1 2 Mayow 



particles, of which it is altogether destitute. And 

 hence it is that the flame of nitre is very different 

 from that which is produced by any deflagrating 

 sulphureous matter. For sulphureous matter burns 

 when igneo-aerial particles are supplied from the air^ 

 but nitre from the igneo-aerial particles closely packed 

 in itself and breaking forth in densest array. Hence 

 it is that the flame of nitre is exceedingly impetuous. 

 That the form of flame depends mainly on the igneo- 

 aerial particles, I shall attempt to show later. 



But the reason why nitre is chiefly produced in 

 places that are largely imbued with sulphur will be 

 evident from what follows. 



Since this treatise was written, Boyle's experiments 

 recently published have come into our hands. In the 

 second of these it is shown that when gunpowder is 

 kindled, by means of a burning-glass, in a glass freed 

 from air, the flame is not propagated, as in other cases, 

 through the whole of its mass, but that only those 

 grains on which the collected solar rays fall take fire. 

 So that it appears that the access of air is necessary 

 even for the kindling of gunpowder. I reply that 

 although that powder will deflagrate by means of the 

 igneo-aerial particles residing in it, in a place where 

 there is no air, and under water, still the access of 

 external air contributes in no small degree to its 

 kindling. For it is to be noted that air, on account 

 of its great elastic power, lies in the closest proximity 

 to the sulphureous particles of the gunpowder and 

 even presses powerfully against them, whence it is 

 that when the powder is once ignited in free air 

 nitro-aerial particles of the air are never lacking to 

 keep up the flame ; while, on the other hand, the 

 igneo-aerial particles in gunpowder are intimately 

 blended with the sulphureous particles only in the in- 



