on the Subject of Heat. 209 



heating of a body is caused by the accumulation of this 

 substance in the body, it follows naturally that the 

 body must be heavier when it is warm than when it is 

 cold. Some natural philosophers have sought to deter- 

 mine this point ; I feel confident, however, that no one 

 has made more decisive experiments in this direction 

 than myself.* 



I was provided with excellent instruments, and spared 

 neither trouble nor expense to arrive, by means of my 

 experiments, at a certain and convincing result. The 

 results obtained are, in few words, as follows. 



I had a ball of very fine gold made, and weighed it 

 when perfectly cold, and again after heating it to such a 

 temperature that it was on the point of melting. Fur- 

 ther, I weighed a considerable amount of water, which I 

 had sealed hermetically in a flask, first in its liquid 

 state, then at the temperature of melting ice, then as 

 actual ice, and then again at its original temperature. 

 All these experiments convinced me that the weight 

 of a body is not changed in the least by heat. 



Now although, as a consequence of the results of 

 these experiments, I was only still more strengthened in 

 those doubts which a number of other natural phenom- 

 ena had raised in my mind with regard to the existence 

 of caloric, still I saw at the same time only too well 

 that the essential point of the controversy was far from 

 being decided thereby. The defenders of caloric would 

 still object (as they have actually done) that this sub- 

 stance is far too subtile to be weighed upon our ordi- 

 nary balances. 



* A paper in which are described in detail all my experiments upon this sub- 

 ject may be found in the Philosophical Transactions for 1799. See also page 1 ot this 

 volume. 



VOL. II. 14 



