NOVUM ORGANUM 141 



of oil, tallow, wax, and the like oily and fat substances, 

 which are not very violent. But a most powerful heat is 

 found in pitch and rosin, and a still greater in sulphur, cam 

 phor, naphtha, saltpetre, and salts (after they have dis 

 charged their crude matter), and in their compounds; as in 

 gunpowder, Greek fire (vulgarly called wild fire), and its 

 varieties, which possess such a stubborn heat as scarcely to 

 be extinguished by water. 



22. We consider that the flame which results from some 

 imperfect rnetals is very strong and active; but on all these 

 points further inquiry should be made. 



23. The flame of vivid lightning appears to exceed all 

 the above, so as sometimes to have melted even wrought 

 iron into drops, which the other flames cannot accomplish. 



24. In ignited bodies there are different degrees of heat, 

 concerning which, also, a diligent inquiry has not been 

 made. We consider the faintest heat to be that of tinder, 

 touchwood, and dry rope match, such as is used for dis 

 charging cannon. Next follows that of ignited charcoal or 

 cinders, and even bricks, and the like; but the most vio 

 lent is that of ignited metals, as iron, copper, and the like. 

 Further inquiry, however, must be made into this also. 



25. Some ignited bodies are found to be much warmer 

 than some flames; for instance, red hot iron is much warmer, 

 and burns more than the flame of spirits of wine. 



26. Some bodies even not ignited, but only heated by 

 the fire, as boiling water, and the air confined in reverbera- 

 tories, surpass in heat many flames and ignited substances. 



27. Motion increases heat, 26 as is shown in the bellows 



26 The correct measure of the activity of flame may be obtained by multiply 

 ing its natural force into the square of its velocity. On this account the flame 



