k 



On Sal Nitrtim and Nitro- Aerial Spirit 135 



lamp in quantity sufficient to illuminate the region 

 round about. Nor again is it to be thought that 

 finer sulphureous particles, flying away far from the 

 original blaze, excite other (nitro-aerial) particles for 

 the kindling as it were of a very meagre flame, 

 namely Light, as the distinguished Willis and others 

 have supposed. For if such were the case, why should 

 the light not endure for a little after the extinction 

 of the lamp ? For it seems to me that the sul- 

 phureous particles proceeding from the lamp just 

 before its extinction, would continue to produce light 

 until they arrived at the extreme limit of the illumi- 

 nated region, for the sulphureous particles which 

 emanate from any burning body do not resign their 

 fiery nature until they have ascended to the furthest 

 limits of the flame. Hence the flame of a lamp 

 usually continues for a short time after its sulphureous 

 matter has been entirely consumed, as was shown 

 above. Yet since the sphere of the blaze is but small 

 and the fiery particles pass through it in an instant, 

 hence it is that the flame quickly expires. As, 

 however, the sphere of light is much wider, it would 

 seem that the luminous particles cannot pass through 

 it so quickly but that the light should continue for 

 some time after the lamp has been removed or 

 extinguished. Further, if light were a somewhat 

 finer flame, what should prevent it from being 

 deflected hither and thither by blasts of wind like 

 flame, in proportion to its consistence, such as that 

 may be? And how, lastly, could rays of light be 

 transmitted instantaneously through the most solid 

 bodies such as glass, if light were propagated by means 

 of sulphureous particles ? For even the extremely 

 small and nimble nitro-aerial particles do not pene- 

 trate bodies so solid, without some interval of time, 



