071 Sal Nitrum and Nitro- Aerial Spirit ii 



grate, we cannot believe that this results from 

 sulphureous particles, for it contains none, but from 

 the igneo-aerial particles contained in it and thrown 

 into very rapid motion. And this will be made still 

 clearer by what follows. 



For it is to be noted that for the production of any 

 flame, it is absolutely necessary, as has been already 

 pointed out, that there should be not only sulphureous 

 particles, but also igneo-aerial particles. To kindle 

 an}^ sulphureous matter, igneo-aerial particles must 

 be supplied, either from the air or from nitre pre- 

 viously added. And this is the reason why sulphur 

 will not take fire in a vacuum unless nitre has been 

 mixed with it. But, on the other hand, for the 

 kindling of nitre there is no need for igneo-aerial 

 particles to be supplied from without, because it will 

 deflagrate readily enough in places from which air is 

 excluded. But for its kindling it is quite indispens- 

 able that some sulphureous matter be mixed with it. 

 For if nitre be thrown into a heated crucible it will 

 not take fire. If, however, any sulphureous matter be 

 previously mixed with it, then the nitre, when thrown 

 into the said crucible, will immediately burst into 

 flame. Nay, nitre can in no wise be kindled by the 

 flame of a candle, or by the solar rays, unless sulphur 

 has been previously mixed with it. And yet the 

 same nitre if thrown upon charcoal will be easily set 

 on fire ; but this happens because the sulphureous 

 particles of the charcoal ignite it. From these con- 

 siderations it is undoubtedly established that nitre 

 has no sulphureous particles contained in it, and this 

 is why, for its deflagration, sulphureous particles must 

 be supplied from without. And hence it follows that 

 nitre supplies in the flame excited by it the igneo- 

 aerial particles only, but by no means the sulphureous 



