NO V U M ORG A N U M . 113 



fore, pass it hastily over. Of all flames that of spirits of 

 wine appears to be the most gentle, except, perhaps, the 

 ignis fatuus, or the flashes from the perspiration of ani 

 mals. After this we should be inclined to place the flame 

 of light and porous vegetables, such as straw, reeds, and 

 dried leaves ; from which the flame of hair or feathers dif 

 fers but little. Then, perhaps, comes the flame of wood, 

 particularly that which contains but little rosin or pitch, 

 that of small wood, however (such as is usually tied up in 

 faggots), is milder than that of the trunks or roots of trees. 

 This can be easily tried in iron furnaces, where a fire of 

 faggots or branches of trees is of little service. Next fol 

 lows the flame of oil, tallow, wax, and the like oily and fat 

 substances, which are not very violent. But a most power 

 ful heat is found in pitch and rosin, and a still greater in 

 sulphur, camphire, naphtha, saltpetre, and salts (after they 

 have discharged their crude matter), and in their com 

 pounds ; 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 metals 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 reverberatories, 

 surpass in heat many flames and ignited substances. 



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

 the blow-pipe, for the harder metals are not dissolved or 

 melted by steady quiet fire, without the aid of the blow 

 pipe. 



28. Let an experiment be made with burning glasses ; 

 VOL. xiv. i 



