OJ^ ON THE NATURE OF HE>IT. 



for, according to the hypothesis, both the therniometer and 

 the ice radiate heat. The thermometer T however radiateg 

 - . to the ice I more than the latter does to the thermometer ; 

 the ice therefore receives caloric, and will be dissolved; but 

 the ice also radiates caloric ; this will be reflected and con- 

 veyed to the thermometer, which will consequently main- 

 , tain a higher temperature, than if there were no ice, from 



which it could receive caloric. 

 CoontRum- ** Count Rumford, not admitting the existence of ca- 

 ford ascTkbes « \0y\q as a distinct matter, endeavours to explain the phe- 

 heat to undu- «. i- i <. i i i • o i i 



lations. *' nomena ot radiant heat from the hypothesis of undula- 



•' tions excited by bodies at a high temperature in an 

 " etherial medium," — The Stahlian theory accounted for 

 the phenomena of oxidation, while philosophers neglected 

 the agency of the atmospheric air in the operation ; and in 

 a similar manner the hypothesis of Count Rumford might 

 explain the radiation of heat and cold, could we forget the 

 PifFicultie^ in manifest influence of the " ambient air,'* Other difficulties 

 ihtehypothe- -^ ^^^j^ hypothesis would occur, in applying it to explain 

 the diflerences between solar and culinary heat; and in ac- 

 counting for the partial interception and partial transmis- 

 sion of culinary heat by transparent media. 



This partial transmission of culinary heat, and its distri- 

 bution in the prismatic spectrum, do not appear to admit 

 of explanation on the ingenious hypothesis of Mr, Leslie. 



With regard to other attempts, which have been made 

 to explain the radiation of cold, and to reconcile it to the 

 general theory, complete satisfaction may be obtained from 

 consulting Mr, Murray's work. 



3. Effects of caloric, 



Effictsofheat. The opinion respecting the mixture of material heat 

 arises chiefly from the considennion of the eff*ects, which 

 the comma ni cation of temperature occasions on the bulk 

 and form of bodies submitted to its action. The explana- 

 tion, which the hypothesis affords, of the immediate effects 

 of heat, is indeed often satisfactory ; yet, although it ap- 

 plies in many cases, it fails altogether in others ; and cannot, 

 I conceive, bear the test of a strict examination. 



Fxpartds bo- j. If the hvpothesja were true, exp'ansion ought invaria- 

 dies generally, ' bly 



