VOL. LXXXIX.] PHILOSOPHICAL TKANSACTIONS. 503 



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, 

 on being heated or cooled, have been made ; and on this supposition, but without 

 however adopting 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, 

 on being frozen, is so considerable, that if this loss has no effect on its apparent 

 weight, it may be presumed that we shall never be able to contrive an experiment 

 by which we render the weight of heat sensible. Water, on being frozen, has 

 been found to lose a quantity of heat amounting to 140 degrees of Fahrenheit's 

 thermometer; or, which is the same thing, the heat which a given quantity of 

 water, previously cooled to the temperature of freezing, actually loses, on being 

 changed to ice, if it were to be imbibed and retained by an equal quantity of water, 

 at the given temperature, that of freezing, would heat iM40 degrees, or would raise 

 it to the temperature of (32° + 140) 1 62° of Fahrenheit's thermometer, which is 

 only 6o° short of that of boiling water; consequently, any given quantity of water, 

 at the temperature of freezing, on being actually frozen, loses almost as much heat 

 as, added to it, would be sufficient to make it boil. It is clear, therefore, that 

 the difference in the quantities of heat contained by the water in its fluid state, 

 and heated to the temperature of 6*1° p, and by the ice, in the experiments before 

 mentioned, was at least nearly equal to that between water in a state of boiling, 

 and the same at the temperature of freezing. 



But this quantity of heat will appear much more considerable, when we con- 

 sider the great capacity of water to contain heat, and the great apparent effect 

 which the heat that water loses on being frozen would produce, were to be imbibed 

 by, or communicated to any body whose power of receiving and retaining heat is 

 much less. The capacity of water to receive and retain heat, — or what has been 

 called its specific quantity of latent heat, — has been found to be that of gold as 1000 

 to 50, — or as 20 to 1 ; consequently, the heat which any given quantity of water 

 loses on being frozen, — were it to be communicated to an equal weight of gold, at 

 the temperature of freezing, the gold, instead of being heated 1(52°, would be 

 heated 140 X 20 = 2800°, or would be raised to a bright red heat. 



It appears therefore to be clearly proved, by my experiments, that a quantity of 

 heat equal to that which 4214 grs., or about 94- oz. of gold, would require to heat 

 it from the temperature of freezing water to be red-hot, has no sensible effect on a 

 balance capable of indicating so small a variation of weight as that of t ooo -tnnr P ar t of 

 the body in question ; and if the weight of gold is neither augmented nor lessened by 

 one millionth part, on being heated from the point of freezing water to that of a 



