206 NOVUM ORGANUM 



ways before us with regard to this nature. This motion is 

 excited either by the mere effort of the body expanding 

 itself when inflamed, or by the assisting effort of the crude 

 spirit, which escapes rapidly from fire, and bursts violently 

 from the surrounding flame as from a prison. The school, 

 however, and common opinion only consider the first effort; 

 for men think that they are great philosophers when they 

 assert that flame, from the form of the element, is endowed 

 with a kind of necessity of occupying a greater space than 

 the same body had occupied when in the form of powder, 

 and that thence proceeds the motion in question. In the 

 meantime they do riot observe, that although this may be 

 true, on the supposition of flame being generated, yet the 

 generation may be impeded by a weight of sufficient force 

 to compress and suffocate it, so that no such necessity exists 

 as they assert. They are right, indeed, in imagining that 

 the expansion and the consequent emission or removal of 

 the opposing body, is necessary if flame be once generated, 

 but such a necessity is avoided if the solid opposing mass 

 suppress the flame before it be generated; and we in fact 

 see that flame, especially at the moment of its generation, 

 is rnild and gentle, and requires a hollow space where it 

 can play and try its force. The great violence of the effect, 

 therefore, cannot be attributed to this cause; but the truth 

 is, that the generation of these exploding flames and fiery 

 blasts arises from the conflict of two bodies of a decidedly 

 opposite nature the one very inflammable, as is the sul 

 phur, the other having an antipathy to flame, namely, the 

 crude spirit of the nitre; so that an extraordinary conflict 

 takes place while the sulphur is becoming inflamed as far 

 as it can (for the third body, the willow charcoal, merely 

 incorporates and conveniently unites the two others), and 



