462 Life of Count Rumford. 



became persuaded that the motion of these liquids was 

 occasioned by their particles going individually and in suc- 

 cession to give off their heat to the cold side of the tube, 

 and he set himself to contrive experiments to prove 

 beyond all doubt that these and probably all other 

 liquids are, in fact, non-conductors of heat. He inferred 

 that if heat is propagated in liquids only in consequence 

 of the internal motions of their particles, then every- 

 thing which tends to obstruct those motions ought cer- 

 tainly to retard the operation, and render the propaga- 

 tion of heat slower and more difficult. It was his object 

 to verify this inference. He contrived, therefore, to 

 make a certain quantity of heat pass through a certain 

 quantity, first, of pure water, confined in a certain tube; 

 and then, repeating the experiment with the same appa- 

 ratus, instead of using pure water, he mixed with it a 

 small quantity of eider-down, which, without altering 

 the chemical properties of the water or impairing its 

 fluidity, served merely to embarrass the motions of the 

 particles of the water in transporting the heat. The 

 Count gives a very minute description of his apparatus, 

 and of the method of his experiments. Remembering 

 his experience in eating hot apple-pies, he determined 

 to test whether apples, which he knew were composed 

 almost entirely of water, really possess a greater power 

 of retaining heat than does pure water. He reduced a 

 quantity of stewed apples, by washing and soaking, to 

 a fibrous remainder, which proved to be less than one 

 fiftieth part of the whole mass, showing that more than 

 forty-nine fiftieths of an apple is little else than pure 

 water. The experiment proved that the conducting 

 power of water, with regard to heat, was impaired when 

 the bulb of his thermometer was surrounded with a 



