^OK II. I doNTiimAKc:^. 561 



distance, or passing tlirouffh different media ; moist heats, such 

 as the halneum Maries, and the dunghill ; the external and internal 

 heat of animals ; dry heats, such as the heat of ashes, lime, 

 warm sand ; in short, the nature of every kind of heat, and its 

 degrees. 



We should, however, particularly attend to the investigation 

 and discovery of the effects and operations of heat, when made 

 to approach and retire by degrees, regularly, periodically, and 

 by proper intervals of space and time. For this systematical 

 inequality is in truth the daughter of heaven and mother of 

 generation, nor can any great result be expected from a vehe- 

 ment, precipitate, or desultory heat. For this is not only most 

 evident in vegetables, but in the wombs of animals also there 

 arises a great inequality of heat, from the motion, sleep, food, 

 and passions of the female. The same inequality prevails in 

 those subterraneous beds where metals and fossils are perpetually 

 forming, which renders yet more remarkable the ignorance of 

 some of the reformed alchymists, who imag'aed they could 

 attam their object by the equable heat of lamps, or the like, 

 burning uniformly. Let this suffice concerning the operation 

 and effects of heat ; nor is it time for us to investigate them 

 thoroughly before the forms and conformations of bodies have 

 been further examined and brought to light. When we have 

 determined upon our models, we may seek, apply, and arrange 

 our instruments. 



4. The fourth mode of action is by continuance, the very 

 steward and almoner, as it were, of nature. We apply the term 

 continuance to the abandonment of a body to itself for an ob- 

 servable time, guarded and protected in the meanwhile from all 

 external force. For the internal motion then commences to 

 betray and exert itself when the external and adventitious is 

 removed. The effects of time, however, are far more delicate 

 than those of fire. Wine, for instance, cannot be clarified by 

 lire as it is by continuance. Nor are the ashes produced by 

 combustion so fine as the particles dissolved or wasted by the 

 lapse of ages. The incorporations and mixtures, which are hurried 

 by fire, are very inferior to those obtained by continuance ; and 

 the various conformations assumed by bodies left to themselves, 

 such as mouldiness, &c., are put a stop to by fire or a strong 

 heat. It is not, in the mean time, unimportant to remark that 

 there is a certain degree of violence in the motion of bodies 

 entirely confined ; for the confinement impedes the proper motion 

 of the body. Continuance in an open vessel, therefore, is useful 

 for separations, and in one hermetically sealed for mixtures, that 

 in a vessel partly closed, but admitting the air, for putrefaction. 

 But instances of the opeiation and effect of continuance must ba 

 collected diligently from every quarter 



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