192 Count Rumford's Inquiry concerning 
heated bodies, (of which, however, I cannot help entertaining 
doubts,) it must be something so infinitely rare, even in its most 
condensed state, as to baffle all our attempts to discover its gra- 
vity. And, if the opinion which has been adopted by many of 
our ablest philosophers, that heat is nothing more than an in- 
testine vibratory motion of the constituent parts of heated bodies, 
should be well founded, it is clear that the weights of bodies can 
in no wise be affected by such motion. 
It is, no doubt, upon the supposition that heat is a substance 
distinct from the heated body, and which is accumulated in it, 
that all the experiments which have been undertaken, with a 
view to determine the weight which bodies have been supposed 
to gain, or to lose, upon being heated or cooled, have been 
made ; and, upon this supposition (but without, however, adopt- 
ing it entirely, as I do not conceive it to be sufficiently proved,) 
all my researches have been directed. 
The experiments with water , and with ice, were made in a 
manner which I take to be perfectly unexceptionable; — in 
which no foreign cause whatever could affect the results of 
them ; — and the quantity of heat which water is known to part 
with, upon being frozen, is so considerable, that if this loss has 
no effect upon its apparent weight, it may be presumed that we 
shall never be able to contrive an experiment by which we can 
render the weight of heat sensible. 
Water, upon being frozen, has been found to lose a quantity 
of heat amounting to 140 degrees of Fahrenheit's thermo- 
meter ; or, — which is the same thing, — the heat which a given 
quantity of water, previously cooled to the temperature of 
freezing, actually loses, upon being changed to ice, if it were to 
be imbibed and retained by an equal quantity of water, at the 
