i8 6 
Count Rumford’s Inquiry concerning 
remained for such a considerable length of time in the heat and 
cold to which they were exposed, I flattered myself that the 
quantities of moisture remaining attached to their surfaces, 
could not be so different as sensibly to effect the results of the 
experiments. — But, in regard to this last circumstance, I after- 
wards found reason to conclude that my opinion was erroneous. 
Admitting the fact stated by Dr. Fordyce, — (and which my 
experiments had hitherto rather tended to corroborate than to 
contradict,) — I could not conceive any other cause for the aug- 
mentation of the apparent weight of water, upon its being frozen, 
than the loss of so great a proportion of its latent heat as that 
fluid is known to evolve when it congeals ; and I concluded, that 
if the loss of latent heat added to the weight of one body, it must 
of necessity produce the same effect on another, and consequent- 
ly, that the augmentation of the quantity of latent heat must, — 
in all bodies, — and in all cases, — diminish their apparent weights. 
To determine whether this is actually the case or not, I made 
the following experiment. 
Having provided two bottles, as nearly alike as possible, and in 
all respects similar to those made use of in the experiments above- 
mentioned, into one of them I put 4012,4,6 grains of water, and 
into the other an equal weight of mercury; and, sealing them her- 
metically, and suspending them to the arms of the balance, I 
suffered them to acquire the temperature of my room, 6i°; then, 
bringing them into a perfect equilibrium with each other, I re- 
moved them into a room in which the air was at the tempera- 
ture of 34°, where they remained twenty-four hours. — But there 
was not the least appearance of either of them acquiring, or 
losing, any weight. 
Here it is very certain, that the quantity of heat lost by the 
