206 



the term caloric ; and the same power, when it en- 

 ters into bodies, not only raises their temperature, 

 but almost universally expands them : hence the sen- 

 sation of heat, temperature, and expansion, are con- 

 sidered as effects, of which caloric is the immediate 

 cause *. The quantities of caloric contained in ho- 

 mogeneous bodies are proportioned to their tempe- 

 ratures and quantities of matter ; but, in other cases, 

 it is established as a general law, that different bodies 

 in equal quantities, whether estimated by weight or 

 volume, contain unequal quantities of caloric f. This 

 property or power in bodies to contain very different 

 quantities of caloric, has, by some, been termed the 

 capacity of bodies for heat, while others express the 

 fact more simply, by employing the phrase specific 

 caloric to denote the relative quantities of heat which 

 different bodies contain. 



164. The greater the quantity of caloric that en- 

 ters into bodies, the more do they become expand- 

 ed ; and if this expansion proceed to a certain ex- 



* This distinction between heat, and the effects which it pro- 

 duces, did not escape the observation of the ancients. Theo- 

 phrastus, iu his book De Jgne, says Bishop Berkeley, distinguish- 

 eth between heat and fire. The first he considers as a principle 

 or cause, not that which appeareth to sense as a passion or acci- 

 dent existing in a subject, and which is in truth the effect of that 

 unseen principle. This invisible fire, he adds, is present in all 

 parts of the earth and firmament, though, perhaps, latent and un- 

 observed, till some accident produceth it into act, and renders it 

 vigible in its effects *. 



f Murray's System of Chemistry, vol. i. p. 350, 



* Sim, par, 157. 17G. 



