the Weight ascribed to Heat . 191 
As I knew that the conducting power of mercury, with 
respect to heat, was considerably greater than either that of 
water, or that of spirit of wine, while its capacity for receiving 
heat is much less than that of either of them, I did not think 
it necessary to inclose a thermometer in the bottle C, which 
contained the mercury ; for it was evident, that when the con- 
tents of the other two bottles should appear, by their thermo- 
meters, to have arrived at the temperature of the medium in 
which they were exposed, the contents of the bottle C could 
not fail to have acquired it also, and even to have arrived at it 
before them; for, the time taken up in the heating or in the 
cooling of any body, is, cceteris paribus, as the capacity of the 
body to receive and retain heat, directly, and as its conducting 
power, inversely. 
The bottles were suspended to the balance by silver wires, 
about two inches long, with hooks at the ends of them ; and, 
in removing and changing the bottles, I took care not to touch 
the glass. I likewise avoided, upon all occasions, and particu- 
larly 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 lose any 
weight, upon being changed from a state of fluidity to that of 
ice, and vice versa, I shall now take my final leave of a subject 
which has long occupied me, and which has cost me much 
pains and trouble ; being fully convinced, (from the results of 
the above mentioned experiments,) that if heat be in fact a sub- 
stance, or matter, — a fluid sui generis, as has been supposed, — 
which, passing from one body to another, and being accumu- 
lated, is the immediate cause of the pine nomen a we observe in 
C c 2 
