72 



and alcalis, when mixed, cause a great ebullition, but 

 no great heat ; whereas the solution of some metals 

 in aqua-fortis, causes intense heat, and emits flame. 

 Aromatic oils, mixed with acid mineral spirits, kindle 

 and burn with violent explosions. 



In these cases, as there is no adventitious fire, there 

 must be fire lying hid in one or other of the bodies. 

 And it is known, much air lies dormant in all bo* 

 dies. It is known likewise, that fire cannot exert 

 itself without the help of air. It being granted then, 

 that fire and air lie dormant in all bodies, there is 

 only required such an action as may set at liberty 

 the particles of air and of fire. By this action the 

 particles of air recover their elasticity, and putting 

 those of fire in motion, eause heat, but not incen- 

 sion, unless this fire meet a proper pabulum, which 

 pabulum is sulphur only, though differently modified, 

 whether in the appearance of brimstone, oil, spirits, 

 metalline sulphur, or the most inflammable of all, ani- 

 mal sulphur, commonly called phosphorus. 



In fermentation, the fire and air being let loose, 

 produce warmth, but seldom kindle, because of the 

 water predominating. But in the effervescence, pro- 

 duced by the solution of metalline sulphur, they kin. 

 die and sometimes cause explosions. Aromatic oils, 

 containing little but the sulphureous parts of the 

 vegetables, immediately kindle and break out into 

 flame. And phosphorus is so highly inflammable, 

 that if it be only exposed to the air a few minutes, it 

 kindles and flames. 



Now all animals contain more or less phospho- 

 rus. Some insects constantly shine in the open air. 

 Many sorts of fish are luminous: some quadrupeds 

 emit light, on a very slight friction. These are proofs 

 of phosphorus lying dormant in animal fluids : and 

 as they all contain air likewise, let only the phos- 

 phoreal and aereal particles be brought into contact, 

 and heat necessarily ensues. 



This clearly explains the cause of animal heat : of 

 which the heart and arteries are the occasion; not by 

 friction, but by the intestine motion, which the cir- 



