On Sal Nitrum and Nitro- Aerial Spirit 67 



CHAPTER VII 



THAT THE ELASTIC POWER OF AIR IS DUE TO 

 NITRO-AERIAL SPIRIT; ALSO OF THE MANNER 

 IN WHICH AIR IS IMPREGNATED ANEW WITH 

 NITRO-AERIAL PARTICLES; INCIDENTALLY OF 

 THE ELEMENTS OF FIRE AND OF COLD 



Thp: experiments of Boyle have proved beyond doubt 

 that air is eminently elastic and therefore spreads and 

 expands immensely when relieved from the pressure 

 of the atmosphere. But it is not so clear to what 

 cause the elastic force of the air is due. I shall, how- 

 ever, state briefly the result of my reflections on this 

 recondite subject. 



In the first place, then, I take it for granted that the 

 air contains certain particles termed by us elsewhere 

 nitro-aerial which are absolutely indispensable for the 

 production of fire, and that these in the burning of 

 flame are drawn from the air and removed, so that the 

 latter when deprived of these particles ceases to be fit 

 for supporting fire, as has been shown above. 



It must also be admitted that the elastic force of the 

 air is due to the same aerial particles as those by 

 which flame is supported — an inference which we 

 deduce from the fact that air deprived of these nitro- 

 aerial particles loses elastic force, as will be established 

 by what follows. 



For firstly we have to note, what almost everybody 

 knows, that if a cupping-glass filled with flame be 

 applied to the skin, the flame will soon go out and the 

 space within the cupping-glass will be almost empty, 

 and as a consequence the skin will be driven into the 



