592 HISTORY OF THERMOTICS. 



fonnd in those great theories which we look upon 

 as clearly and indisputably established. 



Conclusion. We may observe, moreover, that 

 heat has other bearings and effects, which, as soon 

 as they have been analyzed into numerical laws of 

 phenomena, must be attended to in the formation 

 of thermotical theories. Chemistry will probably 

 supply many such ; those which occur to us we 

 must examine hereafter. But we may mention as 

 examples of such, De la Rive and Marcet's law, 

 that the specific heat of all gases is the same"; and 

 Dulong and Petit's law, that single atoms of all 

 simple bodies have the same capacity for heat 1 '. 

 Though we have not yet said anything of the rela- 

 tion of different gases, or explained the meaning of 

 atoms in the chemical sense, it will easily be con- 

 ceived that these are very general and important 

 propositions. 



Thus the science of Thermotics, imperfect as it 

 is, forms a highly-instructive part of our survey, 

 and is one of the cardinal points on which the doors 

 of those chambers of physical knowledge must turn 

 which hitherto have remained closed. For, on the 

 one hand, this science is related by strong analogies 

 and dependencies to the most complete portions of 

 our knowledge, our mechanical doctrines and opti- 

 cal theories ; and on the other, it is connected with 

 properties and laws of a nature altogether different, 

 11 Ann. Chim. xxxv. (1827.) " ib. x. 397- 



