On Sal Nitrum and Nitro- Aerial Spirit lOi 



tioii produced by the fumes, instead of with air, then the 

 water did not rise in the glass after the second action 

 as it did before, because that exhalation could not, 

 like air, be diminished as to its volume by the ferment- 

 ing particles, but was on the contrary increased by 

 them. But this sort of exhalation will be discussed 

 more fully later. 



After this experiment we must suppose that air 

 when breathed by animals loses its elastic force in the 

 following manner. For I assume, in the first place, 

 that the mass of the blood is a liquid conspicuously in 

 a state of fermentation, as will be shown below. Since 

 then through the action of the lungs aerial particles 

 are mixed intimately and in the minutest parts with 

 its fermenting particles, it comes to pass that the aerial 

 particles have their elastic force diminished by the 

 particles of the blood in the same way as by the 

 vapours of fermentation in the aforesaid glass. Indeed 

 it is probable that the fermenting particles of the blood 

 rub the aerial particles interspersed among them and 

 strike out from them the nitro-aerial spirits, and that 

 at last the aerial particles, deprived of their nitro-aerial 

 and elastic particles, become unfit for sustaining life 

 and lose besides a part of their elasticity. 



Now that we have introduced nitro-aerial particles 

 into the mass of the blood, the question at once 

 follows what use they serve. I discussed this subject 

 in my treatise on Respiration published a good while 

 ago. Let me be permitted, however, to add some 

 things here. It is our opinion, then, that as in 

 vegetables so also in animals, nitro-aerial particles are 

 the principal instrument of life and motion. 



For in the first place nitro-aerial spirit when mixed 

 with the saline-sulphureous particles of the blood 

 appears to excite in it vital fermentation. In fact, just 



