ol^ On Chemical Philosophy. 



serve it in one state, or change it into another ; but also whv, 

 when we apply its concentrated actions (or heat, according to 

 its common acceptation,) to substances; or when we mix bodies 

 together, or change their relative position, this power effects 

 their separation, motion, and deposition, or their solution and 

 union ; and if not soluble, moves them in one wav and draws 

 them in another; and all this invarial)ly in the same order, and 

 as invariably attended with the same appearances. And hence f 

 have said that " it is not oiilv the power which binds and unites 

 the particles of matter together, but that also bv which they are 

 separated and carried from one point to another." 



If then, I again repeat, different quantities are required for 

 each species of matter, and if these quantities be relative as well 

 as appropriate shares, then we perceive why cverv increase or 

 diminution of this power, every change of position and ariange- 

 jnent, every solution of one substance in another, must alter 

 these relative quantities, must take so much from one particle 

 and give so much to another. It is thus one body is precipi- 

 tated from it and another is dissolved in it; or if not soluble, thcv 

 are drawn in one way and carried in another, in proportion as 

 thev have relalivelv to each other more or less of this power; so 

 that " all changes are mere exchanges of this power," sepa- 

 rating from one substance and entering into combination with 

 another, passing from one and adhering to another : — Hence we 

 have bv these artificial means, as well as in nature, their sepa- 

 ration, motion and deposition, or their solution and union, on 

 their being moved from one point and carried towards another, 

 &;c. ; and all this, as they are relatively to each other more or less 

 soluble, or relatively require more or less for any given state of 

 existence, is true, in those changes that are produced bv simple 

 mixture, as well as in those where heat, or the concentration of 

 this power, is applied. The power then, I repeat, that accounts 

 for minute changes, such as are in general exclusively considered 

 under chemical affinity, is the same as that which produce-; the 

 more obvious and striking changes; and they differ in effect and 

 appearance, because the extent and rapidity as well as the sub- 

 stances on which, and circumstances in which, they are pro- 

 duced, are infinitely varied both in their quantity and intensity, 

 their nature and their situation. 



Essay IV. 



Thus it is evident, that the power which we designate by the 

 words j^re, heat, or caloric, is verv improperly restricted by mo- 

 dern philosophers to the mere solitary effects of heat and flame: 

 for though these words caloric, Jire, and heat, are all at present 

 used by chemists and philosophers as expressive of the cause and 

 the effect which that cause produces 3 yet in all their writings 



and 



