NOVUM ORGANUM 207 



the spirit of nitre is escaping, as far also as it can, and at 

 the same time expanding itself (for air, and all crude sub 

 stances, and water are expanded by heat), fanning thus, 

 in every direction, the flame of the sulphur by its escape 

 and violence, just as if by invisible bellows. 



Two kinds of instances of the cross might here be used 

 the one of very inflammable substances, such as sulphur 

 and camphor, naphtha and the like, and their compounds, 

 which take fire more readily and easily than gunpowder if 

 left to themselves (and this shows that the effort to catch 

 fire does not of itself produce such a prodigious effect); the 

 other of substances which avoid and repel flame, such as all 

 salts; for we see that when they are cast into the fire, the 

 aqueous spirit escapes with a crackling noise before flame 

 is produced, which also happens in a less degree in stiff 

 leaves, from the escape of the aqueous part Before the oily 

 part has caught fire. This is more particularly observed in 

 quicksilver, which is not improperly called mineral water, 

 and which, without any inflammation, nearly equals the 

 force of gunpowder by simple explosion and expansion, 

 and is said, when mixed with gunpowder, to increase its 

 force. 



Again, let the required nature be the transitory nature 

 of flame and its momentaneous extinction; for to us the 

 nature of flame does not appear to be fixed or settled, but 

 to be generated from moment to moment, and to be every 

 instant extinguished; it being clear that those flames which 

 continue and last, do not owe their continuance to the same 

 mass of flame, but to a continued succession of new flame 

 regularly generated, and that the same identical flame does 

 not continue. This is easily shown by removing the food 

 or source of the flame, when it at once goes out. We 



