514 NOVUM ORGANUM. [bOOK II. 



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 momentancous 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 con- 

 tinued 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 have the two following cross-ways with regard to this nature : 

 ■ — This momentary nature either arises from the cessation of the 

 cause which first produced it, as in light, sounds, and violent 

 motions, as they are termed, or flame may be capable, by its own 

 nature, of duration, but is subjected to some violence from the 

 contrary natures which surround it, and is destroyed. 



We may therefore adopt the following instance of the cross. 

 We see to what a height the flames rise in great conflagrations ; 

 for as the base of the flame becomes more extensive, its vertex 

 is more lofty. It appears, then, that the commencement of the 

 extinction takes place at the sides, where the flame is compressed 

 by the air, and is ill at case ; but the centre of the flame, which 

 is untouched by the air and surrounded by flame, continues the 

 same, and is not extinguished until compressed by degrees by 

 the air attacking it from the sides. All flame, therefore, is pyra- 

 midal, having its base near the source, and its vertex pointed 

 from its being resisted by the air, and not supplied from the 

 source. On the contrary, the smoke, which is narrow at tlie 

 base, expands in its ascent, and resembles an inverted pyramid, 

 because the air admits the smoke, but compresses the flame ; for 

 let no one dream that the lighted flame is air, since they are 

 clearly heterogeneous. 



The instance of the cross will be more accurate, if the expe- 

 riment can be made by flames of diflercnt colours. Take, there- 

 fore, a small metal sconce, and place a lighted taper in it, then 

 put it in a basin, and pour a small quantity of spirits of wine 

 round the sconce, so as not to reach its edge, and light the spirit. 

 JS^ow the flame of the spirit will be blue, and that of the taper 

 veliow ; observe, therefore, whether the latter (which can easily 

 be distinguished from the former by its colour, for flames do not 

 mix immediately, as liquids do) continue pyramidal, or tend 

 more to a globular figure, since there is nothing to destroy or 

 compress it. If the latter result be observed, it must be con- 

 iidered as settled, that flame continues positively the same, whilst 



