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17m An Inquiry concerning the © 
As I knew that the conduéting power of mercury, with 
refpeét to heat, was confiderably greater than either that of 
water or that of fpirit of wine, while its capacity for receiv- 
ing heat is much lefs than that of either of them, I did not 
think it neceffary to inclofe a thermometer in the bottle C, 
which contained the mercury; for it was evident that when 
the contents of the other two bottles fhould appear, by their 
thermometers, to have arrived at the temperature of the me- 
dium in which they were expofed, the contents of the bottle 
C could not fail to have acquired it alfo, and even to have 
arrived at it before them; for, the time taken up in the heat- 
ing or in the cooling of any body, is, cateris paribus, as the 
capacity of the body to receive and retain heat direé#ly, and 
as its conduéting power inver/ely. 
The bottles were fufpended to the balance by filver wires, 
about two inches long, with hooks at the ends of them ; and, 
in removing and changing the bottles, I took care not ta 
touch the glafs. I likewife avoided, ypon all occafions, and 
particularly in the cold room, coming near the balance with, 
my breath, or touching it, or any part of the apparatus, with 
my naked hands. 
Having determined that water does not acquire or lofe any 
weight upon being changed from a ftate of fluidity to that of 
ice, and vice verfd, I fhall now take my final leave of a fub- 
je&t which has long occupied me, and which has coft me 
much pains and trouble ; being fully convineed, from the 
refults of the above-mentioned experiments, that if heat be 
in fact a fubjlance, or matter, (a fluid /wi generis, as has been 
fuppofed,) which, paffing from one body to another, and 
being accumulated, is the immediate caufe of the pheno- 
mena we obferve in heated bodies, (of which, however, I 
cannot help entertaining doubts,) it muft be fomething fo 
infinitely rare, even in its moft condenfed ftate, as to baffle all 
our attempts to difcover its gravity. And, if the opinion which 
has been adopted by many of our ableft philofophers, that 
heat is nothing more than an inteftine vibratory motion of 
the conftituent parts of heated bodies, fhould be well founded, __ 
it is clear that the weights of bodies can in nowife be affected 
by. fuch motion. Py 
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