86 THE REFRACTIVE POWER OF BODIES 



We further perceive, that during the combina- 

 tion of oxygen with two equivalents of carbon, 

 and two of hydrogen, as in the combustion of 

 olefiant gas, above four times as much caloric is 

 evolved as by the union of one atom of oxygen 

 with one of hydrogen ; and that, although the 

 coincidence is less exact between the quantities 

 of heat evolved and the atomic constitution of the 

 remaining compound gases, it is sufficiently so to 

 prove that hydrogen and carbon contain more 

 caloric around their atoms than an equal weight 

 of oxygen ; and that equal volumes of the gases 

 do not afford the same quantities of caloric. It 

 must, however, be admitted, that the results of 

 Despretz are at variance with those of Dulong 

 and Hess, as he found that hydrogen evolves only 

 3-15 instead of 6 times more caloric than the same 

 weight of carbon. 



Let us next inquire whether the power of bodies 

 to refract light may not afford a measure of the 

 relative quantities of caloric around their par- 

 ticles. It w r as suggested by Newton at the close 

 of both the Optics and Principia, that the power 

 of bodies to reflect, refract, and inflect light, is 

 in proportion to the quantity of aether that covers 

 their surface, and surrounds their particles; 

 which aether he also regarded as the cause of co- 

 hesion, elasticity, solution, capillary attraction, 

 and gravitation. For example, he found that in 

 spirit of wine, spirit of turpentine, olive oil, lin- 

 seed oil, camphor, and amber, which are highly 



