188 The English School [lect. 



" suffocated by its own smoke, as some have thought, but 

 " because it is deprived of its aereal sustenance or food 

 "{pabulum). For since there is more room for the reception 

 "of the smoke in the flask, when it is exhausted of air than 

 "when it is full of air, the candle ought to go out more 

 " quickly in the latter than in the former, if its going out was 

 " merely due to the smoke. 



" Moreover sulphureous {i.e. combustible, he uses the time- 

 -honoured Valentinian nomenclature of the different natures 

 " of things) matter, of whatever kind, when placed in a flask 

 " exhausted of air, cannot be ignited either by burning char- 

 " coal or red-hot iron, or by the sun's rays concentrated by 

 " means of a burning-glass. So that there cannot be now the 

 " slightest doubt but that certain aereal particles are altogether 

 " necessary for the lighting of tire ; and indeed our opinion is 

 " that these same particles play the chief part in igniting fire, 

 " and that the form of flame depends mainly on these particles 

 " being agitated in a most destructive manner, as I shall shew 

 " more fully later on. 



" But it must not be thought that the igneo-aereal food (of 

 " flame) is air itself; it is only a more active and subtle part 

 " of it. For a candle enclosed in a flask goes out although 

 " there is still contained in the flask an ample abundance of air. 

 " Now we cannot suppose that the particles of air which existed 

 " in the flask were destroyed by the burning of the candle or 

 " that they escaped and got away, for such particles are unable 

 " to pass through the glass. Moreover it is not probable that 

 " those igneo-aereal particles are a sort of perfected nitre, as 

 " the common opinion runs, for as has been shewn above it is 

 " not the very whole of the nitre but only a certain part of it 

 "which is derived from the air." 



He then goes on to shew that the particles of air, forming 

 the more active and subtle part of air which is thus necessary 

 for combustion, exist in nitre and indeed constitute its " more 

 active and fiery part." For sulphur when mixed with nitre will 

 burn in the absence of air, in a vacuum for instance, or under 

 water. " Thus a squib made of gunpowder of which nitre is an 

 " important constituent will burn right away under water." 



