16 



Professor Apjohn upon a new Method, ^c. 

 (3) 



I shall conclude with the following propositions, which, if not established by, 

 are, at least. In accordance with the results of my researches. 



1st. The simple law so much insisted upon in modern times by Haycraft, 

 Marcet, and De la Rive, and others, that equal volumes of the different gases 

 have the same specific heat, is not the law of nature. 



2nd. The more limited proposition enunciated by Dulong, that the simple 

 gases have under a given volume the same specific heat, is probably not true in a 

 single instance,^ and is altogether at variance with my result for hydrogen. 



3rd. The numbers at which I have arrived correspond tolerably well with 

 those of De la Roche and Berard, except in the case of hydrogen. 



4th. There does not seem to be any simple relation between the specific heats 

 of the gases, and their specific gravities or atomic weights; and philosophers, in 

 searching for such, are probably pursuing a chimera. 



* My number for this gas is deduced from that for nitrogen by the formula a: -f 4 x .2799 = 5, 

 in which x is the specific heat of oxj'gen, and .2799 that of nitrogen. 



f My number for this gas is inferred by calculation from that given by experiment for the mix- 

 ture of it with an equal volume of carbonic acid. The formula is ;p := »n + m — .3192, x being the 

 specific heat of carbonic oxide, .3192 of carbonic acid, and m of the mixture. 



X I would not wish to be understood as speaking with much confidence of the numbers attached 

 to nitrogen and oxygen. But three experiments were made, in consequence of one of the gasometers 

 having begun to leak ; and, moreover, as nitrogen was the gas operated with, in passing by calculation 

 to the specific heat of oxygen, the errors of observation would be multiplied by four. Oxygen, in 

 fact, not nitrogen, should have been the subject of experiment. 



