2io Historical Review of Experiments 



After I had long meditated upon a way of putting 

 this interesting problem entirely out of doubt by a 

 perfectly conclusive experiment, I thought finally that 

 I had discovered it, and I think so still. 



I argued that if the existence of caloric was a fact, it 

 must be absolutely impossible for a body or for several 

 individual bodies, which together made one whole, to 

 communicate this substance continuously to various 

 other bodies by which they were surrounded, without 

 this substance gradually being entirely exhausted. 



A sponge filled with water, and hung by a thread in 

 the middle of a room filled with dry air, communicates 

 its moisture to the air, it is true, but soon the water 

 evaporates and the sponge can no longer give out moist- 

 ure. On the contrary, a bell sounds without inter- 

 ruption when it is struck, and gives out its sound as 

 often as we please without the slightest perceptible loss. 

 Moisture is a substance ; sound is not. 



It is well known that two hard bodies, if rubbed to- 

 gether, produce much heat. Can they continue to pro- 

 duce it without finally becoming exhausted ? Let the 

 result of experiment decide this question. 



It would be too tedious to describe here in detail 

 all the experiments which I undertook with a view 

 of answering in a decisive manner this important and 

 disputed question. They may be found in my memoir 

 On the Source of Heat excited by Friction. I have 

 had it printed in the Philosophical Transactions for 

 the year 1798 ; still these experiments bear too close a 

 relation to my later researches on heat for me to omit 

 attempting at least to give the reader a clear idea of the 

 experiments and of their results. 



The apparatus which I used in these investigations 



