NOVUM ORGANUM. 315 



lead dissolve in aqua fortis ; nor, indeed, does quicksilver (as we 

 remember) ; but silver itself does in a slight degree, and copper also 

 (as we remember), and tin more manifestly ; and most of all iron and 

 steel, for they not only excite a strong heat in the process of dissolution, 

 but a violent ebullition also. Heat appears, therefore, to be originated 

 by conflict, when strong waters penetrate, and pierce, and tear asunder 

 the parts of a body, and the body itself resists. But when bodies 

 yield more easily, scarcely any heat is excited. 



To the Twentieth, 



26. To the heat of animals no negative is subjoined, unless it be that 

 of insects (as has been said), on account of the smallness of their 

 bodies. For in fishes, as compared with land animals, it is rather the 

 low degree than the absence of heat that is noted. But in vegetables 

 and plants no degree of heat is perceived by the touch, nor in their 

 exudations, nor in their pith, when recently laid bare. But in animals 

 there is found a great diversity of heat, both in their parts (the degree 

 of heat differing at the heart, in the brain, and at the surface) and in 

 their accidents, as in vehement exercise and fevers. 



To the Twenty-first. 



27. To this Instance scarcely any negative is subjoined. Moreover 

 the stale excrements of animals have evidently a potential heat, as is 

 seen in the fattening of the soil. 



To the Twenty-second and Twenty-third. 



28. Liquids (whether they go by the name of water or of oil) which 

 possess a great and intense acidity, imitate the operation of heat in 

 the disruption of bodies, and after a time in burning them, and yet to 

 the touch they are not hot at first. But they operate relatively, and 

 according to the porosity of the body to which they are applied. For 

 aqua regia dissolves gold, but does not touch silver, while on the other 

 hand aqua fortis dissolves silver, but does not touch gold ; and neither 

 of them dissolves glass, and so of the rest. 



To the Twenty- fourth. 



29. Let experiment be made as to the action of spirit of wine on 

 wood, and also on butter, wax, or pitch, if it will mek them in any 

 degree by its heat. For the twenty-fourth Instance shows its power 

 of imitating heat in producing incrustations. And let an experiment 

 be made in like manner in the case of liquefactions. Let experiment 

 be also made by means of a graduated glass or thermometer, concave 

 on the outside at the top, by pouring highly rectified spirit of wine 

 into the concavity, and covering it over that it may better retain its 

 heat ; and note if it makes the water descend by its heat. 



To the Twenty-fifth. 



30. Spices and pungent herbs arc felt to be hot to the palate, much 

 more so when taken internally. And so it must be seen on what 



