Hare's Calorimotor. 
605 
fo the. Editor of the American Medical Recorder of Original 
Papers and Intelligence. 
Sir,-In the number of the work above mentioned for July 
1819, you employ the following language, in speaking of the 
calorimotor, a galvanic instrument of which I had published an 
account a short time before; " This instrument appears to us, 
Vol. HL-4 I 606 
Hare's Calorimotor. 
nothing more than an extension of the elementary battery of Wol- 
laston." 
Subsequently, in conversation, I pointed out the injustice of this 
treatment. You admitted the propriety of my animadversions, 
and promised to correct your error, alleging your own incapa- 
city to judge of the subject, and the necessity you had been under 
of adopting the impressions of others whom you had considered 
as judges. It seems however that you have concluded not only 
to reiterate in the Recorder for April, the opinion above men- 
tioned, but to support it by statements which I shall prove could 
never have been made sincerely, had you understood the authors 
to whom you refer. 
In the first place I must observe, that the calorimotor as re- 
presented in the plate annexed to my memoir, consists of four 
galvanic surfaces, or two pairs* with one recipient. I assert, that 
you cannot adduce any analogous contrivance, small or great, of 
Dr. Wollaston or any other person. Such a combination 'of un- 
insulated surfaces, would not probably have occurred to any one 
deeming galvanism to be electricity under a slight modification; 
as that ingenious philosopher has supposed and endeavoured to 
prove. I should have hoped that before criticising my pamphlet, 
you would at least have examined tlie engravings which accom- 
pany it. A much more vivacious and intense ignition may be pro- 
duced, by two large galvanic pairs situated as I have arranged 
them for one recipient, than could be excited by double the ex- 
tent of surface in one pair formed like Wollaston's. After my 
experiments with one large pair were known, Mr. Wetherill, ex- 
pecting to produce more striking or powerful results, made a pair 
of double the size. By this, a wire of platina or iron, whether 
large or small, could not be heated much more than red hot; 
though similar wires by my smaller apparatus of two uninsulated 
pairs, were rapidly fused or burned off. Mr. R. Peale having 
also made an apparatus of one pair more extensive than mine, 
was disappointed as Mr. W'etlrerilI had been. 
I advised him to separate the two surfaces into four surfaces 
alternating. When thus altered, platina or iron duly exposed to 
* See plate and description. Hare's Calorimotor. 
607 
their action, were rapidly thrown into a state of fusion or com- 
bustion. 
I will next observe, that the action of a pair of galvanic sur- 
faces was known not only before the time of Wollaston, but be- 
fore that of Galvani himself. The taste excited by putting two 
plates of different kinds of metals one above, and the other beneath 
the tongue, and bringing into contact, their projecting extremities, 
was just as much the effect of a galvanic discharge as the igni- 
tion produced by the elementary battery. Hence it must be evi- 
dent that it is only in size, arrangement, and application that this 
last mentioned apparatus can possess originality. But in all these 
points I trust that the characteristics of the calorimotor are at 
least equally peculiar. 
Yet as Wollaston constructed a minute galvanic pair for pro- 
ducing ignition, and I constructed a pair enormously large by which 
ignition may be produced; you seem to infer that the one must be 
an extension of the other. It did not occur to you, that both, 
might be opposite varieties of a contrivance previously existing. 
Had the novelty of Wollaston's battery been dependent on the 
isolated fact of its producing ignition, your remarks had been more 
justifiable. But it was nothing new to produce galvanic ignition, 
and from his account of the elementary battery which I shall 
presently quote, it does not appear that he considered the result 
as meriting attention independently of the minuteness of the means 
by which it had been accomplished. It is not to the fact simply 
of his igniting wire that he attaches importance, but to the cir- 
cumstance of his having ignited it by an apparatus almost incon- 
ceivably small. To use his own words, the purpose of his expe- 
riments was " to ascertain the most compendious form of appa- 
ratus by which visible ignition might be produced." 
I am aware that with plates of a moderate size he made an 
instrument for producing instantaneous light, but having neither 
seen any account of that contrivance in the scientific journals, 
nor heard of any, I am doubtful whether it was considered as 
new, unless in the arrangement or application. Even this en- 
largement of his battery destroyed the most striking, and what he 
seems to have deemed the most important distinction, between it 608 
Hare's Calorimotor. 
and an ordinary pair: and admitting that he were the first to 
employ such a pair for the purpose of ignition, there had on that 
account been no more reason for representing him to be the in- 
ventor of this most simple and most ancient galvanic combina- 
tion, than for attributing the invention of the Voltaic pile, to Car- 
lile and Nicholson, because of their priority in applying it to the 
decomposition of water. Granting therefore that the ignition 
which I produced, was nothing but an extension of that which he 
had before effected, it does not follow that my apparatus was 
nothing but an extension of his; nor that there may not be as 
much originality in the enlargement of the original galvanic pair, 
under one form, for the purpose of investigation, as in the dimi- 
nution of it under another form, for the same object. 
But unfortunately for the correctness of your strictures, you 
seem to test my pretensions to experimental invention by one re- 
sult of my contrivance, totally overlooking that, by which charcoal 
was shown to be impermeable to the galvanic fluid, as extricated 
by the calorimotor. The experiment by which this was proved, 
is thus mentioned in my memoir: 
" The thinnest piece of charcoal intercepts the calorific agent, 
whatever it may be. In order to ascertain this, the inside of a 
hollow brass cylinder, having the internal diameter two inches, 
and the outside of another smaller cylinder of the same substance, 
were made conical and correspondent, so that the greater would 
contain the less, and leave an interstice of about one-sixteenth of 
an inch between them. This interstice was filled with wood, by 
plugging the larger cylinder with this material, and excavating 
the plug till it would permit the smaller brass cylinder to be 
driven in. The excavation and the fitting of the cylinders was 
performed accurately by means of a turning lathe. The wood in 
the interstice w'as then charred by exposing the whole covered by 
sand in a crucible to a red heat. The charcoal, notwithstanding 
the shrinkage consequent to the fire, was brought into complete 
contact with the inclosing metallic surfaces by pressing the inte- 
rior cylinder further into the exterior one. 
" Thus prepared, the interior cylinder being made to touch one 
of the galvanic surfaces, a w'ire brought from the other galvanic 
surface into contact with the outside cylinder, was not affected in Hare's Calorimotor. 
609 
the least, though the slightest touch of the interior one caused 
ignition. The contact of the charcoal, with the containing metals 
probably took place throughout a superficies of four square 
inches, and the wire was not much more than the hundreth part 
of an inch thick, so that unless it were to conduct electricity about 
forty thousand times better than the charcoal, it ought to have 
been heated; if the calorific influence of this apparatus result from 
electrical excitement." 
To meet you, however, on the very ground which you have 
chosen, I must first quote Dr. Bostock's account of the experiment, 
of which, it would seem, you consider mine to be an extension ; 
and the passage in my memoir, in which the latter is described. 
" Dr. Wollaston constructed a very curious apparatus, which 
he calls an elementary galvanic battery, the object of which is to 
exhibit the most minute arrangement of electrical substances, by 
which visible ignition can be produced. The smallest that he has 
constructed, consists of a thimble without its top, flattened, until 
its sides were about one-fifth of an inch asunder; a small plate of 
zinc was then contrived to be fixed within the thimble, but with- 
out touching it, and a proper appendage of platina wire was added. 
The zinc plate was less than three-fourths of an inch square, and 
even when water was employed that contained one-fiftieth part of 
sulphuric acid, a platina wire of one three-thousandth part of 
an inch in diameter, and from one-thirtieth to one-fiftieth of an 
inch in length, was readily fused." 
The passage in my memoir above alluded to, is as follows: " I 
had observed that as the number of pairs in Volta's pile had been 
extended, and their size and the energy of interposed agents lessen- 
ed, the ratio of electrical effects to those of heat had increased till 
in De Luc's column they had become completely predominant; and 
on the other hand, when the pairs were made larger and fewer, 
(as in Children's apparatus) the energy of interposed agents not 
being lessened, the calorific influence had gained the ascendency. I 
was led to go further in this way, and to examine whether one pair 
of plates of enormous size, or what might be equivalent thereto, 
would not exhibit heat more purely, and demonstrate it equally 
with the electric fluid a primary product of galvanic combinations. 610 
Hare's Calonmotw. 
The elementary battery of( Wollaston, though productive of an 
evanescent ignition; was too minute to allow him to make the ob- 
servations which I had in view." 
How can an experiment designed for the examination of the 
heat moving powers of the largest galvanic pair ever made, be con- 
sidered as an extension of another, which has for its " object, the 
most minute arrangement of electrical substances, by which visible 
ignition can be produced?" Besides, an extension of the generating 
surfaces alters the character of the ignition. The phenomena of 
the minute battery of Wollaston, appear much more liable to be 
mistaken for those of electricity, than the sluggish movements of 
the calorific principle, as exhibited in a galvanic pair of the largest 
size. By such an apparatus, though inadequate to fuse a very 
small platina wire, I have seen a strip of tin plate, nearly four 
inches broad, kept at a gentle heat for a considerable time. 
Every galvanic observation or modification, subsequent to 
the use of the original elementary pair, may be said to have 
grown out of that contrivance. By multiplying such combi- 
nations, the agency of electricity in galvanism, was displayed. By 
lessening the original pair, Wollaston ascertained the curious 
result, that even when very minute, ignition may be effected by 
it. By enlarging it, I sought to show the phenomena inconsist- 
ent, with the idea that the ignition resulted merely from an electri- 
cal discharge. Commencing both from the same original point, 
we proceeded in opposite directions, and with different designs. 
The fact, that ignition might be produced by galvanism, having 
been long known, it was, in the examination of the characteris- 
tics of this ignition, with a view to the nature of its cause, that 
further elucidation was expected by me. Assuming the cause to 
be electricity, he neither suited his apparatus, nor directed his 
thoughts to such an investigation; while my apparatus, ex- 
pressly designed for this purpose, by magnifying results, made 
them more susceptible of scrutiny, and using charcoal as a test, I 
availed myself of the opportunity to demonstrate the existence of 
a decisive difference between the calorific agent in galvanism, and 
the fluid with which it had been identified by him. It were then 
very unfair to convey the idea, that my experimental enquiry was Hards Calorimotor. 
611 
nothing more than an extension of his. I have already shown, 
that this notion, could not, with propriety, be conveyed, with 
respect to my apparatus. 
Moreover it will be admitted that experiments derive much of 
their value from the hypothetical considerations, by which they are 
induced, or with which they are associated. You have described 
t-he theory which I have advanced as " new, plausible, and inge- 
nious." 
In the following passage in my memoir, it is briefly stated: 
" According to my view, caloric and electricity may be dis- 
tinguished by the following characteristics. The former per- 
meates all matter more or less, though with very different degrees 
of facility. It radiates through air with immeasurable celerity, and 
distributing itself through the interior of bodies, communicates a 
reciprocally repellent power, to atoms but not to masses. Elec- 
tricity does not radiate in or through any matter, and while it 
pervades some bodies as metals with almost infinite velocity; by 
others it is so far from being conducted that it can only pass 
through them by a fracture or perforation. Distributing itself 
over surfaces only, it causes reaction between masses, but not be- 
tween the particles of the same mass. The disposition of the 
last mentioned principle to get off by neighbouring conductors, 
and of the other to combine with the adjoining matter or to escape 
by radiation, would prevent them from being collected at the 
positive pole, if not in combination w'ith each other. Were it 
not for a modification of their properties consequent to some such 
union, they could not, in piles of thousands of pairs, be carried 
forwards through the open air and moisture, the one so well cal - 
culated to conduct away electricity, the other so favourable to the 
radiation of caloric. 
" Pure electricity does not expand the slips of gold leaf between 
which it causes repulsion, nor does caloric cause any repulsion 
between the ignited masses which it expands. But the compound 
fluid extricated by galvanic action which I shall call electro-caloric 
distributes itself through the interior of bodies, and is evidently 
productive of corpuscular repulsion, it is in this respect more 
allied to caloric than to electricitv. t 612 
Hare's Calorimotor. 
11 It is true that when common electricity causes the deflagration 
of metals, as by the discharge of a Leyden jar, it must be sup- 
posed to insinuate itself within them, and to produce a reaction 
between their particles. But in this case, agreeably to my hy- 
pothesis the electric fluid combines with the latent caloric pre- 
viously existing there, and adding to its repulsive agency, causes 
it to overpower cohesion." 
Agreeably to this doctrine, the mysterious difference between 
galvanism and electricity is explained, by supposing the former, 
the result of the joint action of caloric and the electric fluid, their 
ratio to each other in quantity varying according to the apparatus 
used to produce them. In De Luc's column, the electric fluid is 
presumed to be at a maximum, the caloric of course at a mini- 
mum; the phenomena being apparently those of mechanical elec- 
tricity, though the means of production are galvanic. 
In the pile of Volta, or the troughs of Cruickshank and others, 
both fluids are conceived to be active, the ratio of their quantities 
to each other according to the law, stated in the passage already 
quoted. 
To complete the illustration, a third form of apparatus was re- 
quisite, in which caloric should be at a maximum, electricity at a 
minimum. 
Your animadversions in the Recorder for April, are obviously 
intended to promulgate the impression that Children's Battery and 
Wollaston's had left nothing further to be desired. But as the 
characteristics of De Luc's column are, that the size of the gal- 
vanic surfaces shall be very diminutive, their number very great; 
to attain the opposite extreme, it was necessary to seek the 
smallest number, and the largest size that could be made to avail. 
Children's apparatus wanted the former characteristic; Wollas- 
ton's the latter; and though I was the first to supply this defici- 
ency, although my theory of galvanism which you call " plausible 
and ingenious," is as far as you know new, and it must be evident 
that the calorimotor grew up with, and had become a necessary 
prop to that hypothesis; you allege " If Professor H. therefore, 
wished to produce a very powerful evolution of heat without a 
concomitant production of electrical phenomena, his course of Hare's Calorimotor. 
613 
proceeding with a knowledge of the above facts was at once sim- 
ple and obvious." 
As even the discovery of the new world appeared simple and 
obvious to some persons after it had been accomplished by the 
great Columbus, an author must be monstrously vain and madly 
sanguine, who expects that his performances may not be viewed 
in the same way. The language you have here adopted might 
be employed to disparage discoveries which have gained the 
highest applause. You might have said when Nicholson and 
Carlile had effected the decomposition of water by the Voltaic 
pile, if Sir H. Davy wished to decompose substances in which 
the elements were more forcibly combined, " his course was at once 
simple and obvious," he had only to use an apparatus as much 
more extensive, as the decomposition was more difficult. If Dr. 
Black wished to ascertain whether any, and what principles were 
extricated during the calcination of lime-stone, " his course was at 
once simple and obvious," he had only to heat it in a retort, and 
catch the products. After a peculiar gas had thus been discovered 
in lime-stone, Dr. Priestley being desirous to learn whether there 
were not other kinds of gas in nature, " his course was at once 
simple and obvious;" be had only to subject other substances to 
the same process. When Watt had perfected the steam engine, 
and boats had been moved by paddles, if Fulton wished to propel 
them by steam, " his course was at once simple and obvious." 
The galvanic fluid as generated by Children's apparatus, per- 
meates and ignites charcoal. It is therefore a galvanic instrument 
of the middle class, and not analogous to the calorimotor. The 
vivacity of the ignition in Wollaston's battery may awaken some 
doubt whether the disproportion between the component princi- 
ples of the galvanic fluid, as excited by it, is at a maximum as in 
the case of a very large pair like mine. Hence the contrivances 
of these eminent chemists are not only in form unsuitable to be 
classed in the extreme, the opposite of that, in which we find 
De Luc's column; but the phenomena do not warrant such a 
classification. 
I adverted in my memoir to Wollaston's Elementary Battery, 
and the ignition produced by it; when stating the fact of my having 
Vol. III.-4 K 614 
Hare's Calorimotor. 
made, for the purpose of investigation, a larger pair than any 
used before. Independently of the peculiarities of such a pair, 
already mentioned, there is in the distribution of the surfaces, a 
novelty which may be better estimated by turning to the latter 
part of the paragraph already quoted from Bostock, He says, 
speaking of Wollaston: " In the formation of his minute apparatus 
this sagacious experimentalist made an observation of great im- 
portance in enabling us to produce as much effect as possible 
from the smallest quantity of materials. He remarks that the 
zinc plate should have a counterpart of copper opposed to each 
side of it; for in the usual arrangement, although both sides of 
the zinc are oxidated, that side only is efficient which has a cop- 
per surface opposed to if." Agreeably to this arrangement so 
very highly commended, there must be twice as much copper as 
zinc. In my apparatus, every zinc surface has its counterpart of 
copper excepting the last; though the quantity of the metals is the 
same. I have reasons in addition to these, for believing I have 
adopted a more efficient mode of using the same extent of surface, 
than had been devised before. 
In support of the following passage you adduce no authority, 
I aver it to be a statement not only groundless, but contradic- 
tory to Wollaston's own words, to facts that are well known, and 
to your own admission that my theory is as far as you know new. 
You say, " in conformity with those principles, Dr. Wollaston 
constructed an apparatus of two plates only, and found that by 
thus lessening the number of the plates, although very small in size, 
heat was powerfully evolved without a proportional production of 
electrical effect." So far is Dr. Wollaston from distinguishing 
the heat produced by his apparatus from the electrical effect, that 
he considers it an electrical effect. He is the author of an ex- 
periment to show that the galvanic, and electric fluids are the 
same, the latter requiring to be emitted from an impalpable point. 
Had he made the distinction you allege, he had anticipated 
my hypothesis; the fundamental basis of which is, that the igni- 
tion of wire, by the calorimotor results from a current of caloric, 
not of electricity. The diffidence which qualifies your commen- 
dations with the words, " as far as I know," would never have Hare's Calorimotor. 
615 
operated with better advantage to yourself than when writing 
the above mentioned account of Wollaston's hypothetical infer- 
ences. Let Wollaston speak for himself. Annals of Philosophy, 
vol. 6. page 209. He thus expresses himself in a letter to the 
editor: 
" Dear Sir-I now send you a description of a small battery 
which I shewed you some time since, and shall feel obliged by 
the insertion of it in your Annals. Since the ignition of metallic 
wires is rather instructive with respect to the vast quantity of elec- 
tricity evolved during the solution of metal, I made three years 
since a series of experiments for the purpose of ascertaining the 
most compendious form of apparatus by which visible ignition 
might be shewn. 
" The result of these trials was, that a single plate of zinc one 
inch square, when rightly mounted, is more than sufficient to ig- 
nite a wire of platina even when the acid employed is very dilute." 
He says again in the last paragraph of the same letter, " Al- 
though in this description I have mentioned a wire 1 of an inch 
in diameter, I am doubtful whether this thickness is the best, I 
am however pursuaded that nothing is gained by using a finer 
wire; for though the quantity of matter to be heated, be thus 
lessened, the surface by which it is cooled does not diminish in 
the same ratio, so that when the cooling power of the surround- 
ing atmosphere is the principal obstacle to ignition, a thicker 
wire which conveys more electricity in proportion to its cooling 
surface, will be more heated than a thin one, a fact which I not 
only ascertained by trials on these minute wires, but afterwards 
took occasion to confirm on the largest scale by means of the 
magnificent battery of J/r. Children in the summer of 1813." 
Let me next cite the impressions of an editor, who does not 
write, on what he does not understand. " Dr Wollaston's ele- 
mentary galvanic battery described in a late number of the Jin- 
nais of Philosophy, constitutes a discovery of considerable impor- 
tance. It demonstrates the quantity of electricity which is dis- 
engaged during the chemical action of acids on metals, and there- 
by serves to throw much additional light upon the still obscure 616 
Hare's Calorimotor. 
theory of galvanism."* It is unnecessary to state the only deduc- 
tion which can arise from a comparison of these quotations, with 
that above made from your critique. 
The following statement is equally unfounded: "Thomsdorf 
Thenard, Fourcroy, Vauquelin, and particularly Children, have 
demonstrated that the electrical action is not increased by the in- 
crease of the size of the plates, but by the increase of the num- 
bers of pairs, and that on the contrary the evolution of heat is in 
creased with the size of the plates." 
Since the simple galvanic combination of Wollaston was sup- 
posed to afford instruction by the quantity of electricity given out, 
more complex combinations which by your own premises are 
more highly electrical, could not but be viewed in the same way 
The reason given by Dr. Wollaston in the passage above quo- 
ted, why a large wire will be more easily heated than a small 
one is, that it " conveys more electricity," and he has been con- 
firmed in this explanation " by means of the magnificient battery 
of Mr. Children." 
Is it not then evident that he considered electricity as the com 
mon cause of the heat in both bis battery, and that of Children 
If evidence be required of Children's opinion, let us turn to Dr 
Thomson's account of this battery. In Annals of Philosophy, vol. 
7. p. 11. he tells us, " The order in which metallic wires con- 
necting the two poles of this battery became red hot, was as fol- 
lows: 
Platinum 
Iron 
Copper 
Gold 
Zinc 
Silver 
" ,Mr. Children conceives, that the metals conveying electricity, 
became red hot inversely as their conducting power." Sir Hum- 
phrey Davy, in mentioning a large battery of Mr. Children, says 
Cl This battery, when in full action, had no more effect on water 
or on the human body, than one containing an equal number oi 
small plates; but when the circuit was made through metallic 
wires, the phenomena were of the most brilliant kind."f The 
rationale of this difference is, according to the same author, that 
■ Thomson's Annals 
Davy's Elements) p. 84. Hare's Calorimotor. 
617 
" the quantity in the small plates is as much, or more, than such 
imperfect conductors as water, and the human body can carry off 
by a small surface, whilst better conductors, can transmit the 
whole quantity afforded by the large plates, even when used in 
very thin lamina or wires."* 
From these passages it must be evident that Sir H. Davy con- 
siders both the ignition produced by a few large pairs, and the 
shock or decomposition resulting from many small ones, as the ef- 
fect of the same electric fluid, in quantity greater in the first case, 
in the last more intense. It will be found on consulting The- 
nard, that he has no other conception, than that all the effects of 
the pile result from the electricity which it generates or puts in 
motion. 
It is then undeniable, that the very authors whom you errone- 
ously cite, as having demonstrated that heat might be produced by 
galvanic apparatus without a proportional production of electrical 
effect, really consider the heat thus produced, as an electrical ef- 
fect, and of course, had not discovered it to be otherwise. Hence, 
correcting one of your quotations, it would read thus: " Heat and 
electrical effect, was evolved without a proportional production of 
electrical effect!!!" 
Experimental novelties have a two-fold value; first, as they add 
to that captivating splendour to which science owes so much of 
its power, in affording innocent and rational amusement; and se- 
condly, as they tend to create new distinctions, either between facts 
or principles, previously confounded. Those who have witnessed 
the combustion of wire by the calorimotor in its improved state of 
two uninsulated pairs, with the attendant phenomena of the inflam- 
ed hydrogen, allege that it affords one of the most splendid specta- 
cles in the chemical course, especially when compared with the 
simplicity of the process, and the facility of repetition. I submit it 
to my pupils to say how far any experiment with a thimble, and an 
almost inconceivably small wire, can ever, in this respect, come 
in competition with those which I showed them by means of the 
instrument in question. According to the second view of the sub- 
ject, I deem it of more importance to have ascertained, that a 
* Traite de Chimie. 618 
Harels Calorimotor. 
large galvanic pair, or even two uninsulated pairs, will not igmte 
charcoal, than that a small pair will ignite wire. The first men- 
tioned experiment distinguishes the fluid put in motion by one or 
two uninsulated pairs, from that evolved by the Voltaic pile, which 
the latter does not.* 
My theory of galvanism has been republished in some of the 
most respectable journals in Europe, as well as in this country, 
without any idea being excited, that I have not, as you would in- 
sinuate, " given unto Caesar, the things that are Caesar's;" an in- 
junction originally intended to sanction the payment of a tribute 
actually required by Caesar, and in a coin carefully ascertained 
by competent judges to bear his stamp. But it was not designed 
to authorize the officious and unskilful to render unto Caesar, 
things, which Caesar had not demanded of them, which he would 
despise as coming from them, and which might, for aught they 
could judge, bs the property of another. 
Wollaston is too well fortified by his splendid genius and ex- 
tensive acquirements; too well surrounded by his scientific com- 
peers, to require the aid of your eloquence or erudition, to guard 
him from the consequences of any wrong which I have the power 
or disposition to commit. And I doubt, if your readers will feel 
themselves indebted to you, for deviating from the obvious duty of a 
recorder of original papers and intelligence, in order to commu- 
nicate the opinions or misconceptions of yourself or your advisers, 
on the subject of my calorimotor. 
* For the information of readers who may not have witnessed this 
spectacle, I beg leave to state, that by the time the calorimotor is com- 
pletely immerged in the acid solution, the wire in the forceps is rendered 
white hot, and takes fire, emitting the most brilliant sparks. In the interim, 
an explosion usually gives notice of the extrication of hydrogen in a quantity 
adequate to reach the burning wire. Immediately after the explosion, the hy- 
drogen is reproduced with less intermixture of air, and rekindles, corruscat- 
ing from among the twenty interstices, and passing from one side of the ma- 
chine to the other, in opposite directions and at various times, so that the 
combinations are innumerable. The flame assumes various hues, from the so- 
lution of more or less of the metals, and a froth apparently on fire, rolls over 
the sides of the recipient. When the calorimotor is withdrawn from the acid 
solution, the surface of this fluid for many seconds, presents a sheet of fiery 
foam. Hare's Calorimotor. 
619 
Since writing the above, I find from the following observations 
of the celebrated Dr. Thompson, that he considers my apparatus 
as a " new modification of the galvanic battery." 
" Galvanism.-Dr. Hare, Professor of Chemistry in the Medical 
Department of the University of Pennsylvania, has published (in 
a paper to be found in the Annals of Philosofihy^iN. 176,) a theory 
of galvanism differing considerably from all those hitherto start- 
ed. According to him, the galvanic fluid is a compound of calo- 
ric and electricity. The electricity is increased by the number 
of pairs of plates, and when this number is very great, as in De 
Luc's column, the calorific effects become evanescent. The calo- 
ric is evolved by the increase of the surface, and he has shown 
that it may be very intense, when only a single pair of plates, or 
what is equivalent to it, is used. He has given us a drawing of a 
galvanic battery constructed on this principle, which produces 
intense ignition without any electrical phenomena. 
" As I have not yet had an opportunity to study the phenomena 
exhibited by this new modification of the galvanic battery, I 
should consider it as improper to make any remarks on Dr. 
Hare's ingenious hypothesis at present. What I have to say on 
the subject, therefore, I shall reserve for another opportunity."- 
Thomson's Annals of Philoso/ihij. 
EXPLANATION OF THE PLATE. 
A a, Fig. 1st, two cubical vessels, 20 inches square, inside, b b b b a frame 
of wood containing 20 sheets of copper, and 20 sheets of zinc, alternating 
with each other, and about half an inch apart. T T 11 masses of tin cast 
over the protruding edges of the sheets which are to communicate with 
each other. Fig. 2, represents the mode in which the junction between the 
various sheets and tin masses is effected. Between the letters z z, the zinc 
only is in contact with the tin masses. Between c c the copper alone touches. 
It may be observed, that, at the back of the frame, ten sheets of copper be- 
tween c c, and ten sheets of zinc between z z, are made to communicate, 
by a common mass of tin extending the whole length of the frame, between 
T T : but in front, as in Fig. 1, there is an interstice between the mass of tin 
connecting the ten copper sheets, and that connecting the ten zinc sheets. 
The screw forceps, appertaining to each of the tin masses, may be seen on 
either side of the interstice : and likewise a wire for ignition held between 
them. The application of the rope, pulley, and weights, is obvious. The 
swivel at S permits the frame to be swung round and lowered into water in 
the vessel a, to wash off the acid, which, after immersion in the other vessel. 620 
Dr. Eberle's Reply. 
might continue to act on the sheets, encrusting them with oxide. Between 
pp there is a wooden partition which is not necessary, though it may be be- 
neficial. 
Fig. 3, represents an apparatus alluded to, page 419.* It consists of a cou- 
ronne des tasses, reduced to a form no less compact than that of the trough. 
Hollow parallelepipeds of glass are substituted for tumblers or cells. The 
plates are suspended to bars counterpoised like window-sashes. 
The advantages are as follows. The material is one of the best non-con- 
ductors, is easily cleansed, and is the most impervious to solvents. The 
fracture of one of the cups is easily remedied by a supernumerary. They 
may be procured (as in the United States) where porcelain cannot be had. 
The shock from 300 pairs is such as few will take a second time. Some of 
the effects have already been stated.f 
At Fig. 4, one of the hollow glass parallelepipeds on an enlarged scale 
is represented. 
Remarks by Dr, Eberle. 
I have not erased a single word from the above reply, that 
the offended professor, may not imagine that I deprecate the 
severity of his animadversions, any more than I dread the force 
and acuteness of his reasoning. 
The statement given by the professor, relative to the conver- 
sation that passed between us, is, I explicitly aver, erroneous, as 
to its import. I would not, however, be thought to believe, or 
wish to insinuate, that the misrepresentation arose from design. 
I am certain, that this cannot have been the case. Soon after 
the publication of my remarks, on his calorimotor, he accosted 
me, in nearly the following words: " If the person, who wrote 
the remarks on my calorimotor, published in the last number of 
the Recorder, had wished to do me justice, he would have quoted 
this passage," (at the same time pointingout the passage alluded 
to,) " instead of the one, which he did quote." I replied, that I 
wrote the article myself; and, in order to let him know, that the 
opinion, I expressed in that article, is entertained also by others, 
as competent at least, to give an opinion upon subjects of this 
kind as himself, I stated, that not wishing to rely wholly on my 
* Of Vol. II. Hen. Chemistry. 
+ The glasses may be had by applying to Edw. A. Pearson, No. 71 Comhill, Boston. Fy. 2. 
Fit/. 2. 
Fubli^hed bv RJJc^Fer .Vf> J10 Srdbiub S'Phibid* 
Erwwtd bu IVarr J? 
CALO Bl Al OB'OIL 
Fie.l. 
Fia. 1. Ftg. I. 
Fig. I. 
Fig. 5. 
Fig. 3. 
Fig. 2. 
Published In/ It.De^iher <hr° IIO Walnut S'. Fhilad" 
Fnffravcd ti/TyVan'F Dr. Eberle's Reply. 
621 
own judgment in the present case, I had consulted several com- 
petent gentlemen on the point in question, and that they con - 
curred with me in opinion. I further stated, that I would again 
examine into the subject, and if I should find myself in error, I 
would, in a succeeding number of the Recorder, cheerfully correct 
my mistake. 
Having, however, my opinion confirmed, rather than shaken 
by a second examination of the professor's pamphlet, I again, in 
reply to some observations of Dr. Hall on this subject, stated my 
conviction, that his apparatus is in fact and principle, nothing 
more, than an extension of Wollaston's elementary battery. This 
opinion, I supported with arguments, which the professor labours 
to invalidate, in the above reply. Let us see how he has suc- 
ceeded. 
In the first place, then, he alleges, that his apparatus consists 
of two pair of plates in one recipient, whilst Wollaston's consists 
only of one pair, in one recipient, and that therefore, his appa- 
ratus cannot be considered as an extension of the latter. Let us 
try this argument. Wollaston constructed an apparatus, in which 
there are only two minute galvanic surfaces; this apparatus evolves 
an intense heat, without a concomitant production of electrical 
effect. Dr. Hare at first constructed one consisting of two large 
galvanic surfaces; and, as might have been expected from the ex- 
periments of Children, and from the effects of the elementary 
battery of Wollaston, very intense heat was evolved by it. So 
far, then, the professor's calorimotor was truly and obviously 
nothing more, than an extension of Wollaston's battery. They 
were strictly analogous, both in effect and in principle of construc- 
tion; the one was an apparatus of twominute, and the other, one of 
two large plates. But, he did not stop here; he made a duplica- 
tion of his first apparatus;-that is, he combined two simple calo- 
rimotors, each having two galvanic surfaces, in such a manner, as 
to produce one, of four galvanic surfaces, and capable of being 
immersed, in the same recipient. By this contrivance, then, he 
obtained the combined effects of two simple apparatus, constructed 
on the principle of Wollaston's battery. It must not be forgotten 
however that a mere duplication of a simple apparatus, is insuffi- 
Vol. III.-4 L 622 
Dr. Eberle's Reply. 
cient to alter the principle of its action, or the analogy of its 
structure. If the professor were asked, to prove, that a double 
barrelled gun, is not in fact and in principle, an extension of a 
pistol, I am at a loss to know, by what mode of reasoning, he 
would attempt this, unless it should be, by arguments similar to 
those w hich he here employs, in order to prove that his calori- 
motor is not in fact, and in principle, an extension of Wollaston's 
battery. 
Again he says, " the action of a pair of galvanic surfaces was 
known, not only before the time of Wollaston, but anterior to that 
of Galvani himself. Hence, it must be evident, that it is only 
in size, arrangement, and application, that Wollaston's apparatus 
can possess originality. But, in all these points, I trust, the cha- 
racteristics of the calorimotor, are at least equally peculiar.*' 
What does this prove? certainly nothing more than that the pro- 
fessor's calorimotor differs in size, arrangement, and application, 
from Wollaston's. As to its unlikeness to all others in size and 
arrangement, I am not at all disposed to dispute. I never did in- 
timate any doubts on this score. I stated explicitly in my remarks, 
that as a mechanical contrivance, I thought it entitled to merit; 
and I am certain, that the professor will do me the justice to ac- 
knowledge, that I have never asserted it to be similar in sice, to 
that apparatus, of which I consider it an extension. The fact is, 
the principal reason why Wollaston's battery wras inapplicable to 
the purpose which Dr. Hare had in view', in the construction of 
his apparatus, according to his own confession, is, " that it was 
too minute to allow him to make the observations he had in view." 
He was therefore obliged to construct an apparatus of a larger size, 
on (he same principle, in order that he might apply it to his par- 
ticular purposes. It consequently differed in size, arrangement, 
and application from Wollaston's battery, and cannot therefore, 
according to Dr. H. be considered an extension of it. Let us 
try this logic. A. makes a pistol, B. wishes to shoot w'ild geese; 
he finds the pistol " too minute" for his purpose. He therefore 
" examines" w'hat effect " one enormous" barrel will have-whe- 
ther it will not make more noise, and carry a bullet further than 
the pistol. He finds it to do so; but he is still not satisfied; he Dr. Eberle's Reply. 
623 
Seeks to increase the efficacy of his large barrelled gun; he adds 
another barrel,-he constructs a gun of two " enormous" barrels, 
and it answers his purposes. Now, as this gun undoubtedly differs 
from the pistol in " size, arrangment, and application" it cannot 
be considered, according to the dialecticks of the professor, an 
extension of it. Quid vetat ridens discere verum? 
As to its application, I think I am warranted in asserting, that 
the calonmotor differs in no respect as a calorimotor or heat-mover, 
from Wollaston's battery. Both these apparatus are employed to 
evolve great degrees of heat; and both do so, by virtue of the 
same law of galvanic surfaces ;-that law, by which the elec- 
trical action of a battery is not increased by the increase of the 
size of the plates, but by the increase of the number of their 
pairs, whilst the heat-moving power is increased with the size of 
the plates, and the decrease of the number of pairs. It is upon 
the identity of effect, as heat-moving powers, depending on iden- 
tity of principle of construction, and by consequence, on identity 
of galvanic law, that I predicate the opinion I entertain of the 
perfect similarity in the essential characteristics of the tw'O instru- 
ments, and that I consider the calorimotor of Dr. Hare as differ- 
ing in nothing from the elementary battery of Wollaston but in 
external conformation, and that it is manifestly and truly, only an 
extension of it. He seems to lay much stress on the object which 
Wollaston had in view in the construction of his battery, and the 
theoretical notions he entertained respecting galvanism. He thinks 
that, as he himself had a different object in view in the construc- 
tion of his apparatus, it cannot be considered as arising out of 
Wollaston's. Can the purposes, for which an apparatus is design- 
ed, or the particular theory which it is intended to confirm, alter 
the nature of its construction, or the laws of its action? If Wollas- 
ton's theoretical notions relative to heat and electricity, differ from 
those of Dr. Hare, does it follow, that the elementary battery of the 
former, differs in the laws of its action and the principle of its 
construction, from the calorimotor of the latter? Certainly I may 
leave him to enjoy the triumph of such logic. 
It appears, by his own account, that in consequence of the expe- 624 
Dr. Eberle's Reply. 
riments of Children and De Luc, he was led to examine, whether 
by extending the principle which was demonstrated to exist by 
these experimentalists, he might not exhibit heat more purely by 
using " one pair of plates of enormous size, or what might be 
equivalent thereto. The elementary battery, he says, " of Wollas- 
ton was too minute to allow him to make the observations I had in 
view." Is lhis not, in fact, acknowledging that Wollaston's bat- 
tery wanted but extension, or increase of size, to render it a fit appa- 
ratus for the purposes Dr. Hare had in view? Wollaston's appara- 
tus consists of one pair of plates, but they are too small to produce 
sufficient effect for the purposes Dr. Hare had in view. He there- 
fore, very ingeniously, and with vast originality, " was led to go 
farther, and to examine what an apparatus of one pair of enormous 
plates" rvould produce. Having come to this original determi- 
nation, of using " two enormous plates, or what might be equi- 
valent thereto," instead of two very small ones, which were " too 
minute for the observations he had in view," he constructed an 
apparatus, which he thus describes. " Twenty copper and twenty 
zinc plates, about nineteen inches square, were supported vertically 
in a frame, the different metals alternating at one half distances 
from each other. All the plates of the same kind of metal, were sol- 
dered to a common slip, so that each set of homogeneous plates form- 
ed one continuous metallic superficies." This then was the first step 
in the professor's brilliant discovery. By a subsequent one, he ex- 
tended this apparatus, so that by bringing two of this first and simple 
form together, in such a manner as to enable them to be immersed 
at once, in the same recipient, he obtained the combined effects of 
two simple elementary batteries. In this, I willingly confess, there 
is displayed considerable mechanical ingenuity. As a mechanical 
contrivance, it has no small degree of merit. But I maintain, that, 
as a philosophical contrivance, it is a direct and obvious deriva- 
tion from Wollaston's battery. All the essential characteristics of 
their action and construction are virtually identical. If Dr. Hare's 
calorimotor produces an intense heat, without a proportionate de- 
gree of-concomitant electrical effect, it is from the same principle 
precisely, that Wollaston's battery produces a similar effect. If Dr. Eberle^s Reply. 
625 
the effects of Dr. Hare's apparatus are greater than those of Wok 
laston's, it is because the former is an extension of the latter. 
He asks, " how can an experiment designed for the examination 
of the heat-moving powers of the largest galvanic pair ever made, 
be considered as an extension of another, which has for its objects, 
the minutest arrangement of electrical substances, by which visi- 
ble ignition can be produced?" How can it not? Surely if two 
u enormous plates" are employed to evolve a powerful degree of 
heat, there is no contradiction in calling it an extension of another 
experiment in which heat is evolved by two plates of the smallest 
size. 
In the following quotation, the professor again unwittingly ad' 
mits the justice of my remarks relative to his calorimotor. " By 
lessening the original pairs, Wollaston ascertained the curious re- 
sult, that even when very minute, ignition might be effected by it. 
By enlarging it, I sought to shew the phenomena, inconsistent with 
the idea that the ignition resulted merely from electrical dis- 
charges." 
Upon the statement I made, in my remarks on the calorimotor, 
that Wollaston found that heat was powerfully evolved by his 
elementary battery, without a concomitant production of electri- 
cal effect, Dr. Hare remarks: " So far from distinguishing the 
heat produced by his apparatus, from the electrical effect, 
Dr. Wollaston considers it as itself an electrical effect." This 
may be so; but the fact is, that heat was evolved without those 
effects which are usually denominated electrical or galvanic; and 
it is only with facts and not with the speculative opinions of Dr. 
W. or Dr. H. that we have to do on the present occasion. 
The professor then goes on and says, the following statement is 
equally unfounded. " Thornsdorf, Thenard, Fourcroy, Vauquelin, 
and particularly Children, have demonstrated that the electrical 
action is not increased by the increase of the size of the plates, 
but by the increase of the nnmber of pairs, and that on the con- 
trary the evolution of heat is encreased with the size of the 
plates." This statement, I am able to substantiate by the au- 
thority of an Editor, " who does not write on what he does not 
understand,"-one whom I am glad to find Dr. IL respects. 626 
Spalding's pamphlet on Scutellaria-Rejoinder. 
In the 70th, number of the Annals of Philosophy, page 137, 
we find the following paragraph: " Thornsdorf's discovery of 
the efficacy of large metallic plates in producing combustion, was 
the next step in the improvement of the galvanic apparatus. 
This discovery was verified by Fourcroy, Thenard, and Vauque- 
lin. These gentlemen found that the electrical action of the bat- 
tery was not increased by the increase of the size of the plates, 
but by the increase of the number of pairs; but the chemical ac- 
tion, as far as combustion is concerned, and as far as the decom- 
position of those bodies which are very difficult of decomposition 
is increased, w ith the size of the plates." This is the language of 
Dr. Thompson, a chemist, " who does not write about what he 
does not know," and yet Dr. Hare, who I presume writes about 
nothing but what he does know, says it is unfounded! I will leave 
him to settle this with Dr. Thomson. 
Dr. Hare seems to think, that as an editor of a Recorder of 
original communications and intelligence in medicine, I have de- 
viated from my duty in offering my opinion on his calorimotor. 
He moreover insinuates, that I am incompetent to give my opi- 
nion upon the subject which I have ventured to discuss. If the 
professor will look into the prospectus of our Journal, as well as 
into its contents, he will find that it is, as it has always been, a 
part of our plan to review7 books on medicine, and the collateral 
branches, freely and independently. As to my qualifications to give 
an opinion on this or any other subject, Dr. Hare must know more 
of me than he does, before I can allow him to decide.