On Sal Nitriim and Nitro- Aerial Spirit 109 



things than for sustaining animal Hfe. Nor indeed 

 is the mass of the blood in any way suitable for pro- 

 ducing flame ; for although it consists of sulphureous 

 particles, yet these are held so firmly in the embrace 

 of the saline ones that blood will not burn, even when 

 thrown into the fire. But if any fire of this sort were 

 kindled in the mass of the blood when the blood 

 rushes forth from a divided artery, the flame would 

 certainly reveal itself by its own light. For it is not 

 to be thought that any flame is ever kindled which is 

 not luminous and also somewhat caustic and destruc- 

 tive, unless one is disposed to palm off fumes for 

 flame. Nor is it credible that the vital flame is 

 extinguished in the blood as it rushes out of the 

 vessels, for the air by blowing on it is fitted rather to 

 excite than to extinguish fire. And lastly, what are 

 we to think of the vital fire of aquatic animals ? It 

 must indeed be fierce and invincible to burn under 

 water and be such as the whole ocean cannot quench. 

 The existence of subterranean fires is not yet estab- 

 lished ; it is much less probable that there are sub- 

 aqueous fires. With respect to a lucid soul inhabiting 

 the brains of animals, I ask how it is possible that this 

 light which is supposed to enlighten with its rays the 

 whole brain and nervous system, should never be seen 

 by the eye. Truly, fires of this sort and new lights, 

 no less in Anatomy than in Religion, have always 

 seemed to me vain and fanatical. 



With respect to the fermentation of the blood we 

 note further, that if the saline-sulphureous particles 

 in the mass of the blood have been too much elevated, 

 the nitro-aerial particles mixed with them will give 

 rise to a very impetuous effervescence and to febrile 

 heat. And thus it is that an ulcer of the lungs pro- 

 duces a hectic fever ; for the nitro-aerial particles, 



