12 ALL BODIES FULL OF CALORIC. 



its solid atoms ; and that in water, the pores are 

 about forty times greater than its solid particles. 

 (Optics, Book ii. p. 242.) If then it be true, that 

 all bodies are full of caloric, that it occupies 

 827 parts by volume of the atmosphere, and 

 1719 parts of steam, it must be obvious that it 

 constitutes by far the greater proportion by bulk, 

 of the solid globe we inhabit. And if when in- 

 timately combined with the particles of ponder- 

 able matter, its thermal properties are disguised 

 or hidden from the senses, the same thing is true 

 of water and the strong acids, the individual pro- 

 perties of which are concealed while they are in 

 a state of chemical union with rocks, salts, &c.* 



Having thus proved that caloric is a material 

 agent, I now proceed to show that it is a self- 

 active principle, capable of moving itself, and of 

 generating motion in all other bodies. The car- 

 dinal facts which connect its agency with the 

 general theory of physics, may be reduced to the 

 following propositions : 



1. That the activity or moving power of all 



* The above facts will enable us, in some measure, to compre- 

 hend the theory of opacity and transparency, the cause of which, 

 Sir John Herschel thinks, has never yet been satisfactorily 

 explained. For as it is well ascertained that the particles of 

 the atmosphere, steam, gases, water, saline and metallic solu- 

 tions, like glass, and a great variety of crystalline solids, are 

 arranged in regular series, at considerable distances from one 

 another, the rays of light pass through them with slight in- 

 terruption, giving rise to the phenomena of transmission and 

 what, is called transparency. But when the regular arrange- 



