Life of Count Rumford. 463 



quantity of stewed apples. He illustrates his experi- 

 ments by tables. The results showed that heat is 

 propagated in fluids by the transporting of their par- 

 ticles, which are put in motion by the change pro- 

 duced in their specific gravity by the change of tempera- 

 ture, and that there is no interchange of their heat among 

 the particles of the same fluid. 



Finding that the propagation of heat in fluids might 

 be obstructed both by diminishing their fluidity and 

 by obstructing the motion of their particles, the Count 

 next engaged in. experiments to test the comparative 

 effects of these two causes, permitting only one of them 

 to act at the time of each trial. To ascertain the effects 

 produced by diminishing the fluidity of water, he boiled 

 with it a small quantity of starch ; and to determine the 

 effects produced by merely embarrassing the water in its 

 motions, he mixed with it the same proportion of eider- 

 down as before of starch. The results he compares in 

 tables with his experiments made with pure water, and 

 with water infused with baked apples, to show the differ- 

 ent measurements of time consumed by the heat in 

 passing into the thermometer. 



The Count concluded that he had thus proved, almost 

 to a demonstration, that heat is propagated in water in 

 consequence of its internal motions ; that is, that it is 

 transported or carried by the particles of that liquid, 

 and that it does not spread or expand in it as had gen- 

 erally been imagined. He had thus proved concerning 

 water the same scientific fact which he had announced in 

 a paper published in the Philosophical Transactions, in 

 1792, concerning the propagation of heat in air. " The 

 conducting power of water was found to be nearly, if 

 not quite, as much impaired by the mixture of eider- 



