the Laws of Affinity, 14! 



mined from an unknown point of fatnration to another point, 

 the bodies fubmitted to experiment being already combined 

 with a quantity of caloric. The refults, which may be ob- 

 tained between two points of the fcale of the thermometer, 

 have no known connection with the total quantities. To 

 attempt to form a conclusion of one from the other, would 

 be the fame as to pretend to determine the comparative folu- 

 bility of the muriate of foda, and the nitrate of potafh in 

 water, by experiments made only at or towards the point of 

 ebullition or of congelation. In the former cafe we fhould 

 fay that three parts of water would be required for the folu- 

 tion of one part of muriate of foda, and only half a part 

 would be neceflary to diflblve one part of the nitrate of pot- 

 afh ; in the latter, that much lefs water would be required to 

 diflblve the muriate of foda than to diflblve the nitrate of 

 potafh *. 



The force of cohefion in a bodv on its taking the folid ftate 

 obliges a part of the caloric to feparate; in the fame manner 

 as when a fait eryitallizes, it abandons part of the folvent, or 

 even a part of the acid, or of the alkali, with which it might 

 be combined. 



10. It may be faid that the affinities may really be repre- 

 fented bv the tables of capacity ; fince they may afford the 

 meafure of the action of one fubftance upon another, when 

 a common term of faturation is found, fuch as neutralization 

 for the acids and the alkalis, and thcrmometric temperature 

 for caloric ; but nothing could poffibly be concluded for che- 

 mical action at another term of faturation, and more parti- 

 cularly for another constitution, and for all the eircumftances 

 in which the forces of elafticity and cohefion might not be 

 introduced. 



11. Having confidered all the affinities which may jointly 

 produce chemical action, I next examined how, in the com- 

 pounds, they may refult from their conftituent parts, in order 

 to acquire a conception how the varied powers, which pro- 

 duce all the chemical phenomena, can be derived from one 

 (ingle property of fimple bodies. The obfervations prefented 

 on this fubjecl: have fhown, that what principally diftinguifhes 

 compound fubftances, whofe action is confidered as fimple, 

 is, the condenfation of the conftituent parts, on which, a new 

 affinity depends ; an affinity very different from that which 

 the fame parts poifefs in the elaftic it-ate : the elementary 



• This consideration alone> that Specific caloric has no known relation 

 to the quantity of caloric combined in a body, mows that the experiment) 

 by which Rumford has lately pretended to prove that caloric is not a con- 

 ftituent partuf bodies, cannot lead to iuch a coacluiion. 



affinities 



