the Weight ascribed to Heat. 15 



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 unexception- 

 able, 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 Fahren- 

 heit'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 upon 

 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 it 140 de- 

 grees, or would raise it to the temperature of (32 -J- 

 140) 172 of Fahrenheit's thermometer, which is only 

 40 short of that of boiling water ; consequently, any 

 given quantity of water, at the temperature of freez- 

 ing, upon 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 quan- 

 tities of heat contained by the water in its fluid state 

 and heated to the temperature of 61 F., and by the 

 ice, in the experiments before mentioned, was very 



