A SYSTEM OF PARTICLES. 283 



ether diminishes, which I have, elsewliere, shewn reasons for supposing- 

 true {Trans. Camh. Phil. Soc. Vol. vi. Parti, p. 165.) ; on this ground 

 we may explam the high refractive power of water compared with that 

 of ice. 



52. Following this reasoning a little further, it is evident that the 



refractive indices for bodies should increase, cceterh paribus, with the 



specific heat corresponding to equal volumes. We will assume the 



ordmary expression for the refractive energies of the different gases, 



• " -^ u • 



^'^- ~r~' '' """^"S the specific gravity, and compare the results with 



their specific heat. 



In the following Table I have placed, on the left-hand side, the 

 order of the refractive energies of eight different gases, calculated 

 from the above formula, and, on the right, the order of their specific 

 heat ; ni each beginning with the one lowest in the scale. 



The Table of Refractive Energies has been derived principally from 

 ll.r f\ ' Elementaire; that of Specific Heat entirely from 



1^1 M. de La Roche and Berard. 



Refractive Energy. 

 Oxygen. 

 Air. 



Carbonic Acid. 

 Nitrogen. 

 Carbonic Oxide. 

 Nitrous Oxide. 

 Olefiant Gas. 

 Hydrogen. 



Specific Heal. 

 Oxygen. 

 Air. 



Nitrogen. 

 Carbonic Oxide. 

 Carbonic Acid. 

 Nitrous Oxide. 

 Olefiant Gas. 

 Hydrogen. 



The only want of coincidence in these two Tables occurs in the 

 case of carbonic acid. It arises from the specific gravity being very 

 great compared with those of the gases below it. Had we taken some 

 root, as the cube root of the density instead of the simple power 

 for our denominator in the formula for the refractive energy, which 

 .seems more correct, it is not improbable that all our results' would 

 have agreed. 



Vol. VI. Part II. o „ 



