

On Sal NitrtLm and Nitro-A'erial Spirit 99 



nitro-aerial and elastic particles are struck out of them, 

 and the air consequently is deprived of its elasticity, 

 and reduced to smaller volume, as was explained in the 

 previous chapter. 



Aerial particles indeed appear to lose their elastic 

 force in the aforesaid action very much in the same 

 way as in fire, which has been elsewhere shown to be 

 nothing but a very impetuous fermentation. And 

 indeed it is probable that the heat produced by the 

 aforesaid action and also by others of the same sort, is 

 due at least in part to nitro-aerial particles struck out 

 in that way from the air. And this seems to be con- 

 firmed by the fact that if a corrosive liquid be mixed 

 with a salt, or with a metal opposed to it, in a place 

 almost destitute of air, though the two when mixed 

 together effervesce in a conspicuous manner, yet the 

 heat produced by them does not seem to be so intense 

 as it would otherwise be — a fact which has been 

 noted also by the illustrious Boyle. 



I made also an experiment in an exactly similar way 

 to ascertain whether fixed salts mixed with acid 

 liquids and other actions of that kind diminish the 

 elastic force of the air, and found as the result of 

 observation that, if the elasticity of the air is to be 

 manifestly diminished, it is absolutely necessary that 

 the action should be of such a kind that the exhala- 

 tions of the fermentation should last for some time 

 and be disseminated through the air, or at least, that 

 the exhalations if suddenly produced should undergo 

 great condensation afterwards. For it is to be noted 

 that the air in the aforesaid glass is impaired by the 

 fumes dispersed through it even after the iron has been 

 taken out of the spirit of nitre and the fermentation in 

 the vessel has ceased. For otherwise if the air had 

 .been injuriously affected only while the action lasted, 



