On Sal Nitrum and Nitro- Aerial Spirit 12 r 



the minute pores of the air or of nitre itself, and are 

 impelled there into the spherules of the subtle matter,, 

 produce the same effect in the aerial particles, or on 

 anything else impregnated with nitro-aerial particles,, 

 as if, like rigid bodies, they were bent to breaking : so 

 that the igneo-nitrous particles would appear to burst 

 forth with elastic impetus from the air, not otherwise 

 than the small bits of glass from the fractured glass. 

 It is a corroboration of this view that aerial particles- 

 and the particles of nitre itself, in which, namely, igneo- 

 nitrous spirit especially resides, become stiff like rigid 

 bodies and are imbued with elasticity, and are con- 

 sequently of a sort fit for having igneous particles shot 

 out of them with elastic impetus. 



It would be easy to show here that nearly all natural 

 movements, such as the generation and dissolution 

 of things and the internal motions of opposed liquids, 

 are, similarly, to some extent due to the battering of 

 the subtle matter. It is probable indeed that these 

 motions are excited in the same way as fire is kindled ; 

 for fire appears to be nothing but the most intense 

 fermentation of nitro-aerial and sulphureous particles. 

 It certainly does not seem to be suflficient to say with 

 the eminent Willis in regard to these natural motions,, 

 that the more active particles expand, ascend, and 

 finally fly away ; for, in a discussion of this sort, what 

 should specially be shown is why particles at rest 

 begin to move, for whatever is at rest will remain 

 for ever at rest, if it is not set in motion by some 

 cause. With respect to motion of this kind, it appears 

 to me necessary to suppose some perpetually moving 

 matter by the impulse of which these motions are 

 effected. As then the very rapid motion of fiery par- 

 ticles seems to proceed from this, that the sulphureous 

 particles coming up to the particles of nitre or of air 



