\0Q Chemical Ph'dosophii. [Chap. II. 



ground than any Other, and to have b}; far the great- 

 est number of advocates. 



The doctrine of radiant heat, or that heat resem- 

 bles light in being propagated in rays, or right 

 lines, was, in some measure, knov/n to Mariotte, 

 Lambert, and Scheele ; \mt Vvas more clearly esta- 

 blished afterwards by the experiments of Saussure, 

 Pictet, and count liumford; and, fmally, the laws 

 of this propagation were more fully developed and 

 laid down by Dr. Herschel, in his celebrated ex- 

 periments on light and he- :.t before mentioned. 



Count Rumford concluded, from his experiments, 

 that fluids do not conduct heat ; but he ascribes to 

 them what he denominates a carrying power: in 

 other words, he supposes, that, in heating fluids, 

 each particle must come in succession to the source 

 of heat, and receive its portion ; but that, among 

 the particles themsehes, all interchange and com- 

 munication of heat is impossible. The experi- 

 ments by which he considers himself as having 

 established this point are certainly striking, and 

 their results highlj^ curioirs; but the justness of his 

 conclusions has been called in question, and philo- 

 sophers do not seem to view his decision as abso- 

 lute and fmal. Further experiments must decide 

 the controversy. 



The first person who made experiments oxi freez- 

 ing mixtures, was Mr. Fahrenheit, of Amsterdam, 

 at an early period of the' eighteenth century. J3ut 

 the subject was mucli more com])Ietely investigated 

 by Mr. Walker, in a paper published in the PJii- 

 losophical Transactions for 179'5. Since that time 

 several curious additional experiments have been 

 ma'le by professor Lowitz, of Petersburg ; parti- 



