] at such a very low ebb that [he] cannot
treat him with any novelties...... In the mean time” he hopes
his friend, “ yet in the spring of life, is not unmindful of those
ennobling subjects in which [he] had evinced so much ardour
and ability. In the midst of analytical inquiries,” he adds, “ be
pleased to recollect that Euclid existed 300 years before Christ,
and that you are yet nearly a stranger to those Elements which
have conferred imperishable renown on their Author and Com-
piler.” Mr. Swale was ever anxious that the ancient geometry
should be in the ascendant ; nor did he ever omit an opportunity
of impressing the beauties of his “ Divine Geometry” upon the
minds of his younger correspondents. The statical problems
alluded to by Professor Davies occur in this volume, but present
no difficulties worthy of notice, since they relate principally to
the equilibrium of cones, cylinders, and spheres on an inclined
plane, most of which admit of easy geometrical constructions.
In a letter to Mr. John Whitley, pages 74-77, dated “9th Feb.
1809,” he inquires why the “Inseription Problem,” as Mr. Davies
terms it, has bcen reproposed in the Companion, since all “ must
allow that Mr. Lowry’s general method in the Repository is suf-
ficiently elegant ;” but almost immediately adds, “I have disco-
vered a general method of inscribing polygons in a given circle,
each side passing through a given point, which is also applicable
to the ellipse.’ The method itself was subsequently published
in the Apollonius, No. I]. pp. 41-52, and has already attracted
the attention of several of our ablest geometers, amongst whom
may be mentioned Messrs. Potts, Gaskin and Davies ; it is inter-
206 Mr. T. T. Wilkinson’s Additions to the late
esting, however, as a fact in the history of this problem, that
Mr. Swale had been in possession of his method and its exten-
sion so many years before its publication. Pages 82, 83 contain
“an extract from one of [his] mathematical manuscript books ”
relating to the premature death of his friend Mr. Wilham Davis,
editor of the Mathematical Companion ; and a fitting tribute is
paid to his memory in a notice of the event, which Mr. Swale
forwarded for insertion in the Leeds Mercury of the following
week. A few diophantine, dynamical, and other problems occur
in the remaining portions of this volume; but none of them
appear to possess much interest, if we except a dissertation on
the motion of a ball ‘upon elliptical and triangular billiard tables
(apparently suggested by Questions 250 and 270 of the Mathe-
matical Repository), which determines the directions “ of a
sion so that the ball may, for ever, pursue the same track”
a triangular table, to be the sides of the triangle of meena
perimeter inscribed in the given triangular table.
The seventh volume is a bulky octavo, which seems from the
repetitions in the paging to have been made up of several smaller
manuscripts. It bears the same title as the preceding, and opens
with a series of “Lessons” for his son, amongst which are no
fewer than twelve “ original methods of dividing a given line in
extreme and mean ratio.” They bear the date “ 19th May 1833,”
and would seem to have been satisfactory to their author, for he
adds, ‘we have now done justice to this Ancient Problem.”
Many isolated solutions in this volume contain references to the
Geometrical Amusements, and were no doubt intended for
“ Parts II. and III.” of that valuable work ; others appear to
have been copied from older slips relating to his friend Mr.
Nicholson, which, as is said in the Leeds Correspondent, are
“now brought forward as a sincere tribute of friendship and
respect for the memory of that ingenious Geometrician.” In
page 82 he acknowledges the receipt of a letter from Mr. Ley-
bourn, dated “21st May1833,” on which he remarks, “Leybourn
was one of my early scientific correspondents, having written to
him 38 years. I hope yet to spend a week with him at Bagshot.
At the same time I should greet Lowry, another old correspond-
ent, and Cunliffe. On such an occasion we should take our
harps down from the willows and once more tune them to the
cheering songs of science.”
The subject of extreme and mean ratio is again taken up at
page 171, and two other methods of division added to those
already noticed, after which the solution of some rather difficult
surd equations occur which had been sent to him for solution by
Mr. Harding. Much of the remaining portion of this manu-
script is occupied with solutions of geometrical problems selected
Mr. T. 8. Davies’s Notes on Geometry and Geometers. 207
from Simpson’s Exercises, the Mathematical Repository, &c.,
together with a variety of extracts in prose and verse agreeably
to the indications of the title-page ; but nothing appears to merit
particular notice unless it be a short discussion of the different
cases of the problem “to determine P in a line MN of any order,
so that drawing the tangents PV, PT, to two given circles (A),
(B), they shall have a given ratio.” The required point P is
very elegantly shown to lie in the intersection of the given line
with a given circle, which Mr. Swale appropriately terms “ the
circle of tangential ratio,” and which obviou sly becomes the circle
of similitude when the given ratio is that of the radii of the two
given circles. The two MSS. numbered VIII. and IX. have
already been noticed by Professor Davies as volumes I. and II.
on the Mascheronian Geometry, and need not be further noticed.
No. X. is a short paper fully written out for insertion in the
third number of the “ Apollonius ;” it contains fow: coustrue-
tions and demonstrations to the problem of having “a point P
and two parallel lines AQ, BR, given in position, to determine
the position of a line PQR, of section, making the rectangle,
sum of squares, or differences of squares, of the segments AQ,
BR, cut off from the lines given in position equal a given square
(V*);” which are designated by Mr. Swale as “ diversified solu-
tions to the same problem; or brief introductory Lessons for
young Geometricians.” The paper is prefaced by a motto which
inculcates his favourite dogma, that “ variety of method, or ferti-
lity of resource, is increased power,” and appears, with one excep-
tion, to be the only existing manuscript fully prepared for the
press.
The eleventh and last volume in my possession is divided into
two parts; the first of which (pp. 5-87) is devoted to the solu-
tion of diophantine and other “ algebraical inquiries” selected
from various authors, and the second part (pp. 281-338) to the
consideration of numerous original and selected problems under
the title of “Geometrical Amusements, to sooth an incurable
despondency.” Pages 298-308 contain a discussion of the pro-
blem “to determine a point P, in AC, the side of a given triangle
ACB, such that drawing PQ perpendicular and PR parallel to
the base AB, the ratio, sum, difference, rectangle, sum of squares,
or difference of squares, of PQ and PR, may be respectively equal
to given quantities ;” four different constructions and demon-
strations being given to each case. The problem partially con-
sidered in MS, No. X., as extended to the cases of the ratio,
sum, or difference of AQ and BR, occupies pp. 308-316, four
different constructions, &e. being given to each of the six cases,
as in the previous instance. In a similar manner he treats the
problem “to draw PQR, through a given point P, to meet AK,
/
208 On Mr. T. S. Davies’s Notes on Geometry and Geometers.
AL, given in position, in Q and R, so that the ratio, sum, differ-
ence, and rectangle of AQ and AR, may be respectively equal to
given quantities ;” each successive variation unfolding new pro-
perties of the illustrative diagrams, and affording additional
proofs of the extensive powers and ingenuity of their author. A
question from the Mathematician proposed “ about 1750, by John
Turner, who had a school at Heath, near Wakefield, Yorkshire,”
is considered on pp. 327-8 ; and a case of “ Apollonius on In-
clinations” appropriately closes the volume, which, from internal
evidence and the title affixed to the geometrical portion, most
probably contains the latest efforts of Mr. Swale’s untirmg mind.
I have been the more particular in describing the contents of
these manuscript volumes, partly in consequence of their number
and extent, but mostly from the extreme improbability of even a
tithe of them being ever given to the public. Portions occur
here and there, like oases in a desert, which might be selected
for publication in a separate form did the taste for the ancient
geometry warrant such a proceeding ; but since such is not likely
soon to be the case, the probability is that an immense mass of
Mr. Swale’s speculations must ever remain in an incomplete and
unprofitable condition,—a notable monument of misdirected
energy and useless expenditure of valuable time. His systematic
researches on tangencies, maxima and minima, the inscription of
polygons in circles and in each other, printed in his Apollonius,
afford convincing proofs of how much he was capable when his
extensive powers were directed to regular subjects of inquiry ;
for the elegant methods of research employed in these papers,
and the simplicity and beauty of the results obtained, must ever
command the admiration of geometers. His fertility of inven-
tion and originality of conception were inferior to those of no
contemporary geometer; and had he directed those energies to
systematic inquiries which he expended in the solution of some
thousands of isolated and comparatively uninteresting questions,
he might have systematized scattered topics or originated new
theories, in which he would have rivalled Carnot in transversals,
Davies in spherics and porisms, or Chasles in anharmonic ratio,
and have secured for his own name a permanent place in the
history of modern geometry.
What will ultimately become of the MSS. is of course beyond
conjecture. That they will be almost religiously preserved by
his son during his life no one will doubt who is acquainted with
the profound veneration he entertains for the memory of a kind
and indulgent father; but when we call to mind that a second
generation has deliberately burnt the MSS. left by the Stewarts,
and that already much of Mr. Swale’s correspondence, &c. has
been destroyed by an accidental fire, it may not be considered
Rey. T. P. Kirkman’s New Theorems in Combinations. 209
improper to suggest that the remaining manuscripts ought to
be deposited in some public library, where they would at once
be safe and accessible, and like Dr. Simson’s Adversaria at Glas-
gow, ever remain an enduring monument of the genius and in-
dustry of so devoted a geometer.
Burnley, Lancashire,
June 17, 1852.
XXX. Theorems in the Doctrine of Combinations. By the Rev.
Tuomas P. Kirxman, 4.M., Rector of Croft with Southworth.
To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,
| WOULD beg your permission to enunciate the following
theorems in your Journal :—
A. With 7 symbols can be formed 21 triads, so that every
duad shall be thrice employed.
B. Two distinct systems of 7 quadruplets each can be made
with 7 symbols, both exhibiting twice all the 21 duads.
C. A system of 21 quadruplets can be made with 7 symbols,
so that every possible duad shall be six times employed.
D. With 13 symbols can be made three different groups of
triads, each group once containing all the duads.
E. With 15 symbols different triads can be made, so as to
exhaust the possible duads, once, twice, 3, 4, 5, 6, 7, 8, 9, 10,
11, 12, or 13 times.
F, With (12x+3) symbols can be formed triads so as to ex-
haust the duads 6n—1, or 6n+2 times; and with 12n+7 sym-
bols, so as to exhaust the duads 6n+1, or 6n+3 times.
G. With 27 symbols triads can be made, till the duads have
been all twice employed, or all thrice employed.
H. With 4(3n+1) symbols quadruplets can be made, till every
duad has been (2n+1) times employed, and this without repeat-
ing any triplet.
I, With 4 x 2” symbols, quadruplets can be made till every
triad has been once employed.
J. Sixteen young ladies can all walk out four abreast, till every
three have once walked abreast; so can thirty-two, and so can
sixty-four young ladies; so can 4" young ladies.
Croft Rectory, near Warrington,
August 6, 1852.
Phil. Mag.§. 4. Vol. 4, No. 24, Sept, 1852, 1g
[ 210 ]
XXXI. On the supposed Identity of the Agent concerned in the
Phenomena of ordinary Electricity, Voltaic Electricity, Electro-
magnetism, Magneto-electricity, and Thermo-electricity. By
M. Donovan, Esq., M.R.I.A., formerly Professor of Che-
mistry to the Company of Apothecaries in Ireland.
[Concluded from p. 138.]
Srcrion VIII.
| HAVE in a former part of this essay made some observations
on the evidence afforded by the deflections of the galvanometer,
and will now offer some additional considerations on the same
subject, believing that it involves the whole question, namely,
whether these deflections are metrical indications of the opera-
tion of one undecomposable because uncompounded electric fluid
or agent, always the same in its nature, varymg only in quantity
and intensity; or are there conditions of the electric fluid differ-
ing from each other in respect of constitution or composition,
which, independently of quantity or intensity, are far more pow-
erful than ordinary electricity in producing deflections ?
It appears to me, after considering the difficulties in the way
of the hypothesis of identity with as little prepossession or pre-
judice as I am able to view them, that deflections and voltaic
phenomena in general are inexplicable according to the doctrine
of those who consider them due to the operation of ordinary
electricity, acting in great quantity at a low intensity.
I shall now only advert to a few experiments out of a multi-
tude, not in the hope of proving anything, but merely with the
intention of submitting to the judgement of the reader whether
such striking effects can result from an ordinary electricity, so
feeble that its agency is altogether supposititious, and affords no
evidence of its presence except the phenomenon which is the
subject of the doubt. Were it not for analogy, it could not be
maintained that in these experiments ordinary electricity is at
all concerned ; its well-known properties are not recognisable ;
nor is there any evidence of its presence but the effect on the
galvanometer, which it is the fashion to consider obedient to no
other power. Were it not for the circumstances that the agent
which affects the galvanometer is only transferable through con-
ductors of electricity, it would be as natural to believe that in
the following experiments the power concerned is that universal
property of matter called chemical affinity; for, so far as the
mode of action of the bodies is concerned, the deflections might
be viewed as measures of intensity of chemical affinity rather
than of electricity. The hypothesis which appears to me most
consistent with the facts, and perhaps least repugnant to modern
opinions, is to assume, as I have done, the agency of electricity,
On the Constitution of the Electric Fluid. 211
—an electricity, perhaps, the same in the number of its consti-
tuent elements as the ordinary electric fluid; but so different in
the ratio of these to each other, or in their mode of combination,
as to constitute an entirely different power,—a power or agent,
sui generis, exerting its peculiar energies, according to the pre-
dominant element.
For a length of time after the invention of Schweigger’s mul-
tiplier, afterwards improved by Melloni, Nobili and others, and
called the galvanometer, it was doubted if that instrument could
be at all affected by common electricity. At length Colladon
proved that it could, by increasing the insulation of the coil of
wire ; that is, by enabling the coil to carry a greater quantity of
the electric fluid than in the ordinary state it is able to do; or
in other words, by increasing the intensity of the electricity
conveyed. Hence the electricity which the common galvano-
meter coil is capable of carrying, when placed between the two
conductors of an electrical machine, will not without peculiar
contrivances be indicated by the galvanometer, no matter how
powerful the machine may be.
Yet a bit of copper wire, weighing ;7,,nd part of a grain,
arranged voltaically with a platinum wire almost equally small,
and a drop of nitric acid, as already described, caused the needle
to whirl round the circle three times. Does the particle of cop-
per, scarcely visible, generate more electricity in an instant of
time than the powerful electrical machine can supply? Colla-
don’s experiment proves that intensity is the condition of com-
mon electricity which causes deflections ; and the sparks obtain-
able from the coil, while the machine is in action, prove the
high intensity of the electricity contained in it,—an appearance
totally out of the question in the case of the atom of copper. In
opposition to these well-ascertained facts, can it be consistently
maintained that quantity is the effective condition? Admitting
for a moment that it is so, why does not the singly-insulated
coil of the galvanometer act on the needle when it is receiving
torrents of electricity from a powerful electrical machine? Is the
quantity insufficient ? if it be, why does that insufficient quan-
tity become sufficient when the insulation of the wire constituting
the coilis doubled? If it be answered, that it can now carry the
charge of electricity necessary to produce deflection, a greater
quantity being retained by the double silk than could have been
confined by a single one, I reply, that this is a plain acknow-
ledgement that it is intensity which acts, a state which the atom
of copper cannot, and is admitted not to confer; and if the wire-
coil with single silk was incapable of carrying the necessary
quantity of clectricity from the machine to produce deflection,
why is it capable of carrying it from the atom of copper? But
P2
212 Mr. M. Donovan on the supposed Identity of the Agent
above all, why should frictional electricity be affirmed to be suf-
ficient in point of quantity in this special case, when universally
it is declared that it is inadequate to produce voltaic effects on
account of the smallness of its quantity ?
I do not foresee what answer car. be given to these questions,
or how the facts are reconcileable, while the opinion is entertained
that it is electricity, taken in the common acceptation of the
word, which causes deflections. But if we distinguish the agent
excited in the common electrical machine from that which is
effective in the voltaic series, the difference consisting in the
ratio of the constituent elements of the two fluids, then the de-
flection in one case and non-deflection in the other become more
intelligible.
I will now state a few of my experiments: but it is necessary
to premise, that in most of them the action was so transitory,
owing to the peculiar circumstances, that there was no perma-
nent deflection, and the number of degrees to which the swing
of the needle extended, at its first start, was the only measure
which could be observed for comparison.
A glass tray being half-filled with concentrated commercial
sulphuric acid, a plate of platinum was laid in it, and connected
with one of the binding-screws of a galvanometer by means of a
platinum wire. A stick of caustic potash was fastened to the
end of another platinum wire by several coils carried round it;
the other end of this wire was connected with the other binding-
screw of the galvanometer. In a few moments the potash had
attracted sufficient humidity to become a conductor ; its end was
plunged into the sulphuric acid, but not so deeply as to touch
the platinum plate lying in the bottom. The needle whirled
completely round, and with great velocity. A second dip had
no effect; but perceiving that this was caused by a coating of
bisulphate of potash, and having washed it off by a plunge into
water, a repetition of the dip into the sulphuric acid produced a
new deflection. After again washing it, the whole stick of pot-
ash was plunged on its side; the needle again whirled round with
great force.
In order to discover how much of the effect was due to the
platinum plate and wire, I removed the stick of potash, and
dipped the platinum coil to which it had been fastened into the
sulphuric acid; the deflection amounted to 3°; and in another
trial it did not stir.
Becquerel made experiments with acid and alkaline solutions
by a different method, and produced deflections which he attri-
buted to electricity. How, in my experiment, the infinitesimal
quantity of electricity generated could whirl the same needle
round with violence, which refused to stir when a most powerful
concerned in the Phenomena of ordinary Electricity, $c. 218
electric machine poured torrents of electricity into its coil by
direct communication, is beyond my comprehension, unless, as
I have already suggested, frictional electricity contains the mi-
nimum and voltaic the maximum of the effective elementary
constituent which produces these deflections.
The next experiment was with nitric acid and potash; but in
this case, nitric acid being a better conductor, it was not neces-
sary to place a plate of platinum in the bottom. A glass capsule
containing commercial nitric acid was connected with one bind-
ing-screw of the galvanometer by means of a platinum wire.
Another platinum wire, proceeding from the other binding-screw,
was well-connected with one end of a stick of caustic potash.
When the potash was sufficiently moistened by the atmosphere,
its other end was made to touch the surface of the nitric acid:
the needle instantly started 130° westward. The same wire de-
tached from the stick of potash and washed, when dipped in the
acid, only produced a deflection of 2°, and even that was east-
ward. Even dilute nitric acid produced considerable deflection
with potash.
A strong solution of caustic potash touched by a platinum wire,
carrying on its end a bit of platinum foil dipped im sulphuric
acid, caused a deflection of 10°.
I fused some caustic potash in a capsule of virgin silver con-
nected with one of the binding-screws of the galvanometer: from
the other binding-screw proceeded a silver wire tipped with about
a quarter of a grain of sulphur melted on it. The fused potash
being touched with the sulphur, a very curious process of com-
bination took place, and the needle whirled round four times
with great velocity. On trying a new silver wire without any
sulphur, and touching the surface of the fused potash with it,
there was not the slightest effect on the needle.
By means of the instrument called the Russian furnace, I
heated one end of a strip of sheet copper bright red-hot, its other
end being connected with one of the binding-screws of the gal-
vanometer. A copper wire proceeding from the other binding-
screw had a copper knob on its end, on which was fused a blob
of sulphur; on applying the sulphur to the white-hot copper
strip, the needle whirled round twice. To prove that this was
not the effect of thermo-electricity, I connected the ends of two
copper wires with the binding-screws of the galvanometer, one
with each, and brought their other ends into contact by a slight
twist. The flame of a spirit-lamp was applied to the twisted
junction of the wires: when red-hot there was thermo-electric
deflection ; but this at length ceased, and the needle returned
to the meridian. The lamp being still retained in its place, a
drop of burning sulphur was let fall on the junction, when a
214 Mr. M. Donovan on the supposed Identity of the Agent
considerable whirl of the needle took place. In further proof
that the whirl of the needle twice round was due to the chemical
action of the sulphur on the strip of copper, it is enough to ob-
serve, that, on repeating the experiment without the sulphur, the
deflection was trifling.
Two silver wires, treated in the same manner in the flame of
a spirit-lamp, one being topped with sulphur, produced momen-
tary deflection of 90°.
A thin iron wire, connected with the galvanometer, was heated
in the Russian furnace, and being touched by a similar iron wire,
also connected with the galvanometer, with a particle of sulphur
adhering to the point of contact, the needle started off 182°.
Some nitric acid in a glass capsule was connected with one of
the binding-screws of the galvanometer by a platinum wire;
another platinum wire was connected with the other; and its
other end twisted into a knob was first dipped into a little
spirit of turpentine, and then into the nitric acid; there was an
immediate deflection of 40°. J
An iron wire, maintained at a red heat in a spirit-lamp, was
touched at the point with the point of another iron wire holding
a particle of iodine, both wires being properly connected with
the galvanometer ; the flame of the lamp became green, and the
needle started off 100°.
A rod of grain tin, heated in the spirit-lamp to its melting-
point, was touched with a particle of sulphur on the point of a
thin platinum wire; there was a momentary deflection of 56°.
A thin rod of antimony and a zinc wire were heated in the
Russian furnace to the pomt, when both metals melted at the
ends: the zine wire in melting bent down, but still retained its
continuity, and touched the melted drop of antimony still ad-
hering ; the needle instantly whirled round entirely. This is a
difficult experiment to succeed in.
A slender rod of antimony was heated in the flame of the
Russian furnace ; and just as it was in the act of melting at the
point, the drop was received on the end of a rod of grain tin also
in the act of melting: the needle whirled round. If the metals
be not kept free from oxide in these experiments they will fail.
A ribbon of sheet copper was heated to a bright red in the
Russian furnace, and a rod of grain tin was heated at its end to
the melting-poimt; a drop from the tin was allowed to fall on
the white-hot copper, the connexion of the drop with the rod of
tin being still maintained; the needle started off 130°, and in
another trial it traversed the circle entirely. Combination seemed
to have taken place superficially, for the copper was whitened at
the place of contact.
It appears to me, that the three last experiments are sufliciently
concerned in the Phenomena of ordinary Electricity, &c. 215
distinguished from instances of thermo-electricity by the cireum-
stance of fusion and combination.
There is an experiment of Schonbein which seems very difficult
to reconcile to the electrical hypothesis. He says, that if some
yellow solution of cobalt be poured into a glass tube bent into
the form of the letter U, and if a platinum wire, proceeding from
the galvanometer, be immersed in each limb of the tube, it will
be found that on heating the liquid in one of the limbs until it
becomes blue, a stream of electricity will move from the cold to
the heated column of liquid, the strength of the current increa-
sing with the difference of temperature between the two limbs. In
one case Schénbein obtained a deflection of 40°. He obtained
similar results by heating certain acid solutions; and he showed
that these are not cases of thermo-electricity, as might at first
view be supposed, but that the effects are attributable to the che-
mical change occasioned in one of the columns of liquid by the
action of heat*. Many experiments of this kind have since been
made by others.
In the experiment with solution of cobalt, it is very hard to
conceive how a current of electricity could be generated in two
parts of one homogeneous, uninterrupted, and excellent liquid
conductor. The chemical action described by Schénbein is in-
ternal; it is not exerted by the liquid on a second substance, but
on itself, within itself; the platina wires are mere conductors.
The conditions deemed necessary for electrical disturbance are
not present. The experiment, indeed, might be adduced as a
ease wherein mere chemical action, without any electricity, pro-
duced deflection. But if electricity did act, it could scarcely be
of any other’ kind than that described in the beginning of this
essay, consisting of different constituents, the deflecting element
greatly predominating.
In connexion with this experiment of Schonbein, it should be
recollected that the charge of Colladon’s Leyden battery of 4000
square inches, could only produce an average deflection of 20° or
30°, unless with an intense condensation of electricity, and then
he obtained but 40°, the same as Schénbein. Now, if Faraday’s
law be applied to this case, the quantity of electricity in Colla-
don’s and Schénbein’s experiments must have been the same,
Can imagination assist us in conceiving, or reason warrant us in
believing, that when a small tube containing a little solution of
cobalt is heated at one end, a quantity of electricity passes
through it equal to the most intense charge of a Leyden battery
of 4000 square inches, imperceptible to all else except the gal-
vanometer, and acting on that but feebly ?
In my experiments, it is equally difficult to conceive that such
* Poggendorft’s Annalen, 1838, vol. iii. p. 270.
216 Mr. M. Donovan on the supposed Identity of the Agent
powerful deflecting effects could have been produced by the cause
commonly assigned, when it is considered that the galvanometer
which suffered these deflections, when similarly connected with
a powerful electrical machine, proved insensible to its current.
In the experiments wherein fused caustic potash or heated metals
were touched with melted sulphur, there was not more than a
quarter of a grain of the latter, scarcely the half of which acted,
yet the needle sometimes whirled round four times*.
It appears very difficult to comprehend these results, which
are but afew out of many obtained by me, unless it be admitted
that in the phenomena called voltaic, the agent cannot be iden-
tical with that which produces the effects of ordinary electricity.
By supposing that certain elementary forces, which constitute
the electric fluid, exist together in combination while that agent
is in its natural state of equilibrium; and that according to the
circumstances under which it is excited into a state of activity,
the elements present themselves either in their natural state of
combination, or more or less altered in their ratio, and therefore
in their properties, the phenomena receive an explanation, as I
think, less embarrassed with difficulties, but still it must be ad-
mitted with quite a sufficiency of them.
We know that the electric fluid occasionally evinces variable
properties according to the mode of its generation; and this
variation agrees with the notion of difference of ratio of the con-
stituent elements such as has been here assumed. It may be
expedient to advert to a few of these differences of properties.
Water is an excellent conductor of the lowest intensities of com-
mon electricity ; but it is declared on all hands to be not a good
conductor of voltaic electricity, and Sir H. Davy’ says that to
such low intensities it is an absolute insulator. Common elec-
tricity is remarkable for the distance through which it strikes ;
a spark of fifteen inches long may easily be obtained from a
powerful electric machine; but Mr. Gassiot found that a nine-
gallon Leyden battery, charged by a water battery of 1024 pairs
of plates, could only project a spark to a distance of >7,5th of
an inch, and sometimes 57%gths. For a long time it was doubted
if voltaic electricity could project a spark at all through air, un-
less when the poles are gradually withdrawn from contact in a
vacuum. Voltaic electricity overcomes the most powerful che-
mical affinities ; none in fact can withstand its influence, although
it would merely cause gold leaves to diverge a little. But com-
mon electricity, possessing the highest dynamic powers, can only
overcome comparatively the weakest affinities. One is power-
fully magnetic; the other very little so. One, in order to produce
its effects, invariably requires the operation of its two poles; in
* The experiments of Cumming should also be considered.
concerned in the Phenomena of ordinary Electricity, &e. 217
the case of the other, one is sufficient. The magneto-electric
machine, if connected with the galvanometer by means of stout
copper wires, long enough to place the needle out of reach of
the powerful influence of the combined magnets of the machine,
will cause no small deflection when the coils are made to revolve
rapidly. But if, removing the galvanometer, the same arrange-
ment be connected with the insulated gold leaves of a differential
electrometer, the effect on them is barely observable. Here then
we have an electric fluid in operation quite different from ordi-
nary electricity, on account of its much greater effect on the
galvanometer, and its triflmg influence on the electrometer ;
while the current resembles that of a voltaic series, on account of
its chemical and deflective powers, although no chemical action
is concerned in its production. Yet the deflective power of
magneto-electricity is far weaker than the electricity im many
cases produced by a single voltaic combination in which chemi-
cal action is taking place, and which nevertheless would not be
capable of producing decomposition of water, although magneto-
electricity does it with such facility. M. Lamé observes that
thermo-electrie currents are distinguished from voltaic and
magneto-electric currents by their bemg much more difficultly
transmissible through liquids*. It is also worthy of notice, that
no power of common electricity passed through the coil of the
electro-magnetic apparatus is capable of giving a shock, although
the electricity of a pair of zinc and copper plates of an inch
square, or even a pair of zinc.and copper wires, is adequate to
that effect even in a violent degree.
So different and independent of each other are the electric
and yoltaic agents, that the voltaic spark may be taken through
the electric, each retaining its characteristic appearance. And
if a fine platinum wire be made red-hot by means of a voltaic
battery, a current of common electricity may be passed through
it, and drawn from any particular part of the wire in its own
proper form of sparks. The aura electrica produced will cool the
wire when sparks are not taken; but when they are drawn, the
wire on each side of that spot will be as much incandescent as ever.
Not the least remarkable difference of properties between the
electricity evolved by a voltaic combination and that by a fric-
tional machine, is the facility with which the latter is conducted
by all metals, and the obstruction which is experienced by the
former in passing through some. An easy mode of observing
this difficulty of conduction, is by means of an electro-magnetic
apparatus of the construction at present used for medical pur-
poses. If the triad, consisting of one platinized silver plate and
two zine plates, be connected with the coil by twelve feet of
* Cours de Physique de V Ecole Polytechnique, iti. 286,
218 On the Constitution of the Electric Fluid.
rather stout iron wire, the shocks received by applying the
thumb and little finger to the two binding-screws when the
slide is on the seventh pin will be trivial; but change the iron
for copper wire of the same thickness, and the shocks will be
intolerable. Hither of these wires, or of any other metal, would
without the least obstruction conduct the lowest intensity of
common electricity that can be produced.
Conclusion.
Such are a few of the objections which have occurred to me
in considering the explanation of voltaic phenomena. I now
conclude this essay, calling to mind an observation of the eminent
philosopher whose name I have been compelled to introduce
more frequently than I could have wished. He says, “ as every
man who has the courage, not to say rashness, of forming an
opinion of his own, thinks it better than any from which he dif-
fers, so it is only deeper investigation, and most generally future
investigators who can decide who is im the right*,” Should
any one hereafter think it worth his while to prove that my
opinions are mistaken and my objections groundless, I shall
nevertheless reap a valuable reward by having been instrumental
in obtaining explanations of what appeared to be incongruities
and contradictions, until reconciled and harmonized. My object
in questioning doctrines so generally accredited, has been to
suggest, that, in the induction of our theory of voltaic electricity,
we have been misled by a supposed fundamental principle handed
down to us by our original inquirers; and that, so long as the
electric fluid is viewed as an uncompounded agent, there is little
probability of arriving at a just comprehension of its phenomena.
And now, in conclusion, I have only briefly to recapitulate
the objects of the foregoing essay: they are intended to prove
that the agent in electric and voltaic phenomena are altogether
different, not in their elementary constituent principles (assuming
that they consist of such), but in their ratio and mode of com-
bination ; so different in these respects as to constitute agents
which may be considered swi generis as much as any of the various
compounds of elementary matter known to chemists, which,
identical in elements, in no other respect resemble each other.
Tf all this be true, voltaic phenomena are not produced by what
is called electricity.
I have been compelled by the objects of this essay to comment
on the opinions of Professor Faraday fully and freely. He him-
self has declared, that up to the time when he undertook to
examine the question of the identity of the agent in electrical
phenomena, that doctrine had not been fully established. I
* Experimental Researches in Electricity, vol. ii. p. 266.
On the Diurnal Motion of the Magnetic Needle. 219
always felt a strong conviction to the same effect ; and, anxious
to discover if his myestigations had demonstrated the truth of
the contested proposition, I devoted my attention to them par-
ticularly, I hope in a manner consistent with his high position,
and with the respect due to extraordinary talent.
I cannot, however, sacrifice my own convictions to authority ;
and I feel bound to declare that, in my opinion, no one has ever
yet established the identity of the agent in all the phenomena
called electric.
Not having the vanity to suppose that the arguments adduced
in this Essay will convert a reader in whose mind the hypothesis
of identity is already established, I only venture to hope that he
may be induced to reconsider the subject, leaving his judgement
free to the reception of new impressions, If I succeed so far,
my efforts will be sufficiently rewarded.
Far from having exhausted my arguments, I may say with
Cicero, “hujus autem orationis difficilius est exitum quam prin-
cipium, facere: itaque non mihi tam copia quam modus in
dicendo querendus est.’
11 Clare Street, Dublin.
XXXII. On the Decennial Period observed by Dy. Lamont in the
Magnitude of the Diurnal Motion of the Magnetic Needle. By
P, A. Restuuser, Director of the Observatory at Krems-
miinster*,
ee the past year I was occupied with the reduction
and calculation of the magnetic observations which have
been made here since the establishment of the magnetic observa-
tory in the year 1839, These observations refer to the absolute
determination of the elements of the magnetic force, the daily
alteration of the declination and the horizontal intensity, and to
the variations of these two elements on the fixed days of obser-
vation.
The observations on the change of the declination and hori-
zontal intensity were carried out with the magnetometer of Gauss,
being performed Caily since the year 1842 at the hour of 8 o’clock
A.M., 2 o’clock p.m., and 8 o’clock p.m, mean Gottingen time;
I possess therefore already a series of observations extending over
a space of ten years, sufficient to permit some inferences to be
drawn from the obtained data,
With regard, in the first place, to the decennial period disco-
vered by Dr. Lamont, the following is the result of our obser-
vations :—
* From Poggendorfi’s Annalen, vol. lxxxv. p. 412.
220 M. P. A. Reslhuber on the Decennial Period in the
Magnitude of the Daily Alteration of the Declination from
8 o’clock a.m. to 2 o’clock P.M.*
1842. 1843. . 1845. 1846. 1847. 1848, 1849. 1850. 1851.
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March.| 6 56°6|7 0-9] 6 45-4| 7 21-5110 6-0| 9 169/12 43-6|14 42-:0| 9 13-9] 9 11-0
April...10 32-4 |9 33:7| 8 315/11 160113 25-7| 9 58-7|13 19°7|17 43-2|10 34:1|12 5-4
May ...Palih.. ian 7 43°3| 9 54-7112 45-9 /10 20-8 /12 49°5 |14 173/13 548/10 12-9
June.. 4 sb snes 9 32°6| 7 48:4) 9 56-512 421/11 47-2|13 45-2|14 24-5 |13 53-5 |13 24-0
July ...| 8 24:5 |8 55-7|10 11:3) § 50-6 10 52°6|10 39-9|14 34-612 16°1|13 32-5 |10 50-7
August} 7 55°9'8 30:0] 9 56-6) 9 31-0/10 25-7/12 31-6/14 3-3/1] 583/11 305) 8 50-2
Sept...| 6 14°6|7 45-8| 8 21-2| 6 55-6| 6 49:8|10 208/12 1-2) 9 47-5|10 37-9| 7 41-0
Oct. ...| 6 25°35 392] 7 15:1, 6 5-9) 6 321\11 168/12 68| 7 39-2| 9 46-1| 7 24-6
Nov....| 2 361 |2 25°83] 3 22/3 05|3 325| 6 47-4/ 4555/4 7115 4-4/4 21-2
Dec....| 2 13°5|1 588] 1 59°6/ 2 37-3) 2 23615 86) 5 27-0| 2 329| 2411/2 23
Mean..| 6 33-4|6 28-6| 6 14:9| 6 39°6| 7 56-1| 8 42:3 10 55-4/10 39°5| 9 84/8 03
I must remark here in explanation, that these results do not
express the full magnitude of the daily variation ; for, according
to my investigations of the hourly change of the declination
during the day, the minimum declination occurs with us at 7
o’clock in the morning, Gottingen time, the maximum at 1 o’clock
P.M. GOttingen time; hence at 8 o’clock a.m. and at 2 o’clock
p.M. the declination had already decreased a little, and therefore
the quantities noted are a little too small, but certainly not con-
siderably so; at all events they are sufficient to show clearly the
existence of the periodical alteration.
The mean magnitude for the year attains a minimum between
1843-44, a maximum from 1848 to 1849.
I subjected the monthly mean magnitude of the daily change
of declination from 1842 to 1850 inclusive to a strict calculation,
according to the method used in the case of periodic phenomena,
and obtained for the annual course of the above change in the
daily declination the following result :—
1842—50. Observed deviation. | Calculated deviation.
3 12-93 2 29-10
5 0:34 5 16°84
9 21:90 9 19°75
11 39-43 1l 58°77
11 40:91 12 13°97
11 43°74 1l 16:16
10 55°34 10 33°95
10 42°60 10 16-91
8 47:14 9 33°82
8 521 7 42°16
November ......0.- 3 56°84 4 54-49
December ......... 3 0:27 2 32-48
Ce sovsaot 8 10°55 8 10°70
* The quantities wanting in 1842 and 1843 are obtained by interpolation,
Magnitude of the Diurnal Motion of the Magnetic Needle. 221
The divergence, according to this, is least in the month of
January and greatest in the month of May.
It is generally believed that one principal cause of this diurnal
change is to be traced to the warming of the earth. I will not
venture to decide what part is played by the temperature in the
production of these regular alterations ; true it is that a minimum
of the declination occurs in the morning nearly at the time when
the temperature is lowest, and that a maximum occurs in the
afternoon about the time when the temperature is highest. But
the magnetic declination attains a second minimum between 10
and 12 o’clock at night, and a second maximum between 2 and
4. o’clock in the morning; that is to say, two regular maxima
and two minima in the day, while in the temperature only one
minimum and one maximum occurs. If the heat were the only
or even the chief cause of the magnetic variation, the magnitude
of the daily variation of the declination must proceed side by side
with the increase and decrease of temperature during the year,
which is not proved by the observations which have been thus
far made. ‘True it is that the said magnitude is least at the time
of lowest temperature; but at the time of highest temperature
(July) it has already decreased, having attained its maximum in
the month of May.
But another remark involuntarily suggests itself when the
foregomg results are reflected upon :—
The magnitude of the daily variation of the declination through-
out the months of the year runs parallel with the changes in the
humidity of the air ; is smallest at the time of greatest humidity,
and greatest at the time of maximum dryness.
For the proof of this proposition I give here—
a. The mean diurnal deviation of the declination in the single
months.
b. The mean relative atmospheric humidity in parts of 100 in
the single months.
c. The mean temperature in the single months from the year
1842 to 1850.
Mean deviation of
the declination Mean per-centage | Mean temperature
from 2h p.m. to of humidity. in degrees of R.
8h a.m.
‘
January vo... 2 29-10 93-84 — 3-08
February......... 5 16°84 91-90 — 0:39
March..... 9 19°75 83°77 + 1-68
April 11 58°77 72:09 + 673
LC ae ee 12 18:97 70°25 +10°36
BING sosacitaners 1] 16:16 72:43 +1319
1 SP oe 10 33°95 74:37 +1414
August ......... 10 16-91 76°19 +13°73
September ...... 9 33°82 81-62 +10°50
October ......... 7 42:16 89:07 + 6:59
November ...... 4 54:49 92°30 + 2:14
December ...... 2 32-48 94°54 — 0:87
RGAE sassccsssees 8 10:70 82-69 + 6:23
222 M.P. A. Reslhuber on the Decennial Period in the —
The above proposition is proved in a striking manner by the
results of the observations of the year 1851, in which an anomaly
in the temperature and humidity of the months of May and June
is exhibited.
Mean deviation of
1851. the declination | Mean per-centage | Mean temperature
from 8 a.m. to of humidity. in degrees of R,
2h P.M. :
January .. 4 59-7 93°74 — T49
February 5 bl 91°84 — 182
March.. 9 11-0 84:00 + 2:27
April 12 5-4 73°92 + 813
May 10 12:9 74:28 + 7:86
June 13 24:0 67:90 +12:89
July 10 50:7 70°74 +13:29
August ..... 8 50:2 73°54 +1361
September ...... 7 410 82:48 + 9:22
October ..4..464. 7 246 84:93 + 8:23
November ...... 4 21:2 93-60 — 072
December ...... 2 23 94-56 — 121
WERT G eeteettess 8 03 82°13 + 5:85
Iam unable to explain the connexion of these phenomena,
but will leave it to other investigators to follow up this highly
interesting fact which has resulted from our observations.
At the end of his paper Dr. Lamont remarks, “that the
diurnal deviation of the horizontal intensity is subject to a con-
siderable change; but whether of the same period as that which
I have proved to exist in the declination, I am not yet in a posi-
tion to pronounce, &c.,”’
The investigation of the hourly deviation during a day proves
that two maxima and two minima occur, and moreoverasfollows:—
Between 65 and 75 p.m. mean stand.
Between 105 and 115 p.m. a maximum (the least during the
day).
fiom 125 and 15 a.m..a minimum (the least during the
day, greater than the mean horizontal intensity).
Between3®and4 a.m.a maximum (the greatest during the day).
Between 6" and 75 a.m. mean stand.
Between 94 and 11) a.m. a minimum (the greatest during the
day, less than the mean horizontal intensity).
The times of the maxima, minima, and mean magnitude of
the horizontal intensity occur at earlier hours in the warm months
than in the cold ones.
The horizontal intensity during the hours of the day is regu-
larly smaller, while during the hours of the night it is regularly
greater than the mean horizontal intensity.
In order to ascertain whether the horizontal intensity is subject
to a periodical alteration, I chose from our observations, which had
been made three times a day, those made at 8 a.m. and at 8"
Magnitude of the Diurnal Motion of the Magnetic Needle. 223
P.M. ‘The first falls somewhat before the lowest stand (the great-
est minimum), the other a couple of hours before the evening
maximum ; the difference of both therefore does not give the
entire magnitude of the diurnal change in the horizontal intensity.
The deviations, expressed in decimal parts of the absolute
horizontal intensity, are as follows :—
Alteration of the Horizontal Intensity from 8 o’clock a.m. to
8 0’clock P.M. Géttingen time. Difference =8> p.M.—8* a.m.
a | |__|
—0-00076 | —0:00098 | —0:00011| —0-00066
= O14) — -038|. =. .013| + "084| +. 060
+ 000;/+ 090; + 096) + 065) +4 109
4+ 058; + 158/+ 206/4+ 161]+4 347
4+ 230) 4+ 245/+ 275} + 3800/4 412
243; + 402) + 297/+ 405/4+ 355
4+ 205} + 2979/4 268}+ 400| 4+ 385
243| 4 3814/4 326/+ 4385/4 418
4+ 158] + 292;4+ 311] + 221) 4 325
a 108) AI IS) IT nO
Tot UOT et ee eT
i) AS Narrow a} ease. 1ag| tas’) OORT
+0-00088 | +0-00138 | +0-00133| +0-00180} +.0-00208
Mean for 9
years.
+0-00019| +0-00111| —0-00028| —0-00056 | —0-00028
4+ 024, — 008} + o12|/4+ 069; + 024
4+ 230} + 140) + 095; 4+ 059| + 098
wl + 305) 4+ 323) + 22014 1389/4 ° 214
a dbel e ARE Aer er SnO| ae aad
lads yj Sak: WS Agate et a 9 a ee a
+ 506+ 4384/4 3841/4 315| + 348
473} + 430) 4+ 3872/4 2738/4 365
4+. 88814 347(/ 4 $35(4+ 339|4 302
ai (sf am fee Snel I mae 9 ce Eh
4+ 058) 4 053} 4+ 033] 4+ 085] 4+ 037
+ Ql] —» 047|—. 003] = 069) —. 044
+4.0:00273 |} +.0-00230} +0:00203} +0-00152| +0-00178
A minimum of the daily alteration of the horizontal intensity
from 8" a.m. to 8 p.m. is here plainly shown to fall between
1843 and 1844, and a maximum between 1848 and 1849. Hence
the same decennial period occurs in the alteration of the hori-
- zontal intensity as has been proved to exist in the diurnal change
of declination.
In respect to the course of these alterations during the single
months of the year, they appear quite to follow the course of the
temperature. Observations made during several years will eli-
minate the little anomalies which now exist in the warm months,
= ae law to which all is subject will be thus rendered distinctly
visible.
[ 224 ]
XXXII. On the unequal Heating Effect of a Galvanic Current
while entering and emerging from a Conductor. By RicHaRD
Avis, Esq.
To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN, _ Liverpool, July 5, 1852.
i your Supplementary Number for July, p. 529, I observe
a paper by Prof. W. Thomson, wherein he alludes to M.
Peltier’s experiment on the supposed absorption of heat by a
bismuth and antimony joint while conducting a feeble galvanic
current passing (on the supposition of there being one current
only) from the bismuth to the antimony. In the year 18438, I
made some experiments connected with this subject, and as I
came to conclusions which gave a different explanation to M.
Peltier’s researches, I should be glad to avail myself of the me-
dium of your Journal briefly to notice them.
Among the metals bismuth stands as the most imperfect con-
ductor of electricity ; and as the heat developed by an electrical
current passing along a bar is in proportion to the resistance to
conduction, it follows that, m compound metallic bars of uniform
sectional area throughout, the bismuth portion is more heated
than the other parts. In acompound bar composed of antimony,
bismuth and antimony, again, when a feeble galvanic current is
made to pass through this arrangement, the conditions required
for observing M. Peltier’s experiment are supplied; for at the
one end of the bismuth bar the current through the joint is
from antimony to bismuth, while at the other end of the bis-
muth bar the passage through the joint is from bismuth to an-
timony. To ascertain the temperatures at these joints, two
delicate thermometers are attached and enveloped with a little
dry cotton wool, A galvanic current made to pass through this
arrangement elevates the thermometer where the electricity enters
the bismuth more than the one where it quits the bismuth; the
difference between these two thermometers varying with the
changes in the battery from which the electrical current is de-
rived. Now, according to Peltier’s views, the thermometer at
the joint where the current passes from the bismuth to the
antimony, should, during the conduction of a feeble current,
stand lower than the temperature of the atmosphere ; to ascer-
tain this point I have frequently repeated the experiments with-
out being able to note any absorption of heat. With me the
thermometer stands a little above the temperature of the atmo-
sphere; and from a brief notice I have seen of M. Becquerel’s
investigation of this question, I believe that he has likewise failed
to note any absorption of heat. The two joints of the bismuth
On the unequal Heating Effect of a Galvanic Current. 225
invariably showed a different temperature, the one where the
electrical current quitted the bismuth to enter the antimony
being the lower, but always above the temperature of the sur-
rounding air. This property found in the bismuth bar, which
was directly derived from the examination of Peltier’s law, ex-
tends to any other kind of matter, whether in the gaseous, fluid,
or solid state, traversed by a galvanic current ; the only condition
required for the expertment being that the current be brought
to the body tested by conductors which offer less resistance to
its passage than the body itself *.
Thus, although my experiments gave a different explanation
of the observations of M. Peltier, they did not lessen their value ;
for through the study of this supposed absorption of heat during
the passage of a feeble galvanic current a yet more general law
was established, by which a consistent explanation was given to
a remarkable fact noted in Daniell’s Introduction to Chemical
Philosophy, considered by the author of that work at the time
of its publication not to admit of illustration. The fact in
question is one of the conducting wires from a powerful battery
becoming red-hot, while the other wire remains comparatively
cool ; in this case the galvanic current has to pass across a short
space of air, where it encounters great resistance, and thus heats
the wire, where it meets this resisting foree much more than the
wire where it quits the obstructing medium ; the result being
the same as those exhibited in the case of the bismuth bar cited
above, the difference being only one of degree.
In studying the effects presented to us in thermo-electrical
arrangements, the force designated by the term attraction of
cohesion is constantly found to form at the present time an im-
penetrable barrier ; the various properties of metals in their rela-
tions to the imponderables, to tenacity, elasticity, &c., show
what modifications the force of cohesion of attraction can un-
dergo; yet in the present state of science there are no means of
ascertaining what alteration in this force has taken place, save
through the final effect shown by changes in the metal or its
alloys. Any one who may reflect on the subject will perceive
what an extensive range of phenomena is here hidden from view ;
and they will probably think that there the laws, which at present
cannot be traced so as to connect the generation of electricity by
chemical action with that derived from thermal sources, may
ultimately be developed.
' Yours very respectfully,
Ricuarp Aprr.
* Edinb. New Phil. Magazine, vol. xxxvii, p. 301.
Phil, Mag. 8, 4, Vol. 4, No, 24, Sept, 1852, Q
[ 226 ]
XXXIV. Notices respecting New Books.
On Animal Electricity ; being an Abstract of the Discoveries of Emi
pu Bors-Reymonp, Member of the Academy of Sciences, Berlin, &c.
Edited by H. Bence Jones, M.D., F.R.S., Physician to St. George’s
Hospital. London: John Churchill, Princes Street, Soho.
E have long wished to see an English abstract of the researches
of M. du Bois-Reymond, and the book before us answers to
the wish. It commences with a brief but extremely interesting historic
introduction, in which, as might be expected, Galvani and Volta
are the principal figures. Comparing these two celebrated men, the
author observes,—
“No one who wishes to judge impartially of the scientific history
of these times and of its leaders, will consider Galvani and Volta as
equals, or deny the vast superiority of the latter over all his oppo-
nents or fellow- workers, more especially over those of the Bologna
school. We shall scarcely again find in one man gifts so rich and so
calculated for research as were combined in Volta. He possessed
that ‘incomprehensible talent,’ as Dove has called it, for separating
the essential from the immaterial in complicated phenomena; that
boldness of invention which must precede experiment, controlled by
the most strict and cautious mode of manipulation ; that unremitting
attention which allows no circumstance to pass unnoticed; lastly,
with so much acuteness, so much simplicity, so much grandeur of
conception, combined with such depth of thought, he had a hand
which was the hand of a workman.”
The progress of discovery in this department of science is sketched,
and the author afterwards passes on to describe his instruments and
manner of experiment. We have a valuable and instructive chapter
on the improved galvanometer. The helix of the larger instrument
used by the author consists of the astonishing length of 3°17 English
miles of copper wire in 24,160 coils! It would be difficult, if not im-
possible, without drawings to give an intelligible description of the
author’s mode of experiment. Every precaution which experience
could suggest, and the most refined manual dexterity could apply,
has been taken to secure accuracy, and rescue the results from inci-
dental disturbances. The main feature in the experiments is, that
the contact of metals with muscle or nerve, or with each other, is as
much as possible avoided, connexion being established by cushions
of bibulous paper moistened with a saturated solution of salt and
water. Nor is contact with even these permitted, lest an irritating
action should be exerted upon the tissue; the cushions are protected
by a cover of pig’s bladder with a little albumen spread over it, and
upon or against this the tissue to be examined is laid.
The great law established by the author, and of which the so-called
frog current, together with the various phenomena observed by
M. Matteucci, are to be regarded as particular manifestations, more
or less complicated, is one of extreme simplicity. Let us suppose
the circuit all complete with the exception of one small gap, at each
side of which stands a cushion of bibulous paper moistened and pro-
ees
IM th ee. oe
Notices respecting New Books. 227
tected in the manner already described. Let this gap be closed by
the introduction of a cylindrical or prismatic piece of muscle, one of
the transverse sections of which is caused to abut against one of the
cushions, and the other transverse section against the opposite
cushion. ‘The circuit is now complete, the muscle playing the part
of a little battery; the galvanometer is included in the circuit; and
if a current be produced, it will exhibit itself at the galvanometer.
In the above arrangement, however, no current is produced. Let one
of the ends of the muscle remain in contact with the cushion, as
before, and let the muscle be bent up and caused to rest with its
longitudinal section against the cushion; a strong deflection is the
immediate consequence. The direction of this muscular current is
always from the transverse section through the galvanometer wire
to the longitudinal section; and hence the law of action is, that
every point in the longitudinal section is positive to every point in the
transverse section. ‘The current varies in intensity when the points
of the muscle which come into contact with the cushions are changed,
and the points of maximum and minimum action are determined in
amost delicate manner. The distinction between upward and down-
ward currents the author regards as non-essential; in fact, it alto-
gether depends upon which end of the muscle is in contact with the
cushion whether the current is up ordown. The part played by the
tendon is that of a passive conductor of the current generated in the
muscle itself.
The author’s experiments clear up the doubt which existed regard-
ing the influence of contraction on the muscular current. He proves
that, in the act of contraction, the muscular current is always dimi-
nished. A single contraction is unable to show any effect upon the
needle, on account of the inertia of the latter; but when a continuous
spasmodic action is kept up, the effect becomes evident. The con-
vulsions may be obtained by gradually destroying the motor nerve,
by a chemical agent, by poisoning the animal with strychnine, by
passing a current of electricity of varying intensity through the
nerve, or by submitting the latter, by means of a break-circuit wheel,
to a series of successive shocks. From these experiments we select
the following one, as it is explanatory of another which has caused
some discussion among men of science. A live frog was taken and
one of its feet was dipped into a vessel containing a conducting liquid,
while the other foot was dipped into a second vessel of the same kind ;
the ends of the galvanometer wires were also connected with the
vessels. One leg was paralysed by having its ischiatic plexus cut
through. ‘The animal was then poisoned by strychnine, and convul-
sions were the consequence. Now in one leg these convulsions
diminished the muscular current, whereas in the passive leg no such
diminution took place; the equilibrium was therefore destroyed, and
a current exhibited itself on the galvanometer.
It was this result that suggested the celebrated experiment which
gave rise to the discussion before alluded to,—a discussion in which
the veteran Humboldt took the leading affirmative position. Du
Bois-Reymond removed the frog’s feet from the fluid and put his own
fingers in their place; one arm he left passive like the paralysed leg
Q2
228 Notices respecting New Books.
of the frog, while he strongly contracted the muscles of the other
arm. The expected result at once exhibited itself, and a consider-
able deflection was obtained. ‘This result has been abundantly cor-
roborated; the writer may perhaps be permitted to contribute his
personal testimony, he having on a first trial obtained a deflection of
thirty degrees. ‘The sense of the deflection depends upon the arm
contracted; on changing the arm, the deflection is in the opposite
sense.
The electric deportment of the nerves has often been a subject of
anxious inquiry. A nerve possesses a current which exhibits itself
in a manner precisely similar to the muscular one. The arrange-
ment of an experiment with the nerve is in substance the same as
that applied to a muscle, and the direction of the current follows the
same law. It proceeds from the transverse section through the con-
necting wire to the longitudinal section. It is an error to suppose
that the various tissues of the animal body are electromotive towards
each other. Ifthe current due to each particular be shut out, Du
Bois-Reymond shows that no possible combination of muscle, nerve,
tendon, skin and bone, can produce any electric action.
Some slight alterations will probably suggest themselves to the
translator in the preparation of a second edition. ‘The name of the
author—not an easy one to English organs—occurs too often; and
the polemical tone of the book might, in certain places, be soft-
ened down with advantage. In a work of such intrinsic value no
such seasoning is required. ‘The letters referring to the diagram at
page 33 need a trifling correction ; and in one or two cases the word
‘observation,’ although the correct equivalent of the German Beo-
bachtung, might be changed for some other word which would not at
the same time answer to Bemerkung. On the whole, however, the
translation has been carried out with care and fidelity; and the
English investigator must feel indebted to Dr. Bence Jones for pla-
cing such a valuable work within his reach.
Aimosphere: a Philosophical Work. By Grorce Woopuean, Esq.
London: Hippolyte Bailliére.
This book consists of a number of articles, communicated from
time to time to the Mechanics’ Magazine by the author, and doubt-
less thought too valuable by him to be permitted to slumber in
obscurity. The avowed design of the work is to explain the causes
of certain effects whose hidden springs have eluded the researches
of all philosophers, those of Greece included, up to the time when
nature, forgetful. of her previous anguish, rejoiced over the advent of
a Woodhead.
With regard to the work, it is our duty to state that we have
rarely seen so much nonsense crammed into so small a space. We
do not blame Mr. Woodhead for this—not at all; the matter is evi-
dently due to circumstances beyond his control. There is a moral
Daltonism in the world as well as a physical one; and as reasonably
might we censure the great discoverer of the atomic theory for his
devotion to one or two colours, as Mr. Woodhead for his adherence
to two ideas—Ae can’t help it; the blame is not his but another’s.
—— |
ae 5 ee ae
Notices respecting New Books. 229
Light and air are regarded by our author as the two great powers
which uphold the universe. In his opening paragraph he naively
inquires, “Is not the agitation of boiling water caused by air which
enters through the bottom of the vessel, and which rising up
through the water causes the bubbling called boiling?” We really
imagined that Mr. Woodhead, in stating the case thus, had conde-
scendingly placed himself in the position of some interesting little
prattler, standing at his nurse’s knee, and putting to the said nurse
the above philosophical query; and that Mr. Woodhead, in his own
benign way, was going to set the little questioner right. But no—
this is Mr. Woodhead’s own opinion. He believes that the air actually
enters in the manner described; he believes that light is airin a state
of radiation ; and his theory of caloric is, that light penetrates bodies
and makes way for the admission of air into them; and it is the
expressed air of a red-hot piece of iron, which, when it is immersed
in water, causes the ebullition, repulsion, expansion, steam and
hissing.
It is sometimes mournful to observe how the inventions of one
age render the pains and labours of the preceding one valueless.
The ponderous aqueducts of ancient Rome are rendered useless by
the application of the simplest laws of hydraulics; canals are super-
seded by railways; and the Manchester cotton-spinner has often to
cast sound and costly machinery aside, to avail himself of some new
invention. Philosophie endeavour is doomed, in the eternal progres-
sion of things, to share a similar fate; and it is with a certain exalted
sorrow that we contemplate the efforts of Mr. Woodhead’s predeces-
sors. Upwards of thirty years ago Colonel Sabine took up his cold
and perilous post on Melville Island to make pendulum experiments,
and deemed himself lucky in getting away from the place, after a
winter’s exile, without any accident save the loss of five frost-bitten
fingers by an incautious artilleryman. But his troubles might have
been spared had our latter-day genius been present to tell him that
he was pursuing a phantom, and beating the air, in another sense
than the mere literal one, when he set his pendulums agoing. The
retardation of the pendulum and the decrease in the intensity of
gravity in the equatoreal regions, quoth Mr. Woodhead, are attribu-
table to the increased density of the atmosphere in these regions.
His theory is, that the centrifugal force arising from the earth’s
diurnal rotation causes an accumulation of air, and a consequent in-
crease of pressure at the equator,—not at all regarding the mathe-
matical fact, that were the motion of the earth seventeen times
quicker than at present, poor Mr. Woodhead himself, if placed at
the equator, would dance upon nothing, and exercise no practical
pressure at all.
But, to Mr. Woodhead’s mind, the dip of the magnetic needle
affords still stronger and more striking evidence of the above arrange-
ment of the atmosphere. In the direction of the poles the atmo-
spheric resistance is least; the needle points in the direction of least
resistance, and hence its polarity. What will Carl Friedrich Gauss
say to this? Here is also a morsel for the geologist :—The increase
of heat observed as we descend a shaft is caused by the superincum-
230 Royal Society.
bent pressure of the column of air. And for the physiologist :—
Animal heat appears to be caused by the pressure of air in the lungs.
And for the botanist :—The ascent of sap, and the general upward
tendency: of trees and plants, are due to atmospheric pressure, which
is greatest at the roots; the trees and sap ascend, as a balloon in
air, or as a piece of wood in water!
“It is generally thought that in electrolytic decomposition the
gases called oxygen and hydrogen are somehow formed from the
water ;”’ but this is not at all our author’s opinion. He thinks they
are derived from the atmosphere, and that they come from the bat-
tery through the conducting wires; and further, that it is the con-
fluence and pressure of these two aériform fluids which produce the
electric light, the incandescence of wires, and the other calorific and
luminous phenomena of the circuit.
“‘Light,” says Mr. Woodhead, ‘can be caught and examined.”
There is no salt used in the process, and herein Mr. Woodhead’s
experiments differ from certain of our own made on sparrows and
cockrobins at the beginning of the present century. He ‘catches’
the light by ingeniously entrapping it in sealing-wax. Again, solar
light is the power which moves the earth, both on its axis and in its
orbit, and seems also to regulate the motions of the planets. More
solar light appears to impinge upon the earth at the solstices than at
the equinoxes, which Mr. Woodhead sagaciously supposes may ac-
count for the variation of the earth’s distance from the sun. Sir
John Herschel will no doubt be interested to learn all this; he will
henceforth be able to assign their proper value—or no-value—to the
experiments of Mr. Bennet, while a new life begins to palpitate
under the ribs of the defunct corpuscular theory !
It is Leigh Hunt, if we remember aright, who insists on the ne-
cessity of contrast in the composition of what is called humour; such
a contrast, we imagine, exists when we behold a man talking extreme
nonsense with a grave face; and as a choice specimen in this line,
we can conscientiously refer to the book of Mr. Woodhead.
XXXV. Proceedings of Learned Societies.
ROYAL SOCIETY.
{Continued from p. 153.]
April 29, « | Sesame Experiments on Light.’’ By Henry Lord
1852. Brougham, F.R.S., Member of the Institute of France,
and of the Royal Academy of Sciences of Naples.
The author commences this account of his experiments by remark-
ing, that ‘‘ it is probable that some may consider the inference to be
drawn from the following experiments as unfavourable to the doc-
trines of my former paper—I think I can explain the phenomena
according to those doctrines—but be they ever so repugnant, we are
of course in search of truth, and have no right even to wish that the
balance may incline one way rather than another, far less to conceal
any facts which may affect its inclination.”
The leading experiment is this: —A speculum is placed in a beam
Royal Society. 231
of light and is inclined so that the reflected rays shall make a small
angle with the surfaces. Near the speculum the axis of reflected
rays coincides with that of the direct rays, but at a greater distance
the two discs are separate. The speculum being placed horizontally
across the pencil, coloured fringes appear both on the upper and lower
side of the reflected disc. These two sets of fringes are alike in their
colours and in the order of their colours, but the upper fringes are
narrower than the lower, and they diminish in breadth with their
distance from the disc, while the lower ones increase in breadth with
their distance. If only one edge of the speculum is in the pencil
there are only fringes on one side of the disc.
It appears that the breadth of the fringes is in some inverse pro-
portion to the breadth of the speculum. When the speculum is a
triangle with a very acute angle, the broadest fringes, and those most
removed from the disc, answer to the points of the speculum where
it is narrowest, and they increase regularly towards the point which
answers to the acute angle or apex of the speculum. ‘Their form is
hyperbolic.
When the edges of the speculum are parallel, the disc near to it
is filled with groups of fringes which vary in number, in breadth and
in colour, at all the distances from the speculum. At one distance
they form only a dark line running through the disc, and this is deep
purple when examined closely. At a greater distance the fringes
have other colours, and become broader again; and at a still greater
distance they emerge into the shadow on both sides of the disc.
The phenomena of reflexion, it is stated, closely resemble those of
flexion, as to the fringes, their colours, their magnitude, their varia-
tion at different distances from the bending edges, and at different
distances of those edges from each other.
A convenient method of examining the variation of the fringes,
whether of reflexion or of flexion, at various distances, is to incline
the screen upon which they are received, so that it crosses the rays
forming the fringes, which are exhibited upon it, at various distances
from the edges. The line which each fringe describes being the
projection of the line which the rays follow that form the fringe, we
can in this manner observe if the course of these rays after flexion is
rectilinear or curvilinear, the projection being, generally speaking, a
line of the same kind with the original line; and at least never rec-
tilinear if that original line is. curvilinear.
If y=/ («) be the line which the rays follow after flexion; ¢ the
Ss
angle of the screen’s inclination ; ane =m; and 2! the abscisse of
‘the liue of projection; then its equation is y=f(W“1+m?. a). If
the curve of the rays be supposed to be the equilateral conic hyper-
bola, the radius of curvature in the curve of projection, it is stated,
must be less than that in the original line; and so the curvature
is more easily discerned by the eye, As under no circumstances of
inclination of the screen, and at no part whatever of the course of the
fringes could the author perceive the least difference of form from all
the other parts, he infers, either that the rays follow a rectilinear
course, or that their deviation from it must be very small.
232 Royal Society.
Though the phenomenon seem to indicate a crossing of the rays
both in flexion and reflexion, at or near the distance at which the
dark or deep purple line is formed, yet the author has never been
able to observe that an obstacle placed between that point and the
speculum (or the bending edges), made the fringes on the opposite
side of the disc at the screen to disappear, but only the fringes on
the same side with itself.
Referring to Fresnel’s memoir, the author'states that the principle
laid down in it, ‘‘ that the dilatation of the fringes depends solely upon
the breadth of the aperture,” will not afford an explanation of the
phenomena described in his former paper respecting fringes formed
by edges acting in succession, for he there showed that their breadth
and their distances from the direct rays are in the inverse proportion
of the distance of the edges; and if the edges are so placed that the
rays pass parallel to each other, and not diverging, and the edges are
moved to different distances in the same line, e. g. horizontally, then
their distance from each other vertically being the same, the aperture
is the same at all distances of the edges from each other horizontally,
and yet the breadth of the fringes is inversely as the horizontal di-
stance. Further, where the edges are not placed in succession, but
directly opposite to each other, the breadths of the fringes do not
appear to follow the exact inverse proportion of the distances of the
edges (that is the size of the aperture), the observed breadths corre-
sponding more nearly with the curve y=o+ a v being the distance
of the edges, and y the breadth of the fringes.
The author considers that the internal fringes, or those of the
shadows of small bodies, called fringes of interference, require a more
full examination than they have received in certain respects. As re-
gards the central space and the two deep black fringes or intervals
on each side of it, he remarks that no examination with a magnifier,
and no inclination of the screen, at all resolves these colours into
purple as in the dark line before described. ‘They appear to follow
a different law from that of the coloured ones as regards their breadths
in proportion to their distances from the pin or other small object,
at least if they are caused by interference, and if the effect of inter-
ference is inversely as the difference of the length of the rays; for
m
V a+ a2— VB +a2
which nowise agrees with the admeasurements.
The action of transparent plates on the rays, in bending them, re-
sembles in every respect that of opake plates, except that there being
no shadow, the external fringes are not perceived. But the shadow
of the edge of the plate is surrounded by two sets of fringes resem-
bling exactly those surrounding the shadow of a hair or other small
body placed upon the plate’s edge, and following its course, with
this only difference, that this shadow of the transparent plate’s edge
has no internal fringes as the hair or other small body’s shadow has.
that would give for the breadths the curve y=
. May 6.—A paper was read, entitled, ‘‘ On Periodical Laws disco-
verable in the mean effects of the larger Magnetic Disturbances.” —
No. II. By Colonel Edward Sabine, R.A., Treas. and V.P.R.S. &c.
Royal Society. 233
From the discussion of the magnetic observations made at Toronto
and Hobarton in the years 1843, 44, 45, the author in a former
paper adduced evidence of the existence of periodical laws by which
the principal disturbances of the magnetic declination appeared to
be regulated. Having since had occasion to examine the disturb-
ances of the Declination at the same two stations in the three suc-
ceeding years 1846, 47, 48, he states that he had the satisfaction of
finding that the observations of thesesyears confirm every deduction
which he had ventured to make from the analysis of the disturbances
of the former period ; whilst new and important features have pre-
sented themselves in the comparison of the frequency and amount
of the disturbances in different years, apparently indicating the
existence of a periodical variation, which, either from a real or causal
connection, or by a singular coincidence, corresponds precisely, both
in period and epoch, with the variation in the frequency and magni-
tude of the solar spots, recently announced by M. Schwabe as the
result of his systematic and long-continued observations.
The method pursued in examining the laws of the Declination-
disturbances in 1846, 47, 48, is the same as that adopted in the three
preceding years. Every hourly observation which was found to
differ a certain amount from the mean value of the Declination in
the same month and at the same hour was, as before, separated from
the rest. The number of observations thus separated in the period
commencing July 1, 1843, and ending July 1, 1848, was at Toronto
3940, and at Hobarton 3469, being respectively 1 in 9°43 at Toronto,
and 1 in 10°55 at Hobarton, of the whole number of hourly observa-
tions. The disturbed observations being distributed into the several
hours, months, and years in which they had occurred, their numbers
and aggregate values in each particular hour, month, and year, were
ascertained. They were then divided into easterly and westerly deflec-
tions, and the same process of distribution was gonethrough with each
of the divisions. ‘The mean hourly, monthly and yearly number and
aggregate values in the whole period were then taken as the respec-
tive units, and the ratios to these units computed for each of the hours,
months and years; whereby the relations, whether of numbers or
of aggregate values in different hours, different months, and different
years, were shown.
The results thus obtained are discussed separately in the follow-
ing order :—
I. Inequality or variation in the number and aggregate values of
the disturbed observations in different hours. This examination is
made by classing together—lst, easterly disturbances at Toronto
and westerly at Hobarton; and 2nd, westerly at ‘Toronto and east-
erly at Hobarton.
From the first classification, it appears that at both stations there
are fewer disturbances, and their aggregate values are less in the
hours of the day than in those of the night; that 9 p.m. is the hour
of the maximum of frequency and also of value at Toronto, and
11 p.m. at Hobarton; and that the periods of minima are between
2 and 3 p.m. at Toronto, and between 5 and 6 a.m. at Hobarton:
234. Royal Society.
It appears further that the average value has a similar law of varia-
tion to that of the number and aggregate value.
The second classification shows that at Hobarton the contrast both
in frequency and aggregate value is still between the hours of the
day and those of the night, the ratios being, however, in this case
greater than unity during the former hours, and less than unity during
the latter, contrary to what takes place with the easterly disturb-
ances: at Toronto the contrast is between the hours from noon to
midnight, and those from midnight to noon, the ratios being greater
than unity during the latter hours, and less than unity during the
former. In both cases the variation in the ratios appears to be de-
pendent on the hours of /ocal, not on those of absolute time.
From a table showimg the ratios of easterly aggregate values to
westerly at Toronto, and of westerly to easterly at Hobarton, it ap-
pears that, at both stations, the deflection (due to disturbance) of
the end of the magnet of the same name as the magnetic latitude -
is to the west during the hours of the day or from 5 a.m. to
5 p.M.: at a little before 6 p.m. at Toronto, and a little after 6
at Hobarton, the deflections pass through zero (or the undisturbed
position of the magnet) into easterly deflections of that end. The
magnitude of those deflections rapidly augments to a maximum at
9 p.m. at Toronto, and at 10 p.m. at Hobarton; they again pass
through zero between 4 and 5 a.m.; and attain the westerly maxi-
mum at 7 a.m., the variation in the magnetic direction due to the
disturbances depending, like those of number and value, on the hour
of local time.
II. Inequality or variation in the number and aggregate values of
the disturbed observations in different months. From the tables
which are given, it is obvious that there is a systematic variation
in the numbers and aggregate values of the disturbances in the dif-
ferent months; and at both stations the easterly and westerly ratios,
separately considered, differ little in the characters which they assign
to the variation, from the ratios of the two combined. The most
distinctly marked feature is that the disturbances are less frequent
and have a less aggregate value in November to February at To-
ronto, and in May to August at Hobarton, than in the other months
respectively : so that the disturbances are governed by a law de-
pending either on the period of the year, or on /ocal season, not on
absolute time.
III. Variation in the number and aggregate values of the dis-
turbed observations in different years. ‘Taking the ratios of the
numbers and aggregate values of the disturbed observations at
Toronto and Hobarton in the different years (from 1843 to 1848),
to the average annual number and aggregate value respectively, it
appears that there is a remarkable correspondence in the variation of
these ratios in different years at the two stations; and that at each,
both ratios increase progressively from 1843 to 1848, with the single
exception of 1845, in which there is a small diminution in that of
the number and also that of the value. ‘Taking the mean of the
ratios at Toronto and Hobarton, the ratio of the number increases
Royal Society. 235
from 0°60 in 18483 to 1°43 in 1848, and the ratio of the value from
0°52 in 1843 to 1°51 in 1848, the variation in each having much
more the aspect of a periodical inequality than of an accidental va-
riation. Looking to the theoretical importance of the existence of
a periodical inequality of this nature, affecting at the same time, and
in the same manner, parts of the globe most remote from each other,
the author refers to the confirmation it may obtain from contempora-
neous observations at other stations. Pending such confirmations
he remarks that this progressive increase in the amount of disturb-
ance at Toronto and Hobarton, between the years 1843 and 1848,
derives great additional interest and importance from its apparent
connection with an equally remarkable progressive increase which
took place at the same two stations, in the magnitude of the diurnal
range of the Declination in the same years. From the mean magni-
tude of the diurnal variation of the Declination in each month, tables
are deduced showing the mean magnitude or ranges in the four
months constituting the respective seasons, and in the twelve months
constituting the year, in each year from 1843 to 1848, both at To-
ronto and at Hobarton. From these tables it appears that at each
station, for each of the seasons and for the whole year, the diurnal
range of the Declination had a progressive increase during that
period ; the increase for the whole year being from 8'-90 in 1843 to
12!-04 in 1848 at Toronto, and from 766 to 11'-43 at Hobarton.
In support of the opinion that these progressive increases in the
range of the diurnal variation at two stations separated from each
other by nearly half the surface of the globe are independent and
corresponding measures of a general phenomenon, the author ad-
duces the results obtained by Dr. Lamont from the observations at
Munich. From these it appears that the mean range of the diurnal
variation in monthly periods at Munich increased progressively from
7°82 in 1843 to 11°15 in 1848.
The author remarks that the increase so distinctly marked in the
two classes of phenomena between the years 1843 and 1848 tends
to indicate a causal connection subsisting between the disturbances
and the regular diurnal variation. If we suppose the diurnal varia-
tion to be divided into two portions, one of which is nearly uniform
in amount throughout the year (at the same station), whilst the
other has a hemispherical phase, developed in either hemisphere ac-
cording as the sun is in the northern or the southern signs,—it is the
former of these two portions which sustains the variation consistent
with and apparently related to the variation in the number and values
of the disturbances.
That the progressive increase in the mean monthly diurnal range,
from 1843 to 1848, was not confined at Toronto and Hobarton to
the Declination only, but took place likewise in the diurnal variations
of the Inclination and Total Force, is shown by the tables which are
given.
In conclusion the author observes, that ‘in our present ignorance
of the physical agency by which the periodical magnetic variations
are produced, the possibility of the discovery of some cosmical con-
236 Intelligence and Miscellaneous Articles.
nection which may throw light on a subject as yet so obscure should
not be altogether overlooked. As the sun must be recognised as at
least the primary source of all magnetic variations which conform to
a law of local hours, it seems not unreasonable that in the case of
other variations also, whether of irregular occurrence or of longer
period, we should also look in the first instance to any periodical
variation by which we may learn that the sun is affected, to see
whether any coincidence of period or epoch is traceable. Now the
facts of the solar spots, as they have been recently made known to
us by the assiduous and systematic labours of Schwabe, present us
with phenomena which appear to indicate the existence of some
periodical affection of an outer envelope, or photosphere, of the sun ;
and it is certainly a most striking coimcidence that the period, and
the epochs of maxima and minima, which M. Schwabe has assigned
to the variation of the solar spots, are absolutely identical with those
which have been here assigned to the magnetic variations.” From
the results of his observations of the solar spots from the years
1826 to 1850, M. Schwabe has derived the conclusion that ‘‘ the
numbers in the table leave no room to doubt that, at least from the
years 1826 to 1850, the solar spots have shown a period of about
ten years, with maxima in 1828, 1837, and 1848, and minima in
1833 and 1843.” M. Schwabe has not been able to derive from the
indications of the thermometer or barometer any sensible connection
between climatic conditions and the number of spots. The same
remark would of course hold good in respect. to the connection of
climatic conditions with the magnetic inequalities, as their periodical
variation corresponds with that of the solar spots. But it is quite
conceivable that affections of the gaseous envelope of the sun, or
the causes occasioning those affections, may give rise to sensible
magnetical effects at the surface of our planet, without producing
sensible thermic effects.
XXXVI. Intelligence and Miscellaneous Articles.
ON A BRILLIANT METEOR SEEN AT SIDMOUTH.
To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN, Sidmouth, August 23, 1852.
[ HAVE been favoured by two ladies with the subjoined account
of a splendid meteor which they saw on the night of the 12th of
the present month. Probably the whole or a part of their letters
may be deemed worthy of insertion in your Journal. I should pre-
mise that the ladies were in company together when they saw the
meteor—that their accounts of it were afterwards written indepen-
dently of each other—that the time mentioned may be considered
within a minute or two of the mean time at Sidmouth—that the
degrees named were estimated only, as was also the bearing of the
meteor. Several other persons here saw the phenomenon, but I have
been unable to obtain any accurate account of time, altitude or bear-
Intelligence and Miscellaneous Articles. 237
ings. A rough trial with a common quadrant the following day
gave, from the position indicated by a sailor who saw the meteor
(probably at its greatest altitude), about 30°, and about 10° E, of
magnetic north. It is described by all as having cast a strong
shadow—that the hour could have been seen on a watch—that while
globular it approached the fuli moon in apparent size—that no noise
was heard during its appearance. I-also subjoin an extract from
Woolmer’s Exeter and Plymouth Gazette, which evidently refers to
the same meteor.
I am, Gentlemen,
Respectfully yours,
N.S. Hernexen,
Letter No. 1.
“Sidmouth, August 13, 1852.
“TI have written down, according to your request, all the parti-
culars I can remember respecting the beautiful meteor which I saw
last evening. It was about 12 minutes past 9 p.m. when, as I was
walking home, a light—so bright that my figure cast a strong sha-
dow across it—streamed upon the road. I instantly turned “round
and saw in the sky, about 15° W. of Cassiopeia, a meteor the size of
the full moon, and of a warm yellow colour. ‘The ball immediately
shot out into a bar, apparently 7° 30! in length and 1° wide. The
edges of the bar were sharply defined, and the breadth was the same
throughout ; but both the ends were jagged, and in the centre there
was a rent which gradually became wider, until within 30 seconds,
as near as I could guess the time, there was a distance of 30! between
the two portions. In about 30 seconds more the bar lost its sharply
defined appearance and faded into a thin luminous cloud witia pale
diffused light, which disappeared altogether in the course of two
minutes. The meteor appeared to me to be stationary after it had
shot out into the bar, until it had faded into the luminous cloud,
which I fancied had a slow motion towards the east.
“ Awne R. Bennerr.”
Letter No. 2.
“Sidmouth, August 13, 1852.
“As I was returning home about 12 minutes past 9 P.M. on
Thursday the 12th instant, I was startled by seeing the road sud-
denly illuminated by some brilliant light behind me. ‘Turning in-
stantly I saw a bright body in the sky, due north, I think, half-way
between the pole star and the horizon, the constellation Cassiopeia
being to the east of it. ‘The meteor rapidly spread into a horizontal
bar about 7} degrees long and scarcely one in width, the centre and
extremities of a beautiful pale green—two points between bright yel-
low shading into the green on either side; the centre eee paler,
as though a separation were taking place, and gradually the meteor
lost its brilliancy and defined form, becoming more like a small lumi-
nous cloud which slowly faded from my sight. The meteor appeared
stationary, and was visible for 2 minutes, but the intense light lasted
scarcely 30 seconds.
“H, N, Surru.”
238 Intelligence and Miscellaneous Articles.
Extract from Woolmer’s Gazette.
“On the evening of the 12th of August, at } past 9 (query London
time), a meteor broke forth with a slight report, as from the nipple
of a percussion-gun, illuminating the ‘atmosphere around, at an ele-
vation of 48°N.E. midw ay between Perseus and Cassiopeia, and re-
mained stationary and luminous for afew minutes, radiating with its
point to the east.
“ Joun Bremriper.”
** Southmolton, Aug. 16.”
P.S. I may also add, that on the Monday night previous at
nearly eleven o'clock, a meteor, equally if not more splendid, passed
over the town of Sidmouth from north to south, casting a light by
which the hour upon a watch might have been seen; but of this
meteor I have been unable to obtain any further particulars.
N.S. H.
ON THE INDIRECT BLEACHING POWER OF MERCURY.
BY C. F. SCHONBEIN.
I have long since shown that mercury possesses the power of com-
municating to oxygen that condition in virtue of which it colours
guaiacum tincture blue, decomposes iodide of zinc, &c., and produces
those general oxidating effects which are caused by ozone. The
fact that the latter destroys organic colouring matters, suggested the
idea that oxygen under the influence of mercury would likewise
effect this change, and the following experiments prove that this is
really the case.
When 200 germs. of mercury and 10 grms. of water, sensibly
coloured with indigo-solution or an alkaline indigo-sulphate, are
shaken briskly for some time in a tolerably capacious flask containing
oxygen or atmospheric air, it is decolorized precisely as if it lad
been treated with ozone, chlorine or oxygenized turpentine, &c.
Elevation of temperature quickens this decolorization. Water
coloured by cochineal or logwood may be decolorized in a similar
manner, whence it may be inferred that oxygen in contact with
mercury is capable of destroying all organic blue and red colours.
I have recently fully described the decolorization of indigo solution
by oxygen in contact with phosphorus; it may therefore be said that
mercury acts upon vegetable colours like phosphorus, though in a
much weaker degree, that is to say, both bodies, like so many other
inorganic and organic bodies, possess an indirect power of bleaching. ©
If platinum, gold and silver were volatile at ordinary temperatures,
they would also destroy organic colouring matters when shaken with
their aqueous solutions and oxygen. Some years ago I showed that
moistened paper coloured with indigo-selution was bleached in 24
hours by contact with spongy platinum.—Jouran. fiir Prakt. Chem.,
lvi, p. 353.
Meteorological Observations. 239
ON THE INDIRECT BLEACHING POWER OF STIBZTHYLE,
During the last year Prof. L6wig and myself made some experi-
ments in the laboratory at Zurich upon stibethyle, in order to test
its power of bleaching, and it turned out that this remarkable body
destroyed the coiour of indigo-solutions still more energetically than
even phosphorus. We added a small quantity of stibethyle to a
comparatively large amount of indigo-solution, shook the whole with
atmospheric air, and found that the colour was destroyed in a few
seconds.
There can be no doubt that stibmethyle, kakodyle and similar
compounds would act like the stibethyle. These substances are so
oxidizable that they take fire in atmospheric air even, at the ordinary
temperature ; and it may be inferred that they are more powerful
exciters of oxygen than phosphorus, and consequently possess a
great power of bleaching.—Jbid.
METEOROLOGICAL OBSERVATIONS FOR JULY 1852.
Chiswick.—July 1. Fine: cloudy: slightly overcast. 2. Cloudy and fine. 3,
4. Very fine. 5. Excessively hot: thermometer higher in the shade than it has
been for at least twenty-six years: lightning at night. 6. Very hot. 7. Cloud-
less: hot and dry. 8. Dry haze: sultry: clear at night. 9. Very hot. 10. Very
fine. 11. Hotand clear. 12. Sultry. 13. Fine: lightning, with distant thunder
at night. 14. Overcast: thunder: very hot: lightning, with rain at night. 15.
Cloudy and fine: clear. 16. Slight haze: very hot: excessively heavy and con-
stant rain at night. 17. Rain: cloudy and warm: clear at night. 18. Very fine:
heavy clouds: clear. 19. Very fine. 20. Overcast. 21. Light clouds: very fine:
clear. 22—24. Very fine. 25. Overcast: thunder: rain. 26. Cloudy and fine:
clear. 27. Slight haze: very fine. 28—30. Very fine. 31. Heavy dew: very
fine : cloudy.
Mean temperature of the month .........seescseeeseeees Baer, 67°37
Mean temperature of July USS] |. ..5..0002000cc2-.seccsere se 00 60°71
Mean temperature of July for the last twenty-six years... 63 °40
Average amount of rain in July oss... se ceeaseeeeeeeneee tsee. 2°37 Inches.
Boston.—July 1, 2. Fine. 3. Cloudy. 4. Fine: thermometer 84° at 5 p.m.
5. Fine: therm. 91°at2p.m. 6. Fine: therm. 86° at3r.m. 7. Fine: therm.81°
at3p.m. 8. Fine. 9. Fine: therm. 89° at2 p.m. 10,11. Fine. 12. Cloudy.
13. Fine. 14. Cloudy. 15. Cloudy: rain, with thunder and lightning early a.m.
16. Fine: rain, with thunder and lightning p.m.: therm. 86°. 17. Cloudy:
therm.86°3 p.m. 18. Fine. 19—22. Cloudy. 23. Fine. 24. Cloudy. 25. Fine:
rainp.M. 26, Cloudy: rain aA.M.andp.mM. 27,28. Fine. 29. Cloudy. 30. Fine.
31. Cloudy.
Sandwick Manse, Orkney.—July 1. Bright: cloudy. 2. Rain: cloudy. 3.
Bright : cloudy: fine. 4. Cloudy: clear: fine. 5. Bright: clear: cloudy : thunder
and lightning. 6. Rain: cloudy: fine. 7. Hazy: fine. 8. Bright: fine: fog.
9. Hazy: showers: thunder and lightning. 10. Bright: cloudy. 11. Bright:
clear: fine. 12. Bright: fine: cloudy: fine. 13, 14. Bright: fine: clear: fine.
15. Bright: fine: cloudy: fine. 16. Hazy: fine: clear: fine. 17. Cloudy: rain.
18. Bright: cloudy: clear: fine. 19. Hazy: cloudy: clear: fine. 20. Bright:
cloudy: rain: fine. 21. Rain: cloudy: fine. 22. Bright: hazy: fine. 23.
Bright: fine: cloudy: fine. 24. Drops: fine: cloudy: fine. 25, 26. Cloudy:
damp. 27. Damp. 28.Cloudy: fine: cloudy: damp. 29. Fog. 30. Rain: fog.
31. Damp : cloudy : damp.—This month has been remarkably fine and warm.
Mean temperature of July for twenty-five previous years ...... 54°79
Mean temperature of this month ......... sodstsaige cite 8 Sa 61°36
Average quantity of rain in July for six years ...,...... penedea 2°71 inches,
oS 62
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THE
LONDON, EDINBURGH anv DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
[FOURTH SERIES.]
OCTOBER 1852.
XXXVII. Reports on the Progress of the Physical Sciences.
By Dr. Joun Tynvatt, F.R.S.
On the Siereoscopic Combination of Colours, and on the Influence of Bright-
ness on the relative Intensity of different Colours. By H. W. Dove,
Berichte der Akademie, May 1851, and February 1852.
ie the July Number of this Journal for 1851 we gave a de-
scription of several forms of the stereoscope invented and
applied by Professor Dove. The inquiries in which these inven-
tions originated have been since followed up by the learned Pro-
fessor ; and as they have reference to an application of this beau-
tiful, and now highly popular instrument, which has not as yet
been treated by its mgenious inventor, we propose placing the
results, i a condensed form, before the readers of the Philo-
sophical Magazine.
M. Dove’s researches have reference chiefly to the stereoscopic
combination of colours. In 1841 he showed that the stereo-
scopic combination of the complementary colours of polarized
rays produced white light. He now makes use of drawings with
coloured outlines, the colours being either dioptric or catoptric :
the former he obtains by making drawings of white lines upon a
black ground, and viewing the stereoscopic combination through
a coloured glass; in the second case, the figures are drawn upon
white paper in the colours which are intended for combination.
The projection of a convex pyramid was drawn in red lines
upon a white ground, and on the same base the projection of a
concave pyramid in blue lines. On a second leaf the corre-
sponding drawings were made in the same colours for the other
eye. If, on viewing these drawings in the stereoscope, each pair
combined in the usual manner, we should have a convex red
pyramid and a concave blue pyramid, the axes of both forming
Phil. Mag. 8, 4, Vol. 4. No. 25, Oct. 1852, R
242 Dr. Tyndall on the Progress of the Physical Sciences :
one and the same straight line. But it is altogether impossible
to obtain a relief in this case. A hexagon embracing a six-
pointed star is always obtained, the sides of which all consist of
red and blue lines running alongside each other in contact.
When this complicated figure was viewed through a blue glass,
the convex relief, bounded by red lines, started forth ; when a red
glass was used, the hollow pyramid with blue edges was observed.
In the first case the blue lines vanished almost completely in the
blue light; while the red, whose rays were intercepted by the
glass, acted as black, and became subjectively coloured red. In
the second case the red lines nearly disappeared in the red light ;
and the blue, subjectively coloured, combined themselves to a
relief.
To understand what has been here said regarding subjective
colouring, attention to the following facts is necessary. If the
diffused daylight be completely shut out from the eyes, and a
drawing in black outline on white ground be viewed through a
coloured glass, the relief is seen with black edges ; but when
the glass is held at some distance from the eyes, so that the dif-
fused daylight shall also reach them, the black hues assume a
vivid subjective colouring, which becomes stronger the longer
the drawing is regarded. When the glass is coloured blue by
cobalt, the lines appear red; when the glass is a ruby-red, the
outline appears bluish-green.
The result of the above experiment with the blue and red
pyramids is remarkable. Each eye has two drawings presented
to it, and a double combination is thus possible. When the
identity of outline is preserved by the eye, and no regard is paid
to the difference of tint, two plane figures composed of different
colours must be observed. This is the case when the intensity
of both colours is nearly the same. When, however, the intensity
is very different, such, for example, as that brought about by the
red and blue glasses in the case under consideration, the identity
of the outline is overcome by the tendency to form a relief.
The projection for one eye was drawn in white lines upon a
black ground, and for the other eye with black lines upon a white
ground. A most remarkable result was obtained by the stereo-
scopic combination of both. The relief started into existence
with surfaces which shone like graphite, having their edges
formed of dazzling white and deep black lines which run pa-
rallel and in contact with each other throughout. When the
black leaf with the white lines is placed before the left eye,
and the white leaf with the black lines before the right eye, the
white lines in the relief lie to the right of the black ones. When
the leaves are changed, the relative position of the black and
white hues is also changed ; hence the lines appear always pushed
Prof. Dove on the Stereoscopic Combination of Colours. 243
aside cross-wise. Exactly as in the case of black and white,
combinations of both of these with other colours are obtained,
and combinations of the latter with each other. To obtain the
combination of dioptric colours with white and with each other,
drawings in white outline on a black ground are made use of.
When white is to be combined with another colour, a glass of
the required tint is placed before one eye, while the drawing is
viewed by the other eye naked. When different colours are to
be combined, suitable glasses are placed before both eyes. The
most beautiful result is obtained when the colours produced
by a deep blue and a red glass are combined; the relief stands
forth illuminated with violet light and with splendid edges of
red and blue, which run alongside each other in contact. In
the case of colours which nearly approach each other, the edges
are also formed by those double and differently coloured lines.
One result is always observed,—the lines appear pushed aside
cross-wise ; that is, the colour observed by the left eye appears
to the right, and that observed by the right eye appears to the
left.
The following remarkable fact has been observed by M. Dove,
and his observation has been corroborated by others. The pro-
jections of a convex and concave pyramid for the right eye were
drawn upon the same base, and on a second leaf the projection
of a convex only for the left eye. In the stereoscope, therefore,
a convex pyramid was seen, and on the base of the same the
projection of aconcave one. When the ruby-red glass was brought
before the left eye, while the former drawing was regarded by the
naked right eye, both the pyramid and the projection were ob-
served; but it depended entirely on an act of volition whether
the pyramid was observed with red and white boundaries and
the projection in white lines, or the pyramid with white bound-
aries and the projection in red and white outline. It hence
appears that a projection as contour can combine itself with
another as colour to form a relief.
The same phenomena which we have observed with objective
colours exhibit themselves with subjective colours also. On
viewing the drawings formed in black outline on white ground
through the ruby-red glass with one eye, and through the glass
coloured blue by cobalt with the other, permitting the diffused
daylight at the same time to strike the eyes, the reliefis observed
with coloured double parallel lines as edges, as in the other in-
stances: the crossed position of the lines is also observed here ;
so that when the red glass is held before the left eye, and the
. blue glass before the right, the bluish-green lines appear to the
right of the red ;—it will be remembered that the subjective tint
R 2
244 Dr. Tyndall on the Progress of the Physical Sciences :
developed by the red glass is bluish-green, and by the blue
glass, red.
Why is it, then, that the red and blue lines cannot be made
to combine, but always lie alongside each other crossed in the
manner indicated ? M. Dove finds the explanation in the non-
achromatic nature of the eye. That the eye is not achromatic
has been known since the time of Fraunhofer ; but a very simple
way of proving the fact was discovered independently by M. Dove
and M. Plateau about twelve years ago. Ifthe flame of a candle
be viewed through a coloured glass which permits the ends of
the solar spectrum to pass through it, but extinguishes the middle,
at the distance of distinct vision a violet flame is observed. At
a greater distance a red flame is observed within a larger blue
one which embraces the former on all sides and becomes wider
the further we recede from the flame. Within the distance of
distinct vision, on the contrary, the violet flame is encompassed
by a sharp red rim. From a medium distance a long-sighted
eye sees the latter, and a short-sighted eye the former. Hence
the experiment furnishes us with a kind of optometer; to this
purpose M. Dove has applied it in hundreds of cases, and never
found a single individual whose eyes fulfilled the conditions of
achromatism at all distances. Acquainted with this fact, and
observing a certain analogy between it and his stereoscopic ex-
periments, he naturally sought the cause of the phenomena pre-
sented by the latter in the non-achromatic nature of the eye.
A fine white lme drawn upon a black ground was viewed
through the glasses used in the stereoscopic experiments. It
was ascertained that, to be plainly visible, it must be held at a
greater distance from the eye when the red glass is used than
when the blue glass is applied. Sir David Brewster has ob-
tamed an analogous result with pigments (Report of the British
Association, 1848, p. 48). A number of square pieces of gra-
dually decreasing size was cut from the same vividly-coloured
card, and placed one upon the other so as to form a pyramid
with ascending steps, all of the same height. Two such pyramids
were built, the one beside the other; the squares were blue and
red; one pyramid had a blue square for its base, the othera red
one. It was always found that a blue square placed upon a red
one appeared higher than a red square placed upon a blue one ;
so that in the building of the pyramids, each appeared by turns
to exceed the other in height. From this experiment it follows,
that at the distance of distinct vision the lines of convergence of
both eyes enclose a smaller angle in the case of red light than
in the case of blue. Hence if an observer, who sees equally well
with both eyes, have both colours presented to him in the ste-
~ Prof. Dove on the Stereoscopic Combination of Colours. 245
reoscope in the manner already described, the lines cannot coin-
cide, but will project themselves in directions which cross each
other upon a surface which does not pass through the point of
intersection of both directions.
M. Dove next goes on to consider the cause of the glistening,
which, for example, is observed on the surface of varnished
pictures, and which may be destroyed by quenching the
polarized rays with a Nichol’s prism. In every case in which a
surface appears thus shining, there is a reflecting layer, more or
less transparent, through which another body is viewed; the
glistening owes its origin to the combination of the rays reflected
from the surface and those which pass through the transparent
layer from the body behind. This is increased when the number
of alternations of the layers increases. Thus mica assumes a
metallic lustre, and layers of glass plates the appearance of
mother-of-pearl. In the projection of a truncated pyramid im-
tended for a certain eye, the section was coloured with a satu-
rated wash of blue; in the figure intended for the other eye, the
section was coloured yellow. At the moment of combination,
when the resultant green appeared, it seemed as if one layer of
colour had become transparent and that the other was seen
through it. When the coloured section was viewed through a
violet glass held before both eyes, the surface appeared like
polished metal.
These experiments are intimately connected with the phzeno-
mena of irradiation. They establish the fact, that the deport-
ment of black and white towards the eye is exactly similar to that
of two different colours. The lustre obtained by the combination
of black and white is peculiarly strong; so decided, indeed, that
some, and among others the writer of this report, compared it to
the lustre of lead glance or of tin, although the component white
and black were both perfectly dull and lustreless. According to
the explanation already given, one of these surfaces must appear
in advance of the other. The viewing of an object by the naked
eyes by different degrees of illumination with white light is ana-
logous to those experiments with coloured light, where the object,
to be distinctly seen, must be brought nearer in the case of blue
light than with red. A dark object will, under the same conditions,
appear further off than a white one, as the red surface appears
more distant than the blue. At the distance of distinct vision,
the flame of a candle, when viewed through the violet glass, which
permits the ends of the spectrum to pass and extinguishes the
middle, appears violet ; that is, the red flame is as large as the
blue. At the distance of distinct vision, a white object also ap-
ears of the same size as a black one; at a greater distance, the
lue flame embraces the red; that is, beyond the distance of
246 Dr. Tyndall on the Progress of the Physical Sciences :
distinct vision the blue flame is larger than the red one; and so
also beyond this distance, the white object on black ground
appears larger than the black object on white ground. In this
way the pheenomena of irradiation are connected by a chain of
experimental facts with chromatic phenomena, which directl
point the way to the explanation of the former. The complete
explanation is embraced by the proposition, that for a given di-
stance the capacity of accommodation of the eye is different for
white and black.
In a recent paper M. Dove has added some proofs to those
already given of the fact, that blue and red are plainly visible at
different distances. Beyond the point of distinct vision, a micro-
meter drawn in black lines upon a white ground appears as a gray
spot, when drawn in white lines on a black ground it appears asa
bright one. Ifa series of parallel white lines be viewed through
a blue glass, the observer gradually receding until the lines run
into each other and are no longer distinct, from this distance the
lines, if observed through a red glass, will appear quite distinct.
The reader may in this way easily satisfy himself that the distance
of distinct vision is considerably greater for red than for blue.
In the same way it may be plainly shown that the distance for
white is also greater than for blue. It is difficult to obtain pig-
ments of such equal intensity that their combination shall ex-
hibit lustre, but the lustre can be readily obtained as follows :—
A drawing in white lines upon a black ground is combined in
the stereoscope with another in black lines upon a white ground,
and viewed through a coloured glass held before both eyes.
With the ruby-glass and bright light the relief appears like
polished copper. In this way we learn that the results, as
regards lustre and irradiation, obtained with white and black, are
also true for any colours whatever.
It is known that a green spot on a red field, which is moved
quickly hither and thither, appears to oscillate. Wheatstone
has shown that a red heart on blue ground appears to oscillate
still more quickly ; hence the appearance is not to be referred
to the action of complementary colours, but to a difference of
refrangibility. Sir David Brewster was the first to observe on
geological maps that blue and red do not appear in the same
plane, and the reason of this M. Dove considers to be rendered
completely evident by his stereoscopic experiments. His expla-
nation of the fluttermg heart is as follows :—When the sheet is
moved in its own plane, the heart and the ground on which it
rests describe tangents of the same absolute length, but with
radi which the eye regards as different. The angular velocities
Prof. Dove on the relative Intensity of different Colours. 247
of both thus appear to be different, and hence the object seems
to oscillate upon the plane which bears it.
That yellow and red colours approach the nature of light more
than blue is an idea which may be traced throughout antiquity.
In the common language of the Germans, this is expressed by
the terms ‘ screaming yellow,’ ‘ burning red,’ in contradistinction
to ‘deep blue.’ This notion is corroborated by photometric ex-
periments. But with these well-known phenomena, another
stands apparently in complete contradiction. It has often oc-
curred to M. Dove, on quitting a picture gallery on the approach
of night, when he happened to cast a parting glance upon the
paintings, the red colour had altogether disappeared while the
blue appeared in all its strength. Artists are well aware of this
fact ; at least, on questioning such, M. Dove has always found
his own observation corroborated.
The stereoscopic experiments already described furnish an
accurate and beautiful method of observing this fact. On ap-
plying two glasses, one of which permits the homogeneous
blue rays to pass, and the other the homogeneous red ones, the
relief, as already stated, appears with beautiful edges of red and
blue lines which run alongside each other. Although when the
light is intense the red lines appear much the most vivid, the
blue glass made use of being more than ten times the thickness
of the red one, still as the twilight advances the red becomes
weaker and weaker ; it finally disappears altogether, and instead
of the relief formed by the combination of the red and blue out-
line, the blue alone is observed, as projection, upon its proper leaf.
If two red glasses be now placed before the openings of the ste-
reoscope, nothing whatever is seen; while with two blue glasses
the relief appears in blue lines, and remains distinctly visible for
a quarter of an hour longer. Thus the fact of the earlier disap-
pearance of the red rays is placed beyond a doubt :—how is this
to be accounted for ?
It is known that weak impressions on the organs of sense
singly may arouse no consciousness, but do so where they are
quickly and uniformly repeated. On this account the string of the
contra-basso must have a wider amplitude than that of the violin,
inasmuch as the diminished number of vibrations demands a
greater energy to render them heard. Thus also if we wish to make
ourselves heard without great effort, we speak in a higher tone ;
and hence it is that when the deep voice of the seaman, strength-
ened by the speaking trumpet, is lost in the storm, the shrill
pipe of the boatswain still pierces through the howl of winds and
roar of waves. Savart has shown, by means of the toothed-
wheel, that the limit of sensibility of the ear for grave tones is
extended by strengthening the strokes. The complete similarity
248 Dr. Tyndall on the Progress of the Physical Sciences.
of the vibrations causes the most perfect summation of impres-
sions, because the interferences which take place when the times
of oscillation are different then fall away. This uniformity
renders the tone pure, and, in the case of colours, renders them
homogeneous. Blue stands in the same relation to red that a
higher tone occupies with regard to a deeper one. With blue
the vibrations of the retina are more frequent than with red, as
the vibrations of the tympanum are more frequent with a high
tone than with a deep one. Now it is proved that with deep
tones the limit of sensibility becomes contracted when the tones
become weaker; and this is completely analogous to the case,
that by decreasing brightness, the limit of sensibility for the red
rays should become narrower. Hence with weak illumination,
red, as a colour, disappears ; while blue, on account of the greater
frequency of its vibrations, remains longer visible.
“In this way,” observes the Professor, “I explain to myself
the wonderful phenomenon, regarding which, however, strange to
say, nobody has expressed wonder, that by the weak light of the
stars the blue of the firmament is rendered distinctly visible.”
Herewith is connected the fact, that a prismatic spectrum ob-
tamed from light which has passed through a narrow aperture
has its colours towards the red end comparatively stronger when
the light is intense. This is peculiarly plain if the spectrum be
viewed through a dichromatic medium which permits the ends of
the spectrum to pass and extinguishes its middle, thus enabling
both ends to be immediately compared with each other. The
dark space beyond the red end of the spectrum, where the calo-
rific effect is a maximum, would probably become distinctly
visible if the intensity of the sunlight were considerably increased
by concentration. This would be the experiment of Savart ap-
plied to colours. Probably to the subject we are considering
belong the experiments of Sir David Brewster on the lines of
Fraunhofer in this portion of the spectrum ; although the facts
observed appear to be referred to the destruction of spherical
aberration, and not to the illuminating power of the telescope
applied. In a similar manner the limits of action on an iodized
silver plate at the violet end of the spectrum become expanded
with increasing brightness.
If a person pass suddenly from a brightly illuminated room
into a very dark one, and then approach the place through which
the light enters until blue becomes distinct, it will be found that
red is at first much more vivid. The eye must remain for some
time in the darkened xoom before the retina becomes so sensitive
as in deep twilight. When this is attained, the person may re-
cede to a distance from the place where the light enters where
the blue is still distinctly visible, and find that the red has
M. Quetelet on Atmospheric Electricity. 249
vanished completely. Another remarkable fact observed by
M. Dove was, that among the numbers to whom he showed, in
bright daylight, the stereoscopic relief with blue and red edges,
one declared that he saw only the drawing with blue lines, as
through the red glass he could see nothing whatever. The eyes
of this individual in bright daylight were in the same condition
as a pair of normal eyes by twilight.
XXXVIII. On Atmospheric Electricity, according to the Obser-
vations at Munich and Brussels. Letter of M. QuETELET to
M. Lamont, Director of the Observatory at Munich*.
| HAVE long upbraided myself for not having replied to your
obliging letter, wherein you requested me to make compa-
rative observations on the electricity of the air. My purpose
was to request you, in the first place, to give me some instruc-
tions relative to the instruments which you have made use of,
and to the results at which you have arrived, so as to assure
myself that our observations might be compared with each other.
I have been partially able to satisty my desire in this respect by
reading your description of the instruments used at Munich
which you have been kind enough to send me, as well as the
article inserted im the 4th Number of Poggendorff’s Annalen
for 1852.
In running over the table of your observations from 1850 to
1851, I have been struck with the small resemblance which sub-
sists between your numbers and those obtained at Brussels: to
enable you to judge of this, I will set side by side the monthly
results which you give for the hour of noon, and those which I
have obtained myseif for the same hour. Your results are con-
tained in the second column, a, of the following table; mine are
contained in the third column, 6. You have seen from my first
investigation, published in the month of June 1849, that the
numbers immediately observed by the electrometer of Peltier do
not express the absolute values of the electric tension which are
given in the following column, J’, according to each day’s reduced
observations ; hence the last numbers are those which ought to
be compared with yours. In order to facilitate the comparison,
I have reduced all the values to the same unit, to the monthly
mean deduced from the results of the twelve last months which
occur in the table in the columns a, £, and f’.
* From vol. ix. of the Bulletins de ? Académie Royale de Belgique.
Communicated by the Author.
250 M. Quetelet on Atmospheric Electricity,
Observed numbers. Reduced numbers.
Months. Munich. Brussels. Munich. Brussels.
a. d. b. , B. Bt.
May (1850) ...| 3°08 19 145 0-72 0-62 0-91
TIONG i cetenewskses 2°80 14 25 0-65 0-45 0-16
DY esicivs rae nce sss 3:28 12 22 0-76 0:39 0-14
August ......... 3°72 22 84 0:87 071 0:52
September ...... 3:23 28 96 0-75 0-91 0°60
October ......... 4:88 36 153 1-14 I 6 0:96
November ...... 5:51 35 162 1:28 114 1:01
December ...... 7:20 45 272 1-68 1:46 1:70
January (1851).) 6-34 50 440 1:48 1:63 2°78
ebruary......... 98 51 470 1:39 1-66 2°93
Mareh.deacecuens 5:18 28 106 1-21 0-91 0-66
Aprils. .sde 3-04 27 95 0-71 0:88 0°59
May: fese se 2°56 21 53 0-60 0:68 0°33
Jone) Scie... 3-11 19 45 0-72 0:62 0:28
ULYSt sccacseste es 3°15 20 50 0-73 0°65 0-31
AUguSt .....000 3:03 21 53 0-71 0°68 0°33
September ...... 2°85 24 65 0:66 0-78 0-41
October ......... 3°59 29 104 0:83 0:94 0:65
If Munich and Brussels were in the same electric condition,
the numbers @ and #!' would be equal, or at least would present
the same fluctuations. Thus, similar to all physicists who have
examined atmospheric electricity, we find that the electric tension
is stronger in winter than in summer; but the ratio which you
obtain is hardly that of 2 to 1, while for Brussels it is about
9 to 1. Isthis enormous difference due to local causes ? I hardly
believe it. As you have not published, up to the present time,
the summary of your observations, and have not entered into
details with regard to the manner according to which your means
were calculated, I am not aware if all the observations without
distinction have been brought into the calculation or not.
In this state of doubt I was desirous to compare our results
with others obtained in different localities; unhappily, however,
I know but one single series of observations on this interesting
but neglected portion of meteorology ; these are the observations
made at Kew by Mr. Ronalds from 1845 to 1847*. I give them
in the following table with the general results of Brussels, for the
seven years from 1845 to 1851. The observations at Munich,
Brussels and Kew, have reference to the hour of noon; they
have been rendered comparable in three special columns by
taking for unity the monthly mean.
* Report of the 19th Meeting of the British Association held at Bir-
mingham in September 1849; see the memoir of Mr. But, p. 113.
according to the Observations at Munich and Brussels. 251
Observed numbers. Proportional numbers. Brussels.
Months.
Brussels | Kew. |Munich.|Brussels.| Kew. |Munich-| Proportional] Observed
numbers. | numbers.
January ...| 518 | 182-4 | 634 | 2-82 | 2-40] 148] 1-61 50
February...| 333 | 179:3 | 5-98 181 | 2-35 | 1:39 1-45 45
March...... 169 58-2 | 5:19 0:92 | 0:76 | 1:21 1:13 35
1 4! 105 40-7 | 3-04 057 | 0:54 | 0-71 0:77 24
May | o. 027 81 413 | 2-56 0-44 | 055 | 0-60 0-65 20
June ...... 40 26°38 | 3-11 0:22 | 0:35 | 0:72 0:55 V7
4 iS eee 42 318 | 3-15 0:23 | 0-42 | 0-73 0-55 17
August ...| 62 | 285 | 3:03 | 0:34 | 038 | 0-71 0:68 21
September.| 74 31-0 | 2°83 0-40 | 0-41 | 0-66 0°81 25
October ...| 140 65-1 | 3:59 0-76 | 0:85 | 0°83 1:03 32
November .| 230 805 | 5:51*| 1:25 | 1:34] 1-28 1:29 40
December .| 412 | 1263 | 7-20*| 2:24 | 1-65 | 1-68 1:48 46
Neary 503. 2) 184 74-3f| 4:29 | 12:00 | 12-00 | 12:00 | 12-00 31
The result of these observations is, that the electric tensions
in winter and summer are to each other, for Brussels as 9 to 1,
for Kew as 6 to 1, and only as 2 to 1 for Munich. Differences
of such magnitude, if they really exist, possess the highest scien-
tific interest ; if they are due to the imperfection of the instru-
ments, they merit scarcely less attention.
It is essential, in the first place, to examine if the cause of
these differences resides in the manner in which the observations
have been collected, or in their mode of calculation.
Although applying the instrument of Peltier, with some mo-
difications, you have pursued a different method from that fol-
lowed by the above-named physicist to render your results com-
parable. M. Peltier estimated the value of the degrees of his
instrument by transferring the electric charges directly to Cou-
lomb’s balance ; and he indicated by a table the electric tension
corresponding to every angle of deviation @ of the moveable
needle of his electrometer.
I have employed a similar table based upon a principle some-
what different, that of dividing the electricity between two balls
of equal surface. I have found that the table calculated in this
manner for the degrees of my electrometer, agrees perfectly with
that calculated by Peltier from his experiments for the same in-
strument. The two methods of experiment thus exhibit the
same results.
You have preferred following another way: you have had
recourse to calculation ; and, admitting the hypothesis that the
electricity is uniformly distributed in the conductor and in the
moveable needle, you find that the electric tension 7 is very nearly
proportional to the angle ¢; so that we may take y=$+F(¢),
* These numbers belong to 1850, the preceding to 1851.
+ The notice gives the number 75°4, which is not the mean of the year.
252 M. Quetelet on Atmospheric Electricity.
where F(#) represents a small correction dependent on the
angle @. You consider that this correction, and that due to the
torsion of the fibre, may be neglected through the extent of an
are of about 65°, which is represented by nine divisions of your
scale.
This result of your calculation does not agree with the results
deduced from observation by M. Peltier and me, even for feeble
electric tensions. In admitting it, the values 8 and #! of the
first table relative to Brussels would be sensibly equal, which is
far from being the case. This is an essential point, to which I »
permit myself to direct your attention.
Taking, with you, the values directly observed at Brussels as
representing the electric tensions of the air without applying any
correction, I find that my numbers come very near to yours, and
that the ratio of summer to winter is less than that of 3 to 1;
but is this substitution legitimate ?
Permit me to submit to you one other observation: you say
at the fifth page of the description of the new imstruments and
apparatus at the Observatory of Munich, that the electrometer
which you have made use of is constructed after the principle of
the instrument of Peltier used at the Observatory of Brussels ;
but that the method pursued to determine the electric tensions
of the air from the readings of the instrument is essentially dif-
ferent. I find, in fact, in your description all the principal parts
of the electrometer which has served for my observations, and
which was constructed for our observatory by M. Peltier; I
remark, however, one important difference in the proportions:
the ball which surmounts my instrument is considerably larger
than yours, at least if I may infer from the drawing, for you
have given no dimensions.
I could have desired to know the motives which have induced
an observer so skilful as yourself to reduce the ball to a dimen-
sion so small relatively to the stem which it surmounts ; it seems
to me that this reduction must have for its effect a reduction of
the sensibility of your apparatus. It is in this sense that M. Pel-
tier has remarked, that the induced electricity coerced at the
extremity of the stem leaves to that of the contrary name the
rest of the length whereon to distribute itself; but the longer
the stem is relatively, the less will be the’ portion of it which
returns to the indicating needle, and the less will be the diver-
gence.
You will excuse me, my dear confrére, for thus submitting to
you my doubts. It appears to me of the greatest importance to
recognise the true cause of the errors, if such exist ; and I do it
with all the confidence with which your talents, and the love of
truth which auimates both of us, inspire me.
Brussels, August 5, 1852.
[ 253 ]
XXXIX. On the state of Static and of Dynamic Electricity during
several heavy Showers observed at Brussels on the 14th of June
1852. By A. Querutut, Membre de ? Académie Royale de
Belgique*.
| KNOW but few observations made simultaneously during
rains and storms on the static and the dynamic electricity of
the air. These two meteorological elements are, notwithstanding,
of the greatest importance, and rarely march together; that is
to say, during powerful electric tensions it often occurs that no
current is observed; and, on the contrary, very decided currents
sometimes exist while the electrometer exhibits nothing extra-
ordinary.
The showers of which I am about to render an account have
presented some peculiarities which appear to me to be worthy of
attention. The dynamic electricity was observed by means of a
very sensible Gourjon’s galvanometer ; one of the wires was con-
nected with the earth, and the other with a conductor placed on
the roof of the observatory. The static electricity was observed
by means of the atmospheric electrometer of Peltier; the obser-
vations were made on the summit of one of the turrets of the
observatory, and on a small platform placed at an altitude higher
than the surrounding objects.
On the 14th of June 1852 it had rained at different intervals
during the morning; 2°55 millimetres of water were collected.
Towards noon thick clouds floated in the inferior regions of the
atmosphere, between which portions of the heaven and of cwmuli
were visible, whose splendid white» contrasted with their gray
and slightly copper-coloured hues. The Centigrade thermo-
meter marked 13°-6 and the barometer 739°73 millimetres. The
pressure of the atmosphere was passing a state of minimum at
the time. The direction of the clouds, in accordance with that
of the weathercock, indicated a moderate wind in the direction
of W.S.W.
The electrometer of Peltier, interrogated at various times and
at intervals of 2 to 3 minutes, indicated successively —19°,
—30°, —35°, —40°, —30°. A shower was observed to the
W.S.W., and during the last observation a small cloud which
crossed the zenith let fall some drops of rain. It was then about
10 minutes past 12 o’clock at noon, and the nimbus caused by
the rain to the W.S.W. approached insensibly.
I descended to invite M. Bouvy, one of my assistants, to follow
the indications of the galvanometer of Gourjon, while I, by means
of Peltier’s electrometer, might continue my observations on the
summit of one of the turrets of the observatory ; my object being
* From vol. xix. No. 7 of the Bulletins de V Académie Royale de Belgique.
254 M. A. Quetelet on the state of
to form a judgement of the respective states of the static and
dynamic electricity of the air during the fall of rain which would
soon take place. I then quickly reascended.
Towards 125 15™ I recommenced my electric observations,
which I continued at intervals of 2 to 3 minutes; I obtained
successively —46°, —57°, —61°, —64°, —65°; during this
last observation, the nimbus, which approached more and more,
touched the zenith by its nearest edge; the wind became very
sensibly increased, and the first drops of rain commenced to fall ;
the electrometer indicated —69°; and at the moment when the
shower descended —75°, it was 124 33™; two minutes after-
wards the rain fell with less violence, and the electrometer marked
—74°, then —73°. At 125 37™ the darkest portion of the
nimbus had passed the zenith, and the rest of the cloud yielded
no more water; but a fresh shower was forming itself to the south
and south-east, the electrometer marked 0°; consulted imme-
diately afterwards it indicated + 75°. I would have observed the
time, but observed with astonishment that my watch had stopped.
While the rain which set in to the south extended itself to
Brussels, but yielding very little water, it continued to develop
itself with intensity towards the horizon, while in the mean
time new showers were forming to the east, the north-east, and
north. I estimate that the hour was about 12 48™; the rain-
cloud which was in the zenith enlarged itself, and yielded water
for a few minutes; the electrometer continued to be observed
and ceased not to indicate + 75°, the highest degree to which it
attamed*.
At a little past 1 o’clock #he last edge of the cloud touched
the zenith ; the sun shone at intervals; the rain was still very
heavy between the 8. and E.N.E., the electrometer had not ceased
to indicate + 75°; a little after it descended to + 72°, the zenith
commenced to clear itself; the clouds floated away im different
directions; the wind in the inferior regions was still between
the S.W. and the W.S.W.,; and the rain-clouds formed to the
S.E. approached; their edges were strongly indented.
Towards 15 10™ J descended and received the observations
made by M. Bouvy, who being obliged to leave, had ceded his
place to another observer. Here are the indications which he
obtained from the galvanometer while I coliected those of the
electrometer.
Up to two minutes after the commencement of the rain, the
galvanometer had not ceased to preserve its ordinary position of
* In the course of repairs recently made on the instrument, the scale
over which the needle moved was found to be a little contracted. I always
remarked, that by the rapidity of the oscillations of the needle I could
judge of the moment when the electric tension was a maximum.
Static and Dynamic Electricity during rain. 255
equilibrium at 5° A*; the needle commenced to move at 124 35™,
and oscillated between 19° B and 1° A; at 125 35™ its oscilla-
tion extended through an arch comprised between 1° B and
34° B, then between 80° B and 10°5 A. At 125 36™-5 the
rain ceased, and the needle oscillated round its ordimary position
of equilibrium from 0° to 10° A; afterwards from 2°°5 to 9° A;
and finally came to rest at 5°°5 A.
A descending current was thus exhibited, but only during the
descent of the rain, and the needle was brought to a state of
repose at; the moment when the electricity changed its sign m
such a remarkable manner. The oscillations recommenced at
12 48™, contemporaneous with the second rain, which was very
light and of very short duration ; the first impulsion carried the
needle from 8° to 12° A, it then oscillated round its position of
equilibrium from 1° to 8° A, then from 3° to 7° A; the direction
of the current had changed, it was now ascending. A new change
took place afterwards; the needle oscillated from 5° B to 4° A,
then from 2° B to 4° A up to 1 o’clock, when it was again
arrested at 5° A.
I was particularly astonished to learn that the watch of
M. Bouvy had stopped almost at the same instant as my own,
that is at 12 37™, at the moment when the sudden change of
sign of the atmospheric electricity took place. Was it accidental,
or an effect of the electricity ? This it will be difficult to decide ;
I confine myself to the statement of facts.
Setting out from 15 15™, the galvanometer was continually
observed, but it did not forsake its position of equilibrium; I
returned to my electrical observatory and found the electrometer
always indicating +75°. The clouds continued to move in dif-
ferent directions; they were observed to advance towards each
other, to stop, to attract each other, and then mingle together.
The rain-clouds which came from the 8.E. united themselves
insensibly with others from the N.W., the electrometer marked
+72°. The zenith became overcast, some drops fell, +73°;
then at 1» 24™ the rain turned towards the EH. +72°. The
clouds towards the zenith and the 8.W. were so thin as to per-
mit of the solar dise being seen through them, + 64°.
At 15 28™ a little rain; the clouds were directed from the
S.W. to the N.E. in the sense indicated by the weathercock.
The electrometer indicated + 61°; we continued to have glimpses
of the sun. At 14 34™ the sun reappeared, the zenith became
clear, and the electrometer marked zero ; the rain had turned to
the east.
At 1" 56™ the zenith became again charged ; the electrometer
* When the head of the needle points towards B, the current is de-
scending ; when towards A, the current ascends,
256 Prof. Thomson on the Mechanical Action
indicated successively —2°, —18°, —28°, —15°. At 1h 45m
the rain still fell in different directions, but not at Brussels; the
sun shone at intervals, and the electrometer marked —6°.
I ought to remark, that during the showers not a single peal
of thunder was heard, and not the smallest flash of lightning
was visible. .
The example which I have just cited shows how, during the
same shower, according to the instant at which an observation is
made, we may obtain either positive or negative electricity ; this
electricity is very energetic durmg the showers. If the obser-
vation is made at the moment when the sign changes, it may
appear to be nearly null; these inversions, it may be remarked,
are always of short duration.
XL. On the Mechanical Action of Radiant Heat or Light: On the
Power of Animated Creatures over Matter: On the Sources
available to Man for the production of Mechanical Effect. By
Professor WiLtLt1aM THomson.*
On the Mechanical Action of Radiant Heat or Light.
- is assumed in this communication that the undulatory
theory of radiant heat and light, according to which light
is merely radiant heat, of which the vibrations are performed in
periods between certain limits of duration, is true. ‘“ The che-
mical rays,” beyond the violet end of the spectrum, consist of
undulations of which the full vibrations are executed in periods
shorter than those of the extreme visible violet light, or than
about the eight hundred million millionth of a second. The
periods of the vibrations of visible light le between this limit
and another, about double as great, corresponding to the ex-
treme visible red light. The vibrations of the obscure radiant
heat beyond the red end are executed in longer periods than
this ; the longest which has yet been experimentally tested being
about the eighty million millionth of a second.
The elevation of temperature produced in a body by the in-
cidence of radiant heat upon it is a mechanical effect of the dy-
namical kind, since the communication of heat to a body is
merely the excitation or the augmentation of certain motions
among its particles. According to Pouillet’s estimate of heat
radiated from the sun in any time, and Joule’s mechanical equi-
valent of a thermal unit, it appears that the mechanical value of
the solar heat incident perpendicularly on a square foot above
* From the Proceedings of the Royal Society of Edinburgh, February,
1852, Communicated by the Author.
of Radiant Heat or Light. 257
the earth’s atmosphere is about eighty-four foot-pounds per
second.
Mechanical effect of the statical kind might be produced from
the solar radiant heat, by using it as the source of heat im a
thermo-dynamic engine. It is estimated that about 556 foot-
pounds per second of ordinary mechanical effect, or about the
work of “one horse power,” might possibly be produced by such
an engine exposing 1800 square feet to receive solar heat, durmg
a warm summer day in this country ; but the dimensions of the
moveable parts of the engine would necessarily be so great as to
occasion practical difficulties in the way of using it with cecono-
mical advantage that might be imsurmountaple.
The chemical effects of light belong to the class of mechanical
effects of the statical kind ; and reasoning analogous to that in-
troduced and experimentally verified in the case of electrolysis by
Joule, leads to the conclusion that when such effects are produced
there will be a loss of heating effect in the radiant heat or hght
which is absorbed by the body acted on, to an extent thermally
equivalent to the mechanical value of the work done against
forces of chemical affinity.
The deoxidation of carbon and hydrogen from carbonic aad
and water, effected by the action of solar light on the green parts
of plants, is (as the author recently found was pointed out b
Helmholz* in 1847) a mechanical effect of radiant heat. In
virtue of this action combustible substances are produced by
plants ; and its mechanical value is to be estimated by deter-
mining the heat evolved by burning them, and multiplying by
the mechanical equivalent of the thermal unit. Taking, from
Liebig’s Agricultural Chemistry, the estimate 2600 pounds
of dry fir-wood for the annual produce of one Hessian acre, or
26,910 square feet of forest land (which in mechanical value
appears not to differ much from estimates given in the same
treatise for produce of various kinds obtaimed from cultivated
land), and assuming, as a very rough estimate, 4000 thermal
units Centigrade as the heat of combustion of unity of mass of
dry fir-wood, the author finds 550,000 foot-pounds (or the
work of a horse-power, for 1000 seconds) as the mechanical value
of the mean annual produce of a square foot of theland. Taking
50° 34! (that of Giessen) as the latitude of the locality, the author
estimates the mechanical value of the solar heat which, were none
of it absorbed by the atmosphere, would fall annually on each
square foot of the land, at 530,000,000 foot-pounds ; and infers
that probably a good deal more, zp55 of the solar heat, which
actually falls on growing plants, is converted into mechanical
effect.
* Ueber die Erhaltung der Kraft, von Dr. H. Helmholz. Berlin, 1847.
[A translation of this essay will appear in the First Part of the New
Series of the Scientific Memoirs.—Ep.
Phil, Mag.8. 4. Vol. 4. No. 25. Oct. 1852. S
258 Prof. Thomson on the Power of
When the vibrations of light thus act during the growth of
plants, to separate, against forces of chemical affinity, combustible
materials from oxygen, they must lose vis viva to an extent equi-
valent to the statical mechanical effect thus produced; and
therefore quantities of solar heat are actually put out of existence
by the growth of plants, but an equivalent of statical mechanical
effect is stored up in the organic products, and may be repro-
duced as heat, by burning them. All the heat of fires, obtained
by burning wood grown from year to year, is in fact solar heat
reproduced.
The actual convertibility of radiant heat into statical mecha-
nical effect, by inanimate material agency, is considered in this
paper as subject to Carnot’s principle ; and a possible connexion
of this principle with the circumstances regarding the quality of
the radiant heat (or the colour of the light), required to produce
the growth of plants, is suggested.
On the Power of Animated Creatures over Matter.
The question, “ Can animated creatures set matter in motion
in virtue of an inherent power of producing mechanical effect ?”
must be answered in the negative, according to the well-esta-
blished theory of animal heat and motion, which ascribes them
to the chemical action (principally owidation, or a combustion at
low temperatures) experienced by the food. A principal object
of the present communication is to point out the relation of this
theory to the dynamical theory of heat. It is remarked, in the
first place, that both animal heat and weights raised or resistance
overcome, are mechanical effects of the chemical forces which act
during the combination of food with oxygen. The former is a
dynamical mechanical effect, bemg thermal motions excited ; the
latter is a mechanical effect of the statical kind. The whole me-
chanical value of these effects, which are produced by means of
the animal mechanism in any time, must be equal to the mecha-
nical value of the work done by the chemical forces. Hence,
when an animal is going up-hill or working against resisting
force, there is less heat generated than the amount due to the
oxidation of the food, by the thermal equivalent of the mecha-
nical effect produced. From an estimate made by Mr. Joule, it
appears that from } to 4 of the mechanical equivalent of the
complete oxidation of all the food consumed by a horse may be
produced, from day to day, as weights raised. The oxidation of
the whole food consumed being, in reality, far from complete, it
follows that a less proportion than 2, perhaps even less than 2,
of the heat due to the whole chemical action that actually goes
on in the body of the animal, is given out as heat. An estimate,
according to the same principle, upon very imperfect data, however,
is made by the author, regarding the relation between the thermal
and the non-thermal mechanical effects produced by a man at
Animated Creatures over Matter. 259
work; by which it appears that probably as much as } of the
whole work of the chemical forces arising from the oxidation of
his food during the twenty-four hours, may be directed to raismg
his own weight, by a man walking up-hill for eight hours a day ;
and perhaps even as much as } of the work of the chemical forces
may be directed to the overcoming of external resistances by a
man exerting himself for six hours a day in such operations as
pumping. In the former case there would not be more than 2,
and in the latter not more than 3 of the thermal equivalent of
the chemical action emitted as animal heat, on the whole, during
the twenty-four hours, and the quantities of heat emitted during
the times of working would bear much smaller proportions re-
spectively than these, to the thermal equivalents of the chemical
forces actually operating during those times.
A curious inference is pointed out, that an animal would be
sensibly less warm in going up-hill than in going down-hill, were
the breathing not greater in the former case than in the latter.
The application of Carnot’s principle, and of Joule’s discoveries
regarding the heat of electrolysis and the calorific effects of mag-
neto-electricity, is poimted out; according to which it appears
nearly certain that, when an animal works against resisting force,
there is not a conversion of heat into external mechanical effect,
but the full thermal equivalent of the chemical forces is never
produced ; in other words, that the animal body does not act as a
thermo-dynamic engine ; and very probable that the chemical forces
produce the external mechanical effects through electrical means.
Certamty regarding the means in the animal body by which
external mechanical effects are produced from chemical forces
acting internally, cannot be arrived at without more experiment
and observation than has yet been applied; but the relation of
mechanical equivalence, between the work done by the chemical
forces, and the final mechanical effects produced, whether solely
heat, or partly heat and partly resistance overcome, may be as-
serted with confidence. Whatever be the nature of these means,
consciousness teaches every individual that they are, to some ex-
tent, subject to the direction of his will. It appears, therefore,
that animated creatures have the power of immediately applying,
to certain moving particles of matter within their bodies, forces
by which the motions of these particles are directed to produce
desired mechanical effects.
On the Sources available to Man for the production of Mechanical
Effect.
Men can obtain mechanical effect for their own purposes either
by working mechanically themselves, and directing other animals
to work for them, or by using natural heat, the gravitation of
descending solid masses, the natural motions of water and air,
$2
260 Prof. Thomson on the Production of Mechanical Effect.
and the heat, or galvanic currents, or other mechanical effects
produced by chemical combination, but in no other way at pre-
sent known. Hence the stores from which mechanical effect may
be drawn by man belong to one or other of the following
classes :—
I. The food of animals.
II. Natural heat.
III. Solid matter found in elevated positions.
IV. The natural motions of water and air.
V. Natural combustibles (as wood, coal, coal-gas, oils, marsh
gas, diamond, native sulphur, native metals, meteoric iron).
VI. Artificial combustibles (as smelted or electrolytically depo-
sited metals, hydrogen, phosphorus).
In the present communication, known facts in natural history
and physical science, with reference to the sources from which
these stores have derived their mechanical energies, are adduced
to establish the following general conclusions :—
1. Heat radiated from the sun (sunlight being included in this
term) ts the principal source of mechanical effect available to man*.
From it is derived the whole mechanical effect obtained by means
of animals working, water-wheels worked by rivers, steam-
engines, and galvanic engines, and part at least of the mechanical
effect obtamed by means of windmills and the sails of ships not
driven by the trade-winds.
2. The motions of the earth, moon, and sun, and their mutual
attractions, constitute an important source of available mecha-
nical effect. From them all, but chiefly, no doubt, from the
earth’s motion of rotation, is derived the mechanical effect of
water-wheels driven by the tides. The mechanical effect so
largely used in the sailing of ships by the trade-winds is derived
partly, perhaps principally, from the earth’s motion of rotation,
and partly from solar heat.
3. The other known sources of mechanical effect available to
man are either terrestrial—that is, belonging to the earth, and
available without the influence of any external body,—or me-
teoric,—that is, belonging to bodies deposited on the earth from
external space. Terrestrial sources, including mountain quarries
and mines, the heat of hot springs, and the combustion of native
sulphur, perhaps also the combustion of all inorganic native com-
bustibles, are actually used; but the mechanical effect obtained
from them is very inconsiderable, compared with that which is ob-
tained from sources belonging to the two classes mentioned above.
Meteoric sources, including only the heat of newly-fallen meteoric
bodies, and the combustion of meteoric iron, need not be rec-
koned among those available to man for practical purposes.
* A general conclusion equivalent to this was published by Sir John
Herschel in 1833. See his Astronomy, edit. 1849, § (399).
bias ies es)
da; dea; ada; DB; ef
+2 ala; ala; ala; bl; ol!
B; B'; B"; 0; 0
V3 WA Pies. 035.0
* Any quantities might be substituted instead of 2 in the places occupied
by the figure in the above determinant, as such terms do not influence the
result; this figure is probably, however, the proper quantity arising from
the application of the rule, because (as all who have caleulated with deter-
minants are aware) the value of the determinant represented by a matrix
of no places is not zero but unity.
Phil, Mag. 8, 4, Vol, 4. No, 26. Nov. 1852. Z
338 Mr. J. J. Sylvester on Staudt’s Theorems
To arrive, for instance, at the latter of these two forms, we
have only to write the two given matrices under the respective
forms
a:b her OB we 0:0) oBiey
ad }} ¢e 0 O ae 00 fr
ql! pl cl 0) 0) al! 0 0 p" of!
O20 05k O Opt Oe 0 .20
0 0%:0 0 1 OntOm Ono
and then apply the ordinary rule of multiplication. So, again,
to arrive at the first of the above written two forms, we must
write the two given matrices under the respective forms
G0 Biyo oD @. oe Date
GEO. OOO Tan que ape TO we
a! Bb" oO a! Bl Oy!
0 DO el 0 0) AsO
and proceed as before.
This rule is interesting as exhibiting, as above shown, a com-
plete scale whereby we may descend from the ordinary mode of
representing the product of two determinants to the form, also
known, where the two original determinants are made to occupy
opposite quadrants of a square whose places in one of the re-
maining quadrants are left vacant, and shows us that under one
aspect at least this latter form may be regarded as a matrix bor-
dered by the two given matrices.
A second but obvious theorem requiring preliminary notice is
the following, viz. that the value of the determinant to the matrix
By 588 O), gy oe8 Mins 2
43,15 41,23 »0+ Gan; 1
Gni3 Unj23 +++ Anns 1
Ale Relaciies Moston O
is the same as the value of the determinant to the matrix
Ai; Aj, 23 tae Ay ies 1
As 13 As, 23 te Ae es 1
An; Anas +++ Anns 1
- BSE s net ]tge cong)
where in general
A,, s=Ay,gt h,-+ he
hy, higy +++ hy and ky, ka... ky being any two perfectly arbitrary
339
series of quantities. This simple transformation is of course
derived by adding to the respective columns in the first matrix
the last column (consisting of units) multiplied respectively by
hy, ha ...h,, 0; and to the respective lines, the last line (con-
sisting of units) multiplied respectively by /,, eee eg
Suppose, now, that we have two tetrahedrons whose volumes
are represented respectively by one-sixth of the respective deter-
concerning the contents of Polygons and Polyhedrons.
minants
; By Prose | |b BG Jd
® Ye % 1 ote Gs tata al
® Y3 % 1 Es ng & 1
Ly Ye % 1 fi iQ 1
@,5 Yj» 2, representing the orthogonal coordinates of the point r
in one tetrahedron, and & , 7,, § the same for any point (r) in
the other.
By the first theorem their product may be represented
(striking off the last column only from each matrix) by the
matrix
2mE,; BaF; Zax&; La,E,; 1
ZHe,; Le; Vookg; Daeok,; 1
2mE,; XHaeQ; Dtseg; Vayf,; 1
Dmg; Lays Larges; aE, 5 1
qt; i Ls ing 0)
where, in general, any such term as =z, . —. represents
Hp E,+Y,+ +2, +
Again, by virtue of the second theorem, adding
~ 53a; m7 5 Bad sp 5 Bass = 5 hae
to the respective lines, and
Sete G 1 a ae 1 See L eeaae!
528 3 — 526, 3 — 528s 3 — 5%,
to the respective columns, the above matrix becomes (after a
change of signs not affecting the result) the —ith of
(X(x,—&,)?; & (2, —&,)?; 2 (x, —&,)*; 2 (x, —&,)?; 1
2(v.—&,)?; 2% (%_—£q)? ; > (%2—&,)* ; 2 (%.—&,)*; 1
=(v3—&,)* ; 2% (#3—&,)?; = (x3—&)?; >(v,—&,)?; 1
2 (a4—&.)?; = (x4— &)? ; 2(wy—€,)?; 1
=(t4—£,)?;
1; 1; 1; 1; 0
or calling the angular points of the one tetrahedron a, b, ¢, d,
Z2
340 Mr. J. J. Sylvester on Staudt’s Theorems
and of the other p, g, 7, s, 8x 36, i. e. 288 times, their product
is representable by —1x the determinant
(ap); (aq); (ar)? (as)?;
(bp)? (bq)*5 (br)? (bs)*;
(—p)?s (eg)? (er)? Ces)? 5
(dp)? ; (dg)? (dr)* (ds)? 5
i. Ls 1; 1;
and of course if p, g, 7, s coincide respectively with a, 3, e, d,
576 times the square of the tetrahedron abcd will be represented
under Mr. Cayley’s form,
0; .(ab)?; (ac); (ad)?; 1
(ba)? ; Os; nee)? si (Gd) Rij oh
(ca)?; (cb)?; 0; « (ed)?; 1%
(da)?; (db)?; (de)?; 03, «CD
i i 1; bs 0
four out of the sixteen distances vanishing, and the remaining
twelve reducing to six pairs of equal distances. The demonstra-
tion of Staudt’s theorem for triangles is obtamed in precisely the
same way by throwing the product of the two determinants
Ore eH
2 y 1 & 9 A
Weg ALL ea Ney ee
% yz 1 & 13 1
under the form of —ith of
2(#%,—&)?; 2(@,—&)?; 2(@,—§)?3 1
S(t2—&)?; Z(t2—&)*s B(to—F,)?s 1
2(@3—&,)?; 2(*s—Fa)*5 2(ws—Es)?5 1
1 i 1; 0
When the two triangles coincide, calling their angular points
a, b, c, the above written determinant becomes
0; (ab)?; (ac)?; 1
(ba)? ; Os i (ielas, nL
(e2)* en (cby?s 0; 1
1; 1; 1;
* The corresponding quantity to the above determinant for the case of
the triangle (hereafter given) is identical with the Norm to the sum of the
sides. I have succeeded in finding the Factor (of ten dimensions in respect
of the edges), which, multiplied by the above Determinant itself, expresses
oe} Norm to the sum of the Faces, i, e, the superficial area of the Tetra-
edron.
concerning the contents of Polygons and Polyhedrons. 341
or
(ab)* +- (ac)* + (bc)*—2(ab)? . (ac)? —2(ab)?(be)? —2 (ac)? . (bc)? ;
the negative of which is the well-known form expressing the
square of four times the area of the triangle abe.
There is another and more general theorem of Staudt for two
triangles not in the same plane, which may be obtained with
equal facility. In fact, if we start from the determinant
(aa)* (a8)? (ay)?
(ba)? (08)? (by*) 1
(ca)? (¢8)? (cy)? 1
1 1 1
and add to each column respectively the last column multiplied
by e&,?, e&,”, e&,” respectively, we arrive at the form
(ax)?+0&,? (a8)?+e&" (ay)? +e? 1
(ba)? -+e&? (b8)?+e&" (by)?+e&? 1
(ca)?+e&,? (c8)°+e&,* (cy)?+e&" 1
1 i! 1
And considering &,, 7, 3 £2; 7; &s, 73 as the coordinates of «, B, y,
the projections upon the plane of abe of a triangle ABC, whose
plane intersects the former plane in the axis of y, and makes
with that plane an angle whose tangent is (e), it is easily seen
that this determinant is term for term identical with the deter-
minant
(@A)?; (aB)?; (aC)?; 1
(A)?; (BB)?; (bC)?; 1
1
ays livg eS
which therefore expresses —16 times the product of the triangles
abe and «By, 7. e. abe x ABC x cosine of the angle between the two.
A similar method, if we ascend from sensible to rational geometry,
may be given for expressing in terms of the distances the product
of any two pyramids (in a hyperspace) by the cosine of the angle in-
cluded between the two infinite spaces* in which they respectively
lie. To pass from the cases which have been considered of two
triangles to two polygons, or of two tetrahedrons to two polyhe-
drons, generally presents no difficulty ; and for Professor Staudt’s
* In rational or universal geometry, that which is commonly termed infi-
nite space (as if it were something absolute and unique, and to which, by
the conditions of our being, the representative power of the understanding
is limited), is regarded as a single homaloid related to a plane, precisely in
the same way as a plane is to a right line. Universal geometry brings home
to the mind with an irresistible force of conviction the truth of the Kantian
doctrine of locality.
342 Mr. J. J. Sylvester on Staudt’s Theorems
method of doing so, which is simple and ingenious, and does not
admit of material improvement, the reader is referred to the
memoir in Crelle’s Journal or Terquem’s Annales already adverted
to. It is, however, to be remarked (and this does not appear to
be sufficiently noticed in the memoirs referred to), that whilst the
expression for the product of any two polygons in terms of the
distances given by Staudt’s theorem is unique, that for the pro-
duct of two polyhedrons given by the same is not so, but will
admit of as many varieties of representation as there are units in
the product of the numbers respectively expressing the number
of ways in which each polygonal face of each polyhedron adinits of
being mapped out into triangles. I cannot help conjecturing (and
it is to be wished that Professor Staudt or some other geome-
trician would consider this point) that im every case there exists,
linearly derivable from Staudt’s optional formule (but not co-
incident with any one of them), some unique and best, because
most symmetrical, formula for expressing the product of two
polyhedrons in terms of the distances of the angular points of
the one from those of the other. In conclusion I may observe,
that there is a theorem for distances measured on a given straight
line, which, although not mentioned by Staudt, belongs to pre-
cisely the same class as his theorems for areas in a plane and
volumes in space; viz. a theorem which expresses twice the rect-
angle of any two such distances under the form of an aggregate
of four squares, two taken positively and two negatively ; that is
to say, if A, B, C, D be any four points on aright line 2AB x CD
=AD?+BC?—AC?—BD*. I know not whether this theorem
be new, but it is one which evidently must be of considerable
utility to the practical geometer.
Note on the above.
The fundamental theorem in determinants, published by me
in the Philosophical Magazine in the course of last year, leads
immediately to a class of theorems strongly resembling, and
doubtless intimately connected with, those of Staudt.
Thus for triangles we have by this fundamental theorem
2, @ #3 Gin (Earns
Y¥. Yo Ys X Mm No Ng
og oral perp! a
% & £ &, & 2s a & & &, %q ay
=% 1 Ne X 13 Yo Ye + Y~i No 1 X Mm Yo Yo
gees VS | i a | hia oblat & Dincic beus,
a) £3 E, E, % xX
concerning the contents of Polygons and Polyhedrons. 343
and consequently, if ABC, DEF be any two triangles,
ABC x DEF=ADE x FBC + AEF x DBC+AFD x BCE.
This may be considered a theorem relating to two ternary
systems of points in a plane. The analogous and similarly ob-
tainable theorem for two binary systems of points in the same
right line is AB x CD=AC x DB—AD x CB, As in applying
this last theorem to obtain correct numerical results we must
give the same algebraical sign to any two lengths denoted by the
two arrangements XY, ZT, according as the direction from X to
Y is the same as that from Z to T, or contrary to it, so in the
theorem for the products of triangles, the areas denoted by any
two ternary arrangements XYZ, TUV must be taken with the
hike or the contrary sign, according as the direction of the rota-
tion XYZ is consentient with or contrary to that of TUV; so
that three of the six possible arrangements of XYZ may be used
indifferently for one another, but the other three would imply a
change ofsign. If we analyse what we mean by fixing the direc-
tion of the rotation of X¥Z, and reduce this form of speech to its
simplest terms, we easily see that it amounts to ascertaining on
which side of B, C lies, 7. e. whether to its right or left, to a spec-
tator stationed at A on a given side of the plane ABC.
Let us now pass to the corresponding theorems for two tetra-
hedrons put respectively under the forms
7% Uy tz X% &£& & &
% Ye Ys Ya m 2 3 4
& # 2% % ey aoe Aan
Tieeditennsl st oo i egal gland Dobe, sd!
We may represent this product in either of two ways by the
application of our fundamental theorem, viz.
as
” & & &, E, % 2% 2,
"08% Te 1 »~% 4 Ye Ys Ys1+&e
41 & & & b, 2 23 %
| Rey Ps | D tO Ls GD
or as
@ & &, §&, &, % %
Wi Fe Ne Ie a Ya Ua te,
2 % §& & G&S 23
Ad libda Ae 4d: 1» bhe ied
there being four products to be added together in the first ex-
pression and six in the latter; and the rule, if we wish that all
the products may be additive, being that on removing the sign
of multiplication the determinant to the square matrix formed
344 On Staudt’s Theorems of Polygons and Polyhedrons.
by the Greek letters in situ shall always preserve the same sign.
Hence we derive two geometrical formule concerning the pro-
ducts of polyhedrons, viz.
(1.) ABCD x EFGH=ABCE x FGHD—ABCF x GHED
-+ABCG x HEFD—ABCH x FGED.
(2.) ABCD x BFGH=ABEF x GHCD + ABGH x EFCD
+ABEG x HFCD+ABHF x EGCD
+ABEH x FGCD + ABFG x EHCD.
These formulz give rise to an exceedingly interesting observa-
tion. In order that they shall be numerically true, we must
have a rule for fixing the sign to be given to the solid content
represented by any reading off of the four pomts of a tetrahe-
dron, i. e. we must have a rule for determining the sign of solid
contents of figures situated anywhere in space analogous to that
which, as applied to linear distances reckoned on a given right
line, is the true foundation of the language of trigonometry,
and the condition precedent for the possibility of any system of
analytical geometry such as exists, and which, not altogether
without surprise, I have observed in the pages of this Magazine
one of the learned contributors has thought it necessary to vin-
dicate the propriety of importing into his theory of quaternions.
Various rules may be given for fixing the sign of a tetrahedron
denoted by a given order of four letters. One is the following:
the content of ABCD is to be taken positive or negative, accord-
ing as to a spectator at A the rotation of BCD is positive or
negative. Another, again, is to consider AB and CD as repre-
senting, say two electrical currents, and to suppose a spectator
so placed that the current AB shall pass through the longitudinal
axis of his body from the head towards the feet, and looking
towards the other current CD; the sign of the solid content of
the tetrahedron (and, indeed, also the effect, in a general sense,
of the action of the two currents upon one another) will depend
upon the circumstance of this latter current appearing to flow
from the right to the left, or contrariwise in respect of the spec-
tator. Last and simplest mode of all, the sign of the solid con-
tent of ABCD will depend upon the nature (in respect to its
being a right-handed or left-handed-screw) of any regular screw-
line (whether the common helix or one in which the imerease or
decrease of the inclination is always in the same direction) ter-
minating at B and C, and so taken that BA shall be the diree-
tion of the tangent produced at B, and CD the direction of the
tangent produced at C. Inasmuch as of the twenty-four permu-
tations of a quaternary arrangement a defined twelve have one
sign, and the other twelve the contrary sign, these various de-
Mr. J. Napier on Copper Smelting. 345
finitions of the direction, or, as it may be termed, polarity, of a
tetrahedron corresponding to a given reading, whether as taken
each in itself or compared one with another, give rise to, or rather
imply a considerable number of interesting theorems included
in our intuitions of space, and probably belonging to the, in my
belief, inexhaustible class of primary and indemonstrable truths
of the understanding.
7 New Square, Lincoln’s Inn,
October 2, 1852.
LIV. On Copper Smelting. By James Navirr, F.C.S.*
[Continued from p. 271.]
Construction of the Furnaces, &¢.
‘le my last communication I mentioned that the kind or qua-
lity of the fuel has often to be regulated by the nature of
the materials forming the furnace ; for while it is the object of
the smelter to get his charge fused in the shortest possible time,
it is also necessary to prevent fusing the bricks and other mate-
rials composing the furnace. It is therefore a matter of great
consequence that the best materials be used in its construction:
they should not be easily acted upon by heat, nor by the matters
fused upon or in contact with them; such materials not only
last longer, but they allow the smelting operations to be done
with greater facility and perfection.
It may be necessary, in the first place, to endeavour to describe
the nature of the common furnaces in use, reserving any remarks
upon peculiarity of construction for particular operations until
describing these operations.
Calcining-furnace.—The object of this furnace is to keep the
ore, or whatever matters are operated upon, exposed to a red heat
in a free current of air, for the purpose of burning off or volatilizing
the sulphur, arsenic, antimony, or other volatile matters, and oxi-
dizing the iron. This furnace is never used for fusion, and the
materials composing it are not so carefully selected or so refrac-
tory as for a fusing-furnace. The mode of construction is gene-
rally adapted to the object of it, and whether for ore or metal.
The common caleiner ranges from 18 to 22 feet in length, and
from 11 to 14 feet in breadth outside measure, independent of
fire-place ; the roof of the chamber internally above the floor of
the hearth is from 2 to 3 feet. The whole furnace is built upon
arches, the vaults of which serve to receive the ore from the fur-
* Communicated by the Author, who reserves to himself the copyright,
any infringement whereof will invoke legal proceedings.—Eps.
7 g Pp 4
346 Mr. J. Napier on Copper Smelting.
nace, when calcined, by means of holes in the floor of the furnace
or hearth through the roof of the arches.
Each calcining-fwrnace has generally a shaft or chimney of its
own about 40 feet high, except where there is one general shaft.
When the fumes from the calemer are led through a culvert
under ground to the main shaft, which, as will be shown im the
sequel, is the best and most ceconomical, much stuff is caught in
these culverts that is useful.
It need hardly be mentioned, that these furnaces have to be
firmly tied or bound together by means of iron, having large
upright cast iron studs opposite each other round the furnace,
and these held together by means of iron rods passing over and
through the building, which the men have to watch and tighten
up or ease as the expansion or contraction requires; otherwise
the furnace is liable to crack, or, as sometimes takes place, the
bindings break and the furnace splits in two. The furnace is
lined inside with fire-brick built in with fire-clay, so is the fire-
place and bridge. The shaft or chimney has also to be lined
with fire- or flintshire-brick. The cost of an average-sized cal-
cining-furnace without shaft is about £150.
A Fusing-furnace is constructed differently from the calciner, the
object being to get a high heat concentrated in the heayth. The
ordinary size of the hearth of a fusing-furnace is 13 feet long by
8 wide inside measure, of an oval form, resembling the section
of anegg. Generally these furnaces have each a stack or chim-
ney of its own. The inside of the hearth and fireplace is lined
with the best fire-brick; so is the inside of the lower part of
the chimney, passing into flintshire-brick as it ascends. These
are also bound about with iron studs and bars, and some are
cased all round with cast iron. A furnace of the size above
named with stack attached will cost about £130 before anything
be fused in it.
The Roasting-furnace differs little from the fusing-furnace.
They are generally larger in size, and have an opening or door in
the side of the hearth for the purpose of charging, as the matters
are put into it in large pieces which could not pass through a hop-
per. This door is also occasionally opened during the roasting
to admit air to the fused materials, The roasting-furnace is also
furnished with air-holes through the bridge, similar to what is
used in the calciner; the materials used in the construction of
these furnaces must also be of the best quality.
The Refining-furnace is similar to the roasting-furnace, but is
generally a little more oval; it has also a side door for the intro-
duction of the metal, and there is a well left in the bottom of
the hearth close to the front door to allow the metal to be ladled
out to the last portions.
ear
ea i ce
OR een ante
Mr. J. Napier on Copper Smelting. 347
These brief descriptions will enable us now to consider the
nature of the materials best fitted for forming the different parts
of the furnace ; and although modifications and improvements
have been proposed in the construction of some of these furnaces,
which will be referred to afterwards, they do not affect the pre-
sent inquiry.
The hearth or chamber of the furnace may be looked upon as
a large crucible, in which the ore or other matters undergoing
the process of manufacture are melted; it will therefore be
obvious that the matters forming this crucible must be capable
of withstanding a higher heat before melting than the sub-
stances put into it. Lime, silica, alumina, &e. alone, will stand
any degree of heat before fusing; but a mixture of these at a
high heat would combine and form a fusible substance; hence
the relation of the materials forming the lining of the furnace
with the matters to be heated in it has also to be considered.
Thus, were we to line a furnace with pure silica, which no fur-
nace heat would touch, and heat in that furnace lime, oxide of
iron, oxide of copper, &c., the silica and these oxides would soon
fuse and form glass; so that great care is required to prevent this
combination of the bricks with the substances undergoing fusion.
Thus some kinds of brick will answer for one sort of furnace
and not for another; one kind may stand well in the fire-place,
and not be suited for the hearth, and vice versd. Some kinds
will stand in the melted matter that will not stand on the roof
exposed to the fumes; bricks with much alumina in them will
not stand exposed to melted copper. All kinds of brick or
clay give way rapidly round the sides of the furnace at a line
corresponding to the surface of the fused metal. It need hardly
be stated that these remarks are equally applicable to the clay
or other matters used for making the bricks; for good bricks
are of little avail if there be not equally good clay to bind them
together.
Another property requisite in the bricks and clay used for lining
furnaces is, that they must not be liable to erack, cither by the
intense héat or by a sudden current of cold air passing over them
when hot, which in furnaces cannot be altogether avoided. A
erack taking place in the bottom or sides of a furnace is a most
serious affair; neither should the bricks be porous. In making
crucibles, their liability to crack is lessened by mixing with the
clay some sand, ground fire-brick, and graphite. Hessian eru-
cibles, the best of all clay crucibles, are made by mixing the clay
with half its weight of sand. Black-lead crucibles are made by
mixing graphite or plumbago with the clay ; but when too much
of these materials is used, the crucible becomes porous, and
allows the matters fused in them to pass through. The fol-
348 Mr. J. Napier on Copper Smelting.
lowing table from Berthier of the composition of crucibles and
pots known to stand well in working, will serve as data for com-
paring with the bricks and bottoms of the copper furnaces.
Silica, | Alumina, | Oxide of | yfagnesia.
: iron.
Hessian crucibles .....+000... 71 - 25 4
Paris (Beaufoy’s) .......0.00. 65 34 10
Saveignies, near Beauvois...| 72 19 4
English, for casting steel...} 71 23 4
St. Etienne, for casting steel] 65 25 7
Glass pots, Nemours ......... 67 32 1
Glass pots, Bohemia ......... 68 29 2 Trace.
We may here remark generally, that the bricks which contain
the most silica stand the action both of fire and melting matters
best.
Flintshire brick.—This sort is much used in the construction
of furnaces and chimneys in the copper-works of Wales; they
are not used for ling the furnaces where the melted matters
are to come into contact with them, but im parts exposed to great
heat and air-currents. Their analysis gave—
Siliet eis Vtech bet eased
Alominalac dat) are
Protoxide ofiron. . 6:1
Tame fie ease etakich Haed
These bricks are of a blackish-red colour and very hard.
_ Fire-bricks from Lysnewydd, South Wales—Used in large
quantity in the copper-works, both for fire-places and hearths.
Siltcactatiet., acts #2 arodeo
Allumirigint bi.) es to dsed
Dime «thajh.iatines 2S: 7
Protoxide of iron. . 5
99°3
Dinnas bricks, sometimes termed stone bricks.—These may be
considered indispensable in the process of copper smelting. They
are used where melted copper has to come into contact with the
furnace, but are very soon corroded when exposed to the influ-
ence of oxide of copper. They are a coarse-grained brick, resem-
bling in appearance a conglomeration of small pieces of quartz
rather than an artificial brick. Their composition is—
Mr. J. Napier on Copper Smelting. 349
From Penderyn.
From Dinnas.
a am ER 3 Gara
No. 1. No. 2. Nom No.2.
Silica . 95:53 94:05 100 91°95
Alumina . 2°67 455 trace 8-05
Protoxide of iron. 44, F trace "
i a ae 82
99:46 98°60 100-00
The first analysis given is of a large piece of brick ground up,
and which may be taken as a sample of the mass ; but the quan-
tity of lime and clay is not sufficient to bind the whole silica,
were they intimately mixed ; but the silica being in pieces about
the size of an ordinary pea, the alumina and lime causing their
adhesion is in proper proportion to form clay, and is very plastic.
If only a small portion of such bricks be taken for analysis,
nearly pure silica may be obtained, as shown in the third column
of the above table. The matters composing these bricks are
obtained from a quarry in the neighbourhood of Neath. These
matters are crushed under a stone, the materials are then wetted
and the mould for the brick filled. As the plastic ingredients im
these bricks are mechanically mixed, not in chemical union with
the quartz, we believe that ground or crushed quartz mixed with a
small portion of alumina and lime, as shown in the above analysis,
or good fire-clay, would serve the same purpose. Indeed in Chil
such has been tried with success, and it might be much more
extensively adopted. These bricks expand by heat more than
other fire-bricks ; but they do not contract to the same extent,
which is a valuable property in reference to maintaining a solid
and close lining.
Some Dinnas brick from the roof of a refining furnace much
exposed to the escape of oxide of copper, and also to metallic
copper being spurted upon them during poling, and which was
consequently corroded and left spongy, gave by analysis—
Raliea. qu’ jail ntecitade
Oxide of copper 27:0
Oxide of iron . 6
99°8
Another quality of fire-brick sometimes used in the copper
works is from Pembroke.
The following analysis of these is by Mr. John Cameron, of
Spitty Works, to whom we are indebted for several analyses in
these papers. Rilitas See aes
Alumina . 6:90
Oxide of iron 1:50
one rer et. 3°40
Magnesia. . . trace
100°23
850 Mr. J. Napier on Copper Smelting.
The best Newcastle and Stourbridge bricks are equal in qua-
lity for any of the purposes for which the above or Lysnewydd
are used, and often preferable, but they are not so generally em-
ployed. However, none of the ordinary fire-bricks can replace
the Dinnas in the uses to which they are applied.
The fire-clay used for making these bricks should possess
similar properties to the brick. It may be considered the same
materials unaltered by fire; and the same rule applies, viz. the
more silica they contain consistent with their solidity and binding
qualities, the better they answer the purposes of standing high
temperatures. Dinnas clay, that used for binding Dinuas brick,
is simply the materials of which the bricks are formed, made
moist by water.
The following table of analyses of fire-clays from three locali-
ties far apart, will serve as an illustration of quality.
Stourbridge. Monmouth *. Govan t+.
RICAyperedse sats 70-4 63°5 753 80-1 60:2 59°7
Alumina......... 22:7 22-0 16:8 17:9 37:7 375
Oxide of iron... 2 2°9 1:0 1:0 10 23
AM Gr a fesa eee? 5 8 Cs) 1:0 1:0 1:0
Wiatent cs aasenat 4-4 10°8 6
Magnesia ......| trace trace
1000 1000 1000 1000 100-0 1000
Such, then, is the generai chemical character of the fire-brick
and fire-clay used in lining the fusing-furnaces in copper smelting.
Chemical investigation and practical experience have not yet
been sufficiently and simultaneously carried on to enable ana-
lysis to supersede an actual trial; nevertheless it is a very good
guide; and that it is not now more certain, is owing rather to the
paucity of such investigations with a due observation of facts in
relation to analyses than to any discrepancy between principle
and practice.
These fire-bricks and clay are only used to line the side walls
and form the roof of the furnace, but they are not for the bottom
of hearths. When bricks, however refractory, are used for a
bottom, the melted stuff finds its way under and raises them up.
The bottom of a fusing-furnace, however large, must be one solid
piece, and this is obtained by using sand. A fusing-furnace, as
it is now built, stands upon an arch running the whole length and
breadth of the furnace, and brought up square; upon this rise
the side walls, which we have been describing as being lined with
fire-bricks ; the intervening space is where the sand bottom is
laid, which averages from 18 inches to 2 feet in depth. When
* Mr. C. Cowper. + Dr. Penny.
Mr. J. Napier on Copper Smelting. 351
a furnace is built, a fire is kept in it until it is considered to be
sufficiently dry and annealed to be fit for working, The bo‘tom
is made as follows :—Sand is laid upon the brick bottom to the
depth of about 18 inches, which is kept at a red heat for about
24 hours, when a little slag is laid on the top of the sand; the
furnace doors are all closed, and the heat increased to the melt-
ing-point: the slag fuses over the surface, penetrating into and
combining with the sand to about the depth of an inch; when
this is accomplished, the heat of the furnace is gradually lowered.
The whole surface of the sand bottom has now become one piece
of hard glass, adhering firmly to the side walls, forming a com-
plete shallow vessel. This forms what is termed the ¢rue or
lower bottom of the furnace. Upon the top of this bottom is
put a second layer of sand about 6 inches deep, which is treated
in the same manner, and is termed the false or upper bottom.
This upper bottom is of great practical value, as the bottom,
exposed to cold currents, is always liable to crack ; or it may be
separated slightly from the side walls, and allow the fluid to
pass through and under; but it only passes to the surface of the
lower bottom, which is not affected by the erack, flows over if,
and raises the upper in pieces, which is easily withdrawn, and a
new upper bottom put in. Were it not for this provision, and
an opening or crack taking place in the main bottom, or a piece
of it breaking and coming up, the renewing of a bottom would
be a most serious matter, and the copper constantly penetrating
would be a source of great loss. As it is, there is a constant
penetration of the melted matter, more or less according to the
nature of the sand, the care of the workman, and the condition
of the copper in process of manufacture. The nearer it ap-
proaches the condition of metal, the greater the liability to pe-
netrate. Some bottoms of refining and roasting-furnaces have
been often known to contain from twenty to thirty tons of copper ;
indeed, so great is the amount of capital absorbed in this way,
that the average value of each furnace used for fusing may be
reckoned at £500 after one year’s working.
Formerly, instead of the furnace being built upon un arch, as
above described, it was one solid mass of brickwork, in which
case the penetration of metal was much greater, as the free
current of air passing through the arch keeps the bottom cool
and prevents the metal from running through. .
A plan for lessening the quantity of copper penetrating into
the bottom was proposed a few years ago, and we believe is the
subject of a patent. Instead of an arch of bricks, the side valls
are started from the ground, and the sand bottom is supported
by iron plates laid across and resting upon the side walls at the
proper height. Trials with these iron bottom supports did lessen
the penetration a little, but the great hability of the iron plate
352 Mr. J. Napier on Copper Smelting.
to burn through rendered them useless. We have scen one in a
refining furnace give way in a few weeks, and a charge of seven
tons of copper run into the ash-pit, leaving no remedy but to pull
down the furnace to the ground.
We have tried bottoms constructed with bricks and tiles made of
clay and plumbago, and these grooved and tongued to fit into each
other, as the deals of a floor, and cemented together by the same
materials as they were made of. Such bottoms were perfectly im-
pervious to copper; but they were liable, with the slightest inat-
tention, to open at the joints and allow the copper to pass under
and raise the whole. We have also laid the whole bottom with
clay and graphite, baking it carefully to make one solid piece.
Such bottoms we have had in work for five weeks without any
copper penetrating ; but although made about three inches thick,
it was worn through in that time, and required as many days to
renew as a sand bottom requires hours, and which if the sand
be good will last longer. This loss of time is of so much im-
portance where there are forty or fifty furnaces, as to leave no
doubt which to adopt. When a sand bottom is to be renewed,
or when it breaks, the fire is kept up for some time, then a hole
is made in the side of the furnace under the top bottom, when
the copper flows out, where the two bottoms jom. The heat is
continued until as much of the melted matters sweats out as
possible, leaving the sand less tenacious; it is then drawn out
by iron rakes or rabbles. The old bottoms are broken up and
crushed fine, and put into the fusing-furnace with the ore. These
old bottoms, with old lining bricks and clay, are termed cobbing,
a term we may have occasion to use again.
From what has been said respecting the necessity of obtaining
good bricks and clay, it will be obvious that the same care must
apply to the selection of the sand for bottoms. If the sand be
too coarse, the bottom will be porous; if too fine, there is great
liability to crack and break up; should it contain matters that
make it fusible, it soon melts away and mixes with the slags ;
the sand should therefore be as pure silica as possible. The
proper physical qualities of sand best suited for bottoms are easily
ascertained by a little experience and observation ; but the che-
mical character, upon which a great deal depends, must be found
by experiment. The following analyses of a few sands, either in
use or tried for bottoms, will serve as data to judge of the qua-
lities of a sand.
From Coadyall, Wales :—
Sita Hat Rae 0 ae ee
Peroxide ofiron . . 3'2
Aluining O° ee
ET Claas armas te. el
Mr. J. Napier on Copper Smelting. 353
The average wear of bottoms made with this quality of sand
was four weeks to five weeks, when they melted away or became
thin.
Cwm Ivy, Wales :—
Bibles": Sao ere ar
Peroxide of iron . 44
Pie” Pe at et
Marien) Us * S aia
Carbonaceous matters 9
99°5
The average wear of bottoms of this sand was two weeks.
Pembre, Wales :—
No. 1. (Mr. Cameron.) No. 2. (Mr. Field.)
Silica . . 93 Silica . 92°20
Oxide ofiron 4 Carb. oflime 3:46
and alumina Magnesia 0:06
Ty 5, ioe Alumina 1°56
100 Oxide ofiron 1:84.
100°12
Average wear of bottoms made of these sands was six weeks.
But the name of locality is no guarantee as to quality, as the
following two analyses will show.
Pembre :—
No. 1. No. 2.
ihicn/ 2 aye 0 3s Gea 86°66
Oxide ofiron . . . 3:06 5°80
Famanep = Ce RG 5:60
Magnesia and soda . 1:74 1:94
100-00 100:00
Bottoms made with these did not stand longer than two weeks,
and proved liable to break up in a few days.
Bow Common, London, found a little under the surface and
washed before using :—
Biliea sil i OG
Oxide ofiron. . . 33
Lime and magnesia . 2
1000
The average wear of bottoms made of this sand was between two
and three months, showing how analysis and practice agree, and
also that the best bottoms are made with sand containing most
silica.
An aluminous or clay sand, although sufficiently refractory as
Phil. Mag. 8. 4. Vol. 4, No. 26. Nov, 1852, 2A
354:
regards heat, does not make a good bottom for fwmaces where
copper is to come into contact withit. The following were found
quite unsuitable :—
Mr. J. Napier on Copper Smelting.
(Mr. Field.)
Silica . . 85:20 80°4
Alumina): 9.0 22 2375 173
Lime ‘60 24
Oxide of iron “89
Magnesia 20
99°64 100:0
Alumina seems to be the deleterious ingredient in this sand,
and confirms our remarks in reference to fire-bricks and clay.
And this is fully borne out where sand with alumina is found
uncombined and capable of being separated by washing, as in
some parts of Australia.
Sand as dug up, unsuitable for bottoms, not lasting more than
ten or twelve days :—
(A. D. Thomas.)
Smita sd 85:18
Alumina . . 9:10
Oxideofiron. . 38°00
Pumie: “ss, ce f byt IP
Magnesia . 1:60
100:00
This being washed in a smal] running stream, gave a sand which
lasted as bottoms from six to eight weeks, Analysis gave—
Silica . 92:0
Carbonate of lime . . . 56
Carbonate of magnesia 16
Oxide of iron and alumina 8
100:0
It is worthy of remark how a slight difference in the per-eentage
of silica will effect the fusibility—the tear and wear of a bottom.
We are not aware that the Isle of Wight or American sands
used in making crystal have been tried for bottoms. As they
contain upwards of 99: per cent. of silica, the bottoms would
probably prove very lasting; but there might be some danger of
a liability to crack owing to the fineness of the grain.
Roofs of furnaces and lining of stacks or culverts near the fur-
nace are often affected by the volatilized matters passing over
them ; those from the calciner are not so destructive to the bricks,
the heat not being so intense as to cause combination, The
volatile matters only condense and form a deposit or crust upon
On the Mean Temperature of Rivers and the Atmosphere. 355
the bricks, which is generally composed of sulphur, arsenic, an-
timony, iron and copper; but in the fusing-furnace the bricks
are often consumed and worn quite thin. The destruction of
the bricks is greatest when fluxes are used; and if these contain
chlorides, soda or potash, the corrosion of the building extends
a good way along the stack or culvert. Where copper is exposed
in the furnace, the oxides burnmg off often combine with the
bricks and fuse into a solid cake. These deposits and sublima-
tions, their composition, and their causes, will be noticed in their
proper place.
[To be continued. ]
LY. Qn the Causes of the Excess of the Mean Temperature of
Rivers above that of the Atmosphere, recently observed by
M. Renou. By Witt1am Joun Macquorn Ranxing, C.E.,
FRS.E. &c.*
-? appears from the Comptes Rendus for the 14th of June 1852,
(vol. xxxiv. p. 916), that M. Renou of Venddme has for
four years made a series of daily observations on the temperature
of the river Loir at that place, as compared with that of the
atmosphere, and has found that the mean temperature of the
river invariably exceeds that of the air.
His observations for 1851, being the only series yet published,
show that this excess varied between 14 and 3 Centigrade degrees,
and that its average amount was 2°24 Centigrade; the mean
temperature of the river for the whole year having been 12°08
Cent., while that of the air was 9°84.
A similar result has been deduced from a smaller number of
observations made on the Loire at Tours by M. Oscar Valin.
Those facts are interesting, not only in a purely meteorological
point of view, but also as affording an illustration of an important
principle in the theory of heat; and considering the ease with
which observations similar to those of M. Renou may be made
at any place where a meteorological register is kept in the neigh-
bourhood of a river, they appear to be well worthy of the atten-
tion of those members of the British Association who make
meteorology their study.
The object of this paper is to point out how observations on
the excess of the mean temperature of rivers above that of the
atmosphere may be made available for the advancement of our
knowledge of the theory of heat.
As an argument favourable to the opinion suggested by
* Communicated by the Author; having been read to the British Asso-
ciation for the Advancement of Science, Section A, on the 2nd of Sep-
tember 1852.
2A2
356 Mr. W. J. M. Rankine on the Causes of the Excess of the
M. Renou himself and by M. Babinet, that the solar heat, ab-
sorbed and re-radiated by the bed of the river, is the principal
cause of the elevation of its temperature, M. Renou cites the
fact, that he has frequently observed a sudden elevation of tem-
perature in the river immediately follow the appearance of the
sun; but on the other hand it is to be remarked, that M. Renou
has also observed great elevations of temperature take place in
the water when the sun was not visible.
It is worthy of note, as tending to show that the solar radia-
tion is not the principal cause of the excess of the temperature
of rivers over that of the air, that according to the table of the
monthly means of M. Renow’s observations in 1851, this excess
greatly exceeded its mean amount in November and December,
months in which the solar radiation is weak ; and that in De-
cember the monthly mean very nearly reached its maximum,
having been 2°95, while its actual maximum, in May, was 3°09.
It is also to be observed, that while the mean diurnal variation
of temperature was 8°:03 for the air, it was only 0°65 for the
river.
When we consider that it has been proved experimentally by
Mr. Joule, that the heat developed by the friction of all sub-
stances (including in that term the consumption of power by the
agitation of fluids) bears a certain definite proportion to the
mechanical power consumed, it appears probable that friction is
an important cause of the elevation of the temperature of rivers
aboye that of the contiguous air.
Let us suppose that a river flows in a uniform channel,
haying a uniform inclination, with a uniform velocity; and let
i denote the rate of inclination of the channel;
v the velocity of the current ;
then iv represents the height through which each mass of water
descends during unity of time, and also the mechanical power -
due to the descent of unity of weight of water during unity of
time along the channel of the river in question
Now as the velocity of the current is uniform, this mechanical
power must be entirely consumed by friction; that is to say,
transformed into heat. Let
K denote the dynamical specific heat of liquid water; that is
to say, the height through which a given weight must descend
in order to produce mechanical power sufficient to elevate the
temperature of the same weight of water by one degree; then,
according to Joule’s experiments,
K=1590 feet per Centigrade degree,
vi
and Kc
Mean Temperature of Rwers above that of the Atmosphere. 357
represents the number of degrees of temperature generated in a
mass of water by descending during unity of time along the
channel of the river.
The temperature of the river will rise until the loss of heat by
conduction, radiation and evaporation exactly balances the pro-
duction of heat by friction. This loss of heat must be approxi-
mately proportional to the excess of the temperature of the water
above that of the atmosphere.
Let C represent the loss of heat, in degrees, for one degree of
excess of temperature, sustained by unity of weight of water
through unity of surface exposed to the air ;
C! the corresponding coefficient for the surface in contact with
the bed of the channel.
Let M denote the volume of unity of weight of water, that is
to say, 0-016 cubic foot per lb. avoirdupois.
Let s be the area of the transverse section of the river ;
b the breadth of its surface ;
p the periphery of its bed.
Then
MS Mp
prerie
are the areas exposed by unity of weight of water in the channel
to the air and to the soil respectively ; and, if
AT be the excess of the temperature of the river above that of
the atmosphere, .
AT! its excess above that of the soil,
the loss of heat by conduction, radiation and evaporation, in unity
of time measured in degrees, will be represented by
© (COAT -+CpAT).
This quantity being made equal to the gain of heat by friction,
we have for the condition of equilibrium of temperature the fol-
lowing equation :—
i M ; :
c= “- (COATS OpAT) wiswareds wy y
If the temperature of the air and of the soil be the same, so
that AT=A'’, then this equation becomes
=~ (Ch+ Cp) At,
or Sere mee! 27:2)
vis
AT= EM(Ch+ Up) ’
358 Mr. W. J. M. Rankine on the Reconcentration of
It thus appears, that by means of observations of the excess
of the mean temperature of rivers above those of the atmosphere
and of the soil, we may test the soundness of the supposition
that that excess is wholly or partly produced by friction ; and if
that supposition be found to agree with the facts, we may caleu-
late, from observations on different streams under different cir-
cumstances, the numerical values of the constants C and C’,
In order that the observations may be capable of yielding
satisfactory results, they should be made upon a variety of streams
of different forms of section, inclinations and velocities ; and the
part of each stream at which the temperatures are observed
should have a form of section, an inclination, and a velocity, as
nearly as possible uniform.
The following quantities should be observed :—
. The melination of the stream, 2.
. Its area of section, s.
. The breadth of its surface, db.
. The periphery of its bed, p.
. The velocity of the current, v.
. The mean temperature of the air.
. The mean temperature of the soil of the bed.
. The mean temperature of the stream.
The observations of temperature were made by M. Renou
every day at the hours of 4 a.m., 6 a.m., and every hour till
10 p.m. inclusive.
The effect of the solar heat can easily be tested, either by
observing the temperature of a piece of stagnant water adjoming
a river, of equal depth and similar form and constitution of bed
(for the temperature of such a piece of water would exhibit the
effect of the solar radiation unaffected by that of friction), or by
continuing the observations of the temperatures of the river
and of the atmosphere during the night.
As Ido not yet know the form, dimensions, inclination, or
velocity of the Loir, I am for the present unable to illustrate the
principles stated above by numerical examples.
MEOH os Oo We
LVI. On the Reconcentration of the Mechanical Energy of the
Universe. By Witt1aAM Jonn Macquorn Rankine, C.E.,
FE.R.S.E. &¢.*
A ete following remarks have been suggested by a paper by
Professor Wiliam Thomson of Glasgow, on the tendency
which exists in nature to the dissipation or indefinite diffusion
of mechanical energy originally collected in stores of power.
* Communicated by the Author; having been read to the British Asso-
ciation for the Advancement of Science, Section A, at Belfast, on the 2nd
of September 1852.
the Mechanical Energy of the Universe. 359
The experimental evidence is every day accumulating, of a law
which has long been conjectured to exist,—that all the different
kinds of physical energy in the universe are mutually convertible,
—that the total amount of physical energy, whether in the form
of visible motion and mechanical power, or of heat, light, mag-
netism, electricity, or chemical agency, or in other forms not yet
understood, is unchangeably the transformations of its different
portions from one of those forms of power into another, and their
transference from one portion of matter to another, constituting
the phenomena which are the objects of experimental physics.
Professor William Thomson has pointed out the fact, that there
exists (at least in the present state of the known world) a predo-
minating tendency to the conversion of all the other forms of
physical energy into heat, and to the uniform ditfusion of all
heat throughout all matter. The form in which we generally
find energy originally collected, is that of a store of chemical
power, consisting of uncombined elements. The combination of
these elements produces energy in the form known by the name
of electric currents, part only of which can be employed in ana-
lysmg compounds, and thus reconverted into a store of chemical
power ; the remainder is necessarily converted into heat: a part
only of this heat can be employed in analysing compounds, or in
reproducing electric currents. If the remainder of the heat be
employed in expanding an elastic substance, it may be entirely
converted into visible motion, or ito a store of visible me-
chanical power (by raising weights, for example), provided the
elastic substance is enabled to expand until its temperature falls
to the pomt which corresponds to absolute privation of heat ; but
unless this condition be fulfilled, a certain proportion only of the
heat, depending upon the range of temperature through which
the elastic body works, can be converted, the rest remaining in
the state of heat. On the other hand, al! visible motion is of
necessity ultimately converted entirely into heat by the agency
of friction. There is thus, in the present state of the known
world, a tendency towards the conversion of all physical energy
into the sole form of heat.
Heat, moreover, tends to diffuse itself uniformly by conduc-
tion and radiation, until all matter shall have acquired the same
temperature.
There is, consequently, Professor Thomson concludes, so far
as we understand the present condition of the universe, a ten-
dency towards a state in which all physical energy will be in the
state of heat, and that heat so diffused that all matter will be at
the same temperature ; so that there will be an end of all phy-
sical phenomena.
Vast as this speculation may seem, it appears to be soundly
360 On the Mechanical Energy of the Universe.
based on experimental data, and to represent truly the present
condition of the universe, so far as we know it.
My object now is to point out how it is conceivable that, at
some indefinitely distant period, an opposite condition of the
world may take place, in which the energy which is now being
diffused may be reconcentrated into foci, and stores of chemical
power again produced from the inert compounds which are now
being continually formed.
There must exist between the atmospheres of the heavenly
bodies a material medium capable of transmitting light and heat ;
and it may be regarded as almost certain, that this interstellar
medium is perfectly transparent and diathermanous ; that is to
say, that it is incapable of converting heat, or light (which is a
species of heat), from the radiant into the fixed or conductibleform.
If this be the case, the interstellar medium must be incapable
of acquiring any temperature whatsoever; and all heat which
arrives in the conductible form at the limits of the atmosphere of a
star or planet, will there be totally converted, partly into ordmary
motion, by the expansion of the atmosphere, and partly into the
radiant form. The ordinary motion will again be converted into
heat, so that radiant heat is the ultimate form to which all phy-
sical energy tends; and in this form it is, in the present con-
dition of the world, diffusing itself from the heavenly bodies
through the interstellar medium.
Let it now be supposed, that, in all directions round the visible
world, the interstellar medium has bounds beyond which there
is empty space.
If this conjecture be true, then on reaching those bounds the
radiant heat of the world will be totally reflected, and will ulti-
mately be reconcentrated into foci. At each of these foci the
intensity of heat may be expected to be such, that should a star
(being at that period an extinct mass of mert compounds) in the
course of its motions arrive at that part of space, it will be vaporized
and resolved into its elements; a store of chemical power being
thus reproduced at the expense of a corresponding amount of
radiant heat.
Thus it appears, that although, from what we can see of the
known world, its condition seems to tend continually towards
the equable diffusion, in the form of radiant heat, of all physical
energy, the extinction of the stars, and the cessation of all phe-
nomena, yet the world, as now created, may possibly be pro-
vided within itself with the means of reconcentrating its physical
energies, and renewing its activity and life.
For aught we know, these opposite processes may go on
together ; and some of the luminous objects which we see in
distant regions of space may be, not stars, but foci in the inter-
stellar zether.
plder #7]
LVII. Notice on Chloride of Arsenic.
By Dr. Penny and Witt1am Wattact, Esq.*
OME time since we were led to undertake a series of expe-
riments on the properties and composition of the chloride
of arsenic, with the view partly of testing the accuracy of the
researches that have been made for determining the equivalent
of arsenic, and partly of ascertaining the availability of this sub-
stance for the separation of arsenic from other metals, as well as
from organic matters in toxicological inquiries. The publication
of some of our results has been anticipated by Dr. Fyfe’s excel-
lent paper “ On the Detection of Arsenic,” published in the Phi-
losophical Magazine for December 1851. There are, however,
several pots connected with the chemical history of this inter-
esting compound which have not yet been noticed, and we
therefore trust that a brief statement of our investigations may
not be altogether unacceptable to the Philosophical Society of
Glasgow.
Ginelin’s Handbook of Chemistry contains a fair abstract of
the several researches that have been made upon the properties
of chloride of arsenic, with the results of its analysis by Dr. J.
Davy. It has been analysed more recently by Pelouze, who
employed it for the determination of the atomic weight of me-
tallic arsenict. Its production in medico-legal investigations has
been incidentally noticed by several authorities ; but its invari-
able formation by heat from arsenious acid in presence of hydro-
chloric acid has, we think, been frequently overlooked; and in
certain processes recommended for the separation of arsenic from
organic matters, its ready volatility would unquestionably be
very liable to occasion a loss of a portion of the metal.
To these points our attention has been particularly directed,
and our results fully confirm the several statements made by
Dr. Fyfe in the paper referred to. Before giving these results,
however, we shall describe the processes by which we obtained
anhydrous chloride in a state of purity, and the new method by
which we estimated the proportion of arsenic existing in it.
In one process for its preparation, powdered arsenious acid
was put into a retort with a considerable quantity of concen-
trated hydrochloric acid, and the mixture distilled. Anhydrous
chloride and a solution of chloride of arsenic in hydrochloric
acid soon collected in the receiver. The former was found at
the bottom as a dense oily liquid, and the other products floated
above. ‘The anhydrous chloride may be easily separated with a
* Communicated by the Authors, having been read at the Meeting of the
Philosophical Society of Glasgow, January 7, 1852.
+ Comptes Rendus, vol. xx. p. 1047.
362 Dr. Penny and Mr. W. Wallace on Chloride of Arsenic.
pipette, and purified by careful rectification. The principal
objection to this process is, that when the hydrochloric acid is
reduced below a certain point, the anhydrous chloride ceases to
separate from the other distilled products, and thus a small
proportion only is obtained. Our experiments lead us to infer
that little, if any, anhydrous chloride can be obtained with acid
below twenty per cent.
The second method consists in passing dry hydrochloric acid
gas over powdered arsenious acid. The phenomena in this pro-
cess are exceedingly interesting. The absorption of the gas is
immediate, and a considerable elevation of temperature occurs,
water and chloride of arsenic being simultaneously produced.
Almost immediately on contact of the hydrochloric acid gas, the
arsenious acid becomes moist and speedily disappears ; and when
the action is completed, two liquids are found in its place; the
lower one being anhydrous chloride, and the upper one a satu-
rated solution of hydrochloric acid im water, with a small quan-
tity of dissolved chloride of arsenic. The non-production of
hydrated chloride of arsenic in the above circumstances is some-
what remarkable, since the quantity of water produced by the
double decomposition of the two acids is exactly the amount
which is stated to exist in the hydrated chloride ; thus
AsO?+ 3HCl=AsCB+3HO.
In a particular experiment, we found that 50:9 grains of arse-
nious acid absorbed 63:5 grains of hydrochloric acid gas (dried
by oil of vitriol and chloride of calcium), which corresponds very
closely to one equivalent of anhydrous chloride, plus three equi-
valents of water saturated with hydrochloric,acid. This is cer-
tainly the more elegant and more satisfactory process for the
preparation of this substance. In both cases the resulting chlo-
ride is easily purified by distillation.
The methods for the quantitative estimation of arsenic are too
well known to require notice. The new process which we employed
for the analysis of the chloride, is based upon the reciprocal action
of chromic and arsenious acids in presence of hydrochloric acid.
The reaction is exhibited in the following equation :—
3AsCB + 4Cr0? +3HO=3As0° + 2Cr? CB +3HCL.
A weighed quantity of the pure chloride was mixed with water
and caustic potash, and excess of hydrochloric acid subsequently
added. The mixture being gently heated, a quantity of bichro-
mate of potash, barely sufficient to peroxidize the arsenic, was
slowly added. A weak solution of a known quantity of the
same salt was then cautiously dropped into the liquid, till a por-
tion taken out on the end of a rod gave a faint yellow tinge to
a solution of acetate of lead spotted on a slab. The delicacy of
Dr. Penny and Mr. W. Wallace on Chloride of Arsenic. 363
this test, as thus applied, for the detection of bichromate of pot-
ash has been fully shown in the fourth volume of the Quarterly
Journal of the Chemical Society of London. Taking the mean
of two well-executed experiments, it results that 100 parts of
chloride of arsenic correspond to 54:5 parts of bichromate of
potash. In order to deduce from this ratio the proportion of
arsenic existing in the chloride, similar experiments were made
with pure arsenious acid, which gave very nearly the proportion
of 100 of arsenious acid to 100 of bichromate of potash. From
these numbers it is evident that chloride of arsenic contains
41°25 per cent. of metallic arsenic.
The amount of chlorine was estimated in the usual manner as
chloride of silver.
The following table shows the composition of the chloride :—
Theory. Experiment.
Ausenie hi Py SFG 41°32 41°25
3 equivs. Chlorine . 106°5 58°68 58°86
1815 100°00 100-11
It may be as well to mention, that the chloride prepared as
above had the specific gravity of 2°1766. It was strongly acid
to litmus paper, completely soluble in alcohol and in ether ; and
it was also observed to have the power of dissolving a very con=
siderable proportion of arsenious acid.
The action of water on the anhydrous chloride is particularly
remarkable. It is stated by several writers, that the addition of
the proper quantity of water converts the anhydrous chloride
into a hydrate, having the formula AsCl?, 3HO. Our attempts
to obtain this hydrated compound proved unsuccessful. A known
quantity of the anhydrous chloride was mixed with a sufficient
proportion of water to convert it into the hydrate referred to,
and the two liquids well agitated. The mixture became per-
ceptibly warm, but on repose the greater part of the chloride
separated. Additional portions of water were then successively
added, the mixture being allowed to cool after each addition.
The chloride gradually diminished ; and when the total quantity
of water amounted to about 18 equivalents to one of the chlo-
ride, the latter was found to be completely mixed. The resulting
fluid, which had the specific gravity of 1:53, is miscible with a
much larger quantity of water without any visible change, viz.
to the extent of nearly 18 equivalents additional, making a total
of 36 equivalents of water to one of anhydrous chloride. On the
further addition of water, however, a separation of arsenious acid
takes place. The specific gravity of the mixture containing 36
equivalents of water was 1°346.
We have obtained some interesting results by the distillation
364 Dr. Penny and Mr. W. Wallace on Chloride of Arsenic.
of the two fluids, containing respectively 18 and 36 equivalents
of water, an account of which we reserve for a future commu-
nication.
With respect to the heat evolved on mixing anhydrous chlo-
ride and water, we may state that in a particular experiment, in
which 117 grains of the former were briskly agitated with a
quantity of the latter corresponding to 18 equivalents, the tem-
perature rose from 60° to 113° F. Then on allowing this mix-
ture to cool, and pouring in 18 additional equivalents of water,
the temperature increased from 60° to 94°.
From our experiments on this part of the subject, it appears
to us very questionable whether such a hydrate as AsCl?, 3HO
has been obtained.
Several experiments were made for the purpose of ascertaining
the precise conditions necessary for the production and volatili-
zation of the chloride from a heated mixture of arsenious and
hydrochloric acids. The most important result was, that chlo-
ride of arsenic may be detected in the distillate as soon as hy-
drochloric acid itself distils ; and further, that this result obtains
even with very minute quantities of arsenious acid. With strong
hydrochloric acid (containing upwards of 20 per cent. of real
acid), anhydrous chloride collects at the bottom of the receiver
distinct from the other products. But with acid below 20 per
cent., the chloride is found in the distillate in the state of solution.
It may appear singular that chloride of arsenic should so
readily distil over with a liquid which boils at 230° F., when
its own boiling-point is 274°. This apparent anomaly, however,
is explained by the fact, that the chloride distils freely at a tem-
perature very much below its point of ebullitfon.
In evidence of the extreme facility with which arsenious acid
yields the chloride when heated with hydrochloric acid, we may
mention one or two experiments.
Two-tenths of a grain of arsenious acid were heated in a distil-
ling apparatus with 550 grams of hydrochloric acid, specific
gravity 1-100; when one-twentieth of the hquid had distilled
over, the distillate was tested with sulphuretted hydrogen: a
decided precipitate of sulphide of arsenic separated.
In another experiment one grain of arsenious acid was distilled
with 550 grains of the same hydrochloric acid. errs
Intelligence and Miscellaneous Articles. 395
When with these values of c the expansions of the metals by heat
are calculated, we obtain—
a ealeulated. a observed.
Troniys ac(Riepittcs. 0:001070 0:001182
Brass ........ 0°001909 0:001878
Plaga ete)5-.< 0:000968 0:000854
Si] erie ten koe 0:001918 0:001910
A closer correspondence was not to be expected with numbers
which have been determined by such different observers, and upon
which certainly no slight influence is exercised by the particular
condition of the metals experimented with. Iam at the present
time engaged in the determination of two of the values in question
—the elastic constants and the coefficients of expansion by heat for
the same wires—and hope then to arrive at more accurate results.
The pressure of 224325 Russian pounds acted upon the surface
of x square inches, we have then for 1 square inch 71441 pounds,
or more than 4327 atmospheres.
The mechanical equivalent of heat may also be expressed in an-
other way. The above-mentioned metal cylinder is extended to the
amount of ¢ by the gravitation of one pound; the weight p=5
would then lengthen it one inch; we may then express the elastic
force of the cylinder by saying it raises the weight p one inch; for
it holds the force p which has sunk one inch in equilibrium,
If the same cylinder is heated to 212°, it expands to the amount
of a; and according to the above hypothesis, it would expand to the
amount of 2a if the heat acted only in one direction like the weight p.
The quantity of heat which causes this expansion is w.mS, when we
represent by w the quantity of heat which is necessary to raise the
temperature of a cylinder of water of a height and radius equal to
unity from 32° to 212°. Hence it follows that
w.mS
2a
is the quantity of heat which would effect an extension of one inch;
or as forces which bring about equal effects must themselves be equal,
then
But we have also
therefore w=c.
The quantity of heat necessary to heat the cylinder of water from
32° to 212° is then capable of raising 224325 Russian pounds one
inch. This cylinder of water weighs 0-1134 of an English pound
(at the temperature of the greatest density) ; the number of Fahren-
heit degrees between the freezing and boiling-points of wateris 180,
and a Russian pound = 0°9028 of an English pound; we have then
c.0°9028 :
1154, 180 ~ >
396 Intelligence and Miscellaneous Ariacces.
for the number of English pounds which the heat necessary to raise
one English pound of water from 32° to 212° is capable of raising
one inch.
Joule found by experiments on the heat produced by friction 10680.
By experiments on the heat evolved by the compression of air he
found 9876 and 9540. All these numbers agree tolerably well.—
Poggendorff’s Annalen, 1852, No. 6. .
ON THE RAIN-WATER COLLECTED AT THE OBSERVATORY AT
PARIS. BY M. BARRAL.
Up to the end of the seventeenth and beginning of the eighteenth
centuries the atmosphere was reckoned amongst the few elements
admitted at that time. In course of time the researches of Van Hel-
mont, Hales, Mayow, Bergmann, Scheele and Lavoisier, led to the
knowledge of the fact that the atmosphere is a mixture of oxygen
and nitrogen. The later chemists set themselves to the task of de-
termining these constituents with greater exactitude than was pos-
sible to their predecessors. Thus Cavendish, Davy, Marty and
Berthollet showed that the air had the same composition in all cli-
mates. Gay-Lussac ascertained the same fact with regard to air
obtained by him by means of an air-balloon from a height to which
no one had previously attained. He, together with Humboldt,
furnished considerable assistance to Lavoisier in his determinations.
Afterwards, in 1822, Despretz made numerous analyses of the air
and arrived at similar results. Lastly, Dumas, Boussingault and
Regnault have carried the accuracy of the analyses much further by
operating upon larger quantities of air; and it appears that posterity
has nothing more to determine, except whether the ascertained com-
position of the atmosphere be constant, whether the causes, such as
combustion, respiration, &c. which lessen its quantity of oxygen, are
accurately compensated by the known sources of oxygen. The atmo-
sphere contains also vapour of water and carbonic acid. Itisnot yet
ascertained who first discovered the presence of the latter; Black
proved, immediately after the discovery of carbonic acid, that the thin
crust which is formed upon lime-water when exposed to the air,
consists of carbonate of lime.
All the preceding statements referred to the atmosphere in a state
of purity. But winds, storms, and the ascending current of air pro-
duced by inequality of temperature, bear dust and particles of water
from the foam of the sea, with the air which has been in contact with
the ground, into higher regions. Such is, for instance, the red rain,
with which the philosophers of the seventeenth century, Wendelin,
Descartes, Peiresc and Gassendi, occupied themselves to such an
extent.
It was only towards the middle of the last century that it was felt
that the causes of such variations must be ascertained by regularly
continued cbservations. These were undertaken at first only with
the view of determining how far from the point of their origin such
perturbations extend themselves. The study of rain, which, as it
Intelligence and Miscellaneous Articles. 397
falls through all the strata of air lying below the clouds which pro-
duce it, becomes impregnated with any matters contained therein,
was the first thing to which observers directed their attention.
Bergmann was the first who appeared in this sphere. He disco-
vered nitricacid inrain. Then follow Brandes, Zimmermann, Liebig
and Jones.
The most important result of M. Barral’s investigations is, that
the rain in every month contains so much nitric acid and ammonia
that the quantities of both can be determined. The author’s remarks
upon the quantity of chlorides contained in the atmosphere are not
less interesting; but in the determination of these he has had Brandes,
Berzelius, Liebig, Chatin, Meyrac and Isidore Pierre, as predecessors.
Bergmann had stated that traces of nitric acid occurred in the
atmosphere. Brandes, who investigated the air at Salzuffeln from
month to month in 1825, stated that he found in it chloride of
magnesium, chloride of sodium, sulphate and carbonate of lime, car-
bonate of potash, oxides of iron and manganese, and traces of am-
monia, sulphuric acid, and animal and vegetable matters. As regards
the occurrence of chloride of iron, oxide of manganese, and chloride
of potassium, this has already been questioned by Liebig. Liebig,
in the investigation of seventy-seven samples of rain-water, found
nitric acid in ten samples after stormy rain, and traces in two only
of the remaining sixty.
Bence Jones, in 1851, found nitric acid in the rain of London, Mel-
burgh in Dorsetshire, and Clonakelty, by means of iodide of potas-
sium paste, but did not determine its quantity.
In 1851, Barral commenced his investigations upon the rain col-
lected partly upon the platform, and partly in the court of the Ob-
servatory at Paris.
The Commission has tried M. Barral’s process, and found that his
mode of determination was to be depended upon. ‘The process itself
is not further described. .
On the other hand, the following tables give the numbers which
express the quantity of nitric acid in the rain. According to them,
the rain is never equally loaded with nitric acid, and the quantities
of nitric acid which fall with the rain upon one hectare of land are
not in proportion to the quantity of rain. Calculated from the
minimum, 31 kilogs. of nitrogen fall during the year upon one hec-
tare of land in the neighbourhood of Paris.
Average contents of Rain-water from monthly determinations in the
Udometers of ihe Observatory of Paris during the second half of the
year 1851. The numbers refer to one cubic metre of rain-water.
| N. | Nos.| nus] cl. | cao. MgO. | Total.
| ms yrms. ms. ms. s. ‘Ss. Ss.
ib as... 67 | 6-01 | 377 | 388 | “9-03 |... | 24-80
August ......... | 944 20-20 | 4-42 | 2:39 | 8-68 38-31
September ...... 11-95 | 36:33 | 3:04 | 2:39 | 7-16 51-04
October ......... 446) 5°82] 1-08 | 1-84 | 243 13°29
November ...... 4:64 | 9:99 | 2:50 | 2:64 | 4:26 21°51
December ...... 15-01 36-21 | 685 | 0-00 | 7:36 52:54
ysis: 8:36 19:09 | 3:61 | 2-27! 6-48
2:12 | 33°57
898 Intelligence and Miscellaneous Articles.
The same determinations calculated to one hectare of land.
N. | NOs. | NH3.| cl. | cad. | MgO. | Total.
EEE —
kilogs. | kilogs. | kilogs. | kilogs. | kilogs. | kilogs. | kilogs.
324) 74] we | 19:
Aulyd eee: 3°90 | 5°03 | 3-15 9-71
ARTS. .essen 2:18 | 4:89 | 1:04 | 069] 2-12 sce] uae
September ......| 2°94 | 8:89 | 0-77 | 0:59 | 1:81 wwe =| 12:82
October <.....0e 2:26 | 2:81 | 0:53 | 0:88} 1°15 at 6:13
November ......| 1:93 | 4:26] 1:01 | 110] 178] ... 8-91
December ...... 2°50 | 5°95 | 1:17 0:00 | 1:23 eee 9-11
In 6 months ...| 13-71 31-83 | 7-67 | 6:50 | 15°63 | 4-54 | 66:17
Barral then shows how much nitrogen falls as nitric acid and how
much as ammonia. Of the 31 kilogs. of nitrogen, 9 belong to the
ammonia and 22 to the nitric acid. For the separation of the nitric
acid from the ammonia, the author has made use of a method in-
vented by Peligot.
Bineau has lately determined the quantity of ammonia contained
in the rain collected at Lyons, but not the quantity of nitric acid.—
Comptes Rendus, vol. xxxiv. p. 824.
Meyrac has instituted similar investigations, and found that all
rain contains chlorides; the largest quantity of chloride of sodium
found amounted to 2 centigrms. in the litre. This quantity is fre-
quently contained in the water in autumn and winter, and in the
first days of spring. It has always an alkaline reaction, and con-
tains traces of iodine. The ammoniacal salt, which is contained in
rain and snow-water, and which, according to M. Chatin, consists
of carbonate, nitrate, and humate of ammonia, if first acidified with
sulphuric acid and then brought in contact with carbonate of soda,
evolves an empyreumatic odour. As this odour is produced by none
of the above ammoniacal salts, it probably proceeds from other
organic substances.—Jbid, vol. xxxiv. p. 715.
ON THE SALTS OF ANTIMONIC ACID. BY L. HEFFTER.
The results of this careful and accurate investigation are in part
very remarkable and unexpected. The author has found that the
proportion of oxygen in the base to that of the acid is only then as
1 to 5, when the antimoniates of the alkalies are heated to redness
in an atmosphere of carbonic acid gas or of carbonate of ammonia,
and treated with water, which extracts a little carbonate of the
alkali. Even the crystalline antimoniate of soda, which has been
obtained by the precipitation of a solution of antimoniate of potash
by a soda salt, contains an excess of soda united with water, so that
in this salt the oxygen of the soda to that of the acid is in the propor-
tion of 1 to 4:6. By heating to redness it does not entirely lose its
water, because the excess of soda retains the water, which it ex-
changes for carbonic acid when this is presented to it at a red heat.
Something similar takes place with antimoniate of potash and with
all other antimoniates which have been investigated; M. Heffter
Meteorological Observations. 399
has succeeded in obtaining many of them in a distinctly crystallized
state, particularly crystals of the antimoniates of magnesia, cobalt and
nickel, which are isomorphous. They consist of regular six-sided
prisms. In all the salts of antimonic acid which have been inves-
tigated, the proportion of the oxygen of the base to that of the acid
is as 1 to 4°6; they therefore contain some excess of base which is
united to water, so that these compounds are to be considered as salts
which contain two acids, antimonic acid and water. The salts of
antimonic acid also contain water of crystallization: in the crystal-
lized salts this commonly amounts to twelve atoms, whilst if these
salts are obtained in the amorphous state they usually contain only
six atoms of water. The composition of the first may be best ex-
pressed by the formula
RO HO+12(RO SbO*+12H0O).
If it be heated to 212° F. it loses 8 atoms of water; at 390° it
loses 10 atoms, and at 572° 11 atoms. In the salts of antimonic
acid heated to 572° we may therefore assume for one atom of
antimonic acid two atoms of base, of which one is water; andin the
salts heated to 390°, three atoms of base, of which two consist of
water.—Berl. Monatsbericht, 1852, p. 344.
METEOROLOGICAL OBSERVATIONS FOR SEPT. 1852.
Chiswick.—September 1. Slight rain. 2. Foggy: cloudless and hot. 3, 4. Very
fine. 5. Overcast: clear. 6. Very fine: rainat night. 7. Hazy:rain. 8. Heavy
rain: thunder and lightning: cloudy: clear at night. 9. Cloudy: showery. 10.
Cloudy. 11,12. Fine. 13. Very fine. 14. Clear: dry air: densely overcast at
night. 15. Overcast. 16. Fine: clear and cold at night. 17. Slight fog, with
very heavy dew: very fine: clear and cold. 18. Foggy: heavy rain. 19. Cloudy:
uniformly overcast. 20. Slight rain: showery: clear. 21, Boisterous, with rain.
22. Clear: very fine. 23, Overcast: very fine. 24. Foggy: very fine : dense fog
at night. 25. Dense fog: very fine. 26. Heavy dew: foggy: hazy throughout.
27. Dense fog : overcast : heavy rain at night. 28. Constant rain: barometer very
low: foggy. 29. Cloudy : slight showers: cloudy. 30. Overcast : fine but windy:
overcast.
Mean temperature of the month ...... Rett ota seuveent est etcs wee 56°20
Mean temperature of Sept. 1851 .........ccecsceeeeseceeeeeees .. 00°15
Mean temperature of Sept. for the last twenty-six years ... 57°15
Average amount of rain in Sept. ......seseeesseeeeees sencaee veee. 2°52 inches.
Boston.—Sept. 1. Cloudy. 2. Fine. 3,4. Cloudy. 5. Cloudy: rain a.m,
6. Cloudy: rain p.m. 7. Cloudy: rain: thunder and lightning early A.M. : rain P.M.
8. Fine. 9. Fine: rain p.m. 10. Fine. 11—13. Cloudy. 14. Fine. 15. Cloudy:
rain A.M. and p.m. 16. Fine: rain early a.m. 17. Fine. 18. Fine: rain a.m.
andp.m. 19, 20. Cloudy: rain early a.m. 21. Rain: rain a.m. 22. Fine. 23.
Cloudy. 24. Fine. 25—27. Foggy. 28. Rain: rain A.M.andp.m, 29. Cloudy:
rain a.M. 30. Fine.
Sandwick Manse, Orkney.—Sept. 1. Showers. 2. Clear: fine: cloudy: fine.
3, Clear: fine. 4. Bright: clear: fine: aurora. 5. Fog. 6. Hazy: cloudy. 7—
9. Fine: clear: fine. 10. Cloudy: showers. 11. Showers: drops: aurora.
12. Showers: aurora. 13, 14. Sleet-showers. 15,16. Showers. 17. Bright:
showers: aurora. 18, Drizzle: rain. 19. Bright: clear:rain. 20, 21. Bright:
cloudy: rain. 22. Showers: cloudy. 23. Cloudy: rain. 24. Showers: clear.
25. Bright: cloudy. 26. Clear. 27. Showers: rain. 28. Showers: lunar rain-
bow. 29. Bright: cloudy: rain. 30. Rain: cloudy.
Mean temperature of Sept. for twenty-five years «.....e...0 52°22
Mean temperature of this month ......... Satrdrsssdacesucsses 53 *45
Average quantity of rain in Sept. for six years .......::000. 2°49 inches,
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THE
LONDON, EDINBURGH anv DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
[FOURTH SERIES.]
DECEMBER 1852.
LXIII. On Sir David Brewster’s New Analysis of Solar Light.
By H. Hrrmuorrz*.
i a series of papers} published by Sir David Brewster, he
has endeayoured to establish a peculiar view which he en-
tertains regarding the composition of solar light and the gene-
ration of colours. These papers must naturally attract in a high
degree the attention of physicists, both on account of the well-
won renown of their author in the domain of optical science,
and of the new facts which he adduces in support of his asser-
tions. According to him, solar light is compounded of three
different kinds of light, red, blue and yellow; and each deserip-
tion of light possesses rays of all degrees of refrangibility, but
so distributed that red light contains a preponderance of rays of
less refrangibility, yellow more rays of mean refrangibility, and
blue more of greater refrangibility ; hence it is that the first pre-
dominates at the less refrangible end of the spectrum, the second
in the middle, and the third at the most refrangible end. The
remaining colours of the spectrum, orange, green, violet, are
supposed to be caused by the mixture of the three primitive
colours. The prism can only separate those rays from each other
which possess unequal degrees of refrangibility ; if, however,
there exist different kinds of light of the same refrangibility, the
* From Poggendorff’s Annalen, 1852. No.8.,communicated by Dr. Tyndall.
+ “Description of a Monochromatic Lamp, with Remarks: on the
Absorption of the Prismatic Rays,” in Trans. of the Royal Soe. of Edinb.
vol. ix. part 2. p. 433. —‘ On a New Analysis of Solar Light,” Ibid.
vol. xii. part 1. p. 123.—* Reply to the Astronomer Royal on the New
Analysis of Solar Light,” Phil. Mag. S.3. vol.xxx.p. 153,—* Observations on
the Analysis of the Spectrum by Absorption,” Ibid. vol. xxx. p. 461.-—* Re-
marks on the Elementary Colowrs of the Spectrum,” Ibid. vol. XXxil.p.489,
Phil. Mag. 8. 4. Vol. 4, No. 27. Dec. 1852. 2D
4.02 M. H. Helmholtz on Sir David Brewster’s
compound light formed by them must in the prismatic analysis
behave as simple light. ‘To this Brewster replies, that such rays
may be separated from each other by taking advantage of their
difference of absorption in coloured media ; and he has attempted
by means of this method to prove, that in all portions of the
spectrum, rays of all three descriptions, and consequently the
white light due to them union, is to be found. The facts which
he calls in to his support prove, he considers, that homogeneous
light, in the sanse of Newton, that is, light composed of rays
of equal refrangibility (wave-length) only, sometimes suffers
a change of colour in its passage through coloured media, while
the universally accepted theory of Newton asserts that the colour
of homogeneous light depends solely upon its refrangibility
(wave-length) ; that such light may be weakened, nay, com-
pletely extinguished, in its passage through coloured media, but
can never exhibit a change of colour. We must certainly grant
that, ifa single case be established in which the colour of homo-
geneous light is changed by absorption in a coloured medium,
Newton’s theory must be abandoned, and that of Brewster, or
one similar, must be assumed in its stead.
I remark in the first place here, that the number and nature
of the three primitive colours assumed by Brewster are based
upon indirect inferences. In this respect he has retained the
pretty generally received theory of the mixture of colours, accord-
ing to which red, yellow, and blue are the components of all
others ; yellow and blue, for example, producing green. I have
shown in another place* that this theory is based upon the
results of the mixture of the coloured substances merely, but that
the mixture of such substances is by no means equivalent to the
mixing of lights of the same colours,—to cite a particular example,
yellow and blue united do not produce green, but white. The three
colours, red, yellow and blue, can therefore compose no green,
and must, if we are to retain the idea of three primitive colours,
be superseded by others, say red, green and violet, as already
assumed by Thomas Young. By this alteration Brewster’s theory
would undergo no essential change; single conclusions only
would require modification. I will therefore not enter further
upon this subject here, but limit myself to the investigation of
the question, “Is the colour of homogeneous light altered by
coloured media or not ?”
Hitherto Airy+, Drapert, and Melloni§ have sought to refute
* “Ueber die Theorie der zusammengesetzten Farben,” Miiller’s Archiv
fiir Anatomie und Physiologie, 1852.
f Phil. Mag. vol. xxx. p. 73; Pogg. Ann. vol. Ixxi. p. 393.
} Silliman’s Journal, 1847, vol. iv. p. 388; Phil. Mag. vol. xxx. p. 345,
§ Bibl. Univ. de Gen, Aotit, 1847; Phil. Mag. vol. xxxii. p. 262,
New Analysis of Solar Light. 403
the view of Brewster. The first dwelt particularly upon the fact
that Brewster, in the method which he applied, had not the
colours changed by absorption simultaneously with the unchanged
colours before him, and could therefore readily make a mistake
in the comparison, To this Brewster replied, and I can corro-
borate his statement by my own experience, that in his observa-
tions the changes of colour were for the most part sufficiently
striking to be observed without difficulty. Dyaper and Melloni
expressed their doubts regarding the purity of the spectrum used
by Brewster, and thought that the single colours might overlap
each other considerably. From Brewster’s statements in reply
to these attacks, it is evident that no such overlapping of the
colours took place; his later experiments on the number of
Fraunhofer’s lines in the solar spectrum, show further that he
possessed far more complete apparatus for the separation of the
rays of different refrangibility than even Fraunhofer himself, or
perhaps any other physicist. A careful repetition of at least the
most important of his experiments, carried out in exact accord-
ance with his method, and with every precaution hitherto deemed
necessary, has indeed taught me that the facts which he affirms
to have observed are described with perfect accuracy; indeed
nothing else could be expected from so skilful an observer; I
trust, however, to be able to show that his explanation of these
experiments is untenable, and thus to remove the apparent con-
tradiction of the views of Newton.
It is much to be regretted that Brewster nowhere gives a de-
tailed description of his method of observation. Hence it is that
Draper and Melloni might do him injustice by their suppositions,
and hence also, that at the outset I must ask his indulgence in
case I also should allude to possible sources of error which he
has taken pains to avoid. Partly from his replies to his anta-
gonists, and partly from the description in his Treatise on Optics,
London, 1831, I gleaned the following regarding his mode of
observation. In the shutter of a dark room he made a narrow
aperture, and looked at this with the naked eye through a strongly
refracting prism; in the spectrum thus formed he was able to
detect the stronger lines of Fraunhofer, He then introduced
the absorbing coloured medium between the eye and the prism,
and observed the altered spectrum. Besides this, he repeated
the experiment with spectra in which a number of dark bands
were formed by interference, and the different colours separated
in a still more evident manner. Brewster does not state whether
it was direct sunlight, or merely the reflected hght of the sky
which he permitted to enter through the aperture and fall upon
the prism. We must, however, assume that in most cases he
made use of the former; for when the slit is sufficiently narrow
2D2
404 M. H. Helmholtz on Sir David Brewster’s
to show the lines of Fraunhofer, the coloured rays changed by
the absorbing medium, and to which the experiments had refer-
ence, are for the most part so feebly luminous that they can be
clearly seen by direct sunlight only.
The doubts which impressed themselves upon me during the
repetition of these experiments, refer, in the first place, to the
question whether small quantities of white dispersed light might
not have been mixed up with the spectrum; and secondly,
whether the eye under the given circumstances was not prevented
by physiological influences from forming a correct judgement as
to the colours. With regard to the doubt first expressed, it may
be stated that by the method of Brewster all light, with the ex-
ception of that which enters through the aperture, may be com-
pletely cut off; with a good strongly refracting prism, or a com-
bination of two such prisms and a narrow slit, it is possible, so
far as the solar light is regularly refracted, to separate it very
completely into its differently coloured rays, so that in the spec-
trum these shall not at all overlap each other. It must, however,
be remembered that a small portion of light could obtain admis-
sion by another way than that of regular refraction. In the first
place, the dispersion of the light at the limiting surfaces and in
the mass of the glass merits consideration.
If a piece of glass, whether a prism or a lens, be directly shone
upon by the sun and observed against a dark ground, no matter
how clear or how highly polished it may be, a great number of
shining points are always seen in its interior, and minute scratches
upon its surface; both disperse irregularly a sensible quantity
of light, and impart to the whole a smoky appearance. To
render such an examination quite exact, let a sheaf of solar rays
issuing through an orifice in a dark screen fall upon the piece of
glass, and let the eye be brought nearly into the same line as the
transmitted rays, so that the latter shall pass close to the eye
but not enter it. The little irregularities of the surface and
mass then appear brightly illuminated against the black ground
furnished by the screen. The flint-glass prism cut by Plossl,
which I made use of, and which with a telescope showed the lines
of Fraunhofer in great number and perfection*, was not free
from such irregularities. Brewster himself has not left this
point unnoticed ; in his reply to Draper he observes, that besides
the most beautiful prisms of glass, he also used prisms of rock-
salt, of such homogeneity and purity that on looking through
them the substance of the prism was invisible; but he does not
say whether he tested them by direct sunlight in the manner I
have described. In this way many imperfections are rendered
* It resolved, for example, the line D into its two component lines lying
close beside each other.
New Analysis of Solar Light. 405
visible which are totally imperceptible in ordinary daylight.
Prisms of rock-salt were not in my possession, and I can there-
fore form no opinion as to their completeness.
The second circumstance to be taken into account is the re-
peated reflexion of light in the prism. In the majority of prisms
used for experiments on dispersion the two refracting surfaces
alone are polished, the other three being ground dull. If such
a prism be placed upon a dark ground so that the dull surface
shall be illuminated, then within the prism a series of reflected
images of this surface is observed. The two polished sides act
lke an angular mirror, which exhibits a series of circular images
of any object placed between its reflectors. In the case before
us the third surface occupies this position, and we look through
one of the reflectors into the interior. The reflected images of
the third surface appear in exactly the same direction as the
spectra which are observed on looking through the prism; and
as a portion of the incident light usually falls upon the third
surface, illuminating it and its images, a weak white luminosity
is thus created which spreads itself over the spectrum. The
quantity of the reflected light is certainly very small, and in
general will not be at all observed beside the regularly refracted
hght. To cut it off, it is necessary to blacken all the surfaces
well except the two refracting ones.
When the coloured media are introduced between the prism
and the eye, it must be remembered that if the polish of their
surfaces and the purity of their mass be not perfect, light will
also be dispersed by them. As coloured media, Brewster used
for the most part glass plates or coloured fluids, the latter
of course enclosed between glass plates. Regarding the purity
of the glasses I have just spoken ; but in the case of fluids also,
for example of distilled water, we know that through layers of
a certain depth the light which passes is cloudy, that is, a portion
of it is dispersed. Besides this, the reflexions which take place
between two surfaces of the coloured medium, and between them
and the cornea of the observer’s eye, are also to be taken into
account. When the coloured plate has parallel surfaces, the rays
which have undergone repeated reflexion between them create
secondary images of the spectrum which almost completely coin-
cide with the original one, and cannot do much injury. If the
surfaces are not parallel it would be more suspicious, for here
the colours of the secondary images might fall upon other colours
of the primary. To this it must be added, that the incident
light is partly reflected by the cornea, and this reflexion again
reflected by the glass plate; the image thus formed being too
near the eye must appear as a bright luminosity in the field of
view. On account of these circumstances, I prefer placing the
406 M. H. Helmholtz on Sir David Brewster’s
coloured media between the source of light and the aperture, to
placing them between the prism and the eye. By this alteration
a considerable quantity of dispersed light will be excluded from
the field of view.
The description of all these circumstances may appear pedantic,
and I am ready to admit that the irregularly refracted light
must certainly form an extremely small portion of the hght inci-
dent—a portion far too inconsiderable sensibly to affect the
appearance of the spectrum under ordinary circumstances. It
will, however, be seen that it is not too small when added to
colours that have been already greatly weakened by absorption,
to cause a sensible change in the tint of the latter.
The circumstances heretofore spoken of are such as possibly
might be excluded in following out Brewster’s method of expe-
riment. Perhaps there are prisms which are able to withstand
the foregoing test; Brewster’s may perhaps have been properly
blackened, and the coloured media placed before the aperture ;
then indeed regularly refracted light alone would reach the eye.
But there are sources of error resident in the eye itself which
cannot be avoided. I would invite attention to the fact, that
when very bright light of any kind whatever falls upon a portion
of the retina, light of the same kind appears diffused as a weak
luminosity over a great portion of the field of view. The pheeno-
menon is easy to be observed. Let a candle be placed in the
evening in the neighbourhood of a large dark surface, for instance
of a door which opens into a dark room, and let the degree of
darkness of the surface be observed while the light is alternately
concealed by the finger and allowed to strike the eye. It will
be readily seen, that as often as the rays freely enter the eye
a white luminosity appears spread over the surface, being brighter
in the vicinity of the light, and spreading itself weakly over the
more distant portions of the surface. The same is observed when
daylight, and most strikingly when direct sunlight enters the
eye from an orifice in a dark screen. When the orifice is covered
by a coloured glass, the luminosity has the colour of the latter.
I have observed this with my own eyes, which are in good con-
dition, and have also shown it to many others. That the diffrae-
tion of the light by the eyelashes is not the cause of this is
proved by the fact, that the phenomenon is observed when the
lids are drawn far apart.
With regard to the cause of this phenomenon, it has been
hitherto regarded by most observers who have noticed it as purely
subjective ; it was believed to be referrible to an extension of the
excitement to the adjacent fibres of the retina. But it can be
shown that circumstances exist which must cause a small portion
of objective light dispersed within the eye to reach other portions
New Analysis of Solar Light. 407
of the retina than those affected by the regularly refracted light.
To these belong undoubtedly the diffraction of light in the pupil.
When light passes through a narrow orifice, or simply passes the
edge of a dark body, a small portion of it will be always deflected.
Now although the pupil is certainly too large in comparison to
the focal distance of the eye to permit of rings being formed and
a considerable portion of light dispersed, as is the case when a
very small aperture is held close to the eye, still the diffraction
is by no means completely annulled. Further, it may be regarded
as questionable whether the media of the eye are absolutely clear ;
being partly composed of microscopic cells and fibres, as the
cornea and crystalline lens, and in other places traversed by a
great number of fine membranes, as in the vitreous humour.
The presence of little irregularities in the structure of the back-
ward portion of the vitreous humour is further indicated by the
so-called midges of the field of view, and perhaps something
similar is to be found in other portions of the eye. By these also
light must be dispersed. Finally, it is proved by the eye-mirror
constructed by me*, that a tolerable quantity of light is sent
from the illuminated portions of the retina to the pupil, and this
must be reflected back again from the forward surface of the
cornea. It is therefore to my mind an undoubted fact, that a
portion of the light incident upon the eye is deflected so as to
fall upon other portions of the retina. Whether along with this
an extension of the nervous excitation over the retina takes place,
cannot be decided without further investigation ; for our purpose
it is, however, a matter of indifference whether objective light, or
only its subjective perception, is diffused over the retina.
I will now attempt to prove that one of Brewster’s most striking
results is derived from a mixing of the regularly refracted light
with other light which has been dispersed partly without and
partly within the eye. I allude to the isolation of white light in
the yellow of the spectrum by glass coloured blue with smalt.
It is known that by such glass dark bands are generated in the
less refracted portion of the spectrum. Between them stand
several coloured bands, namely (1) the extreme red, embracing
the lines A and B, quite unaltered; (2) a band of reddish-orange
between the lines C and D, extremely weak; (3) a yellow band,
at one end verging into orange, at the other end into green, less
weakened than the foregoing. Between this yellow and the
green occurs an interval not totally dark, while blue and violet
are transmitted without diminution. Brewster draws attention
to the fact, that while the primitive colour of the yellow band
was a rich gamboge, the same viewed through a certain thickness
* See my description of an eye-mirror (Augenspiegel) for the investiga
tion of the retina of living eyes. Berlin, 1851.
408 M. H. Helmholtz on Sir David Brewster’s
of the glass appeared a dull yellow; through a still greater
thickness it appeared to be a greenish-white; and on introdu-
cing other colouring matters, particularly solutions of copper
and red ink, it finally changed into white. This white he further
asserts is not to be decomposed by the prism; but if I rightly
comprehend the meaning of his expressions, he has never tried
this by a second prism—which indeed could not be effected with-
out a considerable modification of the method of experiment—
but infers it merely from the fact that this white light has passed
undecomposed through the first prism.
The blue glass which I had at my disposal showed the phe-
nomena described by Brewster in the following manner. Seen
through one plate, the yellow stripe in a spectrum produced by
the light of the firmament was very feebly luminous, and a
greenish-yellow ; but in the spectrum obtained from the portion
of the heavens which lay near the sun it was a pure and shining
yellow. Observed through two plates, the stripe obtained from
daylight disappeared totally; with direct sunlight it appeared
almost white; with greater intensity of light it verged into
greenish-yellow, and with diminished intensity into blue. Ad-
jacent to this moderately illuminated band the blue and violet
appeared of course splendidly bright, and the extreme red was
also strongly luminous. Seen through three plates in direct
sunlight, the yellow band appeared a bluish-white. The altera-
tion of the colours was somewhat less when the plates, instead
of being introduced between the prism and the eye, were placed
before the aperture, that is, between the source of light and the
aperture. When we consider that the sun is upwards of 50,000
times brighter than the brightest white surface which he illumi-
nates, and that the yellow in the original spectrum possesses the
intolerable brightness of the sun, but seen through two blue
glass plates appears as a moderately illuminated surface of paper,
in the absence of more exact measurements we shall not be far
from the truth in assuming that the hundredth part of the yel-
low passes through one glass, and the ten-thousandth through
two. Now supposing that only the ten-thousandth part of the
coloured light which passes unweakened through the plates is
caused, by the little irregularities before spoken of, to fall upon
the same portion of the retina as that which receives the yellow,
we must certainly obtain colours very different from the latter.
By the mixture of indigo-blue light with yellow, we obtain, as I
have shown in my investigation on compound colours, first a
whitish yellow, then white, which finally passes into a bluish-
white. The colours in the smalt-glass spectrum which lie next
to the yellow, namely red and green, can, by mixing in various
proportions, cause the white to approximate to red or green, as
New Analysis of Solar Light. 409
the case may be, and thus exhibit all the degrees of colour which
are observed through different thicknesses of the blue glass.
According to the method of Brewster, all parts of the spec-
_ trum, weakened and unweakened, are before the eye of the ob-
server at once, and it is therefore impossible to prevent the irre-
gularly dispersed portion of the brighter colours from entering the
eye. Hence the problem reduces itself to thefinding out of another
method of repeating these experiments, by which the disturbing
colours shall be totally, or almost totally, excluded from the field
of view. Ifthe spectrum be observed through a telescope, it is
possible to procure any desired colour isolated from the others,
but the irregular refraction and reflexion of the light without
the eye will be increased by the glasses of the telescope. The
changes of colour of the yellow stripe I found certainly less when
they were viewed thus singly, but nevertheless they still existed.
Another method, however, gave me perfectly satisfactory results.
The method is derived immediately from that of Brewster, if
instead of permitting the unchanged sunlight to enter through
the aperture, we transmit it first through a prism, and then per-
mit those portions only to pass through the aperture whose
changes of colour are to be investigated. My manner of pro-
ceeding is as follows :—Solar rays reflected from a mirror are per-
mitted to enter through a narrow slit into a dark room and to
fall upon a vertical prism. Immediately behind the latter is a
lens which casts the spectrum formed by the prism upon a screen.
In the latter is a second very fine vertical slit. The light of that
band of the spectrum which falls exactly upon the slit passes
through, while the rest is cut off. The observer stands behind
this second screen, the back of which is well blackened, best
covered with black velvet, and looks at the slit through a second
prism of the best possible quality. If in the first prism, or in
the lens, no light was dispersed, then would homogeneous light
alone of a determinate colour arrive at the second slit and pass
through it; and this, on account of its homogeneity, would, when
looked at through the second prism, form no spectrum, but
remain a narrow band, just as if it were seen by the naked eye.
But as a small portion of white irregularly-refracted light enters,
a very feebly luminous spectrum is formed by the latter, in which
a single coloured band, that of the regularly refracted light,
comes very brilliantly forward. The light dispersed in the
second prism and in the eye, belonging, as it does, for the most
part to that of the bright band, cannot when mixed with the
latter change its colour, for it is homogeneous with it. Of the
other colours, those only which are irregularly refracted in the
first prism pass through the slit; and this quantity of light is
so small, that the portion of it dispersed in the second prism and
in the eye of the observer cannot be further perceived.
»
410 M. H. Helmholtz on Sir David Brewster’s
By this method we can obtain bright a band of any breadth
whatever, if instead of the first slit a rectangular opening of
greater or less width is cut out. The spectrum of the first prism
will then be an impure one; that is, at every point of it the
neighbouring bands of colour will overlap each other to a certain
extent; hence regularly refracted light of different kinds passes
through the slit and is decomposed by the second prism into its
component tones of colour. In this way is obtained a more or
less bright, sharply-defined band, furnished with its appropriate
lines of Fraunhofer, and composed of those overlapping colours
which fell from the first prism upon the slit ; while the remaining
portion of the second spectrum, illuminated merely by the di-
spersed light, remains very feebly luminous. In this way the
violet at the other side of the line H, which when the other
colours are present is usually regarded as invisible, can be ren-
dered surprisingly distinct, being obtained free from white light
for a width equal to that between the lines G and H. When
viewed in the ordinary way through a telescope, the remaining
portion of the spectrum being shut out, it is usually mixed with
an inordinate quantity of white light.
If we isolate the light of the yellow band of the smalt-glass
spectrum according to this method, and subject it to the
absorption of a certain number of plates of the glass introduced
before the first or the second slit, or before the eye, we obtain
results totally different from those arrived at by the method of
Brewster. The yellow retains its originally pure and saturated
colour after it has passed through two, three, or even four plates
of the blue glass. I may further remark, that an absolutely
dark room is not essential to the success of this experiment, if
care be taken that the second screen is sufficiently black, and
the plates of glass are placed before the first slit.
Brewster’s explanation is ireconcileable with this observation.
According to his view, the light of the yellow band, when ren-
dered whitish by the cobalt-glass, is composed of rays of equal
refrangibility, and hence by refraction in prisms cannot be further
decomposed into rays of different colours. In the experiment
above described, the light of the yellow band on entering the first
slit appears actually whitish ; but when it is viewed through a
second prism, it is decomposed into pure yellow and hght of
other colours; hence it does not possess the same refrangi-
bility, but, in accordance with the explanation given by me, is
a mixture of rays of different refrangibilities. In Brewster’s
proceeding, a mixture of foreign light, whether in the prism,
glass plates or eye, could not be avoided. From this point of
view it is quite intelligible how the introduction of coloured
media might render the white colour of the band in question
more pure, or cause it to approximate to red or green.
New Analysis of Solar Light. 411
A second possible source of error is to be found in the phy-
siological effect of contrast, which might easily prejudice the
judgement of the colours, particularly when we observe a weakly
illuminated space beside one which is brightly illuminated.
Briicke* has lately drawn attention to the fact, that even quite
obscure portions of the field of view appear, beside bright colours,
to have a luminosity poured over them; that this luminosity is
sometimes of the same colour as the light which excites it, some-
times complementary to the latter, and sometimes altogether
different. He names the colour of this luminosity the induced
colour. By the degree of brightness which he made use of, he
found that red induced its complementary green, but that green
induced green, violet, blue, but that blue and yellow did not
induce any decided colour. A repetition of these experiments
with different degrees of brightness, convinces me that the ex-
pression of Briicke must be modified; when very bright light is
made use of, the same colour is always shed over the dark portion
of the field, a phenomenon the possible cause of which has been
spoken of above. With weak light the induced colour is always
the complementary one, which, as Briicke also has remarked,
becomes much more vivid when the eye is moved than when it
is fixed upon a point; with medium light the deportment of
different colours is different ; sometimes the same colour, some-
times its opposite is produced; sometimes indefinite colourings,
as if the vpposed phenomena were struggling for pre-eminence.
I have also found, in coincidence with the observation of Briicke,
that the complementary colour of red is more easily mduced
than those of violet or green.
To this source it appears to me must be referred a surprising
experiment of Brewster’s, by which he sought to demonstrate
the presence of green light in yellow, orange, and even in red
towards the line C. As absorbing medium he made use of port
wine, Peruvian balsam, pitch, sulphur-balsam, or red mica. I
have repeated the experiments with Peruvian balsam, sulphur-
balsam and pitch. Thin layers of these substances permit the
red, yellow, and green of the spectrum to stand, while they
extinguish blue and violet. In this case, however, green appears
to extend as far as the line D, whose real position is in golden-
ellow, and frequently reaches even beyond this to the vicinity
of the reddish-orange. The green seems to abut immediately
against the red. Hence the yellow-green, yellow, golden-yellow,
and even the orange tone appear to have become green, and the
latter is so vivid that it is indeed difficult to conceive that it
could be a subjective illusion. The presence of such an illusion
* «Untersuchung iiber Subjective Farben,” Denksch. der Akad. d. Wis-
senschaft zu Wien, vol. iii.
412 M. H. Helmholtz on Sir David Brewster’s
is, however, indicated by the circumstance, that the limit of the
green extends much further when the eye is permitted to wander
over the different colours of the spectrum than when it is per-
sistently fixed upon the green portion. In the first case, the
yellow colours strike the retina on places which before were acted
upon by the shining red, and therefore tend to generate the com-
plementary blue-green ; in the second case, the excitation of the
subjective colour upon the contiguous portions of the retina is
much feebler. That the phenomenon is due to a subjective
illusion is immediately shown when the colours are isolated
according to the method which I have above described, and then
looked at through layers of the above-named brown bodies of
different thicknesses; they then appear totally unchanged, and
without the slightest tendency to green.
Looked at through thicker layers of the brown fluids, green,
yellow, and a portion of the orange disappear from the spectrum.
At the edge of the red which remains, a weak rim of green is
observed, even near the line C, where the red has scarcely the
appearance of orange. The green rim is too weakly luminous
and narrow to permit of its light being isolated and singly ex-
amined. That, however, weak orange light beside strong red
may appear green, is easily shown by sticking a small disc of
paper coloured red by vermilion upon a plate of red glass, and
holding the latter against a very bright ground, the bright firma-
ment for example, while the dise is only weakly illuminated.
With a suitable strength of illumination it appears green*,
It further appears to me, that the violet colouring of the blue
to the vicinity of the line F, through absorption by yellow fluids,
olive oil, sap of the Coreopsis tinctoria, &c., belongs to these sub-
jective complementary phenomena. I have repeated the expe-
riment with olive oil, and have plainly seen the violet between
the lines F and G nearly as far as F, but only when this portion
of the spectrum was very feebly illuminated.
The oil does not sensibly change the brightness of the red,
yellow and green ; it weakens the blue considerably, and almost
extinguishes the violet. When I permitted the light of bright
clouds to enter through the slit, the first-named colours appeared
bright, the blue feeble, and the violet was not at all to be seen.
When, however, direct sunlight was passed through the slit, the
portion between the lines F and G appeared brighter and lost
its violet appearance. When isolated from the other colours of the
spectrum in the manner before indicated, the blue appears in its
* The subjective colour is very strikingly exhibited in this experiment.
A red wafer answers the purpose perfectly ; the observer stands ina weakly
illuminated place and looks at the sky, the wafer appears a vivid green or
blue-green.—J. T.
New Analysis of Solar Light. 413
true colour. I believe, therefore, that in the spectrum observed
through olive oil, the carmine-red complementary to the bright
green which lies contiguous to the blue is shed over the latter,
which is thus rendered violet.
There are also other methods which I can recommend in this
and similar cases of testing. Let the absorbing substance be
placed before the greatest portion of the slit, and before the
remaining portion white paper, thick or thin, oiled or not oiled,
which is so chosen that the place to be investigated in the absorp-
tion spectrum shall be equally bright with the corresponding
place of that formed by the light which has passed through the
paper. When the absorption is by oil, it will be seen that in the
paper spectrum also the blue between the lines F and G appears
violet. For the experiment to succeed, it is necessary that the
breadth of the absorption spectrum shall be much greater than
that of the paper spectrum.
By these facts it is plainly proved that subjective changes of
colour can take place in the spectrum, not only in the same
degree as when ordinary colours are brought together, but per-
haps more striking and illusive, on account of the greater vivid-
ness of the simple colours. In other cases these changes cannot
be referred to the induction of complementary colours. An
example of this, to which Brewster refers, is the band in reddish-
orange, which extends about from C to D in the smalt-glass
spectrum. It is much darker than the red and yellow portions
which lie next it, and seems when looked at between these with
an ordinary brightness of spectrum, to possess exactly the same
red tone as the extreme red. In a more brightly illuminated
spectrum it is observed to passinto orange. Brewster first called
the band orange-red*, but afterwards} affirms that Sir John
Herschel found it to be pure redt, and thought he had observed
a change wrought in it by absorption. In this case also the
separation of the band from the remaining portion of the spec-
trum proves that its colour is not in the least degree changed.
The same remark applies to the green-blue tones of colour on
the green side of the line F, which, as Brewster remarks, on
being looked at through a deep blue glass (probably the smalt-
glass) become green. When they are isolated and examined there
is no alteration of colour observed.
Finally, in some of Brewster’s experiments another physiolo-
gical circumstance comes into play ; the same homogeneous light
at different degrees of intensity does not excite the same impres-
sion of colour. When dazzlingly bright, all colours appear white.
* Edinburgh Transactions, vol. ix. part 2. p. 439.
+ In his reply to Airy.
{ Treatise on Light, art. 496 and 506.
414 M. H. Helmholtz on Sir David Brewster’s
This is most easily observed with violet, which, in the spectrum
of direct sunlight and by a moderate degree of brightness, appears
to be a white-gray, retaining only a feeble tinge of violet. Pro-
fessor Moser has shown me that the sun seen through a dark
violet glass appears as completely white as the strongly illumi-
nated clouds observed on looking past the.glass. In like manner
blue, of a degree of brightness which may be borne without
injury to the eye, appears whitish-blue, and, if the brightness be
increased, appears white. Green first becomes yellow-green
before, like yellow, it entirely loses its colour with increased
brightness. Red exhibits the phenomenon with more difficulty
than all others; and only by the highest degree of brightness
have I been able to see it bright yellow in the spectrum, or the
sun of the same colour when looked at through a red glass.
While experimenting on this subject, in order to prevent the
admixture of all light of other colours, I have made use of the
coloured bands of the solar spectrum which were separated and
purified by two prisms in the manner already described, Dif-
ferent degrees of brightness were obtained by applying the
light of brightly illuminated portions of the firmament; but
as, according to Brewster’s theory, the colours of the spectrum
produced by sunlight are not the same as those produced
by the light of the firmament, I also made use of the direct
solar rays, sometimes observing them directly, sometimes trans-
mitting them through two Nichol’s prisms crossed perpendicu-
larly. By reflexion from uncoated glass plates, or by receiving
them upon a white screen, the brightness can be dimmed without
fear of altering any colour.
If, therefore, a certain thickness of the solution of ammonio-
sulphate of copper shows the blue of the spectrum bright and
whitish, while a greater thickness causes it to appear a deep
dark blue, we are simply to conclude that this fluid absorbs blue
rays, but by no means that it has abstracted white light from
the blue. Herein also we find the explanation of the fact, that
the yellow in the spectrum of daylight or of the blue firmament
is scarcely discernible, while in the spectrum of direct sunlight
it takes up a wide space. The pure yellow forms in a flint-glass
spectrum an extremely narrow band, and with the blue light of
the firmament is weaker than its neighbouring colours, so that
in the slightly magnified spectrum it is hardly discernible between
the wide and shinig red and green, When considerably mag-
nified, on the contrary, or when viewed isolated, it is very plam
even with daylight. In the spectrum of direct sunlight, how-
ever, yellow is the most prominent colour and of dazzling bril-
liancy. Green and red, with increased intensity, become also
yellowish, and hence it is that yellow appears so prominent. If,
New Analysis of Solar Light. 415
however, the solar spectrum be enfeebled by reflexion from un-
coated glass plates, or by a pair of Nichol’s prisms crossed nearly
at right angles, the yellow recedes and appears as in the daylight
spectrum. If, besides this, the colours belonging to various groups
of Fraunhofer’s lines be isolated and determined in a spectrum
of moderately strong sunlight and in one of daylight, they will
be found quite alike.
Of the facts which Brewster adduces in support of his theory
one remains over, with regard to which I do not know whether
I can say that I have succeeded in repeating it, and some others
which I was unable to repeat, not having the proper absorbing
media in my possession. The first is obtained with Peruvian
balsam, sulphur-balsam, pitch and mica. The red of the spec-
trum seen through these media is said to appear orange. With
a moderate intensity of light I could observe nothing of the kind,
no matter what might be the degree of thickness of the pitch or
the balsam ; the red retained its colour quite unchanged. Only
with light of a greater intensity, and when a brown luminosity
which surrounded the place gave evidence that a considerable
quantity of light was dispersed, did I see the red somewhat
orange. ‘This, however, in the case under consideration, is to
be referred to the admixture of the dispersed brown of the light
compounded of red, yellow, and a little green, and to the ten-
dency of red to appear yellow when the light isintense. Perhaps
Brewster also made use of such a bright spectrum. When the
red is isolated according to my method, its colour remains totally
unchanged.
Various experiments have been made by Brewster with trans-
parent wafers formed of gelatine. I could not obtain such here ;
and as their colours alone, and not the colouring matters, are
mentioned, I was unable to make them myself. They seem,
however, to me to be not free from objection, at least when placed
between the prism and the eye, inasmuch as the best glutinous
plates when formed of the purest isinglass between plates of
glass, do not belong to the class of transparent bodies. Even
when we are able to see pretty clearly through a single one,
several placed one over the other make the image cloudy—a proof
that they disperse a considerable quantity of light. This would
indeed explain the action said to be exhibited by orange, yellow,
and green wafers—the turning of the red of the spectrum
orange. The dispersion of the predominant coloured light over
the red is suflicient for this. How a green wafer generates a
white band in the blue I am unable to say, inasmuch as I can-
not repeat the experiment.
A pale red glass which absorbs the green between 6 and F
(probably coloured with purple of Cassius) and a pale yellow
416 On the Colours of a Jet of Steam and of the Atmosphere.
which weakens the blue, are said when combined to convert the
blue into violet. The explanation is the same as for olive oil.
Red, reflected from a plate of brass, becomes orange according
to Sir John Herschel. The means of explaining this is given
by Airy in his memoir against Brewster.
I have now mentioned all the facts adduced by Brewster.
Although I have been unable to repeat all his experiments,
I believe the discussion of those which I have succeeded in
repeating, abundantly proves that in his method many hitherto
unobserved influences come into play, which render a sure judge-
ment of the colours impossible and deprive his arguments of all
force. If the assumed connexion of the refrangibility or length of
wave with colour is to be proved erroneous, it must be done by
some more certain method of observation, similar, for example,
to that which I have described in this memoir ; a principal con-
dition of which is, that the colour investigated be separated from
the other colours and rendered. free from every trace of irregu-
larly dispersed light.
LXIV. On the Colours of a Jet of Steam and of the Atmosphere.
By R. Cravustrus.
To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,
i the August Number of the Philosophical Magazine (p. 128)
Mr. Reuben Phillips describes a series of interesting expe-
riments on the colours of a jet of steam, which connect them-
selves with the known experiments of Prof. Forbes upon the same
subject. At the end of his paper Mr. Phillips writes,—
“ Prof. Forbes, after discovermg the red colour of a jet of
steam by transmitted light, connected the red colour of the
clouds with this fact ; and the truth of this connexion is beyond
dispute. So far, however, as I have been able to go, the colours
of the steam-jet are manifestly only influences of ordinary inter-
ference, greatly resembling that produced by thin transparent
plates. Thus in (192) the transmitted light is red, as in Prof.
Forbes’s experiments, but the reflected light is blue. It is
therefore to be inferred, that all the colours of the clouds origi-
nate in interference, caused by minute drops of water, the size
of which determines their colour; while the blue jet (192) is, I
think, strictly analogous to the blue sky.”
With reference to this passage I permit myself to make the
following remarks :—The blue colour of the firmament and the
morning and evening red were explained by me in 1849* upon
* Poggendortf’s Annalen, vol, Ixxvi. p. 188.
Mr. J. P. Hennessy on some Demonstrations in Geometry. 417
the principles of ‘ordinary interference; and some time after-
wards* I applied the same explanation to the colours of a jet of
steam observed by Prof. Forbes.
In one point, however, my view diverges from that of Mr.
Reuben Phillips. He names the water-particles which cause the
interference “drops of water,” while I believe that they are
water-bladders, for which view I have adduced my reasons in a
separate paper.
Besides this, I should like to mention two points with regard
to which I have been unable to obtain from the paper of Mr.
Phillips a clear notion of the author’s opinion.
(1.) Among the various colours of the atmosphere there appears
to me to exist only two simple originating ones; namely, the
blue colour in all its shades, from dark blue to white, due to
interference by refleaion; and orange-red colour in the corre-
sponding shades, due to interference by transmission. The other
colours exhibited at times in various portions of the heavens, as,
for example, purple or green, I hold to be due to the mixing of
the above two colours in their different shades.
(2.) When clouds appear coloured, I believe that the colour
exhibited is for the most part not formed in the cloud itself,
inasmuch as the little bladders generally differ too much in thick-
ness to cause the production of a single determinate colour ; but
that the light, partly on its way to the cloud, and partly between
the cloud and our eye, assumes its colour; even in the appa-
rently clear air there always exist bladders, which, however, are
for the most part so attenuated, that they favour in a particular
manner the formation of the first colours of interference, namely,
blue and orange-red.
I remain, Gentlemen,
Very respectfully yours,
Berlin, Oct. 13, 1852. R. Cruavstus.
LXV. On some Demonstrations in Geometry.
By Joun Pore Hennessy ft.
ERB it possible to give direct demonstration for every
proposition in Euclid’s Elements of Geometry, it would
add, if not to the strength, at least to the beauty of that cele-
brated chain of reasoning; for the reductio ad absurdum, as the
* Die Licht Erscheinungen der Almosphdre, described and explained by
R. Clausius. Leipzig, E. B.Schwickert, 850. Also under the title Beitriige
zur Meteorologische Optik, published by John Aug. Grunert. Part 1. No. 4.
p- 395; and in Pogg. Ann. vol. Ixxxiv. p. 449.
+ Pogg. Ann. vol. Ixxvi. p. 161.
+ Communicated by the Author.
Phil. Mag. 8, 4. Vol. 4. No. 27, Dec. 1852. 2H
418 Mr. J. P. Hennessy on some Demonstrations in Geometry.
most eminent editor of Euclid remarks, “only proves that a
thing must be so, but fails in showing why it must be so;
whereas direct proof not only shows that the thing is so, but
why it is so.”
To render the first book of the Elements in this respect perfect,
it would be necessary to alter the proof of ten propositions ; viz.
the VI., VIII., XIV., XIX., XXV., XXVI., XXVII., XXIX.,
XXXIX. and XL. Dr. Lardner has given direct proofs to the
VIII. and XXV., and I have done so to the XL.*, leaving seven
still proved indirectly ; of these I will proceed to show how the
VL., XIX., and XXVI. may receive direct demonstrations ; of
the remaining four I believe the XXXIX. will at some other
period be proved directly, but that the XIV., XX VII. and XXIX.
never will. I am led to form this opinion of the three last
because they rest on defective premises; the XIV., on the defi-
nition of a right line, which is unintelligible; and the XXVII.
and XXIX. on the theory of parallels.
According to all geometricians, the fundamental rule in geo-
metry is, “that the truth of a proposed principle is to be deduced
from the axioms and definitions or other truths previously and
independently established.” We may therefore place the VL.,
XIX., XX., XXI. and XXVI. after the XXXII., because that
proposition and all others before it are proved independently
of these five.
With this arrangement, the following direct demonstrations of
the VI., XIX. and XXVI. can be given :—
VI. “If two angles (B and G) of a triangle (BAC) be equal,
the sides (AC and AB) opposed to them are also equal.”
Find a point D which is equidistant from A
the three vertical points of the triangle, (X.,
XII. and IV.).
The angles BCD and CBD are equal (V.),
therefore DCA and DBA are equal ; but these
are respectively equal to CAD and BAD, there- ® c
fure CAD and BAD are equal; therefore the remaining angles
ADC and ADB are equal (XXXII.). In these two triangles the
sides AD and DC are equal to AD and DB, and the included
angles equal, therefore AC and AB are equal (IV.).
XIX. If in any triangle (BAC) one angle (B) be greater than
another (C), the side (AC) opposite the greater angle is greater
than the side (AB) opposite the less. *
From the point C draw CD parallel to AB and
equal to AC. B c
As the angle ABC is greater than BCA, the ¥
angle DCB which is equal to ABC (XXIX.) D
must be greater than BCA, therefore the line
* Phil. Mag. S. 3, October 1850.
On the Reduction of Temperatures by Electricity. 419
bisecting the angle ACD must pass between BC and CD. Draw
this line, and produce AB to meet it.
As AEF and CD are parallel, DCE and AEC are equal (XXIX.),
therefore ACE and AEC are equal, therefore AH and AC are
equal (VI.), and therefore AC is greater than AB.
XXVI. If two triangles (BAC, DEF) have two angles, and a
side similarly placed with regard to the equal angles, equal, these
triangles are equal in every respect.
Place them so that the bases form one G
right line, and the equal sides AC and ae
DE are next each other. Produce BA : =
and FE until they meet atG. Jom A
and KE. As the angles ECF and CEF are
equal to ACB and CAB, the remaining angles ABC and EFC
are equal (XXXII.). Therefore BG and FG are equal (VI.).
As AC and CE are equal (Hyp.), the angles DEA and CAE are
equal, therefore GAE and GHA are equal, and therefore GA and
GE are equal; taking these from BG and FG, we have AB and
EF equal, and therefore (IV.) the triangles are equal in every
respect.
If the angles ABC and EFC are obtuse, the point G will lie
at the other side of BF, but the proof will remain the same.
If, however, ABC and EFC are right angles, a different de-
monstration must be adopted. igi
Produce AC and EC until the pro- —[--
duced parts are each equal to AC or
EK
EC. Join BD and FG. In the tri- * é :
angles ACB and DCB, the sides AC
and CB are equal to DC and CBand ® G
the included angles equal, therefore AD forms one continued
right line. In a similar manner EG is proved to be one right
line. In the triangles ACD and ECG, AC and CD are equal to
EC and CG, and the included angles (XV.) are equal, therefore
AD and EG are equal, and therefore their halves AB and EF
are equal.
Queen’s College, Cork.
Sept. 28, 1852.
LXVI. On the Reduction of Temperatures by Electricity.
By Dr. Joun Tynvaut, F.R.S.
[With a Plate. |
To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,
N an abstract of Professor William Thomson’s Mechanical
Theory of Thermo-electric Currents, given in your Supple-
mentary Number for July, reference is made to the well-known
2H 2
420 Dr. Tyndall on the Reduction of Temperatures
experiment of Peltier on the absorption of heat at a bismuth
and antimony joint. This has drawn from Mr. Adie a brief
communication, published in your Number for September, from
which it appears that the writer has never been able to obtain
Peltier’s result ; he virtually denies its existence, and affirms the
true state of the case to be that /ess heat is developed at some
junctions than at others, but that co/d is never generated. An
objection precisely similar to that now urged by Mr. Adie in-
duced Lenz to repeat the experiment fifteen years ago*. To the
experiment of Lenz I took the liberty of drawing Mr. Adie’s
attention in your October Number; I did so because Mr. Adie
had never mentioned it in his remarks, and it seemed to me to
offer a proof of the absorption of heat so obvious as to be imme-
diately appreciated. It does not however appear so to Mr Adie,
for in your last Number I find that he suggests a hygrometric
action as the probable cause of the diminution of temperature
observed by Lénz. I should ill occupy your space were I to
dwell upon conjectures where the ‘law and testimony ’ of experi-
ment are so near at hand, and fact so readily attainable. If the
following results do not convince Mr. Adie, they will perhaps be
the means of clearing away whatever doubt his remarks may
have created in the minds of others.
Experiment No. 1.—In Plate IV. fig. 1, A is a bar of anti-
mony, B a bar of bismuth, both bars being brought into close
contact at J. To the free ends of the bars the wires w w! are
soldered, and dip into the little pools of mercury m m'; cisa
piece of cork through which the wires pass, and by taking which
in the fingers the wires w w! may be easily moved from the pools
mm! tom m'',the warming of the wires being prevented bythe cork.
From m m" wires proceed to a galvanometer, G, whose needles
prove themselves to be perfectly astatic by setting at right angles
to the magnetic meridian}. B is a single cell of Bunsen, from
which, when matters stand as in the figure, a current can be
sent through the bismuth and antimony pair.
The voltaic circuit having been established, the current—a
very feeble one—was permitted to circulate for two minutes, its
direction being from antimony to bismuth across the junction ;
at the end of the time specified the wires w w! were moved from
mm! to m m'', a thermo-circuit being thus formed in which the
galvanometer was included ; the index of the instrument was at
once deflected, and the extreme limit of its first impulsion was
noted; it amounted to
75°.
* Pogeendorff’s Annalen, vol. xliv. p. 342.
+ For an explanation of this, see an abstract of Du Bois Reymond’s
Researches on Animal Electricity, edited by Dr. Bence Jones.
by Electricity. 421
The deflection in this case was similar in direction to that pro-
duced when the warm finger was placed upon the junction.
The wires w w!' were moved back to their former position, and
the apparatus was suffered to cool; by crossing the wires b J’,
causing the former to dip into m and the latter into m!, the vol-
taic current was reversed, its direction across the junction being
now from bismuth to antimony; the same time of circulation
being allowed, on establishing the thermo-eircuit, as before, a
deflection of
68°
was observed. The deflection was the same as that produced
when a small glass containing a freezing mixture was placed
upon the junction.
But Mr. Adie will probably urge, that it is not the cold deve-
loped at J, but the heat developed at some of the other points,
which caused the deflection here. I will not pause to discuss
the objection, but will proceed to an experiment which deprives
it of all force.
Experiment No. 2.—AA!' is a bar of antimony, BB! is a bar
of bismuth cast as im fig. 2, and in contact at the centre.
From the cell B a current was sent through the system, and
during its circulation the ends g g' were unconnected ; neither
heating nor cooling of these ends by the current was therefore
possible. The direction of the current across the junction was
first from antimony to bismuth. After a short period of circu-
lation the current was interrupted, and the ends of the wires
w w! were dipped into the mercury cups g g', which were also in
contact with A'B’; the index was driven through an arc of
40°,
The sense of the deflection in this case showed that the junction
had been heated.
The current was reversed, its direction across the junction
being now from bismuth to antimony ; proceeding as before, the
deflection was
30°.
The sense of this deflection was the same as that produced when
the temperature of the junction was lowered by a freezing mixture.
I see no escape here from the conclusion that heat has been
absorbed; for the ends g g’, exposed as they are to the atmo-
sphere, must have its temperature, while the ends mm’, on which
suspicion might reasonably rest, the current having passed
through them, are wholly excluded from the thermo-circuit.
The reader will observe that this is merely a modification of
Lenz’s experiment with the metallic cross,
But Mr. Adie has tried the cross, and it does not satisfy him ;
422 Dr. Tyndall on the Reduction of Temperatures
very well, we will discard it, and proceed at once to an experi-
mentum crucis. If the arms A! B! are not actually included in
the voltaic circuit, they may seem to be in suspicious connexion
with it. We must remove this source of doubt.
Experiment No. 3.—A and B, fig. 3, represent, as before,
the bismuth and antimony couple, united at one end. M is
a small chamber, hollowed out in a piece of cork and filled
with mercury. A! B! is a second delicate thermo-electric pair,
connected with the galvanometer, but wholly unconnected with
A B. The wires w w’ are sufficiently strong to support A! B’, so
that the junction stands vertically over M, a shght pressure
being sufficient to cause the wedge-shaped end of the pair to
descend into the chamber of mercury. The whole arrangement
was permitted to remain in a room until the temperature of the
surrounding atmosphere was attamed. Matters being in this
state, when the pair A! B’, which I will call the ¢est-pair, was
dipped into the mercury M, no effect was produced on the gal-
vanometer. Now the mercury must partake of the changes of
temperature of the junction with which it is in contact, and the
nature of these changes will be ascertained with great precision
by examining the mercury at proper intervals by means of the
test-pair.
The voltaic circuit was closed, and the current allowed to
circulate for three minutes, passing in the first place from bis-
muth to antimony. The current was then interrupted, and the
test-pair was immediately dipped imto the pool of mercury; the
index of the galvanometer was driven through an are of
40°.
The deflection was similar to that produced by immersing the
end of the test-pair in a freezing mixture. Hence in this case
heat was undoubtedly abstracted from the mercury durmg the
passage of the current.
The apparatus being permitted to resume its equilibrium, the
voltaic current was caused to traverse AB in an opposite direc-
tion. At the end of three minutes the test-pair was again im-
mersed, and a deflection of
45°
was the consequence. The deflection was opposed to the former
one, and demonstrated the generation of heat at the junction.
I am at present unable to see what possible objection can be
brought against this last experiment. A hygrometric effect is
out of the question; and the test-pair A’B! being wholly uncon-
nected with the voltaic current, cannot in any way be influenced
by the latter. The results observed are evidently pure effects of
the heating and cooling of the junction.
by Electricity. 423
It will perhaps be permitted me to cite a single additional
experiment, which exhibits all the necessary evidence without the
reversion of the voltaic current.
Experiment No. 4.—B, fig. 4, is a curved bar of bismuth,
with each end of which a bar of antimony, A, is brought
into close contact. In front of the two junctions are chambers,
hollowed out in cork and filled with mercury as before. A cur-
rent was sent from the cell B in the direction indicated by the
arrow; at M it passed from antimony to bismuth, and at M’
from bismuth to antimony. Now if Peltier’s observation be
correct, we ought to have the mercury at M warmed, and that
at M! cooled by the passage of the current. After three minutes’
circulation the voltaic cireuit was broken, and the test-pair dipped
into M’; the consequent deflection was
38°,
and the sense of the deflection proved that at M! heat had been
absorbed.
The needles were brought quickly to rest ut zero, and the
test-pair was dipped into M; the consequent deflection was
60° ;
the sense of the deflection proved that at M heat had been
generated.
The system of bars represented in fig. 4, being imbedded
in wood, the junction at M cooled slowly, and would have
taken a quarter of an hour at least to assume the temperature of
the atmosphere. The voltaic current was reversed, and three
minutes’ action not only absorbed all the heat at M, but gene-
rated cold sufficient to drive the needle through an are of 20°
on the negative side of zero.
These experiments, Gentlemen, corroborate a result which to
my mind is sufficiently well established without them. Never-
theless I would say, that the conclusions of Mr. Adie are such
as a restricted examination of the subject will most probably
lead to. I have no doubt as to the correctness of his results
described in the September Number of the Magazine; but I
have just as little doubt, that had Mr. Adie varied the strength
of his current sufficiently, he would have spared himself the
statement, that “in his experiments he had never met a fact
which in the least encourages the view that electricity reduces
temperatures.”
I remain, Gentlemen,
Queenwood College, Your obedient Servant,
November 1852. Joun TYNDALL.
[ 424 ]
LXVII. On the Dynamical Theory of Heat. By Wit11aM
Tuomson, M.A., Fellow of St. Peter’s College, Cambridge,
and Professor of Natural Philosophy in the University of
Glasgow*.
[Continued from p. 176.]
Part IV.—On a Method of discovering experimentally the Rela-
tion between the Mechanical Work spent, and the Heat produced
by the Compression of a Gaseous Fluid.
61. Pus important researches of Joule on the thermal cir-
cumstances connected with the expansion and com-
pression of air, and the admirable reasoning upon them expressed
in his paper} “On the Changes of Temperature produced by the
Rarefaction and Condensation of Air,” especially the way in
which he takes into account any mechanical effect that may be
externally produced, or internally lost, in fluid friction, have in-
troduced an entirely new method of treating questions regarding
the physical properties of fluids. The object of the present
paper is to show how, by the use of this new method, in con-
nexion with the principles explained in my preceding paper, a
complete theoretical view may be obtained of the phenomena
experimented on by Joule; and to point out some of the objects
to be attained by a continuation and extension of his experi-
mental researches,
62. The Appendix to my Account of Carnot’s Theory} con-
tains a theoretical investigation of the heat developed by the
compression of any fluid fulfilling the laws§ ‘of Boyle and Ma-
riotte and of Dalton and Gay-Lussac. It has since been shown
that that investigation requires no modification when the dyna-
mical Theory is adopted, and therefore the formula obtained as
the result may be regarded as being established for a fluid of the
kind assumed, independently of any hypothesis whatever. We
may obtain a corresponding formula applicable to a fluid not
fulfilling the gaseous laws of density, or to a solid pressed uni-
formly on all sides, in the followmg manner.
63. Let Mdv be the quantity of heat absorbed by a body kept
at a constant temperature ¢, when its volume is increased from
v to v+ dv; let p be the uniform pressure which it experiences
from without, when its volume is v and its temperature ¢; and
let p+ = dt denote the value p would acquire if the temperature
* From the Transactions of the Royal Society of Edinburgh, vol. xx.
part 2. April 17, 1851.
+ Philosophical Magazine, May 1845, vol. xxvi. p. 369.
{ Transactions, vol. xvi. part 5.
§ To avoid circumlocution, these laws will, in what follows, be called
simply the gaseous Jaws, or the gaseous laws of density.
Prof. Thomson on the Dynamical Theory of Heat. 425
were raised to ¢+ dt, the volume remaining unchanged. Then,
by equation (3) of § 21 of my former paper, derived from Clau-
sius’s extension of Carnot’s theory, we have
1 dp
BSS Bere > Set wide. ee *
M Be dt (a) ?
where 4 denotes Carnot’s function, the same for all substances
at the same temperature.
Now let the substance expand from any volume V to V’, and,
being kept constantly at the temperature f, let it absorb a quan-
tity, H, of heat. Then
v' i d v'
H= /) Mdo=— 7 f° piv ell,
But if W denote the mechanical work which the substance does
in expanding, we have
yi
W= i Chel AA CMe SOLS (8
and therefore
1dw
H= Fa Pilla Dro as bie (d).
This formula, established without any assumption admitting of
doubt, expresses the relation between the heat developed by the
compression of any substance whatever, and the mechanical work
which is required to effect the compression, as far as it can be de-
termined without hypothesis by purely theoretical considerations,
64. The preceding formula leads to that which I formerly gave
for the case of fluids subject to the gaseous laws ; since for such
we have
PY=Pvo(1 + Ee) chia eer ales d OF
from which we deduce, by (e),
!
W=por (1 + Ed) logy Ts reeeeteat-}
ne dw y! E
via =Eporo- log = ay W thar (3) 3
and therefore, by (d),
B= En WY . . . . . . . (4).
which agrees with equation (11) of § 49 of the former paper,
* Throughout this paper, formulz which involve no hypothesis whatever
are marked with italic letters; formule which involve Boyle’s and Dalton’s
laws are marked with Arabic numerals; and formule involving, besides,
Mayer’s hypothesis, are marked with Roman numerals,
4.26 Prof. Thomson on the Dynamical Theory of Heat.
65. Hence we conclude, that the heat evolved by any fluid ful-
filling the gaseous laws is proportional to the work spent in com-
pressing it at any given constant temperature; but that the
quantity of work required to produce a unit of heat is not con-
stant for all temperatures, unless Carnot’s function for different
temperatures vary inversely as 1+ H¢;. and that it is not the
simple mechanical equivalent of the heat, as it was unwarrant-
ably* assumed by Mayer to be, unless this function have pre-
cisely the expression
E
=I. . . . . ° . . . . (I).
This formula was suggested to me by Mr. Joule, in a letter
dated December 9, 1848, as probably a true expression for yp,
being required to reconcile the expression derived from Carnot’s
theory (which I had communicated to him) for the heat evolved
in terms of the work spent in the compression of a gas, with the
hypothesis that the latter of these is exactly the mechanical
equivalent of the former, which he had adopted in consequence
of its being, at least approximately, verified by his own experi-
ments. This, which will be called Mayer’s hypothesis, from its
having been first assumed by Mayer, is also assumed by Clausius .
without any reason from experiment; and an expression for p
the same as the preceding, is consequently adopted by him as
the foundation of his mathematical deductions from elementary
reasoning regarding the motive power of heat. The preceding
formule show, that if it be true at a particular temperature for
any one fiuid fulfillimg the gaseous laws, it must be true for
every such fluid at the same temperature.
66. Of the various experimental researches which might be
suggested as suitable for testing Mayer’s hypothesis, it appears
from the preceding formula, that any which would give data for
the determination of the values of w through a wide range of
temperatures would, with a single accurate determination of J,
afford a complete test. Thus an experimental determination of
’ the density of saturated steam for temperatures from 0° to 230°
Cent. would complete the data, of which a part have been so
accurately determined by Regnault, for the calculation of the
values of « between those wide limits, and would contribute
more, perhaps, than any set of experimental researches that could
at present be proposed, to advance the mechanical theory of heat.
67. The values of w, given in Table I. of my Account of Car-
* Tn violation of Carnot’s important principle, that thermal agency and
mechanical effect, or mechanical agency and thermal effect, cannot be re-
garded in the simple relation of cause and effect, when any other effect,
such as the alteration of the density of a body, is finally concerned,
Prof, Thomson on the Dynamical Theory of Heat. 427
not’s Theory, which were calculated from Regnault’s observa-
tions on steam, with the assumption of 55, (the maximum
density of water being unity) for the density of saturated steam
at 100° Cent., and of the gaseous laws for calculating it by means
of Regnault’s observed pressures, at other temperatures, are far
from verifying equation (I), as appears from the Table of the
p HCL + Et)
E
the following comparative Table shows :—
values 0 » given in the preceding paper, § 51; or as
Col, 1. Col. 2. Col. 3. Col. 4.
<3 Values of #4 according
Values of /4 according : :
- Values of 4 according | to modified assump-
Temperature. is Pes cenpity of to Joule’s formula. tion for density of
saturated steam.
E 1717°6
. [H]- esse iegas «HI:
0 4-967 5:087 5:0388
10 4°832 4-908 4-901
20 4-703 4-740 4-769
30 4-578 4-584 4-643
40 4-456 4-438 4:519
50 4337 4-300 4:399
60 4:22] 4171 4:28)
70 4114 4-050 4172
80 4-013 3°935 4-070
90 3921 3°827 3977
100 3°833 3724 3'887
110 3°753 3°627 3°806
120 3°679 3535 3731
130 3°61] 3°447 3°662
140 3546 3°364 3°596
150 3:487 3°284 3°536
160 3432 3°209 3°481
170 3°382 3°136 3°430
180 3335 3°067 3°382
190 3°289 3001 3°336
200 3°247 2-937 3°293
210 3208 2°876 3°254
220 3171 2°818 3-216
230 3135 2-762 3179
Mr. Joule, when I pointed out these discrepancies to him in
the year 1848, suggested that even between O° and 100° the
inaccuracy of the data regarding steam might be sufficient to
account for them. I think it will be generally admitted that
there can be no such inaccuracy in Regnault’s part of the data,
and there remains only the uncertainty regarding the density of
saturated steam, to prevent the conclusion that ~ cannot be ex-
i - 73 80 that Mayer’s hypothesis would be con-
firmed if, and overturned unless, the density of saturated steam,
instead of following the gaseous laws, were truly expressed by
pressed by J
428 Prof. Thomson on the Dynamical Theory of Heat.
the equations
1
(7+) |
Barish val Beat dikes at NET,
elon: 1+Ex100— Pp
lel= 76935 -ThEr TJ
where [«] denotes the quantity tabulated for the temperatures
0°, 1°, 2°, .«. 230° in Table I. of my Account of Carnot’s Theory ;
and [oc] denotes the density of saturated steam which was
assumed in the calculation of that table, the values of f in the
expression for it being obtained by dividing the numbers tabu-
lated at the end of Regnault’s eighth Mémoire by 760. The
considerableness of the deviations from the gaseous laws which
equation (II) indicates, is seen at once by comparing the num-
bers in column 2 with those in column 8 of the preceding table,
and observing that the coefficient of [eo] in (II) is, for each tem-
perature shown in that table, obtained by dividing the corre-
sponding number in column 2 by that in column 3. Column 4
shows what the values of « would be if the density of saturated
steam at 100° were ine instead of ime and, for other tempe-
ratures, varied according to the gaseous laws.
68. This subject has been very carefully examined by Clausius,
who has indicated the great deviations from the gaseous laws of
density that Mayer’s hypothesis requires in saturated steam, and
has given an empirical formula for the density of saturated steam
founded on that hypothesis, and on Regnault’s observations on
the pressure and latent heat. In this direction theory can go
no further, for want of experimental data ; although, from what
we know of gases and saturated vapours, it may be doubted
whether such excessive deviations, in the case of steam, from the
laws of a “ perfect gas” are rendered probable by a hypothesis
resting on no experimental evidence whatever*,
69. To Joule we are indebted for a most important series of
experimental researches on the relation between the thermal
effects, the external mechanical effects, and the internal mecha-
nical effects (vis viva destroyed by fluid friction) due to com-
pressions and expansions of air in various circumstances}. These
* Joule’s experimental verification of Mayer’s law for temperatures of
from 50° to 60° Fahr. shows, if rigorously exact, that the density of satu-
rated steam at about 10° Centigrade must be ae
it in the calculations of my former paper, but does not go towards indica-
ting any deviation from the gaseous laws of variation in the density of satu-
rated steam at different temperatures.
+ Philosophical Magazine, May 1845.
of what was assumed for
Prof. Thomson on the Dynamical Theory of Heat. 429
researches afford actual tests, which, so far as they go, are veri-
fications of the truth of Mayer’s hypothesis for temperatures
between 50° and 60° Fahr., founded on two distinct methods,
either of which is perfect in principle, and might be made the
foundation of experiments at any temperature whatever.
70. The first of these methods consists simply in determining,
by direct experiment, the heat evolved by the expenditure of a
given amount of work in compressing air, and comparing it with
the quantity of heat created by the same amount of work in
Joule’s original experiments on the heat developed by magneto-
electricity, and by the friction of fluids in motion.
71. The second method is especially remarkable, as affording
in each experiment an independent test of the truth of Mayer’s
hypothesis for air at the temperature used, without requiring any
knowledge of the absolute value of the mechanical equivalent of
heat. In Joule’s actual experiments, the test is simply this :—
the total external thermal effect is determined when air 1s allowed
to expand, through a small orifice, from one vessel into another
previously exhausted by anair-pump. Here the first mechanical
effect produced by the expanding gas is vis viva generated in the
rushing of the air. By the time equilibrium is established, all
this mechanical effect has been lost in fluid friction (there being
no appreciable mechanical effect produced externally in sound,
which is the only external mechanical effect, other than heat,
that can be produced by the motions of a fluid within a fixed
rigid vessel) ; and no truth in physical science can be more cer-
tain, than that by the time thermal as well as mechanical equi-
librium is established at the primitive temperature, the contents
of the two vessels must have parted with just as much more heat
than they would have parted with had the air m expanding
pushed out a piston against an external resisting force, as is
equivalent to the mechanical effect thus produced externally,
Hence if the two vessels and the tube connecting them be im-
mersed (as they are in Joule’s first set of experiments with this
apparatus) in one vessel of water, and if, after time is allowed
for the pressure and temperature of the air to become the same
in the two vessels, the water be found to have neither gained nor
lost heat (it being understood, of course, that the air and all
other matter external to the water are at an absolutely constant
temperature during the experiment), then, for the temperature
of the experiment, Mayer’s hypothesis is perfectly confirmed ;
but any final elevation or depression of temperature in the water
would show that the work due to the expansion is either greater
than or less than the absolute equivalent of the heat absorbed.
72. Mr. Joule’s second experiment on the same apparatus, in
which he examined separately the external thermal effects round
430 Prof. Thomson on the Dynamical Theory of Heat.
each of the two vessels, and round a portion of the tube contain-
ing the small orifice (a stop-cock), has suggested to me a method
which appears still simpler, and more suitable for obtaining an ex-
cessively delicate test of Mayer’s hypothesis for any temperature.
It consists merely in dispensing with the two vessels in Joule’s
apparatus, and substituting for them two long spirals of tube
(instead of doing this for only one of the vessels, as Joule does
in his third experiment with the same apparatus) ; and in forcing
air continuously through the whole. The first spiral portion of
the tube, up to a short distance from the orifice, ought to be
kept as nearly as possible at the temperature of the atmosphere
surrounding the portion containing the orifice, and serves merely
to fix the temperature of the entering air. The following inves-
tigation shows what conclusions might be drawn by experiment-
ing on the thermal phenomena of any fluid whatever treated in
this manner.
73. Let p be the uniform pressure of the fluid in the first
spiral, up to a short distance from the orifice, and let p! be the
pressure a short distance from the orifice on the other side, which
will be uniform through the second spiral. Let ¢ be the con-
stant external temperature, and let the air m both spirals be
kept as closely as possible at the same temperature. If there
be any elevation or depression of temperature of the fluid in
passing through the orifice, it may only be after passing through
a considerable length of the second spiral that it will again arrive
sensibly at the temperature ¢; and the spiral must be made at
least so long, that the fluid issuing from the open end of it,
when accurately tested, may be found not to differ appreciably
from the primitive temperature 7.
74. Let H be the total quantity of heat emitted from the
portion of the tube containing the orifice, and the second spiral,
during the passage of a volume w through the first spiral, or of
an equivalent volume uw! through the parts of the second where
the temperature is sensibly ¢. This will consist of two parts ;
one (positive) the heat produced by the fluid friction, and the
other (negative) the heat emitted by that portion of the fluid
which passes from one side to the other of the orifice, in virtue
of its expansion. To find these two parts, let us first suppose
the transference of the fiuid to take place without loss of mecha-
nical effect in fluid friction, as it would do if, instead of the par-
tition with a small orifice, there were substituted a moveable
piston, and if a volume w of fluid, on the side where the pressure
is higher (p), were enclosed between that and another piston,
and allowed to slide through the tube till the second piston
should take the place of the first, and to expand till its volume
should be uw’. If we adopt the same notation with reference to
Prof. Thomson on the Dynamical Theory of Heat. 431
the volume, v, of the substance between the pistons, kept at a
constant temperature, 7, as has been used uniformly in this and
the preceding paper; we shall have, for the quantity of heat
absorbed during the motion of the piston,
Md ;
or, by the second fundamental equation of the theory, (3) of § 21
of the preceding paper,
1 sda
i 2 Wi dv,
where a denotes the actual pressure (intermediate between p
and p’) of the substance when its volume is v. Again, the work
done by the pistons will be given by the equation
Wa f adotpu-pll Mesa Heel:
If now the transference of the substance from the one portion
of the tube, where the pressure is p, to the other, where the
pressure is p', take place through a small orifice, exactly that
amount, W, of work will be lost as external mechanical effect,
and will go to generate thermal vis viva: The quantity of heat
thus produced will be
= Sw + pupil}.
Hence the total quantity of heat emitted will be the excess of
this above the amount previously found to be absorbed when the
mechanical effect is all external; and therefore we have*
meh of prt 1 "de
H= 54 ge ch Be plu ae av rae i 8
Whatever changes of temperature there may actually be of the
air in or near the orifice, this expression will give rigorously the
total quantity of heat emitted by that portion of tube which
contains the orifice and the whole of the second spiral during
the passage of a volume u through the first spiral, or w! through
any portion of the second spiral where the temperature is sensibly ¢.
75. To apply this result to the case of a gas fulfilling the
gaseous laws, we may put
pu=p'u.
* A more comprehensive investigation, including a proof of this result,
is given ina subsequent communication (Royal Soc. Edinb. Dec. 15, 1851),
constituting part 5 of the present series of articles, which will be re-
published in an early Number of this Journal.
432 Prof. Thomson on the Dynamical Theory of Heat.
Hence (e) becomes
wu! U
Wa f sdv=pulog =plullog? a atG (57
and, by (3), we have
dW Epu uw S«EW
@ 198 9a leer
Hence the expression (/) for the heat emitted becomes
1 E
ie iar fw ME See ed A
76. Lastly, if Mayer’s hypothesis be fulfilled for the gas used
in the experiment, the coefficient of W vanishes by (I.), and
therefore
BEESON 00 era ey A FOC
77. From equation (III) it follows, that if Mayer’s hypothesis
be true, there is neither emission nor absorption of heat, on the
whole, required to reduce the temperature of the air after passing
through the orifice to its primitive value, ¢. Hence, although
no doubt those portions of the air in the intermediate neighbour-
hood of the orifice which are communicating, by their expansion,
vis viva to those contiguous to them will be becoming colder,
and those which are the means of occasioning the portions con-
tiguous to them to lose vis viva, through fluid friction, will be
becoming warmer at each instant; yet very near the orifice on
each side, where the motion of the air is uniform, the tempera-
ture would be constantly equal to ¢. Hence the simplest con-
ceivable test of the truth of Mayer’s hypothesis would be, to try
whether the temperature of the air is exactly the same on the
two sides of the orifice. This might be done by very delicate
thermometers adjusted in the tube at sufficient distances on each
side of the orifice to be quite out of the rush which there is of
air in the immediate neighbourhood of the orifice; but it might
be done in a still more refined manner by means of a delicate
galvanometer, and a small thermo-electric battery arranged so
that one set of the solderings might be within the tube on the
side of the entering current of air, and the other set within the
tube on the side of the current from the orifice. 'The tube on
each side of the orifice would need to be bent so as to bring two
parts of it, at small distances from the orifice on each side, near
enough one another to admit of the battery being so placed.
The only difficulty I can perceive in the way of making the ne-
cessary arrangements is what might be experienced im fitting
the two ends of the battery air-tight into the two parts of the
tube. It first occurred to me that the little battery itself might
be placed entirely within the tube, and the difference of pressure
Prof. Thomson on the Dynamical Theory of Heat. 433
kept up in the two parts by the middle of the battery being fitted
nearly air-tight in the tube by means of wax, or otherwise; but
this arrangement would not be satisfactory, as portions of the
bars of the battery, if not the ends themselves directly, would
be altered in temperature, even if Mayer’s hypothesis were rigor-
ously true, on account of the rushing of the air among them.
No part of the battery ought to be exposed to the rushing of
the air in the neighbourhood of the orifice, and therefore the
middle of the battery would have to be external to the tube, the
ends being cemented into the tube by some indurating cement
sufficiently strong and compact to hold perfectly air-tight on the
side where the pressure is different from the atmospheric press-
ure. By such means as these, I think a very satisfactory series
of experiments might easily be performed to test Mayer’s hypo-
thesis for air through a very wide range of temperatures.
78. Should the differential method of experimenting just de-
scribed indicate any difference of temperature whatever on the
two sides of the orifice, Mayer’s hypothesis would be shown to
be not exactly fulfilled, and, according as the air leaving the
orifice is found to be warmer or colder than the entering air, we
should infer that the heat absorbed, when air expands at a con-
stant temperature, is less than or greater than the equivalent
of the mechanical effect produced by the expansion *.
79. Calorimetrical methods, like those used by Joule, might
then be followed for actually determining the heat emitted or
absorbed by the air in the neighbourhood of the orifice, cr in the
second spiral, in acquiring the temperature of the air in the
entering stream; and by careful experimenting, it is probable
that excessively accurate results might be thus obtained for a
wide range of temperature.
80. The result of each experiment would be a value of uw, in
terms of Joule’s mechanical equivalent, to be calculated by the
following expression, derived from equations (5) and (6).
* Experiments on the plan here suggested have been recently made by
Mr. Joule and myself, and it has thus been ascertained that the air leaves
the rapids in the neighbourhood of the orifice at a lower temperature than it
approached them, even if this temperature be as high as 170° F.; and it
follows that the heat absorbed is greater than the equivalent of the mecha-
nical effect of the expansion, even for so high a temperature, and probably
for much higher. See a paper published in the Supplement to this Volume
of the Magazine, in which these experiments are described,—Nov. 11, 1852.
Phil. Mag. 8, 4, Vol. 4, No. 27. Dee, 1852. 2F
434 Mr. G. B. Jerrard on solving Equations of any degree.
In the second member of this equation p' denotes the pressure
of the air through the second spiral, which would be the atmo-
spheric pressure, or excessively near it, if, as in Joule’s third
experiment mentioned above (described by the author in p. 378
of the volume* containing his paper), the air leaving the second.
spiral be measured by means of a pneumatic trough: p denotes
the pressure in the first spiral, which ought to be constant, and
must be carefully measured; wu! denotes the volume of air which
leaves the apparatus in any time; and H denotes the quantity
of heat emitted in the same time. The experiment might be
continued for any length of time, and each one of these four
quantities might be determined with great accuracy, so that pro-
bably very accurate direct results of observations might be ob-
tained. If so, no way of experimenting could be better adapted
than this to the determination of Carnot’s function, for different
rae sited a in terms of Joule’s mechanical equivalent of
eat.
LXVIII. On the possibility of solving Equations of any degree
however elevated. By G. B. Jurnrarv, Esq.
[Continued from vol. ii. p. 460.)
§ 5.
| DO not think it necessary, after what has been already said,
to state explicitly the objection to Abel’s inference ; but I
cannot dismiss the subject without referrmg the reader to an
admirable disquisition on equations the roots of which have a
given relation among themselves in the Mémoires de Mathé-
matiques of M. Libri.
We might now return to the general equation of the mth
degree. Before, however, resuming the inquiry with which we
set out, I purpose to show how to complete the method, given
in my Mathematical Researches, of transforming equations by
means of symmetric functions. This method, which cannot be
explained in few words, will form the subject of a separate paper.
Long Stratton, Norfolk,
August 27, 1852.
Erratum in vol. iii. p.457, line 37.
‘For will admit read will, when the roots are unequal, admit. The case of
p equal roots is not considered by Abel.
* Phil. Mag. vol, xxvi.
[ 435 ]
LXIX. On Indirect Demonstration. By Professor De Morcan*,
8 bight the phrase indirect demonstration, mathematicians
are accustomed to include two things which are quite
distinct. From this use of language springs confusion between
the different characters of different methods. Geometers have
seldom been very formal logicians ; and their patent of exemp-
tion was signed by Euclid.
Indirect demonstration, as commonly conceived, means demon-
stration of the impossibility of all contradiction. But the fol-
lowing distinctions are required. Let the proposition to be
proved be Every Ais B. To avoid using direct in two senses,
as opposed to converse, and as opposed to indirect, I shall take
the correlatives positive and contrapositive, direct and indirect.
1. The direct positive proposition is Every Ais B. The direct
positive proof takes any A, and shows that it is B.
2. The direct contrapositive proposition, identical with the last,
is Every not-B is not-A. The direct contrapositive proof takes
any not-B, and shows that it 7s not-A.
3. The indirect positive proof attacks the positive contradic-
tion, Some As are not-Bs, and taking an A assumed to be
not-B, shows the assumption to have an absurdity for its neces-
sary consequence.
4, The endirect contrapositive proof attacks the contrapositive
contradiction, Some not-Bs are As, and taking a not-B assumed
to be A, shows the assumption to have an absurdity for its neces-
sary consequence.
The third and fourth have a slightness of distinction which I
maintain to exist also as to the first and second, Applying the
notion} of form and matter to forms, the first and second differ
in form, and also the third and fourth. But the first pair are
opposed to the second pair. The latter pair proceed from denial
of consequence to denial of hypothesis: the former pair proceed
from establishment of hypothesis to establishment of consequence,
When the mathematician uses the second form, he usuall
employs the third or fourth, subordinately, to connect it with
the first. Is this necessary ?
When we say a square is entirely contained within a circle, do
we need an indirect process to establish that outside the circle is
outside the square? Surely any attempt to establish this by
* Communicated by the Author.
+ The algebraist ought to be well accustomed to this application. In
arithmetic 1, 2, 3, &c. are of the form, yards, gallons, &c. are of the matter,
In common algebra, 1, 2, 3, &c. become the matter, and a+, ab, &. are
distinctions of form. In higher algebra a+, ab, &c. become material, and
in p(a+b), &c. belongs to the form. The distinction of form and matter
is often concealed under the distinction of general and specific matter,
r2
436 Prof. De Morgan on Indirect Demonstration.
indirect process contains postulates of reasoning as difficult as
the required transformation, if not of its very nature. Euclid
would not apply the indirect process to prove the conclusion
about a space-area: but he does apply it when the area is what
logicians call the extent of a term. When A is entirely within B,
species within genus, he never admits that all the notions outside
the genus are outside the species, without an indirect demonstra-
tion. From Every not-B is not-A he produces Every A is B,
thus:—If it be possible, let this A be not-B, but every not-B
is not-A, therefore this A is not-A, which is absurd: whence
every Ais B. He might as well argue ito the conclusion of
a common syllogism from the premises, as thus ;—Every A is B,
this is an A, therefore it is a B; for if not let it be not-B, then
- one not-B is A, but every A is B, therefore not-B is B, which
is absurd, &e. Here it is manifest that our reasoning takes
fully as much for granted as the direct transition from premises
to conclusion: we take syllogism for granted in proving syllo-
gism. Euclid does more: he takes syllogism for granted in
proving the antesyllogistic conversion of propositions. This
does well for beginners, to whom simple affirmative syllogism is
more familiar than conversion by contraposition: but I am now
speaking to mathematicians who examine the laws of thought.
It is an easily ascertained fact, that really indirect demon-
stration is uncommon in geometry, except as a (to a logician)
unnecessary help to contrapositive directness of proof. Take
for example, Book I. Prop. 6. A non-isosceles triangle is un-
equally angled (at the base). Now i. 4 is, in one of its contra-
positive forms, as follows. Two sides severally equal to two
sides, with unequal areas, have unequal angles contained. Euclid’s
construction instantly brings out of a non-isosceles triangle two
triangles with two sides severally equal to two sides, and areas in
the relation of whole and part. Hence follows that a non-
isosceles triangle is unequally angled at the base: to the logician
this is identical with Euclid’s form, Equal angles at the base give
equal sides: the geometer who is not a logician is helped over
this last step by the addition of an indirect demonstration.
Seeing that this so-called indirect proof, then, is in its indirect
part seldom anything except the demonstration of the passage
from contrapositive to positive, for the benefit of those to whom
this step of pure logic is of uneasy transition, we may ask how
the necessity for the contrapositive form is to be explained? The
refutation of contradiction is viewed by some geometers as a kind
of lame and imperfect proof. It is, indeed, mostly superfluous ;
but it is rather a crutch proof than a lame proof, when applied
only to help in the conversion of a proposition. With reference,
however, to the unavoidable entrance of both the direct forms, it
Prof. De Morgan on Indirect Demonstration. 437
seems that the contrapositive proposition is often more accessible
than the positive one, because we know more about the negative
terms than about the positive ones: and we have to proceed
from the more known to the less known. It is surely no great
wonder, and no cause of complaint against the nature of things,
that we should sometimes find ourselves in a position in which
we can only proceed to comparison of equals by previous com-~
parison of unequals. On the contrary, it seems clear to me that
it should rather be matter of surprise that we are not obliged
to do something yet more specific in the way of departure from
consideration of equality.
The relations of magnitude (ratios) are infinite in number. If
there were a person well versed in the truths of geometry and
arithmetic, but wholly ignorant of their systematic derivation from
each other, and if this person were informed that he must proceed
to study demonstration, he would imagine that his earliest in-
strument would be —ratio in all its varieties. He would be
surprised when he was told that, for a considerable time, he
would not be required to subdivide ratio into more than three
cases, ratio of equality, and the two forms of ratio of imequality
without any specification of the degree of inequality. But per-
haps he would be more surprised if he were told that, after this
renunciation of the different modes of equality, geometers were
still unsatisfied whenever they had to reason from inequality to
equality. And if he were a logician, though by my supposition
one who had not applied his logic in mathematics, he would be
most surprised to know that geometers never made the con-
trapositive conversion of the universal affirmative except by an
indirect demonstration, and laid the blame on the essential cha-
racter of geometry, instead of laying it on their own neglect of
the study of the pure laws of thought, as they apply in geometry
and everything else.
I have been led to offer these remarks at this particular time
by Mr. Sylvester’s paper contained in your last Number, as to
which I agree almost entirely with all that is Mr. Sylvester’s
own, and differ only as to the view of the imdirect proof which
he holds in common with most other geometers. I cannot
answer his invitation or challenge, because he will perhaps insist
upon my passing from the contrapositive to the positive form
only by an indirect demonstration. But I claim to see identity
in Every A is B and every not-B is not-A, by a process of
thought prior to syllogism: and, proving that the mequality of
the nearer segments makes the inequality of the remoter ones
follow, I conclude that the equality of the remoter ones makes
the equality of the nearer ones follow, as a new logical form of
the preceding conclusion, identical with it in meaning, Of
438 Prof. Challis on the Principles of Hydrodynamics.
course it will be seen that I hold the direct contrapositive proof
to be of a different character from the direct positive proof.
What I have endeavoured to show is, that the difference of cha-
racter is not that which geometers in general attribute when they
lay stress upon the indirect proof by which they turn one form °
of logic into another identical with it. So soon as a geometer
shall find out that he wants proof, as to a square inside a circle,
that what is out of the circle is out of the square, then, and not
before, will he be entitled to insist on the logician proving that
what is out of the genus is out of the species.
I do not intend the preceding criticism to imply that I would
make any great change in Euclid. The best way to learn sepa-
ration is practice upon a mixed material, not observation of the
separation as already made. A teacher may, and should, call
the attention of his pupil to the distinction of the form of thought
and the matter thought on: but the compound product is the
material on which he has to work, and this is presented by Euclid
in its most natural form.
November 1, 1852.
LXX. On the Principles of Hydrodynamics. By the Rev. J.
Cuauus, M.A., F.RS., F.R.AS., Plumian Professor of
Astronomy and Experimental Philosophy in the Unwersity of
Cambridge.
[Continued from vol. i. p. 241.]
rf Bist exposition of the principles of hydrodynamics which I
commenced in the Number of this Magazine for January
1851, and continued in that for March of the same year, I now
propose to resume, having been prevented by failure of health
and want of leisure from returning to the subject at an earlier
period. The propositions contamed in the two former commu-
nications will be referred to as proved, and the notation there
adopted will still be employed, without further indication of the
meanings of the symbols.
The first eight propositions, which were of a general nature,
applying equally to all perfect fluids, were followed by one
which related especially to incompressible fluids, and was thus
enunciated: “To determine the law of action of the parts of an
incompressible fluid on each other.” The use of this proposition
in the solution of a few problems of fluid motion was then exem-
plified. I proceed next to the consideration of an analogous
proposition relating to a compressible fluid; it bemg essential,
according to the views already advocated, to deduce the laws of
the mutual action of the parts of the fluid on each other previous
to any determination of the cireumstances of particular instances
Prof. Challis on the Principles of Hydrodynamics. 439
of motion. The following principle will be found to be of assist-
ance in this inquiry:—The general hydrodynamical equations
being assumed to be exact and sufficient, any analytical cireum-
stances which admit of interpretation with respect to the motion
prior to the consideration of arbitrary cases of disturbance, have
oat to the law of action of the parts of the fluid on each
other.
Proposition X. It is required to determine the law of the
mutual action of the parts of a compressible fluid, the pressure
of which varies in the same proportion as the density.
(1.) The following equation was obtained in the proof of Pro-
position VI. (Phil. Mag. for January 1851, p. 33), viz.
(dp) =udz + vdy + wdz.
Now by an abstract theorem of analysis, the right-hand side of
this equality is integrable if X be a function of a, or more gene-
rally, a function of yy and ¢. The same quantity is integrable
in an unlimited number of ways by particular values of u, v, and
w, depending on particular arbitrary disturbances. But the
supposition that is a function of and f is of a general nature,
and may be made prior to the consideration of any case of
motion. Hence, according to the principle above enunciated,
if this supposition conducts to a result compatible with fluid
motion, that result is indicative of the mode of action of the parts
of the fluid on each other. But by Proposition VII. it was
shown, that if X be a function of yy and ¢, the motion is recti-
linear. Consequently, if the mode of action of the parts of the
fluid on each other be such as to satisfy the condition of making
udx + vdy + wdz integrable, the motion is rectilinear.
At this stage of the reasoning it will be necessary to refer to
the results which were obtained in the January Number (1851),
by a consideration of rectilinear motion perpendicular to a fixed
plane, and rectilinear motion tending to or from a fixed centre,
(Examples I. and II. p. 34-37.) In each of these cases of motion
absurd results were arrived at by reasoning strictly in accordance
with the received principles of hydrodynamics. As those prin-
ciples are not untrue, it hence follows that they are insufficient
for the solution of hydrodynamical problems. Also, as the con-
tradictory results were deduced from true principles, it is certain
that the reasoning involved some false step, which it is essential
to discover. Where the error was committed will appear in the
course of the following investigation.
If the motion be in directions perpendicular to a fixed plane,
and be a function of the distance from the plane, it will be recti-
linear motion, and will satisfy the condition of making udx + vdy
+wdz integrable. May we, therefore, suppose that the parts
440 Prof. Challis on the Principles of Hydrodynamics.
of the fluid so act on each other, that a motion of this kind
results? The absurdity to which, as already stated, this suppo-
sition conducts, proves that it is not allowable. Again, motion
which tends to or from a fixed centre, and is a function of the
distance from the centre, is rectilinear motion, and satisfies the
criterion of integrability of udxz +vdy+wdz. The absurdity, how-
ever, to which the supposition of such motion conducts proves
that this is not the kind of motion resulting from the mutual
action of the parts of the fluid. Neither can it be motion tend-
ing to or from focal lines; for if this were the general law, no
absurdity would result in the particular case of motion tending
to or from a centre. Thus the absurd results above cited are
extremely important, as excluding from our consideration the
kinds of motion just mentioned.
(2.) It remains to consider the case of an azis of rectilinear
motion. The general integrability of udz + vdy +wdz is in this
case only satisfied by the motion along, or immediately conti-
guous to, the axis, the motion at all other points being curvi-
lmear. For the purpose of tracing the consequences of this
supposition, let
d d, d
ie dott ea
f being a function of # and y only, and ¢ a function of z and ¢
only. Further, let the function / be such, that where =0 and
y=0, we have if er
| ane Poe Fe
It is clear that on these suppositions udz + vdy + wdz is integrable,
and that the axis of z is a line of motion. If no contradictory
results, similar to those before indicated, be arrived at by tracing
the consequences of the above suppositions, the motion due to the
action of the parts of the fluid on each other must be of the kind
here assumed, because it is certain, @ priori, that that motion is
unique and perfectly definite.
Now as a first consequence of our hypothesis, we have
(d.fb)=ude+vdytudz. . . . . « (a)
Combining with this equality the general equation of Proposition
LV., viz.
dp . d.pu , d.pv , d.pw _
dt dx dy her Oe eee
and that which the general equation of Proposition V. becomes
when there are no impressed forces, viz.
HA) 4 (Sees (Gat (Ge=
Sap (ag et NG yy +(F 7S dababives >
Prof. Challis on the Principles of Hydrodynamics. 441
and then eliminating by a known process p, u, v, w from the three
equations («), (8), (y), the result will be,
=o. (ia + Ts) ae) Sat |
-26 (7 +l) (i+ Fp)
(of fof Ff af , df df r. - (6)
tia date ded: By a aa)
_ opel 7b __ pa db? Pd
dz dzdt ‘dz? dz?
But since, from what has already been said, this equation applies
only to points on the axis of z, or immediately contiguous to it,
at
da
other terms. And again, as the value f=1 results from the
d,
oe =0, and - =0, it follows
that that value of f is either a maximum or a minimum. The
supposition of a minimum leads to contradictory results, and is
by that circumstance excluded from the investigation. Hence,
the terms involving = and a will be infinitely less than the
values z=0, y=0, which make =
supposing that
af Eh Ae
daz * ae a
Perr. df df
and omitting in (6) the terms involving Ee and ay’ we have for
the motion along the axis,
Be its = ip 446 Ph | dp? dp _
PO OO as tae. teas ea Plat ae)
The arbitrary ak F'(é) disappears if F(¢) be supposed to be
zero or a constant, and this supposition is required by the motion
which is the subject of this investigation, which is independent
of any arbitrary circumstance. Omitting, therefore, F’(¢), the
equation just obtained possesses the remarkable property of being
satisfied by motion along the axis, such that the density and
velocity existing at any instant at any point are propagated with-
out alteration at a certain uniform rate. This property I pro-
ceed to demonstrate. .
On the supposition that the motion is of the kind above
described, the density (p) must satisfy the equation
dp dp
de tgs =
442 Prof. Challis on the Principles of Hydrodynamics.
a, being the constant rate of propagation. For the integral of
this equation is p=F(z—a,t), Now, since
dp _d.pu , d.pv d.pw
at’ de * dy + de
by substituting from the equation above, we have
=0,
do __d.pu , d.pv , d.pw
“ae det “dy a ae
Since w=0 and v=0 for the motion along the axis of z, this
equation becomes
dp _du , dv | dw
vale 75 pdz dx 2 dy + ie
df of ph p_
dx’ v=6b7 dy? w=fa> f=1, and
af . Of _ b?
da? dy? a”
we obtain by substituting,
ae dp __ dp , Hp
(4-3 i dasdlcaniga Sails ss 9 hae tae (e)
The known general Readies which gives the value of the density,
becomes for the motion along the axis of a
a*, Nap. log sptha, ip +8 =
Also, because u=¢o =-
=F(d).
Differentiating with respect to z, 4 he f=;
&.dp &p ee dpdp _ dhe
pdz dzdt ' dz dz* ~~
Eliminating p from (e) by this last equation, the result is
d*h 2
—6 +e T+ (a9 z=) (saat Eat )= 9%
by comparison of which equation with the equation (B), we obtain
Pp &p dp ( @ are i)
qr wae Ge” Tee + Tedt
Now this equation vanishes Ne at if
dp
a +45
=0,
that is, if ¢, =a and “ be functions of z—a,t, and by conse-
quence p be a rintleat of the same quantity, a result in accord-
ance with the original hypothesis respecting p.
Let us, therefore, trace the consequence of introducing the
Prof. Challis on the Principles of Hydrodynamics. 443
condition ¢=F(z—a,/) into the equation (B). Writing for the
sake of brevity v for z—a,¢, and F for F(v), we shall have
dh _ sent gVF db _ ap a?F
df ade = = dedt
Consequently, by substituting in (B),
d?F d¥ d¥?
ra a—a? — 2a + 95) +08= =0.
This equation may be integrated by successive approximations
proceeding according to the powers of F. To the first approxi-
mation,
d’F b?
dy? * a?—a?’
Hence by integrating,
F=m cos (qv+e),
2
b
> so that @,?=a?+ = Con-
where g is substituted for
2
a
uae
p=m cos g(<—at J 1+ ate):
By proceeding to the third approximation, I find the following
results :—
sequently
p=m cos g(z—a,t+c)
273
mga
362
8(4/g%q? = 7
—=f a + 7 eos Bq(2—ayt +0)
aiteate ree alae a? ened )
ir celeste
Having thus shown that the equation (B) is satisfied by the
supposition of a uniform and identical rate of propagation at all
points of the axis, and having found approximately the values of
¢ and a, to which this supposition leads, I proceed to consider
the integral of that equation in a more general manner.
It does not appear that an exact integral of (B) can be
obtained. An integral, however, applicable to the present
inquiry is deducible as follows by successive approximations.
For a first approximation, taking the terms of the first order with
respect to @, we have
EMS ot +b°p=0.
sin 2q(z¢—a,t+c)
(7)
auey Prof. Challis on the Principles of Hydrodynamics.
Putting, for convenience, e for pw for z+at, andy for z—at,
j2
Aa”?
the integral of the above equation in a series proceeding accord-
ing to powers of e is
p=F(u) + G(r) |
+e. {vF\(u) + G,(y) }
+5: (PFW) +0260)
+ &e.,
where
RW=/Pwdm, EW=/Kod, 6)= [Edy ke.
As the functions F and G satisfy the equation (7) independently
of each other, it is permitted to consider them separately. Let,
therefore,
eur Aus
p=G(r) + euGy(v) + 1.2 Ga(v) + T2.3° Gs(v) + &e.
This value of d, containing arbitrary quantities, is not generally
applicable to the present inquiry, which is antecedent to any
case of arbitrary disturbance. It is, however, to be remarked
that @ has particular forms, expressible in finite terms, if forms
of the function G can be found, which will satisfy the equality
4.G,() = + F?Gy+1(v)
dv
for every integral value of x. Now,
Griily)= =f6n(v) dy.
Hence, by the above equality,
d.G,(v) 4
nee ae = ae k G,,(v)dv,
or
d? Gnl¥) = p99 (y) —
gee a. k G,,(v) =0.
The upper sign gives a logarithmic form to the function G,
which is incompatible with any general law of fluid motion, as
also with the value of ¢ already obtained. Taking the lower
sign and integrating, we have
G,,(v) =A cos (kv +e),
which determines the form of the function G. In conformity
Prof. Challis on the Principles of Hydrodynamics. 445
with this result, let G(v)=m cos (kv+c¢). Then it will be found
that i,
gp=m cos 4 Ky 4) tel.
e
k?
‘\,
=m cos g\ z—at pare :
qY e
By using this first approximate value of $, and integrating (B)
to the second and third approximations, exactly the same expres-
sions for ¢ and a, result as those obtained by the former process.
Thus the hypothesis of an axis of rectilinear motion has been
shown to be compatible with the hydrodynamical equations, no
contradiction having been met with in the foregoing imvestiga-
tion. As this conclusion has been arrived at by the indications
of the analysis prior to the consideration of any arbitrary case of
disturbance, it may hence be concluded that the action of the
parts of the fluid on each other is such, that there is always a
rectilinear axis of motion along which the motion is vibratory,
and that all the parts of a vibration are propagated with exactly
the same velocity.
If instead of the function G we had reasoned with the function
F, the same results would have been obtained, with the differ-
ence only that the propagation of the motion would have been
in the opposite direction. Hence as the equation (B) to the first
approximation is satisfied by the sum of the values of @, it fol-
lows that when the vibrations are small, two propagations may
take place simultaneously along the axis in opposite directions.
(3.) Hitherto the reasoning has been carried on by means of
exact equations, and some circumstances respecting the motion
resulting from the mutual action of the parts of the fluid have
been ascertained for velocities and condensations of any magni-
tude. The laws of the curvilinear motion which takes place at
finite distances from the axis of rectilinear motion, and which, as
already stated, does not satisfy the condition of integrability of
udx + vdy +wdz, can probably be arrived at only by successive
approximations, commencing with terms of the first order with
reference to tle velocity and condensation. The reasoning in
future will be restricted to terms of the first order, so that the
equations will be linear.
Now it may be proved as follows, that if terms of the first
order only be retained, the quantity udz + vdy + wdz is integrable
for all distances from the axis of rectilinear motion.
Let the pressure at any point wyz at the time ¢ be a*(1+0¢),
o being a small quantity the powers of which above the first are
Or, putting g for k——, and substituting the values of v and p,
446 Prof. Challis on the Principles of Hydrodynamics.
neglected. Then we have the known approximate equations
adc du edo dv ado dw
de te De eee ae
di
Hence by integration,
do , d.fodt
— OS J. i — are
u=C “ft dt=C—a’?. a
‘do d. fodt
a pe ee
v=C of 7ta0—@
w=C"'— “fz a=0'—o. 2? oy
where C, C’, C" are functions of 2, y, and z not containing the
time. For all cases of motion in which no part of the velocity
is independent of the time, for instance, cases of vibratory
motion, we shall have C=0, C/=0,C”=0. Hence substituting
6 for—a®/odt, it follows that
a 4 : @&
ax’ OS dy’ ies dz’
and consequently that wdx+vdy+wdz is an exact differential.
Since this inference has been drawn prior to the consideration of
any specified case of motion, it must, according to our principles,
be interpreted with reference to the motion resulting from the
mutual action of the parts of the fluid. And as the inference
depends on the assumption that no part of the motion is inde-
pendent of the time, the physical circumstance indicated by the
integrability of udx+ vdy+wdz is, that the motion is vibratory.
In accordance with this conclusion, the foregoing exact investi-
gation of the motion along a rectilinear axis, so far as it is inde-
pendent of any arbitrary forms given to the function F(¢), was
found to be vibratory motion.
Again, the new general hydrodynamical equation, viz.
d dy? dy? dy
tan (d xo
1) pmo
dy?
may be put under the form
Ns +u?+0?+w?+rx(t)=0;
which, if the squares of the velocities be neglected, becomes
ayy es
a +x(t) =0.
This equation gives by integration,
+x) =D,
Prof. Challis on the Principles of Hydrodynamics. 4A7
D being an arbitrary function of x, y and z. It cannot, there-
fore, be argued, as in Prop. VII., that yy is a function of s and ¢,
and by consequence that the motion is rectilinear. Hence the
integrability of udx-+vdy+wdz for small values of u, v, w is
consistent with curvilinear motion, and may be satisfied by the
motion at any distance from the axis of rectilinear motion.
To carry on the investigation of the law of action of the parts
of the fluid on each other to the first order of approximation, I
shall continue to use the same expressions for the velocities as
in the general case; but in consequence of what has just been
proved, these expressions will not now be restricted to points
contiguous to the axis of rectilinear motion. This extension of
their application will be justified if it leads to no contradictory
results. Thus we ee have
at any point whose ae are 2, Y, Z, Bide at any time ¢,
f being a function of w and y only, and ¢ a function of z and ¢
onl
The equation which gives the condensation o to the first order
of approximation is
2g + fl?
otf i =F(Z),
in which F(t) must be made to vanish in order that the reasoning
may be conducted independently of any arbitrary circumstances.
Consequently, after determining ¢ and /, the value of o is given
by the equation
Pot <0. . A SEALER oh, 0/M te
The equation (8) to the first approximation becomes
EF op fL\ 5 gap ba Gk
w6(S4 4 +5) +e Sie aft =0. . « (X)
Now as ¢ is independent of x and y, it has the same value at
all points of any plane perpendicular to the axis of z, and there-
fore the same value as at the point of intersection of this plane
with the axis. But we have seen that for points on the axis the
following equation is true to the first approximation, viz.
ap ef
b?pb—a* —5 dz? + Ga =0. a . e é . (u)
Hence substituting in (A) from (), and striking out the common
factor @, we obtain
d°f af. ef
iat t dp Dee eS SR
448 Prof. Challis on the Principles of Hydrodynamics.
We have thus arrived at an equation for determining f which is
consistent with the original supposition that this quantity is a
function of x and y only.
The next step is to ascertain the particular form of f which
applies to the motion resulting from the mutual action of the
parts of the fluid. As the equation (v) is of the same form as
the equation (), the same process that conducted to a particular
solution of the latter must conduct to a particular solution of the
former. In fact, by this process we obtain
f=a.00s (go-+hy),
which evidently satisfies (v), g and 2 being subject to the con-
dition
2
+= s =4e.
Let g=2 Vecos@. Then h=2 Vesin 8, and the above integral
may be put under the form
f=acos {2 Ve(xcosO+ysinO)}. . . (m)
Now as it was argued that an exact and unique integral of (),
the form of which was indicated by the analysis, referred to the
motion resulting from the mutual action of the parts of the fluid,
by parity of reasoning, the integral (7) of the equation (v) should
receive the same interpretation. But it is to be observed, that
since
d, d,
ux and = $5,
the value of f given by the equation (77) indicates that the part
of the motion parallel to the plane of zy is parallel to an arbitrary
direction in that plane depending on the value of @. There is,
however, an integral of (v) which gets rid of this arbitrariness by
embracing ail directions depending on the arbitrary values of @.
For since that equation is linear with constant coefficients, it is
clearly satisfied by supposing that
fH . 280 cos {2 Ve(x cos O+y sin 6)},
56 being an indefinitely small constant angle, and the summa-
tion being taken from 0=0 to 6=27 in order to embrace every
possible direction of the motion. By performing the summation,
substituting 7? for 2*+y?, and determining @ so as to satisfy the
condition that f=1 where r=0, the result is
ert e376
f=1-@ renee (e)
This value of f, containing no arbitrary quantity whatever, indi-
Prof. Challis on the Principles of Hydrodynamics. 449
cates a general law of the spontaneous mutual action of the parts
of the fluid. I have shown in the Philosophical Magazine for
May 1849 (p. 363), that the same result is obtained by supposing
the arbitrary functions in the general integral to be arbitrary
constants. It may be worth while to indicate still another pro-
cess by which the equation (p) may be deduced. Let
aet+yV—l=p, x—-y/—l=);
and in order to get rid of the impossible quantities, make F and
G the same functions in the general integral of (v). Then by
supposing F(z) = Ae“, and G(v)=Ae"”, ¢ being the base of the
apierian system of logarithms, the following exact value of fis
found :
f= OGELZAN (at oy.
Let c=rcos 0, y=rsin 6; k— =m, ko
the right-hand side of the above equation, viz.
2Ae””°°5? cos nr sin 8,
in terms arranged according to the dimensions of m and”. Then
if, for the reason already alleged, the summation >. 68 be taken
from 0=0 to 6=2r, and the constant A be determined so that
the sum shall be unity when r=0O, the result is
4
27, 4?
which, since m?—n?= —4e, is independent of the arbitrary quan-
tity k, and is plainly identical with the right-hand side of ().
The values that have now been obtained for ¢@ and f define
precisely the motion along, and perpendicular to, the axis of
rectilinear motion.
It may here be remarked, that a discussion of the equation (p)
shows that f has an unlimited number of maximum values which
become less as the distance from the axis is greater, and finall
vanish at an infinite distance. Hence at an infinite distance bs
dn’ and i vanish, and by consequence the velocity vanishes.
Hence also the condensation vanishes. Thus the supposition
already made, that the arbitrary quantity F(¢) is equal to zero,
is shown to be legitimate by the result of the preceding inves-
tigation, no part of which depends on that supposition. The
condensation (c) is therefore correctly given by the equation («),
from which it is readily seen that we haye also
=n; and expand
2
1 + (m?—n?) - + (m?—n?)?, + &e.,
da | d*a
metas ae te aI Ca
As the equation (7) is a unique and exact integral of (v)
Phil, Mag. 8. 4. Vol. 4. No. 27. Dec. 1852. 2G
450 Prof. Challis on the Principles of Hydrodynamics.
obtained prior to the consideration of any case of motion, it
ought, according to our principles, to have a general signification.
It may be supposed to apply to motion which is arbitrary only
so far as the angle @ is determined by some arbitrary circum-
stance. But its application is limited by the condition, that the
motions obtained by giving particular values to @ are those only
into which the origmal motion defined by the equation (p) may
be resolved. As this last motion is dependent on no arbitrary
circumstance whatever, it takes place equally under every initial
disturbance, and any modification or resolution of it implies the
operation of a subsequent disturbance. Let, if possible,
f=acos {2 Ve(x cos 0+y sin 6)}
+aleos4 2 vo(a cose +O+y sins +0) \.
This is to suppose that the motion parallel to the plane of ay is
at each point compounded of two motions in directions at right
angles to each other. Expanding the above expression to second
powers of z and y, we have
fa=a +a! —2ae(x? cos*@ + 2xy sin @ cos 8+ 7? sin?6)
—2a'e(x*sin?@ —2zy sin @ cos 8+ y? cos*6).
By what has been said, this equality must be identical with
f=l—e?=1-e(e*+y’).
Hence geet. ant axal=5.
Hence, as appears from equation (c), if 7, and oc, be the con-
densations corresponding to the two motions into which the
original motion is resolved, and S be the original condensation
on the axis of z,
S =
o= 5 ¢0s {2 Ve(x cos 0+y sin 8) },
S ws
T2= 5 cos {2 We(y cos O—asin 8) },
If the expansions had been carried to higher powers of # and
y, the two values of f would no longer have been identical.
Hence we may infer that the solution (7) is applicable only to
points very near the axis of motion; and that the motion which,
for very small values of r, is defined by the equation f=1—er?,
may be resolved into two sets of motions, alike in all respects,
but parallel to two planes at right angles to each other.
If these results be hypothetically applied to the undulatory
theory of light, the original motion contiguous to the axis, and
symmetrically disposed about it, corresponds to ordinary light,
and the resolution of this motion corresponds to polarization.
[To be continued. ]
P45 J
LXXI. On the relation of Magnetism and Diamagnetism to the
Colour of Bodies. By Ricuarp Apiz, Esq., Liverpool*.
\ \" 7 HILE occupied with some experiments in the latter part
of the year 1850, to test the magnetic properties of a
variety of bodies, I was struck with the preponderance of trans-
parent or white bodies among the class of diamagnetics; I con-
sequently followed this branch of the inquiry, and in the follow-
ing year gave, in Jameson’s Edinburgh Journal, a table to
prove that the diamagnetic metals produced a much. larger
proportion of colourless compounds than the magnetic ones. In
the present instance I propose to return to the subject, to show
that when the inquiry is confined to the oxides and chlorides, a
similar relation subsists, although among the elementary bodies
themselves there appears to be no connexion of the sort ; indeed
they tend to range themselves in an order opposite to that of the
table I have alluded to, oxygen being magnetic and colourless,
while chlorine, iodine, and bromine are diamagnetic and highly
coloured.
It is in their compounds that the tendency of transparent sub-
stances to diamagnetism is seen, and in none is this more satis-
factorily shown than in the most important of all the diamag-
netics, water, for there 8 grs. of oxygen, a decidedly magnetic
body, enter into combination with 1 gr. of hydrogen, a body of
feeble diamagnetic properties, and produce 9 grs. of water, which
the magnet repels, so that the magnetism of 8 parts of oxygen
are more than counterbalanced by the diamagnetism of 1 part.of
hydrogen after ther chemical union. Further, oxygen, where it
forms colourless oxides with metals of very feeble magnetic pro-
perties, produces compounds where the magnetic power of the
oxygen is masked, and there results a diamagnetic body like
water ; of these, Iceland spar, quartz and potash furnish instances.
In these cases, oxygen, although magnetic in itself, acts as a
destroyer of magnetism in the new compounds; and if we turn
to the oxides of the strongly magnetic metals, this property of
oxygen is seen in a manner even more marked. For example, in
the red oxide of iron a great amount of magnetic force is masked
by the union of the oxygen with the iron.
The metals of marked magnetic or diamagnetic properties form
but a small proportion in the general list of metallic bodies ;
three only can be said to be decidedly magnetic, namely, iron,
nickel and cobalt; and four diamagnetic, bismuth, antimony,
zine and tellurium. Diamagnetism never assumes the power of
magnetism ; but in the four metals named, the property is suffi-
ciently marked to manifest itself in the presence of minute im-~
* Communicated by the Anthor.
G 2
452 On the Non-polarization of the Aurora Borealis.
purities, which in the greater part of the other metals often deter-
mines whether the specimen tested is repelled or attracted.
On comparing the oxides and chlorides of the magnetic metals
with those of the diamagnetic metals given, I find that there are
three oxides and three chlorides of the magnetic metals all
coloured ; of the diamagnetic metals, there are three white oxides
and one coloured, and four white chlorides* and one coloured,
showing a great preponderance of white compounds to the dia-
magnetic substances.
Chlorine being a diamagnetic body, might be expected to give
a greater proportion of colourless bodies among the chlorides
than oxygen among the oxides of the same metals. To ascertain
if this was so, I selected thirty-six of the metals which have
been most examined, and tabulated their chlorides and oxides :—
Of the oxides, twenty-four were coloured and twelve white ;
Of the chlorides, nineteen were coloured and seventeen white.
The chlorides, in conformity with this view, are found to fur-
nish more white compounds than the oxides.
LXXII. Non-polarization of the Aurora Borealis. By Wi1t11aM
Joun Macquorn Rankine. C.E., F.R.S.E., F.R.S.S.A., &c.
To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,
Fs tai ips the results which I have obtained are purely
negative, it may be useful to record the fact, that having
on several occasions during the last eight months examined the
light of the aurora borealis with a Nichol’s prism, I have never
detected any trace of polarization. To show that this did not
arise from the faintness of the light, I may mention, that on the
last occasion when I observed it, the polarization of the same
light produced by reflexion from the surface of a river was
distinctly visible, although the direct light was evidently free
from all sensible polarization.
This fact is adverse to the supposition that the light of the
aurora borealis is reflected from crystals of ice.
I am, Gentlemen,
Your most obedient Servant,
Glasgow, Noy. 22, 1852. W.J. M. Rankine.
* One of these is a bichloride.
[ 453 ]
LXXIT. On Copper Smelting. By Jamus Napier, F.C.S.*
[Continued from p. 355.]
- Calcination of the Ores.
(3 ae arranging and classifying the ores when brought into
the smelting-works is a most important operation, affect-
ing the whole after-workings, both as regards the cost and qua-
lity of the copper. The mines and localities from which the ore
is brought are so numerous, that it would be impracticable to have
a separate yard or compartment in the smelting-works for every
one; hence a more general classification is adopted, such as
highly sulphurous ores, including those containing mundie, fluc-
can or clayey ores coloured red or yellow, gray sulphur ores, &e.
Sometimes certain mines or localities are known to produce ores
of a certain quality ; for instance those from Hayle have generally
the character of being stiff (difficult to fuse) ; those from Foey Con-
sols, of making inferior copper, &c. ; these are all classified: then
there are compartments for Cuba and Cobre, for the Irish ore,
for Chilian ore, and for Australian ore ; besides these qualities,
the per-centage of copper in the ore has also to be considered -
two or three lots of ores having respectively 7, 8, or 9 per cent.
of copper, if their other qualities agree, may be put together, but
not ores having 4, 8, and 12 per cent. The object of these
arrangements and classifications of ores in the yard is to enable
the operative smelter to select from and make up a constant
working mixture, having the following characters :—
Ist. That the copper in the mixture be not under 9 nor above
13 per cent. ; if under the former, it is unprofitably poor ; if
over the latter, the slags have a tendency to contain copper,
creating a loss.
2nd. That after being calcined an ordinary time, it will fuse
easily without the necessity of adding flux, giving a clean and
easily fused slag.
3rd. That the mat or coarse metal obtained from fusion contain
as near as possible 30 per cent. of copper. And
4th. That the mixture do not contain ores having impurities
calculated to make the copper of a lower quality than is desired.
There is no definite or fixed rule to guide the smelter in these
classifications except a practised eye in distinguishing the cha-
racter of ores, and the report of the assayer.
It must be borne in mind that we are speaking of ores con-
taining sulphur ; for although carbonates and oxides are brought
* Communicated by the Author, who reserves to himself the copyright,
any infringement whereof will invoke legal proceedings.—Eps.
454. Mr. J. Napier on Copper Smelting.
into the condition of sulphurets in smelting, they are seldom
mixed with the sulphuret ores, but with the calcined coarse
metal from these ores to be described.
M. F. Le Play, in his Procédés Métallurgiques, has divided
the ores imto seven classes, and pointed out their distribution
in the operations in the works as follows :—
Ist. Ores containing from 3 to 15 per cent.. of copper, mostly
pyrites, with sulphuret of iron, and much earthy and other
impurities,
2nd. Ores of the same character as the first, but richer, having
from 15 to 25 per cent. of copper.
3rd. Ores requirig no calcination, having little sulphur and
much oxide of copper, the per-centage of copper being between
12 and 20. .
4th. Ores composed of oxides and carbonates of copper, subsul-
phurets with small portions of pyrites, the matrix being oxide
of iron and quartz.
5th. Same as the first class, but known to have no deleterious
matters in them, such as tin, antimony, &c.
6th. Ores, principally subsulphurets, having a per-centage of
from 60 to 80 of copper.
7th. The waste matters collected about the works termed, as we
have already noticed, cobbing.
As this author describes ten operations as necessary in the
manufacture of copper, his observations and descriptions must
have reference to a period previous to the introduction of so
much rich foreign ore, and some of these descriptions are there-
fore not applicable to the present time, the general routine of
operations bemg now only six. The want of a definite rule to
guide the smelter in mixing his ores is a desideratum we think easily
supplied by investigation and attention. In the last section we
mentioned that silica, alumina, &c. were by themselves infusible,
but at high temperatures readily combine with other matters
and form compounds that are easily fused; and in these com-
binations there are kinds and quantities of these substances much
more easily fused than others. The first object of the smelter
being to separate the metallic portion of the ore from the earths
with the least expense and trouble, the having a mixture that will
give him an easily flowing scoria, is a primary consideration.
This, no doubt, could be easily obtained in the same way as
shown in assaying, by adding flux; but every addition of flux is
a loss in the smelting of copper, and should always be avoided
if possible. In all combinations, to effect perfect fusion
certain proportions are necessary to form a fusible compound, in
the same way asin ordinary combinations. For example, to dis-
Mr. J. Napier on Copper Smelting. 455
solve 32 grains of metallic copper in vitriol, it would require 49
grains of the strongest acid, and nothing less; hence 32 and 49
are their relative combining proportions. The same law holds
good for every substance combining whether by fusion or solu-
tion. The equivalent or combining proportion of silica is 46.
In order, then, to form a compound with silica that will be
easily fused, we must employ equivalents of other substances.
The following is a table of the combining proportions of those
matters found in copper ores, or added as flux to fuse silica: —
Siliea\ 2410 90] of i9joatsog sgaay od) 146
Slakedtime .. ..i94GQ91) 399, 199 GR 057
Carbonate of lime, chalk, shells, &. . 50
Pindispar 00 SSg1aqo- yap HALT, "19¢ . 39
Carbonate ‘of barytes 3°80 8 5.4 2488
Carbonate of magnesia . . . . . 84
Carbonate of soda. . . . . . . 58
Carbonate of potash . . . . . . 69
Protoxideofiron . . . . . . . 86
Peroxideofiron .... .. . 40
Oxide of-eopper 2) acre visu ig4®
Oxidevof lead <3. o. awgoe te OP he
Oxide of tia. as 6 MSOs, ea e067
With these proportions, and an approximate analysis of the
mixture of ores, a pretty accurate idea may be formed, before the
matters are put into the furnace, of the kind of scoriz that will
be formed.
For the general character of the ores we refer to the tables in the
first article, where it will be observed that silica is the principal
earth present. Le Play gives the average composition of all the
ores smelted in a work for a length of time as follows :—
CET OO ISR 9 BITES BO ED
Terie ss STO EEG, PET ITD ae
ie 7 Aes rt Nie Sete A ee 3
et op ci el ali ged ‘Talat adi ay Sth "A
2: 5 naling al aad ahi Eat Mer se el 2 3
Regi? 983 LO OOTY MERLOT SUR
Other metals . OT) INES ‘9
Siipitart 87s (atioje Batlvor elon
Oxygen, carbonic acid, and water =-1°2
100°0
The composition of the slag or scoriz from fusing these ores
is given by the same author as follows :—
456 Mr. J. Napier on Copper Smelting.
Silica combined’... ws 8000
Silica mixed. 2. 2...) .) 805
Oxide: of tron! O68 Pe Se 2B
(Ataimiria ei 20) ot wale gyi Bat RED
Magnesia 6
Different oxides 1:4.
Lime? Hai A es ger it 2:0
Fluoride of calcium. 2°11
Copper 9)
Tron 9
Sulphur ‘6
100:0
By comparing this with the above analysis of ore, we find that
lime and fluor-spar have been added to assist fusion, which should,
when it is possible, be avoided ; it will also be observed that the.
oxide of iron is the principal flux for the silica. The following
table exhibits the general character and composition of different
qualities of slag :—
Silica. |Oxide of Tinie} Oxides of
iron. other metals.
Slag very difficult to fuse, having one |
silicamived, requiring one-fourth longer
time than usual to fuse each charge ...
Slag a little stiff in working, hen
70°77 | 28-4 | 1:2
63'1 | 35°9 2)
GENEDUB sadn. cervupnsessnsdeacesnaccemeonierees
Good thin slag, homogeneous ............0+ 48-2 | 37:0) 40 6
Good slag, easily fused .....16ce +s ceeeeneeeees 57-6 | 41°5 | Trace.
Slag good, and easily fused .............0.+0 55:2 | 38°5 i)
Black glassy slag, easily fused .......+.++++0 65 20:8 | 9°9 3 soda.
The first in the above table had pieces of quartz mixed with
it, which is of very frequent occurrence in the slags, and may to
a certain extent be calculated upon without prejudice to the
fusion of the ores. Indeed, taking the average of analyses we
have made of slags which the smelters term good working slags,
and grinding the whole, mixed and combined quartz together,
the weight of the protoxide of iron averages about one-half that
of the silica, If we take the homogeneous slags, where the silica
and iron are chemically combined, it will be observed how close
the ingredients are to the table of proportions.
To follow the operation of calcination, let it be supposed that
the mixture of ore has the following composition :—
OpOerns: fear i se
ISM) ve de ee ee
oltre et a Fee
INCE sae ee rere
Mr. J. Napier on Copper Sinelting. 457
Here there is more iron than is requisite to fuse the silica; but
were this ore put into a fusing-furnace it could not be melted ; the
iron, copper, and sulphur would fuse together, leaving the unfused
silica or quartz mixed up with it, forming an agglomeration, as
silica will not combine with sulphurets of metals. In the combi-
nation of matters in fusion we have often to be guided by the cir-
cumstances regulating affinity, as for example,—
Iron requires a heat of about 3000° F. to melt it,
Copper mes 1900 wae
Sulphur is separated from these metals at a temperature of about
700° or 800°; but at a temperature of about 1200° the sulphur
and these metals melt together, and their affinity for each other
at this heat is increased. Oxide of iron and quartz combine and
fuse at about 1800°. Bearing these conditions and relations in
mind, it will be obvious that calcination is a primary and essen-
tial operation, the object of which is twofold. The ore contains
a great quantity of silica that must be got rid of by fusion; the
best means for doing so is by oxide of iron. The ore contains
sufficient iron to effect this, which must also be got rid of; but
the sulphur both retains and prevents it from combining with
the silica ; hence the operation of calcination is to drive away the
sulphur and oxidate the iron, which is effected by exposing the
ore to a temperature of from 700° to 1200°, so that the sulphur
is separated from the metals and sublimed. It is evident, there-
fore, that in mixing the ores for smelting, it is as necessary to
mix them in relation to the iron they contain as to the earths.
Other circumstances haye to be considered in mixing ores,
namely, the presence of metals that would be injurious to the
copper if not removed. These are generally tin, antimony and
arsenic ; the latter does not deteriorate copper much, but it mate-
rially affects the operations of calcination and fusion. Arsenic
has a peculiar property over other metals in not having any fluid
range; it remains solid until heated to about 356° F., when it
passes off in a gaseous state, absorbing and carrying along with
it a great quantity of heat which retards the operation of calci-
nation ; so that ores containing much arsenic should be sparingly
mixed with other ores; or what is preferable, should be treated
separately in the calcining operation, and mixed with other ores
afterwards. A large admixture of highly arsenious ores is a great
drawback to the fusion, if the greater portion of the arsenic be
not previously driven off. We have known an extra expense of at
least £20 per week for time, fuel and flux, to have been incurred
during the smelting of a few hundred tons of ores containing
much arsenic, under the impression that they were stiff and re-
quired flux, when an analysis would have shown that fluxes were
458 Mr. J. Napier on Copper Smelting.
not required. But more money is spent in a year uselessly in the
copper-works than would pay the salary of an efficient chemist,
who could define the character of every ore before mixing, besides
making other necessary inquiries which would be useful.
The mixture of ores being selected according to the rule
adopted by the manager, it is carried to the large hoppers
on the top of the caleming furnace and then let down imto the
hearth, where, after drying a little, it is spread equally over the
bottom, covering it to a depth of from six to eight inches. The
quantity of ore put in varies, according to the size of the furnace,
from three tons to six tons. The fire of the furnace is kept low at
first ; after two or three hours the ore on the surface becomes
visibly red, the heat is gradually mcreased to a yellow red ; but
this heat only penetrates to the depth of about an inch, conse-
quently the ore has to be stirred and turned over by means of long
iron paddles every hour, so as to expose a new surface to the action
of the air and fire. This calcination lasts generally nime hours ;
but when ores are known to be stiff, containing much silica and
sulphuret of iron, twelve hours are allowed. The following
changes and chemical actions take place: the sulphur is partly
burned off by combining with oxygen and forming sulphurous
and sulphuric acids, and partly volatilized as sulphur uncom-
bined ; arsenic is volatilized either as metal or oxide ; the copper
and iron lose sulphur and combine with oxygen, which changes
are subject to variations according to circumstances occurring in
the operation.
In order to judge of the time necessary to calcine an ore,
the nature and richness of the mat or coarse metal it will pro-
duce when fused has to be considered ; and this does not depend
upon the richness of the ore in copper when it goes into the
calciner, but upon the quantity of sulphur and iron it contains.
For instance, if we take the following ore and fuse it, adding
flux to combine with the silica,—
Copper...) 22
Fron bsheg eae ele Bd
Shinhkers spc pree
Rae a RS
100
we should obtain a coarse metal or mat having only 26 per cent.
of copper ; and if we take another ore, having the following com-
position ,—
RCL on rer wivilsl retell
| ei Ak iE Np |
Sulphur.........., 12°4
01 a a ER
100-0
Mr. J. Napier on Copper Smelting. 459
and fuse this in the same way, it would yield a coarse metal con-
taining 30 per cent. of copper; so that here the poorest ore gives
the richest mat. In order, then, to show the principle of mixing,
and to obtain a fusible slag without flux, we will take two parts
of the above rich ore and one of the poor ore, giving a mixture
having the composition—
Copper . . . 184
Trop 4. Sse nes PS
Sulphu . . . 25°5
Silica. rose 6 1293
If this be calcined to volatilize half the sulphur, the remaining
half, viz. 12°7, when the ore is fused, will combine thus :-—
4°6 will combine with . . 18°4 copper,
Sl will take . . .«, ... 140 iren;
producing a mat or coarse metal with 40 per cent. of copper.
The oxide of iron being equal to 16°5 will combine with the 29°3
silica, forming the slag. We will enter more fully into these
combinations further on.
With respect to the time any mixture of ore has to be calcined,
the rate at which calcination proceeds has also to be considered,
and forms a most important inquiry. Thus suppose the above
mixture of ores lost half of its sulphur in nine hours, nine hours
more would not suffice to drive off the remaining half.
We took a charge of Cuba ore and calcined twelve hours ;
samples taken out and tried every hour gave the following
results :—
=] a nD a a 2 an 2 a a a
oa |-Z)a2)o3|~2 loses |Z [oe log [23 |=8 [28
S$ a a a a a a a a a a aI a
Copper...) 12-3 | 13-0) 12-2) 12-2) 13-0} 12-2) 13-8) 12-6) 12-6) 12-5) 13-2) 13-8) 12-2
Tron...... 32-7 | 30-0) 24-4) 32-8) 28-7| 31-3) 33-6) 30-6) 30-0) 27-6) 24-3) 40-3) 27-0
Sulphur..| 31-1 | 28-3] 23-6) 18-6) 29-2) 24-4) 12-2) 18-1) 20:0/ 15-9) 18-8) 17-5) 16-2
Silica +| 24-0 | 28-0) 32-0) 28-0) 26-0} 28-0) 34-8) 32-0) 30-0) 30-8) 33-0) 21-0) 40-0
{100-0 99°3| 92-2) 91-6) 96-9) 95-9) 94-4) 93-3 92°6) 868) 89-3) 93°6) 95-4)
The iron in all these is calculated as being in the metallic state,
although in many of them it was much oxidized: a small part
of the sulphur in some of the trials was present as sulphuric
acid. When we take into consideration the several amounts of
sulphur, we observe what appears very anomalous, that there is
less sulphur at the end of six hours than after twelve. It may
be asked, where the sulphur is gone, whence comes it again?
In all our experiments this intermitting action of the sulphur
isexhibited. It is probably connected with the increase of volume
of the sublimed sulphur and sulphurous acid. A sudden evolu-
460 Mr. J. Napier on Copper Smelting.
tion of these fumes will cause an immediate decrease in the quan-
tity of sulphur in the portion of ore then tested; the gases
above the ore being principally composed of sublimed sulphur,
the admission of cold air, which always follows a rapid evolution
of gas, probably the result of a reacting condensation, causes a
portion of the sulphur to be deposited and absorbed again by
the ore, so that the next quantity tried contains more sulphur.
Regularity in the draught and heat of a calciner ought to be
strictly attended to.
Another trial was made with an ordinary mixture of ores, every
door of the calciner being clayed up air-tight, and allowing no
air to be admitted except through the bridge under the fire,
by which it was partially heated. A sample of ore taken out
every hour for six hours and tested for sulphur gave as follows :—
In the Ist 2nd 3rd 4th 5th 6th
ore. hour. | hour. | hour. hour. | hour. | hour.
Sulphur ,..} 166 | 14:7 | 126) 95 14 8-5 9°6
Here we have the same intermitting action after a few hours.
In the next experiment the calcination was continued as long
as sulphur was present; or, as expressed practically, the ore
was calcined dead. The quantity of sulphur was determined every
four hours ; the ore was turned over every two hours; the sam-
ples were taken out as the stirring commenced, and always from
one part of the hearth.
2s] floflasles 25 zi 2 fla 8 of 2 78
Beal 27a] e/" 8] 2 ("2/72/72 (78) "8
Sulphur ...... 25-9) 24-8] 20-7) 14-7| 12-0] 9-3} 7:5 | 4:3| 2°8| 2-4] 0-5] 08
eared t 1-1] 4:1] 6-0) 2-7) 2-9| 1:8} 3:2! 1-5] 0-4] 1:9] 0-2
4hours ..
The intermittent action is not so fully developed in four-hour
trials; but looking at the rate of loss each four hours, there is
no doubt that it existed. It must be remembered in judging of
the rate at which the sulphur passes off from the ore, that in the
above and all calcinations the heat of the furnace is gradually
increasing ; showing the strong aflinity the last portions of sul-
phur have for the metal. :
In the above experiment the quantity of sulphates formed was
also tested ; the following are the results :—
After 4 hours a little sulphuric acid, no copper or iron in
solution.
After 8 hours a little more acid, no metals.
After 12 hours both sulphate of copper and iron.
After 16 hours a mere trace of acid.
461
After 20 hours a half per cent. of copper as sulphate, no iron.
After 24 hours nearly the same.
After 28 hours a mere trace of acid and copper, no iron.
After 32 hours a mere trace of acid and copper, no iron.
After 36 hours trace of acid, no metal.
After 40 hours no trace of acid or metal.
After 44: hours no trace of acid or metal.
Several other experiments were tried of a like kind with similar
results, to which we may have recur to in connexion with others
of a different description in order to arrive at the causes of these
reactions in a calciner,
For the purpose of saving time and fuel a compound calciner
has been tried, and we believe is still in use in some works
where one bed or hearth is placed over the other. The ore is put
into the top bed, then passes through holes in the floor to the
second or middle, and then to the third or lower bed, where it
receives the highest heat ; so that nine hours’ calcination is equal
to three hours in each bed. The first experiments made with
this sort of calciner had for their object to ascertain the length
of time required to calcine dead. The ore was tested for sulphur
every four hours, allowing sixteen hours in each bed ; each sample
was also boiled in water, and the sulphuric acid determined.
Mr. J. Napier on Copper Smelting.
——Sse eee e eee
lst bed. 2nd bed. 3rd bed.
Be bike bk. |: Bo.| Bo| Be Bonde UOTE ACEP ese | 2
ees ee r= a| a a 3 3 s/s} 2138) 8
Sulphur ..|31 30°5, 29-4; 14:8} 11-8 | 22-9) 18-1} 21:0] 15-6] 8 3:0| 4:5) 2°83} 1-5] 0-5
In solu- Iron} Iron Copper Copper|Copper|Copper
tion ... Tron
Beanbags 31. -7| 2-31 84 3) 4 7 1-0 1 -3| -4| -4) -Ol -O
The two following tables contain the results of experiments
made with ores calcined only for a short time, the whole ingre-
dients of the ore being taken in testing.
Table I.—A mixture of ores not analysed before being put into
the furnace.
Ist bed. 2nd bed. 3rd bed.
P Z a _E
Copper...... 12-4! 12-0} 12-4) 12-4, 12-1] 12-0] 12-5! 11-3) 11-7] 13-5] 13-2
Oy Peer 26°3) 26:3) 25-5| 25-2) 24-0) 24-9) 25-0) 25-2) 27-5] 27-5) 27-5
Silica ...4.. 31-9 308) 26°5| 29-1| 30:6) 28-6) 30-8) 28-3) 30:5} 31-6) 33-2
Sulphur ...| 26°38) 28:3) 34-4) 80:4) 28-1) 28-7| 27-4| 28-9} 24-0] 14-7] 18+4
gored 2) 2 *l| +1 tracejtrace|trace tj) a: | a |
acid ... J | | }
462 Mr. J. Napier on Copper Smelting.
Table I1.—Cuba ore not analysed before being put into the
furnace.
lst bed. 2nd bed 8rd bed
w3 ak al «i of ot wi a5 oF 24 ~é ag
Be Bele | Sl SiS lt SS tecehee Sia eaeesl
Copper...... 16°0 15:0) 11:3) 12-0) 16-0) 15-0} 12:5) 12-4) 14-0) 12-4/ 16-5) 16-7
Tron. Je.08. 24-9 25-5) 24°6 26°6, 27°4, 26-0) 28-0) 28-0) 29-7| 30°8) 27-3) 24:5
Silica » c; if less, to b<; in both cases an imaginary
result would follow. Butif the algebraic treatment resulted in d=c,
we should necessarily find W —1 disappear, and the presumed equa-
lity would really exist asa+f. This being the geometric process
generally followed in the reductio ad absurdum, may perhaps throw
some light on the verification of Mr. Sylvester’s important suggestion,
23 Walpole Street, Chelsea, S. M. Dracn,
November 22, 1852.
METEOROLOGICAL OBSERVATIONS FOR ocr. 1852,
Chiswick.—October 1. Fine. 2. Uniformly overcast: very fine: clear. 3, Clear:
very fine: clear: slight rain. 4, Constant and very heavy rain: clear. 5. Clear
and boisterous. 6. Rain: clear at night. 7. Cloudy: fine: uniformly overcast.
8. Overcast: fine. 9. Clear: very fine: rain. 10. Overcast. 11, 12. Very fine.
13. Fine: dusky haze. 14. Foggy: uniform haze: at night clear above, hazy
near the horizon. 15,16. Foggy: cold haze: clear above at night. 17. Dense
fog. 18. Very fine throughout. 19. Foggy: very fine: dense fog at night.
20. Foggy: exceedingly fine: hazy. 21. Foggy: hazy: rain. 22. Hazy: rain.
23. Cloudy: rain. 24. Cloudy: very fine: heavy rain at night. 25. Heavy rain:
clear at night. 26. Slight fog: rain. 27. Rain. 28, Densely overcast : cloudy:
clear. 29. Clear: overcast: rain. 30. Overcast: rain. 31. Clear and fine : bright
sun ; overcast at night.
Mean temperature of the month ............... Poe “pesos 46°38
Mean temperature of Oct. 1851 oo. ..eceeesseceecoees POCOU Tat fet,
Mean temperature of Oct. for the last twenty-six years... 50°50
Average amount of rain in Oct. .............ceeeee sacquadacssedy 2°60 inches.
Boston.—Oct.1, 2. Fine. 3. Cloudy: rain early a.m. 4,5. Cloudy: rain a.m.
and p.m. 6. Cloudy: rainp.m. 7. Fine: rainearly a.m. 8,9. Fine. 10. Cloudy.
11—13. Fine. 14. Foggy. 15—17. Cloudy. 18. Fine. 19. Cloudy. 20. Fine.
21, 22. Rain: rain a. 23. Cloudy: rain a.m. 24,25. Fine. 26. Fine:
rain P.M. 27. Fine: rain a.M.and p.m, 28. Rain: rain a.m. 29, 30. Cloudy.
31. Fine: rain early a.m.
Sandwick Manse, Orkney.—Oct. 1. Clear : hoar-frost : fine : hoar-frost. 2. Rain.
3. Bright: showers. 4. Cloudy. 5. Cloudy: clear. 6, 7. Sleet-showers. 8.
Sleet-showers: cloudy. 9. Drizzle: cloudy. 10. Showers. 11, 12. Bright:
cloudy. 13. Rain: cloudy, 14. Cloudy: fine. 15. Bright: clear: fine. 16.
Fine : hoar-frost : hazy: fine. 17. Fine: cloudy: rain. 18. Rain: cloudy. 19.
Drizzle. 20. Cloudy: drizzle. 21. Fine: cloudy: fine. 22. Hazy: drizzle.
23. Cloudy: clear: fine. 24. Clear: fine: aurora. 25. Clear: fine. 26, 27.
Showers. 28. Showers: bright: clear. 29. Cloudy. 30. Showers. 31. Rain:
cloudy.
ae temperature of Oct. for twenty-five previous years ...... 47°55
Mean temperature of this month ......... GABI¥erase>piagiass ores. 46 °88
Average quantity of rain in Oct. for six years .......... sisneacs 4°39 inches,
* The mode of employment is not stated by the author,
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THE
LONDON, EDINBURGH anp DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
SUPPLEMENT to VOL. IV. FOURTH SERIES.
LXXVI. On the Thermal Effects experienced by Air in rushing
through small Apertures. By J.P. Joutn and W. Toomson*.
0 hypothesis that the heat evolved from air compressed
and kept at a constant temperature is mechanically equi-
valent to the work spent in effecting the compression, assumed
by Mayer as the foundation for an estimate of the numerical
relation between quantities of heat and mechanical work, and
adopted by Holtzmann, Clausius, and other writers, was made
the subject of an experimental research by Mr. Joule+,and verified
as at least approximately true for air at ordinary atmospheric
temperatures. A theoretical investigation, founded on a conclu-
sion of Carnot’s{, which requires no modification § in the dyna-
mical theory of heat, also leads to a verification of Mayer’s hypo-
thesis within limits of accuracy as close as those which can be
attributed to Mr. Joule’s experimental tests. But the same
investigation establishes the conclusion, that that hypothesis can-
not be rigorously true except for one definite temperature within
the range of Regnault’s experiments on the pressure and latent
heat of saturated aqueous vapour, unless the density of the vapour
both differs considerably at the temperature 100° Cent. from
what it is usually supposed to be, and for other temperatures
and pressures presents great discrepancies from the gaseous laws.
No experiments, however, which have yet been published on the
density of saturated aqueous vapour are of sufficient accuracy
to admit of an unconditional statement of the indications of
theory regarding the truth of Mayer’s hypothesis, which can-
not therefore be considered to have been hitherto sufficiently
* Communicated by the Authors; having been read to the British Asso-
ciation at Belfast, Sept. 3, 1852.
+ Phil. Mag. May 1845, p. 375, “On the Changes of Temperature
produced by the Rarefaction and Condensation of Air.”
{ Transactions of the Royal Society of Edinburgh (April 1849), vol. xvi.
part 5, “‘ Appendix to Account of Carnot’s Theory,” §§ 46-51.
§ Trans. Royal Soc. Edinb. (March 1851) vol. xx. part 2; or Phil. Mag.
S. 4. vol. iv. “ On the Dynamical Theory of Heat,” § 30.
Phil, Mag. 8. 4, No. 28. Suppl. Vol. 4. 2I
482 Mr. J. P. Joule and Prof. Thomson on the Thermal Effects
tested either experimentally or theoretically. The experiments
described in the present communication were commenced by the
authors jointly in Manchester last May. The results which have
been already obtained, although they appear to establish beyond
doubt a very considerable discrepancy from Mayer’s hypothesis
for temperatures from 40° to 170° Fahr., are far from satisfac-
tory; but as the authors are convinced that, without apparatus
on a much larger scale, and a much more ample source of me-
chanical work than has hitherto been available to them, they
could not get as complete and accurate results as are to be
desired, they think it right at present to publish an account
of the progress they have made in the inquiry.
The following brief statement of the proposed method, and the
principles on which it is founded, is drawn from §§ 77, 78 of
Part LV. of the series of articles on the Dynamical Theory of
Heat republished in this Magazine from the Transactions of the
Royal Society of Edinburgh in 1851* (vol. xx. part 2. pp. 296,
297).
Let air be forced continuously and as uniformly as possible,
by means of a forcing-pump, through a long tube, open to the
atmosphere at the far end, and nearly stopped in one place so as
to leave, for a short space, only an extremely narrow passage, on
each side of which, and in every other part of the tube, the passage
is comparatively very wide ; and let us suppose, first, that the air
in rushing through the narrow passage is not allowed to gain any
heat from, nor (if it had any tendency to do so) to part with any to,
the surrounding matter. Then, if Mayer’s hypothesis were true,
the air after leaving the narrow passage would have exactly the
same temperature as it had before reaching it. If, on the contrary,
the air experiences either a cooling or a heating effect in the cir-
cumstances, we may infer that the heat produced by the fluid fric-
tion in the rapids, or, which is the same, the thermal equivalent
of the work done by the air in expanding from its state of high
pressure on one side of the narrow passage to the state of atmo-
spheric pressure which it has after passing the rapids, is m one
case less, and in the other more, than sufficient to compensate
the cold due to the expansion ; and the hypothesis in question
would be disproved.
The apparatus consisted principally of a forcmg-pump of
10! inches stroke and 13 internal diameter, worked by a
hand-lever, and adapted to pump air, through a strong copper
vessel} of 136 cubic inches capacity, (used for the purpose of
ine also Dynamical Theory of Heat, part 5. Trans. Roy. Soc. Edinb.
1852.
+ This and the forcing-pump are parts of the apparatus used by Mr.
Joule in his original experiments on air. See Phil. Mag. S. 3. vol. xxvi.
p- 370 (1845).
experienced by Air in rushing through small Apertures. 483
equalizing the pressure of the air,) into one end of a spiral leaden
pipe 24 feet long and ;4ths of an inch in diameter, provided
with a stopcock at its other end. The spiral was in all the expe-
riments kept immersed in a large water-bath.
In the first series of experiments, the temperature of the bath
was kept as nearly as possible the same as that of the surround-
ing atmosphere ; and the stop-cock, which was kept just above
the surface of the water, had a vulcanized india-rubber tube tied
to its mouth. The forcing-pump was worked uniformly, and
the stop-cock was kept so nearly closed as to sustain a pressure
of from two to five atmospheres within the spiral. A thermo-
meter placed in the vulcanized india-rubber tube, with its bulb
near the stop-cock, always showed a somewhat lower temperature
than another placed in the water-bath*; and it was concluded
that the air had experienced a cooling effect in passing through
the stop-cock.
To diminish the effects which might be anticipated from the
conduction of heat through the solid matter round the narrow
passage, a strong vulcanized india-rubber tube, a few inches long,
and of considerably less diameter than the former, was tied on
the mouth of the stop-cock in place of that one which was
removed, and tied over the mouth of the narrower. The stop-
cock was now kept wide open, and the narrow passage was
obtained by squeezing the double india-rubber tube by means of
a pair of wooden pincers applied to compress the inner tube very
near its end, through the other surrounding it. The two ther-
mometers were placed, one, as before, in the bath, and the other
in the wide india-rubber tube, with its bulb let down so as to be
close to the end of the narrower one within. It was still found
that, the forcing-pump being worked as before, when the pincers
were applied so as to keep up a steady pressure of two atmospheres
or more in the spiral, the thermometer placed in the current of
air flowing from the narrow passage showed a lower temperature
than that of the air in the spiral, as shown by the other. Some-
* When the forcing-pump is worked so as to keep up a uniform pressure
in the spiral, and the water of the bath is stirred so as to be at a uniform
temperature throughout, this temperature will be, with almost perfect accu-
racy, the temperature of the air as it approaches the stop-cock. It is to
be remarked, however, that when, by altering the aperture of the stop-cock,
or the rate of working the pump, the pressure within the spiral is altered,
even although not very suddenly, the air throughout the spiral, up to the
narrow passage, alters in temperature on account of the expansion or con-
densation which it is experiencing, and there is an immediate corresponding
alteration in the temperature of the stream of air flowing from the rapids,
which produces often a most sensible effect on the thermometer in the
issuing stream.
212
484 Mr. J. P. Joule and Prof. Thomson on the Thermal Effects
times the whole of the narrow india-rubber tube, the wooden pin-
cers, and several inches of the wider tube containing the thermo-
meter, were kept below the surface of the bath, and still the cooling
effect was observed ; and this even when hot water, at a tempe-
rature of about 150° F., was used, although in this case the
observed cooling effect was less than when the temperature of
the bath was lower.
As it was considered possible that the cooling effects observed
in these experiments might be due wholly or partly to the air
reaching the thermometer-bulb before it had lost all the vis viva
produced by the expansion in the narrow passage, and conse-
quently before the full equivalent of heat had been produced by
the friction, and as some influence (although this might be
expected to diminish the cooling effect) must have been produced
by the conduction of heat through the solid matter round the
air, especially about the narrow passage, an attempt was made
to determine the whole thermal effect by means of a calorime-
trical apparatus applied externally. For this purpose the india-
rubber tubes were removed, and the stop-cock was again had
recourse to for producing the narrow passage. A piece of small
block-tin tube, about 10 inches long, was attached to the mouth
of the stop-cock, and was bent into a spiral, as close round the
stop-cock as it could be conveniently arranged. A portion of
the block-tin pipe was unbent from the principal spiral, and was
bent down so as to allow the stop-cock to be removed from the
water-bath, and to be immersed with the exit spiral in a small
glass jar filled with water. The forcing-pump was now worked
at a uniform rate, with the stop-cock nearly closed, for a quarter
of an hour, and then nearly open for a quarter of an hour, and
so on for several alternations. The temperatures of the water
in the large bath and in the glass jar were observed at frequent
stated intervals during these experiments; but, instead of there
bemg any cooling effect discovered when the stop-cock was
nearly closed, there was found to be a slight elevation of tem-
perature during every period of the experiments, averaging
nominally *06525° F. for four periods of a quarter of an hour
when the stop-cock was nearly closed, and ‘06533° when it was
wide open, or, within the limits of the accuracy of the observa-
tions, ‘065° in each case; a rise due, no doubt, to the rising
temperature of the surrounding atmosphere during the series of
xperiments. Hence the results appear at first sight only nega-
tive ; but it is to be remarked that, the temperature of the bath
having been on an average 31° F. lower than that of the water
in the glass jar, the natural rise of temperature in the glass jar
must have been somewhat checked by the air coming from the
experienced by Air in rushing through small Apertures. 485
principal spiral; and had there been no cooling effect due to
rushing through the stop-cock when it was nearly closed, would
have been more checked when the stop-cock was wide open
than when it was nearly closed, as the same number of strokes
of the pump must have sent considerably more air through the
apparatus in one case than in the other. A cooling effect on the
whole, due to the rushing through the nearly closed stop-cock,
is thus indicated, if not satisfactorily proved.
_ Other calorimetric experiments were made with the stop-cock
immersed in water in one glass jar, and the air from it, conducted
by a vulcanized india-rubber tube, to flow through a small spiral
of block-tin pipe immersed in a second glass jar of equal capacity ;
and it was found that the water in the jar round the stop-cock
was cooled, while that in the other, containing the exit spiral, was
heated, during the working of the pump, with the stop-cock
nearly closed, and a pressure of about three atmospheres in the
principal spiral. The explanation of this curious result is clearly,
that the water round the stop-cock supplied a little heat to the
air in the first part of the rapids, where it has been cooled by
expansion and has not yet received all the heat of the friction,
and that the heat so obtained, along with the heat produced by
friction throughout the rapids, raises the temperature of the air a
little above what it would have had if no heat had been gained
from without ; so that about the end of the rapids the air has a
temperature a little above that of the surrounding water, and is
led, under the protection of the india-rubber tube, to the exit
spiral with a slightly elevated temperature. This is what would
necessarily happen in any case of an arrangement such as that
described, if Mayer’s hypothesis were strictly true ; but then the
quantity of heat emitted to the water in the second glass jar, from
the air in passing through the exit spiral, would be exactly equal
to that taken by conduction through the stop-cock from the water
inthe first. In reality, according to the discrepancy from Mayer’s
hypothesis, which the other experiments described in this com-
munication appear to establish, there must have been somewhat
more heat taken in by conduction through the stop-cock than
was emitted by it in flowing through the exit spiral; but the
experiments were not of sufficient accuracy, and were affected by
too many disturbing circumstances, to allow this difference to be
tested.
To obtain a decisive test of the discrepancy from Mayer’s
hypothesis, indicated by the experiments which have been
described, and to obtain either comparative or absolute determi-
nations of its amount for different temperatures, some alterations
in the apparatus, especially with regard to the narrow passage
«
486 Mr. J.P. Joule and Prof. Thomson on the Thermal Effects
and the thermometer for the temperature of the air flowing from
it, were found to be necessary by Mr. Joule, who continued the
research alone, and made the experiments described in what
follows.
A piece of brass piping,
a (see the accompanying
sketch drawn half the
actual size), was soldered
to the termination of the
leaden spiral,and a bit of
ealf-skin leather, 5, ha-
ving been tightly bound
over its end, it was found
that the natural pores of
the leather were sufii-
cient to allow of a uni-
form and conveniently
rapid flow of air from
the receiver. By pro-
tectg the end over
which the. leather dia-
phragm was bound with
a piece of vulcanized
india-rubber tube c, the
former could be im-
mersed to the depth of
about two inches in the
bath of water. A small
thermometer*, having a spherical bulb 4th of an inch in diameter,
was placed within the india-rubber tube, the bulb being allowed
to rest on the central part of the leather diaphragm +.
In making the experiments, the pump was worked at a uni-
form rate until the pressure of the air in the spiral and the tem-
perature of the thermometer had become sensibly constant. The
water of the bath was at the same time constantly stirred, and
by various devices kept as uniform as possible during each series
of experiments. The temperature of the stream of air having
been observed, the same thermometer was immediately plunged
into the bath to ascertain its temperature, the difference between
the two readings giving of course the cooling effect of the rush-
ing air,
* We had two of these thermometers, one of which had Fahrenheit’s,
the other an arbitrary scale.
+ The bulb was kept in this position for convenience sake, but it was
ascertained that the effects were not perceptibly diminished when it was
raised 4 of an inch above the diaphragm.
experienced by Air in rushing through small Apertures. 487
According to theory*, the cooling effect for a given tempera-
ture would be independent of the kind of aperture and of the
copiousness of the stream, and would be simply proportional to
the logarithm of the pressure, if the insulation of the current
against gain or loss of heat from the surrounding matter were
perfect, and if the thermometer be so placed in the issuing stream
as to be quite out of the rapids. On this account the values of
the cooling effect divided by the logarithm of the pressure were
calculated, and are shown in the last columns of the tables of
results given below. When this was done for the first two series
of experiments, the discrepancies (see columns 5 of the first two
of the tables given below) were found to be so great, and, espe-
cially among the results of the different experiments for the
higher temperature of 160° F., all made with the pressure and
other circumstances as nearly as possibly the same, so irregular,
that great uncertainty was felt as to the numerical results, which
must obviously have been much affected by purely accidental
circumstances. At the same time it was noticed, that in the case
of Series 1, in which the temperature of the bath was always as
nearly as possible that of the atmosphere, and different pressures
were used, the discrepancies showed a somewhat regular tendency
of the value of the cooling effect divided by the logarithm of the
pressure to increase with “the pressure; which was probably
owing to the circumstance that the stream was more copious,
and that less of the cooling effect was lost (as some probably was
in every case) by the conduction of heat from without, the higher
the pressure under which the air approached the narrow passage.
Hence in all the subsequent experiments the quantity of air
pumped through per second was noted.
The following Tables show the results obtained from ten series
of experiments conducted in the manner described :—
* See Account of Carnot’s Theory, Appendix II. Trans. Royal Soc.
Edinb. vol. xvi. p. 566; and Dynamical Theory, § 75, Trans. Royal Soc.
Edinb. vol. xx. pp. 296; or Phil. Mag. vol. iv. p.431. The numbers
shown in the table of § 51 of the former paper being used in the formula
of § 75 of the latter, and 1390 being used for J, we find (according to the
numerical data used formerly for deriving numerical results from the theory)
how much heat would have to be added to each pound of the issuing stream
of air to bring it back to the temperature it had when approaching the narrow
passage; and this number, divided by *24, the specific heat of air under
constant pressure, would be the depression of temperature (in Centigrade
degrees) actually experienced by the air when no heat is communicated to
it in or after the rapids.
488 Myr.J.P. Joule and Prof. Thomson on the Thermal Effects
Series 1.
Col. 1. Col. 2. Col. 3. Col. 4, Col. 5.*
sy : Cooling effect
Quantity of air a divided by
di ic| T t f | Pr f . :
Rehcpertcont| athe | instars C2MH95 feet, | ogni a
D
A. T P. D iccF
Not noted. 61 1-79 65 1-98
Not noted. 61 2-64 0-9 2°13
Not noted. 61 2:9 07 151
Not noted. 61 3°22 15 2:95
Not noted. 61 3:4 1-4 2°64
Not noted. 61 361 1-4 2°51
Not noted. 61 361 13 2°33
Not noted. 61 3°61 1:4 2°51
Not noted. 61 3°84 15 2°57
Not noted. 61 411 I 4 2:77
Mean...... Gh SiS ie. basi Aes. oaue 2:39
Series 2
Not noted. 160 2:64 0-264 0°62
Not noted. 160 2°64 0:396 0:94
Not noted. 160 2°64 0:66 1:56
Not noted. 160 PHT: eg 0:528 1:25
Not noted. 160 2°64 0°66 1:56
Mean...... 160 2-64 0:502 118
Series 3.
56 170°8 361 0:396 071
56 170'8 411 0-528 0:86
56 1708 4-}1 0:66 1:08
56 1708 4-11 0-726 1:18
56 170'8 4:26 0:66 1:05
8-4 170:8 4°78 0-858 1:26
8:4 1708 4:98 0-858 1:23
Mean 6:4 170'8 4:28 0-67 1:05
Series 4,
Patt Sebi ewe Lely sree by ier eae Oe Le eee: ait Sy
56 37°8 3-4 0:8 1:51
56 38:8 3-4 11 2:07
56 37:9 3-61 06 1-08
56 44:4 3:04 11 2:28
56 453 3:04 0-9 1:86
56 46:3 3:04 10 2:07
aecave ee AT eects
* The true value of — for any particular temperature would be the
depression of temperature that would be experienced by air approaching
the narrow passage at that temperature and under ten atmospheres of pres-
sure, smce P is measured in atmospheres, and the common logarithm is taken.
experienced by Air in rushing through small Apertures. 489
Table (continued).
Series 5.
Col. 1. Col. 2. Col, 3. Col. 4. Col, 5.
. : Cooling effect
Quantity of air divided b
d in cubic} T Pre f ai : cae
ae Pore a i A a of 3 Semoshn Saat Cooling effect. Pee, i
D
4 = e » log P.
8-4 46°8 3°84 1-2 2-06
8:4 38:7 411 1:8 2:93
8-4 39:3 4-11 18 2-93
Mean 8-4 AVGPAPEASD. SESE OA 2°64
Series 6.
11-2 39°7 4-4 ileyy 2°64
11:2 409 4-4 1-9 2:95
11-2 41-9 4-4 5 2°33
11.2 43 4-4 15 2:33
Mean 11:2 41°38 4:4 1°65 2-56
Series 7
1-4 64:1 1-9 03 1-08
1-4 64-2 1:87 0:45 1:65
1-4 64:0 19 0-4 1-43
1-4 64-2 1:9 0:5 1:79
1-4 64:3 19 0-45 161
Mean 1:4 64-16 1-894 0:42 151
Series 8.
2:8 64:2 2-41 0:5 131
2:8 64:3 2-41 05 1:31
2°8 64:5 2-41 0-5 131
2°8 64:7 2-41 07 1°83
28 64:7 2-4) 0-6 1:57
Mean 2°8 64:48 2-41 0:56 1-46
Series 9.
56 646 29 0:8 1-73
56 64:7 2-9 0:8 1-73
56 64:8 3°04 08 1-66
56 65°0 2:97 07 1:48
Mean 5°6 OTA Tie bplereaee ree itl lim esac: 165
Series 10.
11-2 65 411 12 1:95
11-2 65°1 4-11 13 2:12
11-2 65°1 411 1-4 2:28
Mean 11-2 65°06 411 l- 2°12
490 Mr. J. P.Joule and Prof. Thomson on the Thermal Effects
The numbers in the last column of any one of these tables
show, by their discrepancies, how much uncertainty there must
be in the results on account of purely accidental circumstances.
The following table is arranged, with double argument of tem-
perature and of quantity of air passing per second, to show a
comparison of the means of the different series (Series 3 being
divided into two, one consisting of the first five experiments, and
the other of the remaining two).
Table of Mean Values of — in different series of experiments.
o
Quantity of air passing per second.
14 | 28 | 56 | 84 | 12
ome
of bath.
Tem
The general increase of the numbers from left to right im this
table shows that very much of the cooling effect must be lost on
account of the insufficiency of the current of air. This loss
might possibly be diminished by improving the thermal insula-
tion of the current in and after the rapids; but it appears pro-
bable that it could be reduced sufficiently to admit of satisfactory
observations being made, only by using a much more copious
current of air than could be obtained with the apparatus hitherto
employed.
The decrease of the numbers from the upper to the lower
spaces, especially in the one complete vertical column (that under
the argument 5°6), shows that the cooling effect is less to a
remarkable degree for the higher than for the lower temperatures.
Even from 41° to 65° F. the diminution is most sensible; and
at 171° the cooling effect appears to be only about half as much
as at 41°.
The best results for the different temperatures are probably
those shown under the arguments 8°4 and 11:2, being those
obtained from the most copious currents ; but it is probable that
they all fall considerably short of the true values of for
D
log P
the actual temperatures ; and we may consider it as perfectly esta-
blished by the experiments described above, that there is a final
cooling effect produced by air rushing through a small aperture at any
temperature up to 170° F., and that the amount of this cooling effect
experienced by Air in rushing through small Apertures. 491
decreases as the temperature is augmented. Now according to the
theoretical views on this subject brought forward in the papers on
“ Carnot’s Theory,” and “ On the Dynamical Theory of Heat,”
already referred to, a cooling effect was expected for low tempe-
ratures; and the amount of this effect was expected to be the
less the higher the temperature ; expectations which have there-
fore been perfectly confirmed by experiment. But since the excess
of the heatof compression above the thermal equivalent of the work
was, in the theoretical investigation, found to diminish to zero*
as the temperature is raised to about 33° Cent., or 92° Fahr.,
and to be negative for all higher temperatures, a heating instead.
of a cooling effect would be found for such a temperature as
171° F., if the data regarding saturated steam used in obtaining
numerical results from the theory were correct. All of these
data except the density had been obtained from Regnault’s very
exact experimental determinations; and we may consequently
consider it as nearly certain, that the true values of the density
of saturated aqueous vapour differ considerably from those which
were assumed. Thus, if the error is to be accounted for by the
density alone, the fact of there being any cooling effect in the air
experiments at 171° Fahr. (77° Cent.) shows that the density of
saturated aqueous vapour at that temperature must be greater
than it was assumed to be in the ratio of somethmg more than
1416 to 1390, or must be more than 1°019 of what it was assumed
to be: and, since the experiments render it almost if not abso-
lutely certain, that even at 100° Cent. air rushing through a
small aperture would produce a final cooling effect, it is probable
that the density of steam at the ordinary boiling-point, instead
saan as it is generally supposed to be, must
d 1430°6
Be. something more than 1390
1645°
With a view to ascertain what effect would be produced in the
case of the air rushing violently against the thermometer-bulb,
the leather diaphragm was now perforated with a fine needle, and
the bulb placed on the orifice so as to cause the air to rush
between the Icather and the sides of the bulb, With this
arrangement the following results were obtained :—
of being about
of this; that is, must exceed
* See the table in § 51 of the Account of Carnot’s Theory, from which
it appears that the element tabulated would have the value 1390, or that
of the mechanical equivalent of the thermal unit, at about 33° Cent.
492 Myr. J. Cockle on the Method of Symmetric Products.
Series 11.
D
A is P D iogP
11-2 64 3-22 35 6-90
11-2 64 3:31 3:5 673
112 64 3°61 3:8 6:82
11-2 64 2:30 4-0 11-05
11-2 64 331 61 11-73
11-2 64 2-58 47 11-41
11-2 64 4°78 5:3 7°80
11-2 64 1-9 40 14-34
Mean 11:2 Ge Ae rete eer Se SO eae 9-60
The great irregularities in the last column of the above table
are owing to the difficulty of keeping the bulb of the thermo-
meter in exactly the same place over the orifice. The least varia-
tion would occasion an immediate and considerable change of
temperature ; and when the bulb was removed to only + of an
inch above the orifice, the cooling effects were reduced to the
amount observed when the natural pores alone of the leather
were employed. There can be no doubt but that the reason
why the cooling effects experienced by the thermometer-bulb
were greater in these experiments than in the former is, that in
these it was exposed to the current of air in localities in which
a sensible portion of the mechanical effect of the work done by
the expansion had not been converted into heat by friction, but
still existed in the form of vis viva of fluid motion. Hence this
series of experiments confirms the theoretical anticipations for-
merly published* regarding the condition of the air in the rapids
caused by flowing through a small aperture.
LXXVII. On the Method of Symmetric Products. By Jamzs
Cocxiz, M.A., of Trinity College, Cambridge ; Barrister-at-
Law of the Middle Templet.
as “ivesa conclusions of Abel and Sir W. R. Hamilton respect-
ing the impossibility of solving equations of the fifth
degree are rendered doubtful by recent mvestigations of Mr. G.
B. Jerrard. New fields of research thus seem to open upon us,
My present object is to point out the general scope of the method
of symmetric products, and to offer some remarks which ma
assist in the inquiry as to how far that method is calculated to
throw light upon the theory of equations of the higher degrees.
* See Dynamical Theory, § 77. Trans. Royal Soc. Edinb. vol. xx. p. 296;
or Phil. Mag. Dec. 1852.
+ Communicated by the Author.
Mr. J. Cockle on the Method of Symmetric Products. 498
2. Any x symbols v,, v, . , v» may be considered as the roots
of an equation of the form
UO" + 8,0"! + su? +. + §, 0.
Let V, be a linear and homogeneous function of these symbols
and of the form indicated by
V=% 44,0 +B 03+Y,04+- +61 +30,+
Also let the product of m such functions be denoted by 7,,(v,),
so that
T,,(0,)=V\VoVg+» Vm—1V,-
Then, if m=n—1 and n be not greater than 4, we may so deter-
mine #, @,...as to render the product 7,_,(v,) a symmetric
function of v. The case in which n=2 is scarcely an exception,
for we have
Dy —Ve= {(¥1 +2)? —4eyr0}4,
and the anomalous function corresponding to the symmetric pro-
duct is, in a manner, symmetric. I shall denote this last func-
tion by P’.
3. The m factors constituting a product may be regarded as
the roots of
Vt VV t+ ty, 0.
If when the products are symmetric we make
Ta(Us)=P., m3(v4) =P,
the values of V which constitute the above two symmetric pro-
ducts are derived from the respective equations
V?—(3v, +5,)V+P,=0;
V8 — (40, + 8,) V? + (80,? + 48,0, — 3,2 +48,)V —P,=0 ;
in both of which cases
=n, +5),
and ¢, and ¢, are functions in which 2, is the only symbol that
occurs unsymmetrically.
4. Let the result of the elimination of x, between
2" + px"! + pou" +... +p,=0,
be represented by
PNY + Gey 2 + «+ 19,0
Then, when 1 is either 3 or 4, f is so constructed as to make
T,-1(Y,) or P,, vanish. We are thus conducted to solutions of
cubic and biquadratic equations. It is a sign of the generality
and
494 Mr. J. Cockle on the Method of Symmetric Products.
of the method of symmetric products that if we make
y=flv)=(a+2)",
we arrive at the solution of a cubic which I gave at pp. 248, 249
of vol. i. of the Cambridge Mathematical Journal. A sketch
of the process by which this solution is shown to fall under the
method will be found at pp. 228, 229 of the 52nd volume of
the Mechanics’ Magazine. Ina note to my paper on the Method
of Vanishing Groups published in the Cambridge and Dublin
Mathematical Journal for May last, I developed the application
of the method of symmetric products to the solution of a biqua-
dratic. As my purpose is not to repeat but to endeavour to
extend former results, I shall content myself with referring to
the latter paper.
5. There is a species of symmetric function which I have called
‘ critical,’ and considered in this Journal (8. 3. vol. xxviii. p. 191),
and with great detail in the third and concluding volume of the
Mathematician. Their characteristic property, and one that has
an important bearing on the theory of equations, is that if to
each of the quantities (y,, Yo)-,%n for example) symmetrically
involved there be added the same quantity (b), the transformed
function (of y, +, y.+0,...) is free from b, and does not differ
in value from the original one. Let us represent a certain
normal form of homogeneous critical function by ¢,,(y,,), where,
as above, m is the degree and n the order of the function ; and let
[P'o(yo)=C], do(ys)=Cor 3(y4)=Co,
and in general
Prn—- 1 (y,,) == C,.
Then, if c’, c, and ¢c, be certain determinable constant multipliers,
and, as in the preceding article, y be supposed to replace vin P,
the following relations hold,
[P'=c(C)*], P,=e,C,, P,=c,Cs.
6. When 2 is greater than 4, can we obtain the analogous
relation
P.=e,0e2
Or, if not, and we have
Tn—1(Yn) = CgiCys; Se Bigs, o Psy eras (a)
what are the value and properties of R,_,? Or, can we attain any
available results by taking a value of m greater or less thann—1 ?
If R,,_, vanishes, the answer to the second of these questions
will give an affirmative reply to the first. And, under any cir-
cumstances, there are considerations which seem to render such
an assumption as (a) a desirable one.
7. Any proposed extension of the method of symmetric pro-
-
Mr. J. Cockle on the Method of Symmetric Products. 495
ducts to the higher prime equations will find a type in its applica-
tion to those of the fifth degree ; and the questions incidentally
suggested in the latter case will equally arise, perhaps in a more
general form, in the discussion of equations of the higher degrees.
When the degree is composite, simplifications of the processes
will probably be obtainable. But I shall here confine myself to
quintic equations, in the theory of which the following questions
now present themselves: (1) Is there a symmetric product ? and
(2), if not, does our search after one suggest an unsymmetric func-
tion with any peculiar properties?
8. Retainmg the assumption m=n—1, and continuing to
replace v by y, let
T4(Ys) =CqCy+ Ry=P,+ Uy,
where P, is symmetric and U, evanescent or unsymmetric, and
it remains to be seen whether R, is equal to Uy.
9. It is first to be remarked, that f(z) may always be deter-
mined so as to reduce the equation in y to the form
Y+qsy?+9s=0. . . » » « « 6B)
And when this relation subsists P, becomes equal to zero.
Hence, if a symmetric product exist, there will be no difficulty
in making it vanish. If not, we may always assume that
T4(Ys) = Uy.
For effecting the transformation (4) we may avail ourselves of
Mr. Jerrard’s process, or of the more convenient one which I
have given for the purpose (Phil. Mag. S. 3. vol. xxxii. pp.50,51),
and in which the solution of $(2, y, z)=0 is supposed to be
effected by the Method of Vanishing Groups.
10. The quantity P, may be expressed by
=P t+E® .yPyot FS. y? y+ GE. yPyoygt HE - Ny yoyss 3
and, guided by the analogy afforded by the application of the
method to biquadratics, I shall first proceed to inquire whether
m4(y;) can be made to take the above form. If not, our object
must be to reduce the unsymmetric part U, within the narrowest
possible limits. Whether the process which follows be the most
advantageous for our purpose may be a subject of future and
formal inquiry. But its strong primd facie claims warrant its
adoption here.
11. As well to fix our ideas as to facilitate our operations, let
us write
Yi=N+4,YotBiyst+Nyat O45,
Yo=y1 + 4Yot Boys + Vea t OoYss
Y3=91 + 43a + Bsa +Ys¥at S545,
Yg=Yi + 44Yo+ ByYat Vast S445
a(Ys) =, YoVs¥q.
496 Mr. J. Cockle on the Method of Symmetric Products.
12. The conditions requisite for the symmetry of the terms
in 7 are
1 Say 4%304= 8 BB 384= 1 VaVs¥a=5,90539s-
13. The conditions derived from the terms in y,°y, and y,7,° are
BS > .a=> i Pmes Yo Oe \
B . MH tgts=Z . Bi BoR3== . WYaV3== - 919095
14, Those derived from the terms in 7,°7,” are
F=> .a,2,.=2 .8,8:=2 . Wye - 6,0.
15. Hence, each of the four expressions
(2415 95 ay 4), (Biy Bay By, Ba), (Yas Yer Yr Ya)» (B13 S95 855 84)
involves the four roots of the equation
“A—H24F2?—Ez+1=0.... . (¢)
in some (hypothetically) determinable but as yet undetermined
order. That order must of course be excluded which renders
the values of Y equal, for in such case we should be led to the
relation
T4(Ys)=N'>
a nugatory result,
16. The equation (c) is recurring, and its roots are of the
forms A, A-!, w, w!. We are, consequently, at liberty to start
with the assumptions
@=A, G=A', ag=p, a,=p
And here for the present at least I leave the discussion, with the
remark that if no evanescent form of U, be discoverable, that func-
tion may possibly be found to possess the properties of a modulus
of the given equation. A theory of conjugate equations may hence
arise. If Abel’s argument be undisputed, it is hard to conceive
that the theory of equations should not admit of an extension
analogous to that which he himself gave to the theory of elliptic
integrals. If its validity be denied, we may pursue our present
course with more sanguine anticipation. The consequences of
supposing that U,, is equal to zero will be a subject for after
inquiry.
2 Pump Court, Temple,
November 1, 1852.
Postscript. 1 shall perhaps be forgiven for adding, that in the
Philosophical Magazine for June 1843 (S. 3. vol. xxii. pp. 502,
503), I gave a solution of an imperfect cubic which is free from
at least one defect under which that of Cardan labours,—the
arbitrary character of the operation by which the indeterminate
result of substitution is broken up into two separate equations.
I have also there obtained roots in an unobjectionable form. The
process is one of great simplicity.
ce |
[ 497 ]
LXXVIII. Note on the Heat of Chemical Combination.
By Dr. ANDREWws*.
N the last Number of this Journal, I observe that Dr.Woods,
referring to some observations of mine at the late meeting
of the British Association in this place, states that I had pre-
viously conjectured one of the fundamental truths suggested by
his theory, viz. “that decomposition produces as much cold
as the combination of the elements produced heat,” and after-
wards claims “by right of prior publication” the proof of this
law. Dr. Woods’s first paper on this subject appeared in the
Philosophical Magazine for October 1851. Now in a paper of
mine on the Thermal Changes accompanying Basic Substitutions,
which was published in the Philosophical Transactions for 1844,
and for which the Council of the Royal Society awarded one of
the Royal Medals, the following passage occurs (p. 32) :—
“Tn the preceding observations it has been assumed, that 2f
the union of two substances be attended with the evolution of a cer-
tain definite quantity of heat, their separation will be attended with
the absorption of the same quantity of heat. Although this pro-
position in the abstract is very probable, it requires to be demon-
strated by direct experiment ; and it is the more important to
do so, as it will furnish, if true, a means of verifying the accu-
racy of our results. The reactions now described enable us to
test it by experiment in one particular set of cases. In fact, if
we take three bases, such as potash, oxide of copper, and water,
capable of displacing one another in the above order, and if we
measure the changes of temperature produced when the first and
second, first and third, and second and third bases displace one
another, then the change of temperature arising from the first
substitution should be equal to the difference between the changes
of temperature produced by the two latter. A few examples will
illustrate this point.”
In a subsequent paper, which appeared in the Numbers of this
Journal for May and June 1848, I revert to the same subject.
After comparing the quantity of heat produced by the precipita-
tion of metallic copper by zine with the quantities produced by
the combination of those metals with oxygen, and with that due
to the substitution of oxide of zine for oxide of copper, I proceed
to remark “that this comparison assumes the truth of the prin-
ciple (which I have in other inquiries endeavoured to illustrate,
and is indeed almost self-evident), that when, in the course of
any chemical reaction, the constituents of a compound are sepa-
rated from one another, there is a quantity of heat thereby
* Communicated by the Author.
Phil. Mag. 8. 4. No, 28. Suppl. Vol. 4. 2K
498 Mr. Grove on the Electro-chemical Polarity of Gases.
absorbed equal to that which would have been evolved if the same
substances had entered into combination.”
_ It would, I conceive, be impossible to express a physical law
in language more precise, or having less of the character of con-
jecture. I have not considered it necessary to extend this Note
by quoting the experimental proofs, which will be found partly
in the papers from which I have made these extracts, and partly
in my other publications on the Heat of Combination.
Queen’s College, Belfast,
November 12, 1852.
LXXIX. On the Electro-chemical Polarity of Gases.
By W. R. Grovs, Esq., M.A., F.RS.*
[With a Plate.]
hve different effect of electricity upon gases and liquids has
long been a subject of interest to physical inquirers. There
are, as far as I am aware, no experiments which show any ana-
logy in the electrization of gases to those effects now commonly
comprehended under the term electrolysis. Whether gases at all
conduct electricity, properly speaking, or whether its transmis-
sion is not always by the disruptive discharge, the discharge by
convection, or something closely analogous, is perhaps a doubtful
question ; but I feel strongly convinced that gases do not con-
duct m any similar manner to metals or electrolytes.
In a paper published in the year 1849+, I have shown that
hydrogen or atmospheric air intensely heated, showed no sign
of conduction for voltaic electricity even when a battery of very
high intensity was employed.
In the Eleventh, Twelfth, and Thirteenth Series of Faraday’s
Experimental Researches, the line of demarcation between induc-
tion across a dielectric and electrolytic discharge is repeatedly
adverted to; induction is regarded as an action of contiguous
particles, and as a state of polarization anterior to discharge,
whether disruptive, as in the case of dielectrics, or electrolytic,
as in electrolytes. See §§ 1164—1298—1345—1368, &e.
Mr. Gassiot, in a paper published in the year 1844, has
shown that the static effects, or effects of tension, produced by
a voltaic battery, are im some direct ratio with the chemical
energies of the substances of which the battery is composed ; in
other words, that in a voltaic series, whatever increases the de-
composing power of the battery when the terminals are united
by an electrolyte, also increases the effects of tension produced
by it, when its terminals are separated by a dielectric.
* From the Philosophical Transactions for 1852, part i.; having been
received by the Royal Society January 7, and read April 1, 1852.
+ Philosophical Transactions, 1849, p. 55, { Ibid. 1844, p. 39.
Mr. Grove on the Electro-chemical Polarity of Gases. 499
In none of the above papers, and in no researches on electri-
city of which I am aware, is there any experimental evidence
that the polarization of the dielectric is or may be chemical in
its nature, that, assuming a dielectric to consist of two substances
having antagonist chemical relations, as for instance, oxygen and
hydrogen, the particles of the oxygen would be determined in
one direction, and those of the hydrogen in the other; the only
experimental result bearing on this point with which I am ac-
quainted, is the curious fact which was observed by Mr. Gassiot
and some other electricians who experimented with him in the
year 1838, viz. that when two wires forming the terminals of a
powerful battery were placed across each other, and the voltaic
are taken between them, the extremity of the wire proceeding
from the positive end of the battery was rendered incandescent,
while the negative wire remained comparatively cool; it was at.
that time believed that there was some effect exhibited here extra
the voltaic circuit. Shortly afterwards I showed that with all,
or at all events a great number of metals, the positive terminal
was more heated than the negative, and that the portion of the
crossed wire which was positive became more incandescent than
that of the negative, from the greater heating effect developed at
the positive point when the disruptive discharge took place. I
suggested as an explanation of this phenomenon, the possibility
that in air, as in water, or other electrolyte, the oxygen or elec-
tro-negative element was determined to the positive terminal,
and that from the union of the metal with that oxygen a greater
heating effect was developed. This, with some other impres-
sions, | mentioned in a letter to my friend Dr. Schénbein, not
intended for publication, but which shortly afterwards found its
way into print*,
Though by no means thinking that this explanation was in
every respect satisfactory, there were many arguments in its
favour; and the fact strongly impressed my mind as evincing a
very striking difference in character between the effect of the
discharge at the positive and negative terminals, and as present-
ing, as far as it went, a distant analogy to the effect of elec-
trolysis.
In the year 1848, while experimenting with Mr. Gassiot with
a nitric acid battery consisting of 500 well insulated cells, I made
the following experiment :—Two wires of platinum ;);th of an
inch in diameter, forming the terminals of the battery, were
immersed in distilled water; the negative wire was then gra-
dually withdrawn until it reached a point a quarter of an inch
distant from the surface of the water. A cone of blue flame was
now perceptible, the water forming its base, and the point of the
* Philosophical Manin men vol, xvi, p. 478.
500 Mr. Grove on the Electro-chemical Polarity of Gases.
wire its apex; the wire rapidly fused, and became so brilliant
that the cone of flame could be no longer perceived, and the
globule of fused platinum was apparently suspended in air and
hanging from the wire; it appeared sustained by a repulsive
action, like a cork ball on a jet d’eau, and threw out scintilla-
tions in a direction away from the water. The surface of the
water at the base of the cone was depressed, and divided into
little concave cups, which were in a continual agitation. When
the conditions were reversed and the negative wire immersed,
the positive wire being at the surface, similar pheenomena ensued,
but not nearly in so marked a manner; the cone was smaller,
and its base much more narrow in proportion to its height.
This experiment, the beautiful effect of which requires to be
seen to be appreciated, indicates a new mode of transmission of
electricity partaking of the electrolytic and disruptive discharges.
Not possessing a battery of this enormous intensity, I have not
been able to examine this phenomenon more in detail; but I
have from time to time made many other experiments on the
voltaic are taken in various gaseous media, with the view of
ascertaining the state of the intervening media anterior to,
during, and after the discharge ; these experiments have hitherto
given me no results of any value. In the voltaic are, the intense
heat developed so affects the terminals and so masks the proper
electrical effect, that the difficulty of isolating the latter is ex-
treme; and I haye latterly sought for some modified form of
electric discharge which should be intermediate between the vol-
taic are and the ordinary Franklinic discharge, or that from the
prime conductor of a frictional machine ; for something, in short,
which should yield greater quantitative effects than the electrical
machine, but not dissipate the terminals, as is done by the vol-
taic arc.
An apparatus, to which M. Despretz was kind enough to eall
my attention recently at Paris, seemed to promise me some aid
in this respect. It was constructed by M. Ruhmkorff, on the
ordinary plan for producing an induced current, viz. a coil of
stout wire round a soft iron core, with a secondary coil of fine
wire exterior to it, having an ingenious self-working contact
breaker attached ; from the attention paid to insulation im the
construction of this apparatus, very exalted effects of mduction
could be procured. Thus in air rarefied by the air-pump, an
aurora or discharge of 5 or 6 inches long could be obtained from
the secondary coil, and in air of ordinary density a spark of one-
eighth of an inch long.
I procured one of these apparatus from M. Ruhmkorff; the
size of the coil portion of the apparatus is 6°5 inches long, 4
inches diameter; the length of the wires forming the coils are
Mr. Grove on the Electro-chemical Polarity of Gases. 501
(I give M. Ruhmkorff’s measurements) stout wire, 30 metres
long, 2 millimetres diameter, 200 convolutions ; fine wire, 2500
metres long, + millimetre diameter, 10,000 convolutions. These
measurements will only be taken as approximative, and indeed
the exact size is immaterial to the consideration of the experi-
ments which I am about to detail. I will not give my experi-
ments in the order in which I made them, as I should have to
describe many fruitless ones, but I will place first that which I
consider the most important and fundamental.
Ist. On the plate of a good air-pump was placed a silvered
copper plate, such as is ordinarily used for Daguerreotypes, the
polished silver surface being uppermost. A receiver, with a rod
passing through a collar of leathers, was used, and to the lower
extremity of this rod was affixed a steel needle, which could thus
be brought to any required distance from the silver surface; a
vessel contaiming potassa fusa was suspended in the receiver, and
a bladder of hydrogen gas was attached to a stopcock, another
orifice enabling me to pass atmospheric air into the receiver in
such quantities as might be required*. A vacuum being made,
hydrogen gas and air were allowed to enter the receiver in very
small quantities, so as to form an attenuated atmosphere of the
mixed gas: there was no barometer attached to my air-pump,
but from separate experiments I found the most efficient extent
of rarefaction for my purpose was that indicated by a barometric
height of from half to three-quarters of an inch of mercury ; and
except where otherwise stated, a similarly attenuated medium
was employed for all the following experiments.
Two small cells of the nitric acid battery, each plate exposing
4. square inches of surface, were used to excite the coil machine,
and the discharge from the secondary coil was taken between
the steel point and the silver plate. The distance between these
was generally =0°1 of an inch, but this may be considerably
varied. When the plate formed the positive terminal, a dark
circular stain of oxide rapidly formed on the silver, presenting
in succession yellow, orange and blue tints, very similar to the
successive tints given by iodizing in the ordinary manner a
Daguerreotype plate. Upon the poles being reversed and the
plate made negative, this spot was entirely removed, and the plate
became perfectly clean, leaving, however, a dark, polished spot
occasioned by molecular disintegration, and therefore distinguish-
able from the remainder of the plate.
The experiment was repeated a great many times, and with
varying proportions of gas, and I found that with proportions
varying from equal volumes of hydrogen and air to those of one
volume of the former to two and a half of the latter, the experi-
* See a figure and description of the apparatus at the end of this paper.
502 Mr. Grove on the Electro-chemical Polarity of Gases.
ments succeeded ; better, I should say, when there was rather
an excess of hydrogen as compared with the equivalent of oxygen
in the atmospheric air; about one volume of hydrogen to one
and a half of air succeeded well; when excess of air was present,
oxidation took place whether the plate was positive or negative,
and when excess of hydrogen was present no oxidation took place.
2nd. I experimented with an air vacuum (to borrow an ex-
pression of Dr. Faraday), and found that omdation took place
whether the plates were positive or negative, but in different de-
grees; when the plate was positive, a small circular spot was
rapidly formed, quickly deepening in colour, and apparently
eating into the plate; when the plate was negative, a large dif-
fuse spot was formed, the oxidation was more slow, and the plate
not so rapidly corroded.
3rd. I now operated with a hydrogen vacuum ; when the plate
was clean no discoloration took place, the plate retained its polish,
though after a long continuance of the discharge a molecular
change was perceptible, producing a frosted appearance similar
to the mercurialized portions of a Daguerreotype.
When the plate had been previously oxidated by the discharge
in an air vacuum, the oxidation was rapidly and beautifully
cleared off by the discharge in the hydrogen vacuum, and this
whether the plate was positive or negative, the effect being, how-
ever, better and more rapidly produced in the latter case.
4th. I substituted respectively for the steel needle, wires of
copper, silver and platinum, and found the effect produced by all
and with nearly equal facility ; if there were any difference, the
platinum point was the least efficient; this may be due to the
peculiar effect of platinum in itself combining the gases, or to
its imoxidable character, the oxygen being thrown off from its
surface, and not uniting with it as with the more oxidable metals ;
the flame or luminous appearance which surrounded the wire
when the platinum was negative, was larger and more diffuse
than with the other metals,
5th. As air, notwithstanding its containing a great excess of
nitrogen, gave an effect of oxidation at both electrodes, though
different in degree, I increased the proportion of nitrogen by
passing into the receiver nitrogen which had been formed by the
slow combustion of phosphorus, the phosphorous acid having
been well washed away, and potash being always in the receiver ;
no more air was allowed to be present than the very small quan-
tity contained in the apertures of the stopcock; with this mix-
ture, Viz, a maximum of nitrogen and a minimum of oxygen,
and rarefied as before, a similar effect was produced to that shown
in the mixture of air and hydrogen, the positive plate being oxi-
dated by the discharge, and the spot when made negative being
Mr. Grove on the Electro-chemical Polarity of Gases. 503
reduced. The effect of reduction was not so rapid or so readily
produced as when hydrogen was used, but was very decided.
6th. With nitrogen, as much deprived of oxygen as I could
procure, the colours of oxidation were not exhibited, but a dark
spot apparently due to disintegration was produced, which was
not removed by the plate being made negative; if, however, the
coloured spot was produced by the plate bemg made positive in
an air vacuum, they were removed by the plate being made ne-
gative in a nitrogen vacuum, leaving, however, a darker spot
than that which was exhibited when they were reduced in hy-
drogen. Even when produced in an air vacuum, and then a
very perfect exhaustion effected, such as would reduce the mer-
cury in the barometer to the height of 4,th of an inch, the spot
was partially reduced when the plate was made negative.
7th. An oxyhydrogen vacuum was formed, the gases being in
the proportion in which they form water; and thanks to the
attenuated atmosphere, it was easy to take the discharge in this
mixture without producing detonation or any sudden combina-
tion of the gases, a possibility pointed out by Grotthus*. With
this mixture the effect took place as with the mixture of atmo-
spheric air and hydrogen. I expected it to have been more effi-
cient, but it was rather less so than the mixture of air and
hydrogen ; whether it be that the presence of nitrogen lessens
the tendency to combine of the gases oxygen and hydrogen, and
thus enables the electrical polarization and discharge to operate
more efficiently, whether .the nitrogen has a specific effect in
aiding the electro-chemical effect, as I have shown it has in one
peculiar caset, or whether any unknown effect of nitrogen is
concerned, I do not undertake to pronounce; I can only say
that, in several repetitions of the experiment, it appeared to me
that the mixture of atmospheric air and hydrogen was more
efficient in exhibiting this phenomenon than that of oxygen and
hydrogen.
8th. Different proportions of oxygen and hydrogen were em-
ployed, and here also I found that within a tolerably wide margin
I could vary the proportion of the gases; three volumes of hy-
drogen to one volume of oxygen I found to be a very efficient
mixture.
9th. I now substituted for the silver plate, plates of the fol-
lowing metals :—bismuth, lead, tin, zine, copper, iron and pla-
tinum, the former three metals being burnished, the latter
polished,
Bismuth showed the effect nearly, if not quite as well as silver ;
it was oxidated in an air vacuum, reduced in a hydrogen vacuum,
and oxidated or reduced in the mixed gas according as it formed
the positive or negative terminal.
* Annales de Chimie, vol. \xxxii. + Phil. Trans. 1843, pp. 110, 111.
504 Mr. Grove on the Electro-chemical Polarity of Gases.
Lead oxidated easily, but the spot of oxide could with difficulty
be reduced. Tin, zinc, and copper required the admission of a
great quantity of air to produce oxidation ; and I could not suc-
ceed in reducing the oxide by the electrical discharge, at least so
as to restore the polish of the plate; a blackening effect was mm
some degree produced. Iron was not oxidated until the receiver
was nearly filled with air, and then a small spot of rust was
formed which I could not reduce. With all the metals a slight
whitish film like the mercurialized portion of a Daguerreotype
was visible beyond the circle marked by the discharge when the
plate was rendered positive, which film was removed by negative
electrization in a hydrogen vacuum; it seemed to me that this
film, as well as others among those I have described, was affected
by light, but I did not turn aside to examine this effect. Pla-
tinum showed no effect either of oxidation or reduction.
10th. As it was impossible to operate with an atmosphere of
chlorine with the apparatus which I possessed, and wishing to
vary the electro-negative element, I iodized a silver plate by the
vapour of iodine to a deep blue colour, and then made it nega-
tive in an atmosphere of hydrogen; the iodine was beautifully
removed in a circle or dise opposite the pot which formed the
positive terminal.
11th. I now substituted for the coil apparatus a very good
electrical machine, the cylinder of which was 16 inches diameter,
and the prime conductor of which, when the machine was pro-
perly excited, gave a spark of 8 incheslong. With this machine,
and in an attenuated atmosphere of one volume hydrogen: plus
two of atmospheric air, I produced the effects of oxidation
and reduction very distinctly, the plate being in turn connected
with the conductor and with the ground; but the comparative
minuteness of the spot after many turns of the machine, showed
the great superiority of the coil machine for producing quanti-
tative effects over the ordinary electrical machine ; and I question
whether I should have detected the phenomenon with the latter,
had I not become previously well acquainted with it by the former
apparatus. Probably an extensive series of the water battery or
a steam hydro-electric machine would succeed equally well, or
better than the coil machine.
12th. A solution of hyposulphite of soda removed the spots
formed by electrization irom the silver plate just as 1t removes
the iodine from an iodized plate.
13th. In some of the above experiments I remarked a ten-
dency in the spots produced by the discharge, to show circles or
zones of oxidation in different degrees, and in a more markea
manner than would be accounted for by the different colours of
the thin films of oxide formed. I determined to examine this
effect, and selected, after some experiments, an atmosphere of
Mr. Grove on the Electro-chemical Polarity of Gases. 505
one volume oxygen mixed with four volumes of hydrogen, and
attenuated by the air-pump as in the previous experiments.
The plate was made positive, and the point was placed success-
ively opposite different portions of the silver plate, at distances
of 5th, # ths, 3,ths, “ths, and sthsof aninch. The results
are given, as nearly as I can copy them, in the accompanying
Plate V. figs. 1 to 5.
The colour of the central spot was a yellow-green in the centre,
surrounded by a blue-green, then a clear ring of polished silver,
then an outer ring crimson, with a slightly orange tint on the imer
side, and deep purple on the outer ; the exterior portion of the spot
was, as far as my eye could judge, of a colour complementary to the
interior of the external ring, and the central portion of the spot of
a colour complementary to the exterior portion of the rng. The
colours varied with the time, density of gas and other conditions,
but generally showed this complementary tendency. Symptoms
of a faint polished ring were visible beyond the outer ring, and
could be rendered more distinct by breathing on the plate. As
the distance between the point and the plate was increased, the
colours became fainter, and the rings more diffuse, and beyond
the distance I have given nearly lost their defined character ;
but the first three distances, or those of soth, soths, and 3ths
of an inch, gave very beautifully defined rigs. The lumi-
nous appearance on the needle in these experiments extended
from three-fourths of an inch to an inch from the point. Fre-
quently a small polished speck was visible, exactly opposite the
point of the needle. Sce fig. 6. When the plate was made ne-
gative, the other conditions being the same, a polished space
appeared opposite the point of the needle, surrounded by a dusky
and ill-defined areola; its colour, when regarded from a point
opposite the incident light, was brown tinged with purple; and
when in the same direction as the light, a greenish white, similar
to the tint seen on mildew or on some of the lichens: these spots
were very different from the positive spots, and in some degree
the converse of them; but they were not nearly so well defined
or capable of being produced with the same uniformity. I have
endeavoured to represent one of them at fig. 7.
14th. In order to ascertain whether the polished ring inter-
vening between the oxidated central spot and oxidated external
ring were a mere negation of effect or an antithetic polar effect,
such as would occasion reduction, I formed in an air vacuum
two large spots on a silver plate, with one the plate being made
negative, and with the other positive, oxidating them until they
began to pass from deep orange to purple. I then perfectly
exhausted the receiver, swept it with the gas employed in the last
experiment, and then took the discharge in a vacuum of that
506 Mr. Grove on the Electro-chemical Polarity of Gases.
gas, viz. one volume oxygen + four hydrogen; the plate being
positive and the needle ths of an inch over the centre of each
spot in turn, a ring of clear polish was formed rapidly in both
the dark discs, just at the distance where the ring of polish
appeared in the last experiment. I then exposed a clean portion
of the plate to the needle without any other change, and on
allowing the discharges to pass, formed the rings just as im the
last experiment.
15th, I examined some of the spots with an achromatic micro-
scope, magnifying 200 diameters; I could not, however, discover
any feature which the naked eye did not show, or any peculiar
molecular state ; the polishing scratches on the plate were highly
magnified, but the electrized spots only showed more dimly the
colours or the lights and shadows which they exhibited to the
naked eye,
16th. I took the discharge on a silver plate in vacua of the fol-
lowing gases respectively :—Oxygen, protoxide of nitrogen, deut-
oxide of nitrogen, carbonic acid, carbonic oxide and olefiant gas.
The first four gases presented nothing remarkable; the plate
was oxidated whether positive or negative, as m a vacuum of
atmospheric air. In the protoxide of nitrogen the colour of the
discharge was a beautiful crimson on both terminals.
In deutoxide of nitrogen a greater tendency to reduction was
shown when the plate was negative than in the other three
gases, and there was also a tendency to the formation of rings.
In carbonic oxide the plate was oxidated when positive, and the
oxide reduced when negative, just as with a vacuum of air
and hydrogen, but rather more slowly; with a mixture of five
volumes of carbonic oxide and one volume of oxygen, the rings
were formed very distinctly, particularly if the plate was made
negative first, and then positive. The luminous spot on the plate,
when positive in this gas, was coloured green.
When the plate was negative in olefiant gas it darkened, show-
ing the rings of colour produced by thin plates, and very distinet
from the other rmgs of which I have spoken. After a short
time a pulverulent deposit was formed on the plate, giving bril-
liant sparks or stars of light which were not shown by any
other gas,
This deposit was too minute for analysis ; but I have no doubt,
from the gas used and the appearances presented, it was carbon.
I have given in the above experiments the conditions under
which they succeeded best ; but upon repetition, although the
exact volumes of gases and other conditions were carefully
attended to, they sometimes required a slight alteration to suc-
ceed, variations taking place from causes which I could not
detect ; thus it was sometimes necessary to add a little more
—s si
i i is i i te ee ee
Mr. Grove on the Electro-chemical Polarity of Gases. 507
hydrogen, sometimes a little more oxygen or air, to alter slightly
the state of attenuation in the gas, &e.
The necessarily varying condition of the battery, and the state
of the contact breaker, slight impurities in the gases or on the
surface of the plates would. be quite sufficient to account for these
irregularities. I mention them for the guidance of any one who
may wish to repeat the experiments; a very little practice will
enable any electrician to have the results at his command. When
there is too great a proportion of air or oxygen, oxidation takes
place at both poles ; when too much hydrogen, reduction takes
place at both; and to effect oxidation or reduction by reversing
the direction of the discharge, an intermediate condition is requi-
site; so if the gas be not sufficiently attenuated, the oxidation is
too rapid, and the plate too much corroded to bring out the
effects clearly ; if too much attenuated, too long a time is required,
and the effect is feeble and indistinct.
I have above selected all the experiments which I consider
material in this, I believe, new class of phenomena. The spots
produced by electrical discharges, both on conducting bodies and
on electrics, have been before noticed and experimented on; one
class by Priestley*, and another class by Karsten+ and others;
but as far as I am aware, no distinct electro-chemical action in
dry gases, depending upon the antithetic state of the terminals
and presenting a definite relation of the chemical to the electrical
actions in gaseous media, has been pointed out. I now proceed
to consider the relation which these results bear to other elec-
trical phenomena.
As may be gathered from my opening remarks, the experi-
ments above detailed appear to me to furnish a previously deficient
link in the chain of analogy connecting dielectric induction with
electrolysis. The only satisfactory rationale which I can present
to my own mind of these phenomena is the following, The
discharges being interrupted (as is evident from the nature of
the apparatus, and may be easily proved by agitating a mirror
near them and regarding their reflected images in the moving
mirror), the gaseous medium is polarized anterior to each dis-
charge, and polarized not merely physically, as is generally
admitted, but chemically, the oxygen or anion being determined
to the positive terminal or anode, and the hydrogen or cation
being determined to the negative terminal or cathode; at the
instant preceding discharge there would then be a molecule or
superficial layer of oxygen or of electro-negative molecules in con-
tact with the anode, and a similar layer of hydrogen or of electro-
positive molecules in contact with the cathode, in other words,
* History of Electricity, 2nd edition, p. 624.
+ Archives de l Electricité, vol. ii. p. 647 ; vol. iii, p. 310,
508 Mr. Grove on the Electro-chemical Polarity of Gases.
the electrodes in gas would be polarized as the electrodes in
liquid are. The discharge now takes place, by which the super-
ficial termini of metal or of oxide, as the case may be, are highly
ignited or brought ito a state of chemical exaltation at which
their affinities can act; the anode thus becomes oxidated, and
the cathode, if an oxide, reduced. I have elsewhere* shown
strong reasons for assuming that the electric or voltaic discharge,
the moment polarity is subverted, may be regarded as an in-
tensely heated state of the electrodes, and of the intermedium
across which it passes ; and my present explanation is perfectly
consistent with, and derivable from, my previous views of the
disruptive discharge.
Two other theories might be proposed to account for the phe-
nomena I am considering ; the one, that the disruptive discharge
itself is analogous to the electrolytic, and that the oxygen and
hydrogen are reciprocally transferred by the discharge itself;
this would not, I think, be consistent with the generally known
facts connected with the discharge, and is entirely ineffectual in
explainmg the Experiments 2 and 3, where either the posi-
tive or negative terminal can be made either to oxidate or reduce,
according to the nature of the chemical medium present, while
these experiments are entirely in accordance with, and the results
of them flow as a necessary consequence of, the view first ad-
vanced. The other theory which may be advanced is, that by
dielectric induction the gases may be bodily separated, a layer,
not molecular, but corporeal or voluminous, if I may be allowed
these expressions, of oxygen being developed on the side next
the anode, and one of hydrogen next the cathode, the gas imter-
vening between the terminals being thus divided, as it were, into
two halves: this would certainly be a most curious phenomenon,
but I believe it to be so inconsistent with the vast mass of accu-
mulated facts in electrical science, and likely to have produced
in cosmical phenomena so many results which, if existing, must
long ere this have been detected, that I will not do more than
advert to it.
I have adopted the views which I have first stated as being
the least removed from ordinary theories or modes of regarding
electrical phzenomena, and because in the present instance I can
present the phenomena in no other way which is in the least
degree satisfactory to my own mind, while this view to me well
accounts for them. Assuming then for the present this view,
we get a close approximation, I may say an identity of the state
of polarization m gaseous non-conducting dielectrics, and in
electrolytes anterior respectively to discharge or to electrolysis.
* Philosophical Transactions, 1847, pp. 10, 16,21. Correlation of Phy-
sical Forces, p. 50, 2nd edition.
Mr. Grove on the Electro-chemical Polarity of Gases. 509
Faraday observes, Experimental Researches, 1164, “In an
electrolyte induction is the first state, and decomposition the
second.” My present experiments show, I believe, that in induc-
tion across gaseous diclectrics there is a commencement, so to
speak, of decomposition, a polar arrangement not merely of the
molecules, irrespective of their chemical characters, but a che-
mical alternation of their forces, the electro-negative element
being determined or directed, though not travelling in one direc-
tion, and the electro-positive in the opposite direction.
This arrangement is only evidenced at present, as it is in
electrolysis, by the action at the polar extremities or termini of
the dielectric; possibly future researches may show, by the
action of polarized light, by magnetism or some other means of
analysis, that the polarity extends, as we theoretically believe it
does, through the whole intervening matter.
In the Experiment No. 5 with oxygen and excess of nitrogen,
reduction takes place by the effect of negative electricity and
heat, at least there seems every reason from analogy to believe
that the effect of the nitrogen is only negative, protecting the
plate from oxygen,'or at furthest catalytic, aiding the reduction
as sulphuric acid aids the electrolysis of water. Upon the state
of association of the gases in what is generally called mixture, I
venture an opmion with the greatest diffidence. I have always
inclined to the opinion that the difference between physical ad-
mixture, as it is termed, of gases and chemical union, is one of
degree, and the views of Dalton ever presented to my mind grave
difficulties*. My present results seem to me in favour of the
chemical view, as otherwise we can scarcely imagine electricity
as effecting in the instances given a merely physical separation ;
it may indeed be said that there is composition and decomposition
produced by the same discharge; but this is very difficult to
conceive, and can hardly apply to the cases of oxygen with
nitrogen and of carbonic oxide.
Tn the experiments I have detailed, the flame or visible effect
of the electric discharge coincided with the chemical effect ; when
the plate was positive, a small globule of flame of a purple colour
was visible on the part of the plate attacked, and a bluish flame
extended over an inch or more of the needle. When the plate
was negative, a wider and less-defined disc of blue flame extended
over the part of the plate opposed to the positive point, like a
splash of liquid thrown upon it, and a pencil of light appeared
on the point. Sometimes, but not always, this flame avoided
the oxidated portion, probably from its inferior conducting
power; and when this was the case, reduction took place in a
much slighter degree, or not at all; sometimes, and I observed
* Philosophical Transactions, 1843, p. 112.
510 Mr. Grove on the Electro-chemical Polarity of Gases.
this particularly with bismuth, the flame attached itself to the
oxidated portion, and then reduction immediately followed. Here,
as in all the electrical phenomena that I can call to mind, we
get the visible effects of electricity associated with physical
changes in the matter acting, changes of state in the terminals,
polarization of the intervening medium, or both*, These experi-
ments furnish additional arguments for the view which I have
long advocated, which regards electricity as force or motion, and
not as matter or a specific fludt.
The chemical polarity of gases shown, as I believe, in this
paper, associates itself with an experiment which I made known
in a lecture at the London Institution im the year 18431, and
which was subsequently verified by Mr. Gassiot § with more per-
fect apparatus than I possessed, viz. that when dises of zine and
copper are closely approximated, but not brought in contact,
and then suddenly separated, effects of electrical tension are ex-
hibited, the one dise making the electroscope diverge with posi-
tive, and the other with negative electricity, showing that the
effects ascribed by Volta to contact can be produced without con-
tact, and by mere approximation, the intermediate dielectric
being polarized, or a radiation analogous, if not identical, with
that which produces the images of Moser taking place from plate
to plate.
The present experiments also associate themselves with the
gas battery, where, though an electrolyte is used as the means
of making the action continuous, or producing what is called
current electricity, the initiating effect is gaseous polarity, the
films of gas m contact with the respective plates of platinum
having antithetic chemical and electrical states.
The results detailed in Experiment 13, appear to open a
new field of research. Priestley observed concentric circles pro-
duced by the electrical discharge from a powerful Leyden bat-
tery, which he describes as consisting of minute cavities and
globules of fused metal ||. In my experiments there is an alter-
nation of oxidation and reduction, a medium capable of producing
both being present ; the lateral effect and complementary colours
have to my mind something closely resembling the phenomena
of interference in light, although from the polar character of the
* Gases at present believed to be elementary, probably undergo a quasi
chemical polarization by electricity; thus portions of oxygen are changed
to ozone, &c. See a recent paper by MM. Fremy and KE. Becquerel,
Comptes Rendus, Paris, March 15. [Phil. Mag. July 1852, p. 543. tNale
added to the Proof, W. R. G.
+ Printed Lecture at the London Institution, 1842, p. 28. Correlation
of Physical Forces, p. 48.
{ Literary Gazette, 1843, p. 39. § Phil. Mag., October 1844,
il History of Electricity, ‘2nd edition, p. 624,
Mr. Grove on the Electro-chemical Polarity of Gases. 511
force, it is difficult to imagine any precisely analogous condition
of electricity. The discharge taking place from different parts
of the needle and extending from its point to a considerable
distance over its surface, would give different lengths for the
lines of polarization and discharge to the different parts of the
dise on the silver plate affected by the discharge ; and assuming
electricity to be propagated by undulations, there would be inter-
ference ; but instead of alternations of light and darkness we
get alternations of positive and negative electricity. The ring
of polished metal between the central spot and the exterior ring,
quite distinguishes these rings from the ordinary colours of thin
plates, i. e. colours, the annular succession of which depends
only on the different thicknesses of the film ; here doubtless the
colours of the oxidated portions are colours of thin plates. Ex-
periment 14 shows clearly that the action by which the polished
ring is formed is a polar action of the discharge, and not a mere
absence of action.
When the plate is negative, the effect is, as I have observed,
less marked and more uncertain; but in this case it should be
recollected that the visible discharge issues from the point, and
does not extend, or extends to a very small degree, over the sur-
face of the needle.
If the phenomena were such that the central portion were
always clear, while around it was one, and one only circle of
oxide, it might be accounted for by the hypothesis, that the lines
of polarization and discharge between a point and flat surface
assume the form of a hollow cone ; but a cone of negative bounded
by cones of positive action, still gives the idea of some lateral
fits or phases of undulation.
The high rarefaction of the medium by the discharge, and its
intermitting character, might occasion pulsations by the inrush-
ing of the stirrounding gas, and thus vacua in circles might be
formed at the places where the action of oxidation is rendered
null; but this view is, I think, inadmissible; it does not account
for the effects obtaining only in certain mixtures, it does not
account for the reducing action, the plate being positive, and
presents other difficulties. The point involved in Experiments 13
and 14, though not perhaps the least valuable one given in this
paper, presents apparently a wide field of inquiry; I therefore
will not further dilate on it at present, and hope to make it the
subject of future investigation.
December 27, 1851.
Postscript, April 24th.
{ may, I trust, be permitted to add to this paper one or two
experiments on the subject last discussed. Assuming that the
512 Mr. Grove on the Electro-chemical Polarity of Gases.
alternations of oxidation and reduction were produced by inter-
ference in consequence of the discharge proceeding from suc-
cessive points of the terminal or terminals, a difference of effect
might be anticipated if the electricity passed from a point only,
and not from a line as was the casein Experiment 18. I there-
fore sealed a platinum wire ,jth of an inch in diameter into a
piece of glass tubing, and then ground the extremity to a flat
surface, so that the section only of the wire was exposed; this
wire was placed opposite, and at 0°07 of an inch distance from
the polished silver plate, in a mixture of one volume of oxygen
with five volumes of hydrogen attenuated until the barometer
stood at half an inch; discharges from the secondary coil were
then passed, the plate being positive, and a round dark spot of
oxide formed represented at fig. 8; the platinum sealed in glass
was then removed and the steel needle substituted for it, all else,
viz. plate, gas, barometer height, &c. being the same: the system
of rigs represented at fig. 9 was now produced.
Another experiment was made, directed to the same point: a
wire of copper 0:04 inch diameter, and a thread of glass of the
same diameter were attached by sealing-wax at their extremities
in a horizontal position 0°025 of an inch from different parts of
a silver plate, bemg insulated from the silver by the wax inter-
posed at the extremities. The gaseous mixture and barometric
height being the same as in the last experiment, and the silver
plate made positive, when the platinum wire sealed in glass was
brought near the plate, and the discharges passed, a spot similar
to fig. 8 was formed; but when the coated point of platinum
was brought over the copper wire at 0:02 inch distance, a figure
consisting of two separated semicircles was formed, having spots
in the bisection of the chords, as shown at fig. 10, the portion
between the spots and the semicircular line of oxide being of
polished silver. With the glass thread the effect was the same,
but produced with greater difficulty and not so well defined.
In many repetitions of these experiments which I have made,
I have invariably produced the alternately polished and oxidated
rings from the bare wire, and have not procured them from the
coated wire, except to a very slight degree, and under certain
circumstances, which, as far as I could trace, were as follows :—
1st. When the extremity of the wire was very near the plate,
so that it had a sensible magnitude with reference to the mter-
vening space, a slight formation of minute rmgs could be detected
at the commencement of the experiment.
2nd. When the experiment was long continued, or when the
coated platinum wire had been used for previous experiments, a
set of rmgs, not consisting of an alternation of oxidated and
Mr. Grove on the Electro-chemical Polarity of Gases. 513
polished rings, but of annuli of different degrees of oxidation,
were formed.
When the experiment is continued for some time, a dark
deposit is formed on the glass around the extremity of the pla-
tinum wire, giving an extended conducting surface ; and this
may be the reason why such rings are formed, though these
rings, in all the cases which I have observed, differ broadly from
the rings formed by the bare needle or wire, not having the inter-
posed spaces of perfectly bright silver; and in all the cases the
difference of effect produced by the coated and the bare wire is
very marked; in by far the greater number of experiments,
when proper precautions are taken, not the slightest formation
of rings takes place with the coated wire ; with the bare wire, in the
gaseous mixture last mentioned, I have always seen them formed.
Thus there are three systems of rings which may be formed
by the discharge. First, rings such as those seen in the ordinary
eases of thin plates; these I have only observed with olefiant
gas, though probably there are many other conditions in which
they may be produced. Secondly, rmgs formed. by the super-
position of layers of oxides, possibly arising from the fact that at
certain definite periods portions of the plate become by oxidation
inferior conductors, and other portions are attacked, and being
at a different distance undergo a different molecular change by
oxidation. Thirdly, and to me far the most interesting set of
phenomena are presented by the rings alternately bright and
oxidated, showing effects of oxidation and reduction by the same
current on the same plate, and which only take place in certain
gaseous mixtures, of which, up to this time, one volume oxygen
+ five volumes hydrogen is the most efficient which I have
obtained.
I cannot at present see any better mode of explaining these
phznomena than by regarding them as analogous to the pheeno-
mena of interference in light; though doubtless if this be a right
view, the very different modes of action of light and electricity
would present very numerous phenomenal distinctions. Alter-
nations of opposite polar electrical actions in the discharges pass-
ing in the same direction are, I think, very clearly shown in these
experiments, and this appears to me a result worthy of attention.
Though acquainted with Nobili’s beautiful experiments on the
formation of coloured rings by deposition in electrolyzed liquids,
yet as I was working on gases it did not occur to me to refer to
his memoirs*; I have done so since making the experiments
given in this postscript, and find that with regard to the rings
so formed by electrolysis, he suggests interference as a possible
explanation.
The dark space in the discharge to which Faraday has called
* Ann. de Ch. et de Phys. vol. xxxiv.
Phil, Mag. 8. 4, No, 28, Suppl. Vol, 4. 21L
514 Mr. Grove on the Electro-chemical Polarity of Gases.
attention, may possibly be connected with these phenomena. I
have observed, that in a well-exhausted receiver containing a
small piece of phosphorus, the discharge is throughout its course
striated by transverse non-lumimous bands, presenting a very
beautiful effect, and a yellow deposit, which, as far as I have
yet examined it seems to be allotropic phosphorus, is deposited
on the plate of the air-pump and on the neighbouring substances ;
to show this effect well the needle should be positive and the
plate negative, and the distance between them about an inch.
I could dilate much further on these experiments, but have
already trespassed perhaps too far for a postscript. Variations
in the form of the terminals, in the nature of the gas, vapour, or
gaseous mixture, in the density of the gas, in the intensity and
quantity of the discharge, in the nature of the-plate, &e., will
occur to those who may feel inclined to repeat these experi-
ments, and if | am not over-sanguine, promise results of much
interest.
Additional Note on the dark discharge, July 9, 1852.
I find the transverse dark bands can be produced in other gases when
very much attenuated, probably im all; and I rather think the reason why
they are more easily seen in the phosphorus vapour is, that all the oxygen
having been consumed a better vacuum is formed.
In addition to these bands, and under circumstances where they are barely
visible, there is always seen a well-defined dark space intervening between
the glow surrounding the negative, and the stream of light proceeding from
the positive terminal; it appears independently of the length of the dis-
charge, though a space of an inch is a convenient distance for exhibiting
the effect well.
This dark discharge is elaborately described by Faraday as produced by
the ordinary electrical machine, Experimental Researches, § 1544 et seq.
Having im my mind the analogy of interference, it seemed to me that this
dark space might be due to the crossing of the lines of discharge from the
successive points of the needle, the knob, or plate from which the negative
discharge-issues.
As the positive discharge appears to issue from a point, and not to sur-
round the wire, as does the negative, the position of the dark space in close
approximation to the negative terminal was in favour of this view; if cor-
rect, it should follow that if the terminals were coated points instead of
wires, knobs or plates, this dark space would not be observed, or its position
would be changed. Experiment verified this expectation ; when platmum
wires sealed in glass were employed and a good vacuum formed, the line of
luminous discharge was contmuous when the platinum poimts were brought
to a distance of half an inch.
When these terminals are so far separated as not to give a continuous
line of discharge, a pencil appears on each terminal, which gradually be-
comes fainter and fainter towards the middle of the intervening space ; and
if the distance be great, the discharge ceases to be luminous towards the
middle of the mtervening space, from excessive diffusion; but this will be
seen to be a very different effect from the abrupt and well-defined dark
space which appears in close approximation to the negative terminal when
the coated wires are not employed.
On a Theorem relating to the Products of Sums of Squares. 515
When the positive terminal is coated and the negative one bare, the dark
space appears on the point of the bare wire, the wire itself being surrounded
by a lambent flame; but with the converse arrangement there is no such
dark space. All this is much in favour of interference taking place, the
coincidence of positive and negative phases of the discharge producing at
certain poimts mutual neutralization.
Description of Plate.
PuatE V.
Figures 1 to 10 show the spots and rings in the order referred to: it
should be observed that printed figures give but a very imperfect
notion of the actual effects.
Fig. 11 is the coil apparatus, the contact breaker being in front.
Fig. 12. The air-pump, of a construction which I proposed many years ago,
and have found most useful for electrical or chemical experiments
on gases.
P. An inperforate piston, with a conical end, which, when pressed
down, fits accurately the end of the tube, the apex touching the
valve V, which opens outwards.
A. Aperture for the air to rush from the receiver when the piston
has been drawn beyond it.
B. Bladder containing the gas to be experimented on.
The piston-rod works air-tight in a collar of leathers, and the
operation of the pump will be easily understood without further
description.
If it be required to examine the gas after experiment, a bladder,
or tube leading,to a pneumatic trough, can be attached at the ex-
tremity over the valve V.
LXXX. Demonstration of a Theorem relating to the Products
of Sums of Squares. By Arvaur Cayiry*.
R. KIRKMAN, in his paper “On Pluquaternions and
Homoid Products of Sums of 2 Squares” (Phil. Mag.
S. 3. vol. xxxiil. p. 447), quotes from a note of mine the following
passage :—“ The complete test of the possibility of the product
of 2” squares by 2” squares reducing itself to a sum of 2” squares
is the following: forming the complete systems of triplets for
(2"—1) things, if eab, ecd, fac, fdb be any four of them, we
must have, paying attention to the signs alone,
(ead) (+t eed) = (+fuc)( + fab) ;
i. e. if the first two are of the same sign, the last two must be
so also, and vice versd; I believe that, for a system of seven,
two conditions of this kind being satisfied would imply the satis-
faction of all the others: it remains to be shown that the com-
plete system of conditions cannot be satisfied for fifteen things.”
I propose to explain the meaning of the theorem, and to establish
the truth of it, without in any way assuming the existence of
imaginary units.
* Communicated by the Author.
2L2
516 Mr. A. Cayley’s Demonstration of a Theorem
The identity to be established is
(w* + a?+6?+ ...)(w?+a?—b?..)
=u +aypt+bP+ ...
where the 2” quantities w, a,b,c... and the 2” quantities
W,, a, b, c,. +. ave given quantities in terms of which the 2” quan-
tities w,, a, 5), ¢, ... have to be determined.
Without attaching any meaning whatever to the symbols
a, b,, ¢,..+ I write down the expressions
w+aa,+bb,+ec,..., Waa, t+bb,+ee,..+5
and I multiply as if a,,b,,c,... really existed, taking care to
multiply without making any transposition im the order infer se
of two symbols a,b, combined in the way of multiplication.
This gives a quasi-product
ww, + (aw, + aww)a,+ (bw, +bw)b,+ ...
+aan,?+bbb?2+...
+abajb,+abb,a,+...
Suppose, now, that a quasi-equation, such as
a,b,¢,= +
means that in the expression of the quasi-product
GRC. en, MEAT Ve 2
are to be replaced by
for] a, Cop b, a,
fey) ay; —b pail)
and that a quasi-equation, such as a,6,c,=—, means that in the
expression of the quasi-product :
fer
DOG Oth g Mh int sls, Crs: B. Be
are to be replaced by
ug 0b Git esi bas wba cep
It is in the first place clear that the quasi-equation a,b,c,= +
may be written in any one of the six forms
4,6,c5= +, 5,¢,4,=+, ¢4,6,.=+
a.c,o,.=—, ¢,boa,=—, bac=—;
o"O°O fopmohate) o°-0O°O ?
and so for the quasi-equation a,b,c,=—. This being pre-
mised, if we form a system of quasi-equations, such as
a,0,¢,= +, a,dseg= +&ce.,
where the system of triplets contains each duad once, and once
only, and the arbitrary signs are chosen at pleasure ; if, more-
over, in the expression of the quasi-product we replace a,?, b,?,...
each by ~—1, it is clear that the quasi-product will assume the form
Wy + Ayo +b yb, + ey Cyt 6+ +;
relating to the Products of Sums of Squares. 517
Wp Ap Oy Cy «++ being determinate functions of w, a, b, Cy ++ +5
W,, 4, b,c, .- homogeneous of the first order in the quantities
of each set; the value of w, being obviously in every case
w,,==ww,—aa,—bb,—cc,...
and a,,b,,¢,.-- containing in every case the terms aw,+ aw,
bw,+bw, cw,t+eqw,... but the form of the remaiming terms
depending as well on the triplets entering into the system of
quasi-equations as on the values given to the signs + ; the
quasi-equations serving, in fact, to prescribe a rule for the forma-
tion of certain functions W,, Ay) 5 ¢, - - - » the properties of which
functions may afterwards be investigated.
Suppose, now, that the system of quasi-equations is such that
€5 0.0.5. 8.6, oh,
being any two of its triplets, with a common symbol e,, there
occur also in the system the triplets
Fo %o os we db, 5 Jo Go Foy Jo 95% 5
and suppose that the corresponding portion of the system is
C5 Me Do =€} C5 Cg do =E
So % C=5 fod b=0'
Jo d,=t, Jo b, ft
where ¢, £4, ¢', 2,’ each of them denote one of the signs + or
— ; then e,, f,,, 9, will contain respectively the terms.
e(ab,—a,b) + é' (cd, —¢2)
&(ac,—a,c) + ¢'(db,—d,b)
u(ad,—a,l) + U(be,—b,) ;
and e,?+f,?+g) contains the terms
(a2 +b? +c? + d?) (a7? +b? +¢7+4?.) —aa?—0°b? — cc? — ad?
+ 2[ee! (ab,—a,b) (cd, —¢d)
+ ¢'(ac,— a,c) (db,— db)
+! (ad,—a,d) (be,—6,c)].
And by taking account of the terms ew,+ ev, fut fe, gw,+ ge
ine, fp J,respectively, we should have had besides in e,? +f? +9,/7
the terms
(P+f?+9*. wer th +g).
+ 2(ce,+ f+ 99),
Also w,? contains the terms
ww? + aa? +b? + cc? + dd).
—2(ce, +. H+ 99) 5
518 Ona Theorem relating to the Products of Sums of Squares
whence it is easy to see that
wp +a7?+b72+¢7+... =(w+a?4+h +c?...)
(w?+a?+b7+¢?...)
+22 [ee! (ab,—a,b) (cd,—c,d)
+ (ae, —a) (db, —d)
ut! (ad,—ad) (be,—b,c) ].
where the summation extends. to all the quadruplets formed
each by the combination of two duads such as ab and cd, or ac
and db, or ad and be, 7. e. two duads, which, combined with the
same common letter (in the instances just mentioned e, or f, or g),
enter as triplets into the system of quasi-equations—so that if
y=2”"—1, the number of eytiaete is
meal lies) vl te ae Dia
And the terms oe the sign = will nae identically if only
ed = (2! =u,
but the relation ee’=w! is of the same form as the equation
ee’ = &'; hence if all the relations
ef=t
are satisfied, the terms under the sign > vanish, and we have
(w,?+4,7+6,7?+6,7 000) = (W240? +4574 67002) (w?4+47?+b7 +4670)
which is thus shown to be true, upon the suppositions—
1. That the system of quasi-equations is such that
£5 a, bos & 7) d,
being any two of its triplets with a common symbol e,, there
occur also in the system the triplets
SoA. fe) Co» So4,6,
JoFo%o, Iob lo
2. That for any two pairs of triplets, such as
C4053 So %4 and f,4,¢, Sod,
Oo-O0 6.
the product of the signs of the triplets of the ae pair is equal
to the product of the signs of the triplets of the second pair.
In the case of fifteen things a, b,c... the triplets may, as
appears from Mr, Kirkman’s paper, be chosen so as to satisfy
the first condition; but the second condition involves, as Mr.
Kirkman has shown, a contradiction ; and therefore the product
M. H. Helmholtz on the Theory of Compound Colours. 519
of two sums, each of them of sixteen squares, is not a sum of
sixteen squares. It is proper to remark, that this demonstration,
although I think rendered clearer by the introduction of the idea
of the system of triplets furnishing the rule for the formation of
the expressions w,, a, 5, ¢,, &e., is not in principle different
from that contained in Prof. Young’s paper on an Extension of
a Theorem of Euler’s, &c., Irish Transactions, vol. xxi.
2 Stone Buildings, Oct. 8, 1852.
LXXXI. On the Theory of Compound Colours.
By H. Hetmuorrz*.
pee eaNOUs rays of different wave-length and colour di-
stinguish themselves in their physiological action from
tones of different times of vibration, by the circumstance that
every two of the former, acting simultaneously upon the same
nervous fibres, give rise to a simple sensation in which
the most practised organ cannot detect the single composing
elements, while two tones, though exciting by their united
action the peculiar sensation of harmony or discord, are never-
theless always capable of being distinguished singly by the ear.
The union of the impressions of two different colours to a single
one is evidently a physiological phenomenon, which depends
solely upon the peculiar reaction of the visual nerves. In the
pure domain of physics such a union never takes place ob-
jectively. Rays of different colours proceed side by side with-
out any mutual action, and though to the eye they may appear
united, they can always be separated from each other by physical
means.
The investigation of this compound action has led to the
theory of primitive colours, from the combination of which all
others are, or can be, obtained. This theory, however, lias been
based from the beginning upon a single mode of experiment ;
namely, that in which colouring substances are mixed together,
the results being assumed to be the same as would follow from
the union of the coloured lights themselves,—an assumption the
untruth of which I purpose in the following pages to prove.
Pliny mentions the fact that the oldest Greek painters were
able to represent all things by means of four pigments, while in
his time a much greater number was made use of, but without
the ability to produce an equal effect. Leonardo da Vinci,
equally celebrated as an artist as for his scientific treatment of
painting, was not aware of the theory of the three so-called pri-
mitive colours; besides black and white, which however are
* From Miiller’s Archiv and Poggendorff’s Annalen, 1852. No.9. Com-
municated by Dr. Tyndall.
520 M.H. Helmholtz on the Theory of Compound Colours. -
strictly speaking not colours, he mentions four, namely yellow,
green, blue, and red. The primitive colours red, yellow, and
blue, afterwards generally recognized, have been made the basis
of an experiment of Waller described in the Philosophical Trans-
actions for 1686, hence before the time of Newton’s investigations
on the decomposition of white light by the prism, and when no
other method of compounding colours save that of mixing the
colouring matters was known. In later attempts to classify the
natural colours according to their composition by the three pri-
mitive ones above mentioned, Castell, the astronomer Mayer,
Lambert, Hay, and Forbes*, have all taken as basis of their en-
deavours the mixing of the colouring matters. As representants
of the primitive colours from which all others might be formed,
Mayer made use of cinnabar, kings-yellow, and mountain-blue ;
Lambert, carmine, gamboge, and Prussian-blue, which give purer
mixtures ; and Hay, whose skill in the choice and use of colours
for this purpose is praised by Forbes, carmine, chrome-yellow,
and French ultramarine.
Some physicists attempted to demonstrate the objective exist-
ence of the three primitive colours. Mayer was the first to
give utterance to the view that the three primitive colours might
correspond to three different kinds of light, red, yellow, and blue,
each of which furnished rays of all degrees of refrangibility.
According to this, at every point of the spectrum red, yellow and
blue rays are mixed together, which however do not differ in re-
frangibility, and therefore cannot be separated by the prism.
At the red end of the spectrum the red light was supposed to
be predominant, at the blue end the blue, in the middle the
yellow. The same view was afterwards expressed by Brewster ;
and this celebrated physicist imagined that he was able, by ab-
sorption in transparent coloured media, actually to separate the
different kinds of light in all parts of the spectrum.
After his discovery of the composition of white light, Newton
assumed the existence of seven principal colours in the spectrum :
red, orange, yellow, green, blue, indigo, violet. He chose this
number probably because of the analogy which he sought between
the colours and the musical intervals of the scale, and this also
suggested the divisions of his seven-coloured disk. This accounts
for the distinction which he has drawn between blue and indigo-
blue. That this distinction has been made in the blue is, in all
likelihood, to be referred to the fact that in most prisms the blue
portion is comparatively expanded, aud the breadth of the bands
* T. Castell, Farbenclavier. Mayer in Géttinger gel. Anzeigen 1758,
p- 147. J. H. Lambert, Beschreibung einer Farbenpyramide: Berlin, 1772.
D. R. Hay, Nomenclature of Colours. J.D. Forbes in Phil. Mag. 8. 3.
vol. xxxiy. p. 161.
san Pg — tg
M. H. Helmholtz on the Theory of Compound Colours. 521
was compared by Newton to the intervals of the scale. Besides
this he must have been content with very incomplete apparatus,
and could therefore make but few observations on the artificial
union of two or more prismatic colours; the results of these
seemed, on the whole, to correspond with those obtained from the
mixture of coloured substances. Besides these experiments he
made others on the mixture of coloured powders.
Newton always obtained his spectra from sunlight, and did
not apply the methods necessary for the complete separation of
the differently coloured rays; hence it is that he did not ob-
serve the lines of Fraunhofer in the spectrum. Wollaston*
was the first to obtain a spectrum so pure as to permit of a few
of these lines being seen in it. Through a very good flint-glass
prism he looked with his naked eye at a fine sht, through which
diffused daylight entered, and saw, what indeed under these cir-
cumstances may always be observed, four well-defined coloured
bands in the spectrum; red, yellow-green, blue, and violet.
The transitions from reddish orange through orange and yellow
into green-yellow, from green into blue, and from blue into
violet, are so speedy in the flint-glass spectrum, that without the
help of a magnifying telescope they entirely escape the eye. In
this case the lines G and H of Fraunhofer bound violet very
sharply on both sides. The transition from green to blue is
marked by the lines b and F, and the narrow strip of pure yellow
being, in diffused daylight, very feebly luminous, it recedes in
the presence of the stronger red and green, so that these two
colours appear immediately contiguous. Wollaston therefore
assumes four primitive colours ; red, green, blue, and violet.
Thomas Young accepted Wollaston’s description of the spec-
trum, and altered to correspond with it his theory of colours,
which first assumed the three primitive colours generally recog-
nized, red, yellow, and blue, in the place of which he now set
red, green, and violet ; this necessitates the belief that he was
aware of the fact that from prismatic red and green yellow may
be obtained, and from prismatic green and violet blue. The
theory of Young before mentioned is important, inasmuch as in
it a definite physiological significance is assigned to the three
primitive colours. He assumes that the particles which lie upon
the surface of the retina are capable of peculiar vibrations, and
that at each place particles exist possessing three different times
of vibration corresponding to the velocities of the oscillations of
the three primitive colours, violet, green, and red, which are to
each other in the ratios of 7, 6, and 5. If the number of vibra-
tions of a luminous ray were 5, it would only act upon the nerves
capable of the sensation of red; if the number were 53, the red
* Philosophical Transactions, 1802, Pt. 2. p. 378.
522 M.H. Helmholtz on the Theory of compound Colours.
and green sensations would be simultaneously aroused, and thus
the mixed sensation of yellow generated.
I have been equally unsuccessful with Forbes in my efforts to
find among Newton’s followers, up to the latest period, experi-
ments on the mixture of the single prismatic colours. It appears
as if the question was regarded as completely exhausted by the
experiments with the mixed powders. Even the divergent results
given by the rotating disk were insufficient to convince experi-
menters that difficulties lay concealed here.
The referring of all colours to the three primitive ones has, in
the case of the different observers, three different senses :—
1. That the primitive colours were such as permitted of the
formation of all others from their combinations.
2. Or, as supposed by Mayer and Brewster, that the primitive
colours correspond to three different kinds of objective hight.
3. Or, as supposed by Thomas Young, that they correspond
to three primitive modes of sensation experienced by the visual
nerves, and from which the remaining sensations of colour are
composed.
To the second of these views and the reasons by which Brewster
has endeavoured to support it, I will return in another place, and
believe that I am in a position to refute it. The two others
must, at all events, be tested by the prismatic colours, these
being the purest and most saturated that we possess. This shall
be the object of the present paper.
The means which I have made use of to obtain the combi-
nations of the colours of the spectrum, two by two, is as follows:
I cut ima black screen two sufficiently narrow slits (4 of a line
wide) which together form aV. Both ave inclined at an angle of
45° to the horizon, the angle which they enclose being thus a right
angle which points downwards. This slit is observed. from a
sufficient distance (12 feet) through a telescope and prism. The
prism is placed close before the object-glass of the telescope, in
the position of minimum deflection, and the edge of its refracting
angle stands vertical. It is known that, looking through a ver-
tical prism at a vertical slit, a rectangular spectrum is observed
in which the coloured bands and the lines of Fraunhofer occupy
a vertical position. If through a vertical prism an oblique slit
be observed, the spectrum assumes the form of an oblique-angled
parallelogram, with two opposite sides horizontal and two others
parallel to the inclined slit. The bands of colour and the lines
of Fraunhofer are here, of course, parallel to the slit. When our
compound angular slit is thus observed, the spectra of its two
legs partially cover each other, and, as in the one the bands of
colour are directed from the left above to the right below, in the
other from the right above to the left below, they mutually i in-
M. H. Helmholtz on the Theory of compound Colours. 528
tersect each other at right angles. Every coloured band of the
one intersects in the common field of the spectra each band of
the other, and thus we at once obtain the total combinations
capable of beg formed out of every two simple colours.
As it is necessary to illuminate the slit uniformly through its
entire extent, direct sunlight cannot be well applied, and we
must content ourselves with the light of the firmament, or of a
white surface shone upon by the sun. These lights are in
general completely adequate to the purpose.
The flint-glass prism which I made use of, permitted, when
direct sunlight and a narrow slit were applied, a great number
of the finer Fraunhofer’s lines to be seen. In the spectrum of the
angular, and somewhat wider slit above described, the stronger
lines, at least, were distinctly visible, particularly those which
Fraunhofer has distinguished by the letters A, B, D, E, b, F, G, H.
The presence of these lines assures us, in the first place, that in
the spectrum of each distinct limb of the slit the differently
coloured rays could not overlap each other, and hence that we
had to deal with pure coloured rays ; and, secondly, they increase
greatly the facility of examining the mixed field, through which
they are distinctly seen torun. My telescope possessed a pair of
cross wires which cut each other at right angles, and these I set
parallel to the dark lines of the coincident spectra. The wires
thus mark, at the upper and lower rim of the illuminated field,
the two simple colours which are mixed together at their point
of intersection.
It is necessary to be able to alter the relative intensity of the
mixed colours. This I accomplished by bringing the prism from
its vertical position into a more or less inclined one. It was so
attached to the forward cylindrical end of the telescope as to
permit of its being turned round the axis of the latter, and thus
might be brought into any required position relative to the hori-
zon. In order to explain how, by this means, the intensity of
the light of the spectrum is changed, let us fix our attention
upon a single slit. The intensity of the spectrum depends upon
the quantity of light which falls from the slit upon the prism
and telescope, and on the apparent magnitude of the spectrum
to the illumination of which this light is applied. The quantity
of light received does not change when the prism is turned round
the axis of the telescope, but the illuminated surface of the spec-
tral image changes. he latter, as already remarked, possesses
the form of a parallelogram. Two of its sides are parallel to the
slit, and always of the same length as the slit appears im the
telescope ; the two other sides stand perpendicular to the re-
fracting edge of the prism, and their length depends solely upon
the dispersive power of the latter. The spectrum therefore forms
524 M.H. Helmholtz on the Theory of Compound Colours.
a parallelogram the sides of which are constant, but whose angles
can be altered by turning theprism round the axis of the telescope.
The known propositions of elementary geometry teach us that
the superficial contact of such a parallelogram is a maximum
when its angles are right angles, the area decreasing more and
more as the obliquity of the angles is increased. Now as the
same quantity of light illuminates a smaller surface more brightly
than a larger one, the apparent brightness of the spectral image
must be a minimum when the image is a rectangle, that is, when
the refracting edge is parallel to the slit, and the brightness
must increase as the angle enclosed by the slit and the refracting
edge increases.
The two legs of our angular slit, when looked at through a
vertical prism, give two spectra equally bright, inasmuch as the
refracting edge is inclined towards each at an angle of 45°; when
however the prism is turned round the axis of the telescope, one
of the angles becomes greater and the other smaller, the relative
brightness of the spectra being thus caused to vary in any re-
wired degree.
The brighter a spectrum is made in this way, the more closely
are its coloured bands pressed together: lest this should too
much prejudice the spectrum’s purity, it is advisable to obtain
great differences of brightness in another way than that just in-
dicated. This is accomplished with great facility by placing
pieces of paper, oiled or not oiled, of greater or less thickness,
behind one of the slits. These permit only a small portion of
the incident light to shine through, while through the other slit
passes the unenfeebled light of heaven.
When a field is obtained in the manner described, covered
with the mixtures of every two pure colours of the spectrum, the
observer readily convinces himself that the hues, particularly
those in the whiter portions of the field, cannot be estimated
while saturated colours stand beside them.
It is therefore absolutely necessary to separate the portions
regarding whose colour we wish to form a judgement, from the
remaining ones. When the telescope is used in the observations,
the means of effecting this is very simple. Let the cross wires
be fixed upon the place in question, and let the observer recede
to a distance of one or two feet from the eye-end of the instru-
ment. From this distance only a small portion of the spectrum
is visible through the eye-glass, the colour of which may be
estimated apart from the disturbing influence of the dazzling
colours adjacent. If the observer be long-sighted enough, the
intersection of the cross wires is seen from this distance with the
naked eye, at all events by aid of a weak concave glass suited to
the eye. In order to rediscover the observed combinations with
M. H. Helmholtz on the Theory of Compound Colours. 525
dispatch, and to show them to others, I place at the above
distance from the eye-glass a dark moveable screen, with a small
round orifice, through which the observer looks towards the eye-
glass of the instrument. If it be wished, instead of the com-
pound colour, to see the two composing simple ones, one slit
after the other may be closed by a second person, so that only
one of the two mixed colours remains standing; or a second
small prism is introduced between the eye and the orifice ; and
thus, instead of a single bright spot in the eye-glass of the tele-
cope, two with distinct colours are observed. For the more
certain determination of mixed colours which approach very
nearly to white, it is useful to encircle the opening of the eye-
piece with a sheet of white paper illuminated by white light,
and to compare its colour with the observed one. I have also
noticed that the eye is rendered less sensitive to fine differences
of colour by long gazing upon very whitish mixed colours; and
it is therefore advisable to permit the eye to rest at times, or to
allow it to wander over the surrounding objects. When the ob-
servation is renewed, a mixture of colour is often plainly detected
in the apparent white which had previously escaped observation ,
and which, when long looked at, again disappears.
In this way it is possible to obtain the total combination of
every two of the simple prismatic rays in all degrees of relative
strength, and to observe them undisturbed by the presence of
other colours. My observations, the principal points of which I
have had corroborated by the testimony of several other persons
practised in the judgement of colours, thus avoiding whatever
error the subjective defects of my own eyes might occasion, have
furnished the following results, some of which differ, in a sur-
prising manner, from the views on this subject heretofore held.
1. Red gives with orange a redder orange; with yellow,
orange: the mixed colours do not differ sensibly from the de-
grees of orange which appear in the simple spectrum. With
green it gives a yellow, which, less saturated, is paler than the
simple yellow, and which, when red is predominant, passes
through orange into red, and when green is predominant, passes
through yellow-green into green. With the green-blue tones of
the spectrum, a flesh-colour is obtained ; with the sky-blue ones,
a rose-red colour, which, when blue predominates, passes into
whitish violet, but when red predominates, passes into carmine-
red. When, finally, the red is combined with the indigo and
violet rays, which lie further towards the end of the spectrum, a
purple-red of increasing depth and saturation is obtained.
2. Orange gives with yellow a yellower orange ; with green, a
pale yellow; with blue, flesh-coloured tones, which, with indigo
and violet, pass over into carmine-red.
526 M.H. Helmholtz on the Theory of Compound Colours.
8. Yellow with green gives a greenish yellow, similar to the
tones which lie between these colours in the spectrum. With
sky-blue it gives a weak greenish white; with indigo-blue, pure
white; with violet, a weak flesh-coloured white, which, when
violet predominates, passes over into whitish violet, and when
yellow predominates, to a whitish yellow.
4. Green gives with blue, green-blue; with indigo, a bright
blue, which however is much duller and whiter than that of the
spectrum ; with violet also it gives a bright blue.
5. Blue with indigo gives the tones of colour which lie be-
tween them; with violet, a dark blue, which however is less
saturated than the indigo of the spectrum.
6. Indigo with violet gives the intervening tones.
The most surprising fact, and that which deviates most from
the views hitherto entertained, is, that of the colours of the spec-
trum there are only two which together give pure white, that is,
which are complementary to each other. These are yellow and
indigo-blue, two colours from the combination of which it has
been hitherto invariably imagined green would result. The
yellow which is made use of in this mixture is a very narrow
band in the spectrum, lying between the lines D, H, and about
three times more distant from E than from D,—a yellow which
approximates neither to orange nor to green, and among the
pigments is best represented by chromate of lead (chrome-yellow).
The blue made use of with this has a greater width, and em-
braces the degrees of this colour distinguished by Newton and
Fraunhofer as indigo, from about the centre between F and G@
almost to G. Among pigments, dark ultramarime represents
this colour better than the more violet indigo. When the colours
to be mixed are obtained from two equally bright spectra of a
flint-glass prism, the light used being that of the clouds, then
the exact centre between the lines F and G is the pomt which
possesses the proper luminous intensity for the production of
white. Towards the violet and the line G the blue becomes
more feebly luminous, and hence it must here be strengthened
in comparison to yellow, in order that white may be obtained.
For this reason, in the spectrum of a whitish blue firmament,
for example, the white falls near the line G. The brighter blue
of the spectrum, which approaches nearer to the line F, gives
with pure yellow, by the proper arrangement of their relative
intensities, tones which are very similar to white, but which
nevertheless are not without a feeble colouring. The same remark
applies to violet when mixed with a greenish yellow. The tint
approximates, in most cases, to flesh-colour, or to a bluish and
greenish hue; it is, however, sometimes difficult to assigh a
distinct name to the tint ; but I have never succeeded in obtaming
M. H. Helmholtz on the Theory of Compound Colours. 527
from these colours a clear pure white. If the investigation were
conducted with instruments more complete than those applied
by me, and which would permit of the formation of a larger field
of compound colours, the limits of those rays which produce
white would probably be estimated with greater accuracy, inas-
much as the comparison of the hues of large surfaces is capable
of being effected with much more ease and sharpness.
By the rays which produce white, the whole width of the spec-
trum is divided into three sections. ‘The first of these corre-
sponds to the red, and, if we compare the ratio of the luminous
vibrations with those of sonorous waves, answers to about the in-
terval of a small third,the middle green section to a great third, the
third and violet section being somewhat smaller than a small
third. Colours of the first and second sections combine to tones
of yellow, with transitions into red, flesh-colour, white, and green;
those of the second and third combine to blue, with transitions
into green, white, and violet; those of the first and third com-
bine to purple-red, with transitions into flesh-colours, rose, and
violet.
‘With respect to the combimation of three simple colours, we
may conclude that white can only be the result when rays from
the three different sections of the spectrum ave suitably united.
At least it cannot be supposed, although all possible combi-
nations. cannot, of course, be exhausted by experiment, that
the yellow or yellowish colours, for example, which are derived
from the red and green sections, can, by the addition of one or
more colours contained in these sections, red, yellow, or green,
pass over into white. This remark is also applicable to the mix-
tures of the green and violet, as also to those of the red and
violet sections. We may, on the contrary, succeed in obtainmg
white from various combinations of three colours taken simulta-
neously from the three sections. For this purpose I have made
use of a black screen with three slits, Two of these were parallel
and inclined at an angle of 45° to the horizon; they stood at
such a distance from each other, that, when observed through
the prism at the ordinary distance, the violet of the one fell upon
the red of the other. The slit from which the violet is obtained
must be made about twice as wide as the other, for otherwise the
violet is too feeble in comparison with the red. A third slit,
which is to yield green for the mixture, was cut between the two
others and at right angles to them, so that the three slits
together presented a figure similar to a Z, The spectrum of the
third slit intersects at right angles the purple stripe given by the
two others, and generates a series of mixed colowrs in which the
whitest portion is easily sought out. By turning the prism
round the axis of the telescope, the mixed colows can be so
528 M. H. Helmholtz on the Theory of Compound Colours.
made to balance each other that pure white is procured. Thus
we obtain white from red, green, and violet, which may be com-
bined to three pairs of complementary colours; namely,
Simple red and compound dull blue-green.
Simple green and compound purple-red.
Simple violet and compound dull yellow.
It is a striking fact, that, while the complementary colours of
simple red and violet are only distinguished from certain tones
of the spectrum by their less saturated appearance, the former
nevertheless give, with simple red and violet, white, the latter
not.
Newton’s few observations on the combinations of every two
prismatic colours coincide with my results. He finds that the
primitive colours can be obtained by the combination of the
neighbouring ones at both sides of the former; for example,
orange can be formed from red and yellow; yellow, from orange
and green-yellow ; green, from green-yellow and sea-green, and
also, but not so good, from yellow and blue (eyaneum) ; blue,
from sea-green and indigo. He has also formed from red and
violet, purple-red. White he could only obtain from the three
colours, red, violet, and green; and in order to render the ex-
periment successful, he even recommended the application of
spectra whose colowrs were not completely separated. In this
case more than three single colours are mixed together.
It will, on the contrary, be observed, that my results on the
action of prismatic colours differ materially from those obtained
by the mixing of colouring substances. In particular, that yellow
and blue do not furnish green, but at most a weak greenish
white, contradicts in the most decided manner the experience of
all painters during the last thousand years. The reason of the con-
tradiction will, however, be rendered quite plain by reflecting a
little upon the manner in which colouring substances act upon
light. The substances used in painting, as all coloured bodies
of regular structure which we possess in large pieces, for example,
crystallized cinnabar, crystallized chromate of lead, cobalt-glass,
from which smalt colours are made, are transparent, or at least
translucent. When light falls upon them, a portion of the
latter will be reflected from the exterior surface as white light ;
another portion enters the substance, and by the unequal ab-
sorption of the component simple rays becomes coloured, is
reflected at the posterior limiting surface of the body, and returns
to the eye of the observer, which, by means of this particular por-
tion of light which has entered the body and been reflected within
it, sees the latter coloured. When, however, we grind a colour-
ing substance to powder, the observer sees not only that portion
of the incident light which is reflected at the forward and poste-
M. H. Helmholtz on the Theory of Compound Colours. 529
rior surfaces of the uppermost layer of powder-particles, but also
that reflected from the second, third, fourth, &e. Of light per-
pendicularly incident, a single glass plate reflects only 34, two
such plates only +4, very many plates almost the whole. We
can conclude from this, that of the light which falls upon the
fine white powdered glass, the smallest portion only is reflected
from the uppermost particles, a much greater portion being
reflected by those beneath. This must also be the case with
coloured powders, at least with those simple rays whose colour
they bear, and which are permitted to pass without absorption ;
the greater portion of light of this kind comes from the deeper
layers, having traversed in their passage a number of powdered
particles.
Let us consider what will be the case when we mix together
powders of different colours, for example, yellow and blue. The
blue particles which lie wpon the surface will give blue light, the
yellow which lie upon the surface will give yellow light ; both toge-
ther will combine to form white or greenish white. It is quite
otherwise, however, with the light which returns from greater
depths. This must pass through yellow and blue particles, and
hence from a distance below the surface such light only will
return as can penetrate both the yellow particles and the blue
ones. Blue substances generally permit green, blue, and violet
light to pass through them in sensible quantity ; yellow, on the
contrary, permits red, yellow, and green to pass. Green, there-
fore, is the only ight which will pass through both, and hence
from the deeper layers of the mixed powder only green light can
return. Now, as the quantity of light reflected from the super-
ficial portions of the powder is, according to what has been
already said, generally much smaller than that which returns
from the deeper layers, the consequence is, that the green of the
latter is by far the most predominant, and thus determines the
colour of the mixture.
When therefore to a blue powder we add a yellow one, the
colour of the mixture is less altered by the addition of the yellow
rays to the blue, than by the circumstance that of the latter rays
the violet and blue portions are lost, and the green alone remains.
For this reason also mixtures of two colouring substances of
nearly equal intensities are in general darker than their consti-
tuents, especially when the latter possess such colours as stand
far apart in the prismatic series, and hence contain but few rays
of a common nature. Thus cinnabar and ultramarine, instead
of the rose colour, which corresponds to the composition of their
rays, give a black-gray which approximates somewhat to violet.
The theory of pigmentary colours here presented is simply de-
rived from the generally recognized laws of physics; it explains
Phil, Mag. 8.4. No, 28. Suppl. Vol. 4. 2M
530 M. H. Helmholtz on the Theory of Compound Colours.
the pheenomena, so far as I am able to see, completely ; showing
that the mixture of the substances and the combination of their
colours are two processes altogether distinct, and hence that the
results obtained from the former furnish no conclusion regarding
the latter. Only when we have to deal with colowrs which stand
but slightly separated from each other in the spectrum does the
composition of the coloured light give nearly the same results as
the mixture of the pigments, for then the compound colour is
similar to the tones of the spectrum which lie between both the
simple ones.
There are, however, two other methods of combining the light
proceeding from pigments, which yield results altogether in har-
mony with those obtained from the combination of similar
prismatic colours. The first of these methods is the union of the
colours upon the rotating disc. It has been long noticed, that
results thus obtained are different from those derived from the
mixture of the pigments. I repeated the experiment with yellow
and blue. For the former I either made use of gamboge or
chrome-yellow, for the latter ultramarine or mountain-blue.
With quick rotation a pure gray is obtained. The difference of
the two methods is exhibited very strikingly when the middle of
the disc is coated with a mixture of both pigments, while the
rim is divided into sectors coloured by the pure pigments them-
selves. With quick rotation the middle of the disk appears
green, the rim gray. The former is much darker than the latter,
which according to the foregoing theory must be expected.
Of the other method I have never yet found a description, but
can recommend it as very convenient. It is free from the defect
of the gray appearance of the mixed colours which is observed
upon the rotating disk, and admits, on the contrary, of the
generation of a perfect white from complementary-coloured
pigments. Let a glass plate, with plane and parallel surfaces,
be placed perpendicular to the leaf of a table, and let a coloured
wafer be placed before it. The image of the wafer is reflected
by the glass plate; the apparent place of the image is at the
other side of the plate, and also on the surface of the table. Let
another wafer of a different colour be placed upon the exact spot
where the image is observed, this second wafer being seen through
the glass. The observer’s eye will thus be affected by two de-
scriptions of rays, both of which appear to proceed from one and
the same body, one of which however belongs to the transmitted
and the other to the reflected ight. Hence he observes a wafer
the colour of which is compounded of those of the two wafers
actually before him. To make the experiment with greater con-
venience, it is only necessary to use a very small glass plate, as
thin as possible, and with plane parallel surfaces; this is to be
M. H. Helmholtz on the Theory of Compound Colours. 531
fixed at right angles to the table at about the distance of distinct
vision. The observer looks obliquely through the plate down-
wards towards the table, and places the wafers in a position
which is suitable for the combination of their colours. The
nearer both are brought to the imaginary intersection of the
plane of the table with the glass plate, the more obliquely will
the rays fall upon the plate, the fewer will pass through, and
the greater will be the number reflected; so that, in this case,
the colour of the reflected light will be predominant. Conversely,
the colour of the transmitted light will be predominant when the
wafers are removed to a distance from the line of intersection ;
and in this way it is possible to alter the relative intensities of
the combining colours in any required degree. In this experi-
ment both wafers are placed upon a black ground * ; or if whitish
combinations of colour be required, which it is necessary to com-
pare with pure white, one of the wafers (the brightest is best)
is placed upon a white, the other upon a dark ground. Observed
through the glass plate, the wafer appears in the compounded
colour upon a white ground. It is manifest that in this way
the colours of all coloured surfaces whatever, as also those of
coloured glasses, may be combined.
Colours thus composed are distinguished by their brightness
and clearness from those obtained by the mixture of the colour-
ing matters; they do not always agree with the latter, but, on
the contrary, yield the same results as those obtained when the
prismatic colours are united. Blue and yellow, in particular, do
not give green, but white. As the representative of the yellow,
I made use of paper disks which I had washed with bright
chrome-yellow or gamboge. Of blue colourmg matters laid on
disks in the same manner, a beautiful sky-blue cobalt gave, with
both kinds of yellow, pure white ; artificial ultramarine, reddish
white ; and bright Prussian blue, a weak greenish white. Cin-
nabar combined with blue gives rose-colour ; the same red colour
combined with green gives yellow, &c. In short, these experi-
ments prove, that not only the simple coloured rays of the spec-
trum have other laws of action than those hitherto generally
assumed, but that quite similar laws apply to the combination of
the colours of pigments. It does not appear to me doubtful that
these new laws will supersede the old ones which were based upon
the mixture of the colouring substances.
It is best, however, to commence with the simple colours of
* T have repeated the experiment with a single yellow wafer on a blue
ground, the image of the wafer projected upon the latter gives a white
spot.—J. T
2M2
582 M. H. Helmholtz on the Theory of Compound Colours..
the solar spectrum, because these are the purest and most per-
fect, and even with a moderate intensity of light make an almost
dazzling impression ; beside which, all pigmentary colours appear
dull and gray. Newton has already given the rule, that each
simple colour can be obtained from the union of the two next it.
My own investigations corroborate this. I must, however, at the
same time remark, that the distance of the combined colours
must not be too great, when it is sought to obtain from their
union a colour similar to that which lies between them. This is
particularly the case in the central portion of the spectrum. Red
and yellow give an orange, the appearance of which appears to
be quite the same as that of the simple orange; and, in like
manner, the indigo which results from the combination of blue
and violet is scarcely to be distinguished from the simple indigo.
On the contrary, yellow-green and blue-green give a green the
tone of which indeed corresponds to the intervening tone of the
spectrum, but which is decidedly duller and more whitish, so that
the simple green can be obtained from such colours only as
scarcely differ from it in appearance. Yellow and blue appear
in this respect less sensitive than green. The former may be
pretty well obtained from orange and yellow-green, but very pale
from red and green; the latter, again, may be well obtained
from the combination of blue-green and indigo, but is very dull
when formed of green and violet. With regard to the end colours
of the spectrum, red and violet, Newton in his coloured disk
places them in contact with each other, and subjects them to the
rule which refers to the union of neighbouring colours mentioned
above. From indigo-blue and very little red it is indeed possible
to generate a kind of violet, which however always approximates
more to white or rose-colour than the simple violet. Much more
incomplete appears to my eyes the imitation of red by orange
and violet ; their combinations always pass into tones of carmine-
red or of white, and I have not succeeded in obtaining a tolerable
imitation of the pure red of the spectrum.
Hence if we propose to ourselves the problem of imitating the
colours of the spectrum by the union of the smallest possible
number of simple colours, we find at least five of the latter
necessary for this purpose, namely red, yellow, green, blue,
violet. I must, however, leave the question undecided, whether
these are completely sufficient, and whether with better appa-
ratus, which would permit of the illumination of larger surfaces
by the simple colours, and by the corresponding compound ones
placed adjacent, a practised eye might not detect differences
which with my apparatus could not be recognized. If, however,
we wish to limit ourselves to three colours, it would be best to
M. H. Helmholtz on the Theory of Compound Colours. 533
choose the three simple ones which admit of the least perfect
imitation, namely red, green, and violet: we should then obtain
a yellow and blue, which, when compared with the colours of
our pigments, would appear saturated, but which would not bear
comparison with the yellow and blue of the spectrum. These
are the three which Thomas Young proposed as the three primi-
tive colours. Red, green, and blue would not answer so well ;
for were these three chosen, the mixed violet would appear worse
than the mixed blue of the former three. The three primitive
colours commonly chosen are altogether insufficient, because from
them green can never be obtained.
According to the above we must also abandon the theory of
three primitive colours, which, according to Thomas Young, are
three fundamental qualities of sensation. If the sensation of
yellow by the yellow rays of the spectrum were due to the fact
that by them the sensations of red and green were simultaneously
excited, and both working together produced yellow, exactly the
same sensation must be excited by the simultaneous action of
the red and green rays; nevertheless by the latter we can never
obtain so bright and vivid a yellow as that produced by the yellow
rays. The same remarks apply to blue, which would be formed
from the mixture of green and violet ; and to violet, which would
be formed from the mixture of blue and red. To retain in this
sense the theory of primitive colours, five such, at least, must be
assumed. On the contrary, to represent and classify the dull
and comparatively impure colours of natural bodies, in the sense
of Lambert and Forbes, three primitive colours would be quite
sufficient. But, for a sure and a scientific classification, it would
be necessary to apply a method of combining colours different
from the mixing of pigments.
By the union of every two simple colours we are met by two
new impressions, namely white and purple-red, with their de-
grees of transition into the simple colours before named. The
purple-red belongs to the saturated colours which cannot be
otherwise obtained than from the extreme red and violet, with-
out a loss of brightness. White, on the contrary, can be obtained
in an infinity of ways, without the eye being able to distinguish
one white from the other. We obtain it for example from simple
yellow and blue, from simple red, green, and violet, or from
these five simple colours taken together ; and besides these, from
several more complicated combinations. In contrast with colowrs
it is therefore regarded as indifferent light. The remaining
combinations of every two simple colours appear to the eye as
transitions of the simple colours and purple into white ; but in
further combinations, as above remarked, they behave in a
534 Mr. J. Newman on a new Evaporating Gauge.
manner essentially different from the colours of the spectrum
when the latter are weakened by the addition of white hght.
In conclusion I give the following small table; it furnishes
a general view of the combinations of every two colours, and in
its construction five colours are assumed, by the union of which
the colours of the spectrum are represented with sufficient
accuracy. In the first horizontal and the first vertical series
stand the simple colours; the compound colours which follow
from their union are found at the intersection of the correspond-
ing horizontal and vertical columns.
Violet Blue Green Yellow | Red
Red | Purple | Rose Dull-yellow | Orange | Red
Yellow} Rose White Yellow-green | Yellow
Green | Pale-blue| Blue-green | Green |
Blue | Indigo | Biue
Violet | Violet
LXXXII. Description of a new Evaporating Gauge.
By Mr. Joun Newman.
To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,
| HAVE for many years noticed that the meteorological jour-
nals kept by scientific observers omit all mention of the
quantity of water evaporated from the earth’s surface. This
omission has, I believe, arisen from the want of a correct instru-
ment, or one sufficiently delicate in its indications.
After much consideration, I beg to hand you for insertion in
your Journal, the description of an instrument which I believe
will be found efficient, adding to the completeness and useful-
ness of the meteorological notices of those who are pleased to
use it.
It consists, as you will observe (from the accompanying sketch),
of a short cylinder 12 inches in diameter, having connected with
it, by means of a stopcock, a glass tube graduated to hun-
dredths, and terminating in a lower vessel, which will con-
Notices respecting New Books. 535
tam a sufficient quantity of so
water to be raised by artificial
pressure into the upper one for
exposure to the atmosphere.
To use the apparatus, pour
water into it until it rises to the
zero in the glass tube, then by
means of a syringe force air
through the tube x into the
lower vessel, so as to raise the
water into the upper one to any
height you please. Now shut
off the stopcock beneath to
retain the water in the upper
vessel; then, having exposed
the apparatus for any length of
time that is required, open the
cock, when the water will run
into the lower vessel, filling it
and part of the glass tube, the
divisions of which will now indi-
cate in hundredths the quantity
of water evaporated.
I am, Gentlemen,
Your obedient Servant,
122 Regent Street, Joun NEWMAN.
London, Noy. 10, 1852.
LXXXIII. Notices respecting New Books.
Life Contingency Tables.-—Part I. The Chances of Premature Death
and the Value of Selection among Assured Lives. By Epwtn
James Farren, Fellow of the Institute of Actuaries, and one of the
Actuaries authorized to certify Tables for Friendly Societies.
JHE continual increase which has been, for many years past,
taking place, more particularly in this country, in the amount
of property either assured upon human life, or in some way or other
depending upon it, has rendered the accurate determination of its
average duration a matter of the utmost importance; and accordingly
many most laborious researches have from time to time been entered
upon, with a view to ascertain not only the true rate of mortality
prevailing amongst the general population, but also that found to
obtain in particular localities, or under circumstances not of an ordi-
nary character.
In the very able work before us, Mr. Farren has proposed to him-
self the resolution of a problem looked at with much interest by
536 Notices respecting New Books.
persons familiar with this subject; availing himself of certain data
collected by competent persons, with great care and precision, from
the records of several of the principal assurance companies, he has
endeavoured to show the effect of selection amongst assured lives,
that is, to what extent the rate of mortality is diminished during a
given year amongst persons of all ages pronounced to be eligible for
assurance at the commencement of that year. A table formed from
such observations might, as Mr. Farren says, “‘ be expected to display
the extreme value of selection, and thus afford a minimum rate of
mortality ;” for it must be remembered, that, in the ordinary tables,
the numbers exposed to the chance of death at every age are made
up of persons selected at that and almost all previous ages. Com-
pared with such tables, and with one exhibiting the rate of mortality
prevailing amongst the male population of England and Wales, the
results obtained by Mr. Farren are very curious. We give the fol-
lowing brief abstract to enable the reader to judge of them :—
Mr. Farren’s General mortality | Mortality amongst the
results. amongst assured lives.| male population.
Ages. Mortality per 1000. | Mortality per 1000. Mortality per 1000.
21 to 30 62214 81342 9:1347
| 31 to 40 74866 | 9°73820 11:7947
41 to 50 11-4201 13:397] 15-2106
51 to 60 21-3524 23°4302 22-9492
61 to 70 41-4718 46°7017 48°8562
It will here be seen, that selection operates at all ages with con-
siderable force in diminution of the ordinary mortality, and that, as
might be expected, the force has a tendency to increase as the age
increases. It is probable that the general effect would be still greater,
but that it is counteracted by the efforts continually made to effect
assurances on not very good lives, ‘‘ the more precarious the life the
greater the inducement, as Mr. Milne observes, for persons interested
in its continuance to get it insured.” One remarkabie feature in
the tables is the comparatively low rate of mortality amongst the
general population in the last decade but one, that obtaining amongst
assured lives being actually higher. Mr, Farren accounts for this,
partly by a peculiarity in the construction of Mr. Fart’s table (the
mortality amongst the male population), and partly by the supposi-
tion, ‘‘ that persons seeking life assurance at the ages in question
form a better criterion of their own health than at other periods of
life, and thus render the task of selection by parties having an oppo-
site interest more than usually difficult.” It will probably be con-
ceded, that about the period of life referred to, intimations of latent
diseases are of more general occurrence than at any earlier one, and
that in later life their development makes them apparent; but these
considerations scarcely seem to suffice for explanation of the anomaly.
We have not space to follow Mr. Farren through many other in-
genious deductions, but we must not pass by without comment the
Notices respecting New Books. 537
learning and ability displayed by him in the adoption of methods for
the construction of his tables. After exhibiting various modifications
of the function a2", first applied by Mr. Gompertz to these investi-
gations, Mr. Farren makes use of the calculus of finite differences
for the purposes of interpolation till the age of seventy-one. After
that age, because ‘‘ the admissions are too few to admit of the sup-
position that the same mixed generic law will continue to prevail,”
=
he has recourse to the formula \” 7=)'/ —, by means of which,
and the theory of equations of z dimensions, the remainder of the
table is interpolated.
Lastly, the means are afforded of tracing, from the original data,
the several values made use of; so that the whole series of opera-
tions may be followed, and the connexion between the first and last
values easily confirmed. As Mr. Farren wisely observes, ‘ all mo-
dern publications on these subjects must principally depend, for
even ordinary acceptance, upon the attention paid to such details ;”
nothing, he may be assured, was better calculated to secure for his
labours the confidence they so. evidently deserve. He is quite right,
we think, when he says that tables of mortality solely depending for
their adoption on the authority of the authors framing them, will
eventually be discarded.
Brief Astronomical Tables for the Expeditious Calculation of Eclipses
in all ages. By W. Drew Snooker. §. Highley and Son, Fleet
Street.
These tables are constructed with the view to enable the histo-
rical student to verify dates by the calculation of eclipses named
in history. For this purpose strict. mathematical accuracy may
be dispensed with; and the smaller equations which enter into
the determination of the times of full and new moon, and the rela-
tive position of the three bodies, may with more or less risk of error
be omitted from the calculation. The tables are well arranged, and
the rules for using them clearly expressed and exemplified.
The author appears to handle his subject with familiarity ; and if
the correctness of the tables may be relied upon, and the time and
other circumstances of the phenomena to which they are applicable
is capable of being educed from them with that degree of accuracy
which the author affirms, we think his little book may be found
useful in supplying a desideratum which is likely to have been felt
by many of the class of students for whose use it is intended,
Preparing for Publication.
An Elementary Introduction to the Study of Paleontology; with
numerous Figures Illustrative of Structural Details. By F. M’Coy,
Professor of Geology and Mineralogy, Queen’s College, Belfast,
Also, by the same Author,
A Manual of the Genera of British Fossils ; comprising Systematic
538 Intelligence and Miscellaneous Articles.
Descriptions of all the Classes, Orders, Families, and Genera of Fossil
Animals, found in the Strata of the British Isles; to be completed
in four or five Parts, forming one volume, 8vo, of about 500 pages,
with nearly 1000 Wood Engravings.
LXXXIV. Intelligence and Miscellaneous Articles.
ON A REMARKABLE DEPOSIT OF TIN-ORE AT THE PROVIDENCE
MINES NEAR ST. IVES, CORNWALL. BY WILLIAM JORY HEN-
WOOD, F.R.S., F.G.S.*
YF FXHE Providence Mines, in the parish of Lelant, comprise the mines
formerly known as Wheal Speed, Wheal Laity, Wheal Com-
fort, and Wheal Providence, long worked on the eastern side of the
hill which slopes from Knill’s monument to the sea.
(a.) Observations on the eastern workings in the slate, and on the
western within the granite formation, have already appeared in the
Royal Cornwall Geological Society’s Transactions+. ‘The interme-
diate tract now to be described is wholly in granite, of which the upper
beds are composed of a basis of grayish felspar and quartz, imbedding
medium-sized crystals of white felspar, as well as numerous small
groups of schorl in radiating crystals: but near the productive parts
of the Jodes the rock is mostly rather coarse-grained, its basis is
greenish-gray felspar, black mica, and quartz; and the included por-
phyritic crystals of felspar are either of a pale buff, a pink, or a red-
dish-brown hue.
(b.) The veins are :— >
The Cross-Course or Trawn, which bears about 22° W. of N., and dips E.f
The Wheal Comfort lode es : 15°W. of N., .. Ww.
and Wheal Laity lode or lodes se 7.8.08 Wi. baie es
Connected with the Wheal Comfort lode there is a ‘‘ Carbona$,”
to which further reference will be made presently.
It may be here stated generally, that the Cross-course is from one
foot and a half to two feet in breadth, and is composed of disinte-
grated fine- -grained granite, divided by numerous joints parallel to
the *‘ walls ;” as well as by many other curved and irregular ones
which intersect each other in every imaginable manner, and are
filled with oxide of iron, and closely but unconformably striated.
The Wheal Comfort lode varies in width from a few inches to more
than six feet. At a distance from the Wheal Laity lodes it is of
granite very thinly impregnated with tin- -Ore 5 the remainder con-
sists of quartz, schorl-rock (capel), brown iron-ore, and greenish
¥ From the Transactions of the Royal Geological Society of Cornwall,
vol. vii.
T Vol. v. pp. 16-20, plate 2. fig. 7, Tables 21 and 22.
{ The “directions” have reference to true north, the “dips” are from
the horizon.
§ I have already described a similar, though a much smaller formation,
in one of these mines. —Corn, Geol. Trans, vol. v. Table 22.
Intelligence and Miscellaneous Articles. 539
and brownish felspar, in some places—near the Wheal Laity lodes—
abounding in tin-ore. é
At about 105 fathoms deep this lode is connected with one of those
curious deposits of tin-ore locally called ‘‘ Carbonas *,” as yet un-
known in any other part of Cornwall. The union takes place about
14 fathoms south of the contact between the Wheal Comfort and the
Wheal Laity lodes ; and for 10 fathoms above and 20 fathoms below,
as well as for the whole distance between the Wheal Laity lodes and
the Carbona, the Wheal Comfort lode when alone is very productive ;
but immediately when the Wheal Comfort lode and the “ Carbona”
separate in descending,—each taking its own downward course,—the
lode becomes unproductive, and so also remains as far southward
as it has yét been traced.
At the northern contact of the Wheal Comfort lode and the ‘ Car-
bona”’ there is a rich mass of quartz, felspar, schorl, and tin-ore, at
least 15 feet in width for about 5 fathoms in length: both south-
ward of and below this spot the /ode preserves its usual direction and
dip; but the ‘‘ Carbona”’ southward bears about 5° east of the course
of the dode, and holds nearly perpendicularly downward. Descend-
ing about 5 fathoms it abuts on the granite rock, and is seen no
deeper ; except that as it is pursued southward, the irregular granitic
bed on which it rests declines at an angle of about 8°. With the
exception of a single short string or pipe, no trace whatever of the
“Carbona” has rewarded the numerous researches which have been
made at greater depths. Nothing can, however, be more irregular
than its size and various ramifications. Though the upper edge of
the “‘ Carbona” generally continues to touch the lower side (foot-
wall) of the Jode, in some places the contact is only a few inches, but
in others as much as two fathoms and a half wide. Again, in some
cases the continuity of the “‘Carbona” where it joins the lode, is
almost entirely cut off by intervening masses of granite; the union
with the main body being still preserved, though merely by “‘ pipes ”
or “ pillars”’ of /ode-like matter. Many portions of the “‘ Carbona”
are as much as five or six fathoms high, others not more than four
or five feet; some parts are two fathoms and a half wide, whilst
others do not exceed six inches. The largest portions are, however,
seldom or never entirely separated from each other by the containing
rock, for there is always a sufficient connexion to conduct the
miner from one large and rich mass to another.
The composition of the Wheal Comfort lode has been already
noticed; but notwithstanding their intimate connexion, that of the
*Carbona”’ is wilely different, as its tin-ore occurs chiefly in quartz
and schorl, which minerals, either separate or mixed, constitute the
far greater portion of this remarkable deposit.
* Some persons pretend to derive this term from the ancient Cornish
language, whilst others suppose it to have been recently coined by the
miners. Both the word itself and the metalliferous deposit it is meant to
designate are, I believe, confined to the St. Ives mining distriet.—-Corn,
Geol. Trans. vol. y. p. 21, note.
540 Intelligence and Miscellaneous Articles.
Everywhere eastward the Wheal Laity lode is but a single vein,
of about a foot and a half wide, and composed of quartz, earthy
brown iron-ore, greenish, and in some places brick-red felspar, a
little tin-ore, together with some vitreous copper-ore and iron pyrites.
Westward, however, it consists of at least two separate veins, called
for distinction sake the Wheal Laity north and south lodes; and some-
times there is also a third vein. At one spot the third vein is simply
crystallized felspar, and the axes of the crystals are parallel to each
other, but lie across the vein; in other parts it is slightly productive
of tin-ore. The Wheal Laity north, and Wheal Laity south lodes, in
general from a foot to a foot and a half in width, are occasionally
much wider. Greenish felspar, quartz, schorl, and occasionally brown
iron-ore, are their chief ingredients: in some parts both veins are
rich in tin-ore; vitreous copper ore, copper and iron pyrites also
occur, but are not common constituents. In the deepest part of the
mine (i. e. at 150 fathoms deep) the Wheal Laity north lode is for
some fathoms in length about two feet in width, and is then com-
posed of chlorite, vitreous copper ore, and iron pyrites, and has a
vein of rather fine-grained granite on one side. At a depth of 120
fathoms, and about 60 fathoms west of the portions already described,
where the same /ode consists of granite, quartz, red iron-ore, and a
little tin-ore, there is connected with its northern side (foot-wall) an
offshoot or excrescence about 4 fathoms in all directions, but most
irregular in figure, and having many small vein-like branches, ‘This
mass, consisting chiefly of chlorite, quartz, and iron pyrites, is not
only far richer in tin-ore than the adjoining portion of the lode, but
is remarkably different in mineral composition. We have thus the
same ore richly impregnating, not only the Wheal Comfort lode and
the “‘Carbona,” two parallel but entirely dissimilar deposits, but also
the Wheal Laity lode, which has a direction nearly at right angles
to them.
(c.) The intersections of the lodes just mentioned exhibit almost
an epitome of that class of phenomena.
(1.) The Wheal Laity and the Wheal Comfort lodes cross each
other ; still at some levels there is no evidence to show that either
is cut through; whilst at others the Wheal Comfort lode not only
intersects, but also heaves the Wheal Laity lode. It is not the least
remarkable circumstance attending this intersection that the Wheal
Laity lode is a single vein everywhere eastward of the Wheal Comfort
lode, whereas westward of their contact it is divided into two, and in
some places even into three distinct and separate veins.
(2.) All these veins are intersected by the Cross-course, and all
are heaved by it; the two larger (the Wheal Laity north and the
Wheal Laity south lodes) in general from 10 to 15 fathoms; the dis.
placement of the smaller vein is, however, much less considerable,
and does not exceed six fathoms and a half.
Again, notwithstanding the Wheal Comfort lode and the Cross-
course have opposite inclinations, they respectively heave the Wheal
Laity lodes in the same direction.
At a depth of 110 fathoms, where the Wheal Laity north lode is
Intelligence and Miscellaneous Articles. 541
for some distance unproductive, whilst the Wheal Laity south lode is
rich in tin- ore on both sides of the Cross-course, and for some fathoms
both above and below the gallery (/evel), the Cross-course consists
of a rich vein of tin-ore for the whole interval (five fathoms) between
the eastern portions of the two Jodes, as well as of a fine mass of the
same ore at its contact with the western part of the Wheal Laity
south lode.
(3.) At 130 fathoms deep the Wheal Laity south lode is also
heaved, but in an opposite direction, by a vein of granitic clay (the
Flucan). This flucan is not prolonged to either of the other Wheal
Laity veins; nor, indeed, does it reach any other gallery (devel) even
on the same lode.
(4.) The Wheal Comfort lode and the Cross-course have the
same direction, but, as already observed, opposite inclinations; and
are so situated that they come into contact on the line of their dips
at about 130 fathoms deep. From the point where they first touch
each other they descend perpendicularly side by side for about three
fathoms, each keeping the same relative position it had previously
when separate (viz. the Cross-course on the west, and the Wheal
Comfort lode on the east). Atlength, however, the Jode cuts through
the Cross-course. After this intersection, though they have changed
sides, and their relative position is reversed, -they still proceed
together, but now take the line of the /ode’s previous underlie for
several fathoms. When they separate, the lode preserves its dip;
but the Cross-course, though it resumes the previous direction of
its inclination, dips eastward far more rapidly than before. It may,
indeed, be generally observed, that a vein which has been displaced
by another, whether the intersection be horizontal or vertical, makes
(if I may be permitted the expression) an effort to resume its original
course.
(5.) The Wheal Laity lodes are intersected as well by the Wheal
Comfort lode and the Cross-course during their union, as by each of
them when separate; the union, however, has little or no influence
on the extent of the heave.
Many details of local, and some, indeed, of general interest,
scarcely need be mentioned, as this paper may be deemed supple-
mentary to my remarks on the St. Ives District* ; and especially
to a description of a similar interesting formation at the St. Ives
Consolidated Mines, which has already appeared in the Transactions
of the Royal Geological Society of Cornwall}.
A small stream issues from the Wheal Laity north lode at 150
fathoms deep, having a temperature of 71°; whilst that of the water
discharged by the pump at the adit (45 fathoms from the surface)
is only 63° 6' f.
* Corn. Geol. Trans. vol. v. p. 16. + Ibid. p. 21.
{ Observations on the temperature of other parts of the Providence
Mines are recorded in the Society’s Transactions, vol. v. p. 390.
542 Intelligence and Miscellaneous Articles.
ON THE NATURE AND NAME OF OZONE. BY C. F. SCHONBEIN.
MM. Ed. Becquerel and Fremy* have recently confirmed the ob-
servation, already made by others, that ozone may be produced in
the purest possible oxygen when this is subjected to the influence
of electrical discharges. ‘These physicists are on this account of
opinion that ozone is to be regarded as allotropic oxygen, and pro-
pose to call it “‘ Orygene élecirisé.” 1 consider this term inappro-
priate, and upon the following grounds :—
1. Oxygen may be ozonized not only by electricity, but also by
ponderable substances, as for instance phosphorus, or in other words,
may be so influenced that it will effect oxidations even at ordinary
temperature which would not otherwise take place. According to
my opinion there is no disengagement of electricity during the
modification of oxygen by means of phosphorus, the oxygenization
of turpentine, &c., whence it appears to me to follow that the forma-
tion of ozone, through chemical action, is unconnected with electri-
cal action, at least directly. I have recently endeavoured to show
that under suitable circumstances 1000 grms. of phosphorus con-
vert 1720 grms. of oxygen into ozone, and indeed with tolerable
rapidity. In order to ozonize this quantity of oxygen by means of
electrical discharges, the electricity of a thunder-storm would pro-
bably be necessary ; for even the most powerful discharges which
we are able to pass through oxygen or air artificially, produce com-
paratively but an extremely small amount of ozone. If, therefore, a
disengagement of electricity took place during the contact of phos-
phorus with oxygen or atmospheric air, and if this electricity was
the cause of the formation of the ozone which occurs under these
circumstances, we might expect to observe the most violent electrical
phznomena, in a flask where large quantities of ozone were pro-
duced under the influence of phosphorus. But we are not acquainted
with anything of the kind, the production of ozone goes on quietly
and noiselessly, and no signs of electrical disturbance can in any
way be detected. Consequently, if ozone can be formed from com-
mon oxygen without the aid of electricity, it appears to me that the
term ‘‘ Oxygene ¢électrisé”’ is altogether inappropriate, and it might
with equal justice be called “ Oxygene phosphorisé.”
2. It is well known that oxygen possesses in many of its combi-
nations the eminently oxidizing properties of ozone, for which rea-
son it appeared to me desirable to express the particular condition
of the oxygen in the nomenclature of these substances. This would,
however, be difficult if the name “ electrified oxygen ” is adopted.
If, for example, the peroxide of lead is called ozonized oxide of
lead, the peroxide of nitrogen ozcnized nitrous acid, these names
are convenient, and are in harmony with the formula PhO+O, NO?
-++20, which I have proposed for these bodies.
Since the above-mentioned physicists themselves affirm that ozone
* Comptes Rendus, Mar. 15, 1852, p, 399; Phil. Mag. July 1852,
p. 543.
Intelligence and Miscellaneous Articles. 543
is merely allotropic oxygen, there cannot be any danger of errone-
ous impressions being formed as to the nature of the body, from the
use of the name hitherto employed, to which I shall therefore
adhere until a better one than that proposed by these gentlemen is
found. Although the experiments of MM. Becquerel and Fremy
have not taught us anything essentially new, still some of their
statements have a peculiar interest ; for instance, the circumstance
that ozone is produced even in a closed glass tube, filled with
oxygen, when electrical discharges are allowed to strike upon its
exterior. ‘The production of ozone is here evidently the result of an
electrical induction in the oxygen from the exterior and through the
glass. A similar induction takes place on a large scale on the
occasion of every flash of lightning, a very striking instance of
which I had once an opportunity of observing. Some years since a
small chapel on the Rhine-bridge at Basle was struck by lightning.
All the rooms in my house, which is about a hundred paces distant,
were filled with a strong odour of ozone at the moment of discharge,
and the same was the case in all the neighbouring houses, so that
the inhabitants of each imagined that their own dwelling had been
struck by the lightning. It is also deserving of especial notice, that
the smell of ozone was perceived in rooms which were closed, as
well as in those which were in connexion with the exterior atmo-
sphere. This appeared to me to prove satisfactorily that the ozone
was not carried into these houses by currents of air from the place of
the discharge, but was actually produced in them by induction, and
I have no reason now to consider that this view was incorrect; in-
deed it is precisely the same fact upon a large scale which the
French physicists have observed on a small one.
M. de la Rive, in speaking of the investigations of MM. Bec-
querel and Fremy, puts forward a new hypothesis for the explana-
tion of the alteration effected in oxygen by means of electricity, &c.
He is of opinion that in ordinary oxygen the atoms are not separate,
but combined in groups forming molecules. Since, in the chemical
combination of bodies, the atoms unite in single pairs, the cohesion
of the atoms forming a molecule of oxygen would oppose their che-
mical combination with the atoms of other substances, and thus
account for the chemical inactivity which oxygen manifests under
ordinary circumstances towards other bodies. He regards phospho-
rus, electricity, &c. as possessing the power of breaking up the
molecules of oxygen into separate atoms, on account of which its
chemical activity is increased, and it is rendered capable of oxidizing
bodies at the ordinary temperature.
According to this view, ozone must be considered as atomic and
oxygen as molecular oxygen. However comprehensible this hypo-
thesis may be, I cannot avoid some hesitation in giving my assent
to it.
1. We must, if we adopt it, regard ordinary oxygen as a body
which is at the same time both solid and fluid. The molecules must
be regarded as solid, inasmuch as they are supposed to be formed
5A Intelligence and Miscellaneous Articles.
by the strong cohesion of individual atoms. But as ordinary oxygen
is gaseous, the hypothesis in question must also assume that each
separate molecule acts repulsively upon similar molecules. It might
therefore reasonably be asked, why do the oxygen molecules repel
each other, while the atoms constituting such molecules mutually
attract? When 10, 100, 1000 atoms of oxygen unite together form-
ing one molecule, why does not each such number of atoms combine
to form a larger solid body? Why is the oxygen gaseous?
2. Ozone remains unaltered in the cold; by heat it is converted
into ordinary oxygen, in which condition it remains after cooling.
M. de la Rive must therefore explain this change by assuming that
oxygen, consisting of separate atoms (ozone), again assumes a mole-
cular state when its temperature is raised; in fact, that heat faci-
litates the cohesion of the oxygen atoms, an action the opposite of
that which is generally ascribed to this agent.
3. Ozone possesses smell, while ordinary oxygen does not; the
former is a violent poison, the latter an indispensably necessary sup-
porter of animal existence. That these great differences in the phy-
siological action of oxygen and ozone should be owing merely to a
different state of mechanical aggregation of the elementary atoins,
appears to me very difficult to imagine.
4. Itis known that by chemical union with certain bodies oxygen
acquires the same oxidizing properties as it acquires when free
under the influence of electricity or contact with phosphorus. For
example, when one equivalent of nitric oxide ( NO’) combines with
two equivalents of oxygen gas, the latter enter into a condition of
chemical activity precisely similar to that which ozone possesses.
It would be difficult to explain how passive oxygen had in this case
been converted into action, according to the hypothesis of M. de la
Rive. Probably we must assume that NO® breaks up the molecules
of ordinary oxygen gas, entering into combination with it, and con-
verts it into the ozonized or atomic condition.
Some years since, Mr. Hunt put forward an hypothesis as to the
nature of ozone, which is precisely the opposite to that of De la Rive ;
according to it the ordinary oxygen was in an atomic, and ozone in a
molecular condition. Hunt brought forward no facts of any kind in
support of his hypothesis, and I remarked at the time that the op-
posite view might be entertained with equal justice, and I still con-
sider both hypotheses of equal value. So long as we are unac-
quainted with ozone in a pure state, and especially do not know
positively anything of its state of aggregation, specific gravity, &c.,
it appears advisable to postpone all theorizing on the subject, and
especially the advancing of hypotheses which are themselves based
only upon hypotheses, such, for example, as that which assumes the
existence of atoms. With regard to my own opinions, I do not
venture to hazard the most remote conjecture as to the cause of that
difference in the properties of ordinary oxygen and ozone, differ-
ences which are quite as mysterious as remarkable. 1 will, how-
ever, state that it has never yet entered into my mind to seek this
Intelligence and Miscellaneous Articles. 545
cause in the state of mechanical aggregation of oxygen atoms, a
course which is certainly not very probable in my case, as I enter-
tain doubts as to the correctness of the dogmas of our modern
atomic doctrines.—Journ. fiir prakt. Chem. 1852.
ON THE QUANTITATIVE DETERMINATION OF OZONE.
BY C. F. SCHONBEIN.
Since ozone combines even in the cold with silver forming per-
oxide, while ordinary oxygen behaves indifferently towards this
metal, I have endeavoured to determine the quantity of ozone in a
given volume of air by means of the peroxide of silver formed.
If, for example, 60 litres of artificially ozonized air afforded 100
milligrms. of peroxide, I assumed that it contained 13 milligrms. of
ozone, presupposing that ozone was nothing more than allotropic
oxygen.
This method, besides its tediousness, is otherwise objectionable,
and I endeavoured to discover a more convenient process, in which
I believe I have succeeded. Instead of silver I employ a solution of
indigo in sulphuric acid ; and numerous experiments have convinced
me that this reagent admits of accuracy and rapid operation, for the
quantity of ozone in several litres of air may be determined by it
within a few minutes, even to a small fraction of a milligramme.
This method depends upon the property possessed by ozone of de-
colorizing the indigo solution, a property which ordinary oxygen
is altogether destitute of ; and, likewise, upon the fact that the most
minute quantity of this solution colours a large volume of water.
The strength of the indigo solution, which I find the most con-
venient, is when 10 grammes of it are decolorized by 1 milligrm. of
oxygen.
In preparing this test solution, I take 100 grms. solution of indigo
prepared according to Berzelius’s directions, add an equal quantity
of hydrochloric acid, and heat the whole until it boils. I then add
to the hot liquid small portions of a dilute solution of chlorate of
potash of known strength (one per cent.), shaking the mixture
continually until it has become brownish yellow. If, for example,
100 milligrms. of chlorate have been employed to decolorize the
indigo solution, I infer that this effect has been caused by the 39
milligrms. of oxygen contained in that quantity of the salt, and
consequently that 1 milligrm. of oxygen is capable of decolorizing
100°29 grms. of the solution of indigo. To render this solution of
such a strength that exactly 10 grms. of it are decolorized by
1 milligrm. of oxygen, I mix 100 parts with 290 parts of water and
preserve it in stoppered bottles.
In order to determine the quantity of ozone in a flask of air con-
taining for example 30 litres, and acted upon to the greatest pos-
sible degree by phosphorus, I pour 300 grms. of the test-solution
into a glass, and add about one-half to the gas at once. The closed
flask is then shaken for some minutes, and a small quantity of the
liquid poured out to see if it is decolorized. If so, I dip a small
Phil. Mag. S. 4. No, 28. Suppl. Vol. 4. 2N
546 Intelligence and Miscellaneous Articles.
strip of moist iodide of potassium paper into the vessel, and if this is
coloured, add more solution of indigo until the decolorization is
complete, when the quantity of solution employed gives the amount
of ozone in the gas.
When, for example, 250 grms. of the test-solution are decolorized,
the weight of ozone causing this effect would be 250--10=25 mil-
ligrms., in which amount there is no allowance for the quantity of
air displaced by the 250 grms. of solution. If the volume of the
tested gas reduced to 32° and 76 centim. bar. amounts to 30 litres,
and the weight of ozone in it to 30 milligrms., this air contains ;.5,
ozone, since under these conditions a litre of air weighs 1298 mil-
ligrms, and in this quantity of air there is 1 milligrm. ozone.
My recent_.experiments have proved that atmospheric air may be
ozonized to the extent of =,4,, by means of phosphorus ; and did not
ozone act so energetically upon phosphorus, a much higher degree
of ozonization might be attained. At this point, however, the pro-
duction and consumption of this substance appear to be equal, and
ignition of the phosphorus takes place in consequence of the rapid
oxidation.
I have already often pointed out the great similarity between the
effects produced by chlorine and ozone. One instance of this is the
fact that like chlorine it combines with phosphorus at ordinary tem-
peratures. There can therefore be no doubt that this body would
immediately take fire in pure ozone gas, as in chlorine, even in the
cold.
As the above-mentioned test-solution of indigo is very dark blue,
it may be very greatly diluted, and still appear deeply coloured.
I therefore employ two more dilute solutions of such a strength,
that 10 grms. of one is decolorized by 1°10 milligrm., and 10 grms.
of the other by 1°100 milligrm. of oxygen. By this means it is evi-
dent that even very small fractions of a milligrm. of ozone may be
detected and estimated.
With this very delicate reagent Ihave found that ozone diluted with
500,000 times its volume of atmospheric air may still be recognised
by its smell, sufficiently proving that the pure ozone must have a
most intense odour.—/bid.
ON THE MOTION OF FLUIDS FROM THE POSITIVE TO THE NEGA-
TIVE POLE OF THE CLOSED GALVANIC CIRCUIT. BY M. WIE-
DEMANN.
The author has communicated to the Prussian Academy of Sciences
a memoir on the mechanical action of the voltaic circuit, which is of
essential interest and importance. The apparatus employed con-
sisted of a porous earthenware cell, closed at the bottom and termi-
nated above by a glass bell firmly cemented to the upper edge of
the cylinder. Into the tubulure of the bell a vertical glass tube was
fitted, from which a horizontal tube proceeded so as to permit the
fluid raised to flow over into an appropriately placed vessel. A wire
serving as the negative pole of a battery passed down through the
Intelligence and Miscellaneous Articles. 547
glass bell into the interior of the porous cylinder, where it terminated
in a plate of platinum or copper. Outside the porous cylinder
another plate of platinum was placed, and connected with the posi-
tive pole of the battery. The whole stood in a large glass vessel,
which, as well as the interior porous cylinder, was filled with water.
The intensity of the current was measured by a galvanometer. As
soon as the circuit was closed, the liquid rose in the porous cylinder,
and flowed out from the horizontal tube into a weighed vessel. The
results obtained by means of this apparatus were as follows :-—
1. The quantity of fluid which flows out in equal times is directly
proportional to the intensity of the current.
2. Under otherwise equal conditions, the quantities of fluid flowing
out are independent of the magnitude of the conducting porous
surface.
To avoid any uncertainty arising from the laws of the flow of
liquids through small orifices, Wiedemann measured the intensity of
the mechanical action of the current by determining the height of a
column of mercury which would hold the transferring force in equi-
librium. For this purpose a graduated tube or manometer filled
with mercury was attached to the extremity of the horizontal tube
above mentioned. With different currents and porous surfaces of
different extent, the mercury in the manometer rose to different
heights. By the measurements of these heights, the following results
were obtained :—
3. The height to which a galvanic current causes a fluid to rise is
directly proportional to the intensity of the current, and inversely
proportional to the extent of the free porous surface.
The mechanical action of a galvanic current may also be referred
to its simplest principles by the following proposition :—
4. The force with which an electric tension, present upon both
sides of a section of any given fluid, urges the fluid from the positive
to the negative side, is equivalent to a hydrostatic pressure which is
directly proportional to that tension.
In this manner therefore we obtain a simple measure of electric
tension and its mechanical action in terms of atmospheric pressure,
and consequently of gravity.
The above laws hold good only for fluids of the same nature.
When different fluids are subjected to the action of the currents, the
mechanical action is greatest upon those which oppose the greatest
resistance to its passage. The requisite data are still wanting to
determine the precise connexion between the mechanical action and
the resistance; but observations made with solutions of sulphate of
copper of different degrees of concentration, appear to shew that the
quantities of fluid transferred in equal times by currents of equal in-
tensity are nearly proportional to the squares of the resistances.—
Silliman’s Journal for November 1852, p. 420.
2N2
548
INDEX to VOL. IV.
ADIE (R.) on the unequal heating
effect of a galvanic current while
entering and emerging from a con-
ductor, 224, 380; on the relation
of magnetism and diamagnetism to
the colour of bodies, 451.
Air, on the thermal effects experienced
by, in rushing through small aper-
tures, 481.
Andrews (Dr. T.) on a new aspirator,
330; on the heat of chemical com-
bination, 497.
Anthropie acid, on the properties and
composition of, 75.
Antimonic acid, on the salts of, 398.
Arsenic, new method of detecting,
in cases of poisoning, 361.
Artesian wells near Silsoe in Bedford-
shire, remarks on, 102.
Aspartic acid, researches on, 275.
Aspirator, description of a new, 330.
Atmosphere: a Philosophical Work,
reviewed, 228; on the electrical
condition of the, 126; on the causes *
of the excess of the mean tempera-
ture of rivers above that of the,
355 ; on the colours of the, 416.
Atmospheric electricity, researches on,
126, 249.
Aurora borealis, report on observa-
tions of the, 59; on the non-polar-
ization of the, 452.
Barral (M.) on the chemical compo-
sition of the rain-water collected at
the Observatory at Paris, 396.
Barry (Dr, M.) on the spiral structure
of muscle, with observations on the
muscularity of cilia, 81, 177.
Bashforth (Rev. J.) on the conducting
powers of wires for voltaic electri-
city, 120.
Bassie acid and its salts, 21.
Bat’s wing, on the rythmical contrac-
tility of the veins of the, 385.
Berberine, on the occurrence of, in
the Columba wood of Ceylon, 99,
Berlin (M.) on the supposed new me-
tal donarium, 156.
Biot (M.), report on M. Pasteur’s re-
searches on aspartic and malicacids,
275.
Bois-Reymond’s (E. du) discoveries
in animal electricity, abstract of,
reviewed, 226.
Bomerang, observations on the, 79.
Bone, on the structure and develop-
ment of, 467.
Books, new :—Smyth’s Aides Hart-
welliane, 69; M. du Bois-Rey-
mond’s Discoveries in Animal Elec-
tricity, 226; Woodhead’s Atmo-
sphere, 228; Farren’s Life Contin-
gency Tables, 535 ; Snooke’s Astro-
nomical Tables for the Calculation
of Eclipses, 537.
Brewster’s (Sir D.) new analysis of
solar light, observations on, 401.
Bromopyromeconic acid, on the pro-
perties and composition of, 167.
Brougham’s (Lord) experiments and
observations on the properties of
light, 1, 230.
Brown (J. I'.) on some salts and pro-
ducts of decomposition of pyrome-
conic acid, 161.
_ Brunner (C.) on the preparation of
pure silver from the chloride, 78.
Bunt (T. G.) on pendulum experi-
ments, 272.
Carbonic acid, new apparatus for the
determination of, ive
Cayley (A.) on Steiner’s extension of
Malfatti’s problem, 465; on a the-
orem relating to the products of
sums of squares, 515.
Challis (Rev. J.) on the principles of
hydrodynamics, 438.
Chapman (Prof. E. J.) on Artesian
wells near Silsoe in Bedfordshire,
102.
Chemical combination, researches on
the heat of, 370, 497.
INDEX.
Chemistry, early Egyptian, remarks
on, 142.
Childrenite, chemical constitution of,
8
Cilia, on the muscularity of, 81, 177.
Clausius (R.) on the colours of a jet
PA eam and of the atmosphere,
416.
Clays, analysis of several, 349.
Coals, analyses of, 265.
Sepeeles indicus, on the fatty acid of,
Cockle (J.) on the method of sym-
metric products, 492.
Colours, on the stereoscopic combina-
tion of, 241; on the relative in-
tensity of different, 246; on the
theory of compound, 519.
Combinations, theorems in the doc-
trine of, 209.
Copper smelting, observations on, 45 ;
dressing of the ores, ib.; assaying
of the ores, 192; fuel suitable for,
262; construction of the furnaces,
345; calcination of the ores, 453.
Crowder (W.) on the fatty acid of
Cocculus indicus, 2).
Damour (M.) on the supposed new
metal donarium, 156.
Davies’s (T. S.) notes on geometry and
geometers, 28, 201.
Diamagnetism, on the relation of, to
the colour of bodies, 452.
Donarium, analysis of the supposed
new metal, 156.
Donoyan (M.) on the supposed iden-
tity of the agent concerned in the
phznomena of ordinary electricity,
voltaic electricity, electro-magnet-
ism, magneto-electricity and ther-
mo-electricity, 33, 130, 210.
Dove (H. W.) on the stereoscopic
combination of colours, 241.
Drach (S. M.) on the formulization
of horary observations presumed
@ priori to be nearly of a periodic
nature, 152; on the non-existence
of “on roots in analytic geometry,
4
Electric fluid, on the constitution of
the, 33, 130, 210.
Electricity, on the state of statie and
dynamic, observed during several
heavy showers, 253; on the reduc-
tion of temperatures by, 224, 380,
419.
549
Electricity, animal, notice of Du Bois-
Reymond’s researches in, 226.
, atmospheric, researches on, 249.
5 voltaic, on the conducting
powers of wires for, 120.
Electro-magnets, on the lifting powers
of, 124.
Elliot (Capt.) on the lunar atmo-
spheric tide at Singapore, 147.
Equations, onthe possibility of solving,
of any degree, 434.
Evaporating-gauge, description of a
new, 534.
Farren’s (E. J.) Life Contingency
Tables, reviewed, 535.
Fat, human, on the composition of, 75.
Fluids, on the motion of, from the
positive to the negative pole of the
closed galvanie circuit, 546.
Fremy (E.) on the sulphurets which
are decomposable by water, 153.
Galvanic current, on the unequal
heating effect of a, while entering
and emerging fromaconductor, 224.
Gases, on the electro-chemical polarity
of, 150, 498.
Geometry, new theorem in, 366; on
some demonstrations in, 417.
Geometry and geometers, notes on,
28, 201.
Glaisher (J.) on the meteor of the
12th of August 1852, 292.
Gray (J. E.) on the bomerang, 79.
Grove (W. R.) on the electro-chemi-
cal polarity of gases, 150, 498; on
the dark discharge, 514.
Hamilton (Sir W. R.) on continued
fractions in quaternions, 303.
Heat, on the dynamical theory of, 8,
105, 168, 424; on the mechanical
action of radiant, 256; on the ab-
sorption of, by a bismuth and anti-
mony joint, 318; on the amount
of, produced by the combination
of several metals with oxygen, 370,
497 ; on the mechanical equivalent
of, 393.
Heffter (L.) on the salts of antimonie
acid, 398.
Heineken (N. 8.) on a brilliant me-
teor seen at Sidmouth, 236.
Heintz (Dr.) on the composition of
human fat, 75.
Helmholtz (11.), new analysis of solar
light, 401; on the theory of com-
pound colours, 519.
550
Henfrey (A.) on the structure of the
stem of Victoria regia, 151.
Hennessy (J. P.) on some demon-
strations in geometry, 417.
Henry (T. H.) on the composition of
Wootz, or Indian steel, 42.
Henwood (W. J.) on a remarkable
deposit of tin-ore, 538.
Herapath (Dr. W. B.) on the chemi-
cal constitution and atomic weight
of the new polarizing crystals pro-
duced from quinine, 186.
Huxley (T. H.) on the morphology of
the Cephalous Mollusca, 385.
ge scree on the principles of,
8.
Infinitesimals, on the early history of,
in England, 321.
Invertebrate animals, on the blood-
rs and chylo-aqueous fluid of,
8.
Tron, on the occurrence of metallic,
333
Jerrard (G. B.) on the possibility of
solving equations of any degree,
however elevated, 434.
Jones (T. W.) on the rythmical con-
tractility of the veins of the Bat’s
wing, 385.
Joule (J. P.) on the thermal effects ex-
perienced by air in rushing through
small apertures, 481.
Kirkman (Rey. T. P.) on theorems in
the doctrine of combinations, 209.
Kupffer (A. F.) on the mechanical
equivalent of heat, 393.
Lagrange (F. de) on a new arrange-
ment of the yoltaic pile, 77.
Lamont (Dr.) on the decennial period
in the magnitude of the daily mo-
tion of the magnetic needle, 145.
Lefroy (Capt.) on observations of the
aurora borealis, 59
Lettsom (W. G.) on the occurrence of
metallic iron in fossil wood, 333.
Light, remarks on Lord Brougham’s
experiments and observations on
the properties of, 1; experiments on,
230; on the change of refrangi-
bility of, 388; on Brewster’s new
analysis of solar, 401.
Lowenthal (J.) on a new method of
precipitating oxide of tin and se-
parating it from other bodies, and
of combining it with silk, woollen
and cotton fabrics, 476.
INDEX.
eo on the colouring matters of,
472.
Magnetic disturbances, on periodical
laws discoverable in the meaneffects
of the larger, 232.
Magnetic needle, on the decennial
period in the magnitude of the
daily motion of the, 145, 219.
Magnetism, on the relation of, to the
colour of bodies, 451.
Mahla (F.) on the peroxide of silver,
318.
Malfatti’s problem, researches cun-
_ nected with Steiner’s extension of,
465.
Malic acid, researches on, 275.
Mallet (Dr. J. W.) on a new fossil
resin, 261.
Matter, on the power of animated
creatures over, 258.
Mechanical energy, on the dissipation
of, in nature, 304; on the recon-
centration of the, of the universe,
358.
Mercury, on the indirect bleaching
power of, 238.
Metals, on the heat produced by the
combination of, with oxygen, 375.
Meteor of the 12th Aug. 1852, ob-
servations on the, 236, 292.
Meteorological observations, 79, 152,
159, 239, 319, 381, 399, 479.
Miller (J. F.) on the meteorology of
the English Lake district, 152.
Mineralogical notices :—Childrenite,
118; orangite, 156; scleretinite, 261.
Mollusca, on the morphology of the
Cephalous, 385.
Morgan (Prof. De) on the early history
of infinitesimals in England, 321 ;
on indirect demonstration, 435.
Morgan (C. De) on the structure and
development of bone, 467.
Murray (J.) on the tides, bed and
coasts of the North Sea or German
Ocean, 466.
po on the spiral structure of, 81,
77.
Napier (J.) on copper smelting, 45,
192, 262, 345, 453.
Newman (J.) on a new evaporating
gauge, 534.
Ozone, on the nature and name of,
542; on the estimation of, 545.
Pasteur (M.) on aspartic and malic
acids, 275.
INDEX.
oe experiments, account of,
272.
Penny (Dr.) on the chloride of arsenic,
and on the detection of arsenic in
cases of poisoning, 361.
Perris (J. D.) on the occurrence of
berberine in the Columba wood of
Ceylon, 99.
Phillips (R.) on the electrical condi-
tion of the atmosphere, 126; on
the colours of a jet of steam, 128.
Polygons and polyhedrons, on Staudt’s
theorems concerning the contents
of, 335.
Polynomials, homogeneous quadratic,
observations on, 138.
Powell (Rev. B.), on Lord Brougham’s
“ Experiments and Observations on
the properties of Light,” 1.
Pyromeconic acid, on some salts and
products of decomposition of, 161.
Pyrometer, description of a new, 157.
Quaternions, on continued fractions
in, 303.
Quetelet (A.) on atmospheric elec-
tricity, 249; on the state of static
and of dynamic electricity observed
during some heavy showers, 253.
Quinine, chemical constitution and
atomic weight of the new polarizing
erystals produced from, 186.
Rain-water collected at the Observa-
tory at Paris, chemical examination
of the, 396.
Rammelsberg (Prof.) on the chemical
constitution of Childrenite, 118.
Rankine (W. J. M.) on the causes of
the excess of the mean temperature
of rivers above that of the atmo-
sphere, 355; on the reconcentra-
tion of the mechanical energy of the
universe, 358 ; on the non-polari-
zation of the aurora borealis, 452,
Resin, on a new fossil, 261.
Reslhuber (P. A.) on the decennial
period in the magnitude of the
diurnal motion of the magnetic
needle, 219.
Royal Society, proceedings of the,
47, 230, 306, 381, 465.
Rubian, researches on, 472.
_ Sabine (Col. E.) on periodical laws dis-
coverable in the mean effects of the
larger magnetic disturbances, 232.
Schaffner (Max.) on an apparatus for
the determination of carbonic acid,
Sig.
551
Schonbein (C. F.) on the mdirect
bleaching power of mercury and of
stibethyle, 238 ; on the nature and
name of ozone, 542; on the quan-
titative determination of ozone, 545.
Schunck (E.) on rubian and its pro-
ducts of decomposition, 472.
Scleretinite, on the composition of, 261.
Silver, on the preparation of pure,
from the chloride, 78; on the per-
oxide of, 318.
Smith (J. D.) on early Egyptian che-
mistry, 142.
Smyth’s (Capt. W. H.) Audes Hart-
wellianz, reviewed, 69.
Snooke’s (W. D.) Astronomical Tables
for the Calculation of Eclipses, no-
ticed, 537.
Solar light, new analysis of, 401.
Squares, on a theorem relating to the
products of sums of, 515.
Stalactites and stalagmites, on the
existence of organic matter in, 155.
Stars, on the colours of double, 71;
investigation of the orbit of y Vir-
inis, 73.
Staudt’s (M.) theorems concerning
the contents of polygons and poly-
hedrons, observations on, 335.
cients on the colours of a jet of, 128,
416.
Stearophanic acid, on the composition
of, 21; occurrence of, in human
fat, 75.
Steel, Indian, on the composition of,
2.
Steiner’s extension of Malfatti’s pro-
blem, researches connected with,
465.
Stereoscopic combination of colours,
on the, 241.
Stibeethyle, on the indirect bleaching
power of, 239,
Stokes (G. G.) on the change of re-
frangibility of light, 388.
Sulphurets decomposable by water,
researches on the, 153.
Swale’s merits as a geometer, ob-
servations on, 28, 201.
Sylvester (J. J.) on homogeneous
eee polynomials, 138; on
taudt’s theorems concerning the
contents of polygons and polyhe-
drons, 335; on a simple geometri-
cal problem, 366.
Symmetric products, on the method
of, 492,
552
Temperatures, on a new mode of
measuring high, 157; on the re-
duction of, by an electric current,
224, 380, 419.
Thermometers, on the construction of
standard, 306.
Thomson (Prof. W.) on the dynamical
theory of heat, 8, 105, 168, 424;
on the mechanical action of radiant
heat or light, 256; on the power
of animated creatures over matter,
258; on the sourees available to man
for the production of mechanieal
effect, 259 ; on a universal tendency
in nature to the dissipation of me-
chanical energy, 304 ; on the ther-
mal effects experienced by air in
ee through small apertures,
Tide, lunar atmospheric, at Singapore,
remarks on the, 147.
Tides of the North Sea or German
Ocean, researches on the, 466.
Tim, new method of precipitating oxide
of, 476.
Tin-ore, on a remarkable deposit of,
538.
Tomes (J.) on the structure and de-
velopment of bone, 467.
Tyndall (Dr. J.) on the progress of
the physical sciences, 241; on the
absorption of heat by a bismuth
and antimony joint, 318; on the
reduction of temperatures by elec-
tricity, 419.
Victoria regia, on the structure of the
stem of, 151.
INDEX.
Voltaic electricity, on the conducting
powers of wires for, 120.
Voltaic pile, new arrangement of the,
77; on the mechanical action of
the, 546.
Wallace (W.) on the chloride of
arsenic; 361.
Wells (D. A.) on the existence of or-
ganic matter in stalactites and sta-
lagmites, 155.
Welsh (J.) on the general process
adopted in graduating and com-
paring the standard meteorclogical
instruments for the Kew Observa-
tory, 306.
Wiedemann (M.) on the motion of
fluids from the positive to the ne-
gative pole of the closed galvanic
circuit, 546.
Wilkinson (T. T.), additions to the
late Mr. Davies’s notes on geo-
metry and geometers, 28, 201.
Wilhams (Dr. T.) on the blood-proper
and chylo-aqueous fluid of inverte-
brate animals, 148.
Wilson (J.) on a new mode of mea-
suring high temperatures, 157.
Wood, fossil, occurrence of metallic
iron in, 333.
Woodhead’s (G.) Atmosphere : a Phi-
losophical Work, reviewed, 228.
Woods (Dr. T.) on chemical combina-
tion, and on the amount of heat
produced by the combination of
several metals with oxygen, 370.
Wootz, on the composition of, 42.
END OF THE FOURTH VOLUME.
PRINTED BY TAYLOR AND FRANCIS,
RED LION COURT, FLEET STREET.
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