I 



On Sal Nitriim and Nitro- Aerial Spirit 13 



dividual grains, and are not carried to those that are 

 kindled ; so that the flame of the powder is speedily 

 extinguished in a vacuum, owing to a break in the 

 continuity of the igneo-nitrous particles. But how 

 greatly the elasticity of the air helps to produce fire 

 will be more fully established by what will be said 

 below. 



From what has been already said, it is, I think, to 

 some extent proved that nitre contains in itself the 

 igneo-aerial particles required for the production of 

 flame. Wherefore, since some part of nitre is derived 

 from the air and igneo-aerial particles exist in it, it 

 seems we should affirm the proposition that the aerial 

 part of nitre is nothing else than its igneo-aerial 

 particles. 



But now since the aerial part of nitre exists in its 

 acid spirit, but not in the fixed salt, which, as we have 

 already shown, forms the rest of the nitre, we may 

 conclude that the igneo-aerial particles of nitre ^ which 

 are identical with its aerial part, are hidde7i in the 

 spirit of nitre^ and constitute its aerial part. 



Indeed, it is probable that the spirit of nitre is a 

 compound, and that some of its particles are flexile, 

 humid, and of a grosser nature, being apparently 

 derived from terrestrial matter — as I shall endeavour 

 to show below — but that other particles are rigid, 

 dry, and extremely subtle, agile, ethereal, and really 

 igneous, and yet, being united with saline particles in 

 a fluid and moist condition, are unfitted for entering 

 on a fiery movement, and that these at any rate are 

 derived from the air. 



With regard then to the aerial part of nitrous spirit, 

 we maintain that it is nothing else than the igneo- 

 aerial particles which are quite necessary for the 

 production of any flame. Wherefore, let me hence- 



