Inquify inU the Lawt of /^nlty. '' »i 



A R T I C L E Vn. 



Of the ^Sl'ion of Caloric. 



In this chapter Cit. Berthollet examines the a£tion of caloric upon boclies, and the phe- 

 nomena it produces in the various combinations or dccompofitions. Articles VIII. and I^. 

 contain a great number of experiments on efflorefcence and on folvents. 



What Cit, Berthollet underftands by efflorefcence, is the property of riling above the 

 mafs, and of feparating from it by chemical action. 



In order that foda may rife in efflorefcence, he obfenres, it muft ncceffarily have com- 

 bined with carbonic acid, which it can attraft from the air of the atmofphere ; but the 

 aftion of the carbonic acid, which is very fmall in quantity, and in an elaftic ftate, cannot 

 fenfibly add to the force which has produced the feparation of the foda, from the combi- 

 nation in which it is found ; it only feparates the eliminated part, and hinders it from 

 continuing to aft upon the combination. 



With refpeft to folvents, the author is of opinion that their ufe is to overcome the 

 refiftance which arifes from the cohefion of the parts intended to be brought into a£tion» 

 or from their elafticity, and to increafe their mutual contaft. 



Solvents adl upon fubftances, which they diflblve by their affinity and their quantity, 

 like all fubftances which have a tendency to combination ; and to thefe is applicable all 

 the do£trine of the combination of bodies. The author takes water for his example, which 

 is moft frequently employed as a folvent, 



Cit. Berthollet then examines the circumftances in which this adion may change or fen- 

 fibly modify the refults 3 and this leads him to offer a feries of experiments ; on which he 

 eftabllflies a luminous theory. 



This article is concluded by fome remarks upon caloric. The author conceives it to aft 

 upon bodies which are not equally dilatable in a manner Cmilar to folvents, by attacking 

 the force of cohefion, and thus enabling the particles to exerclfe their mutual adlion. Ita 

 aGion concurs with thofe of the folvents, in oppofing the force of cohefion : whence it 

 happens, that the folution of a fait by water varies according to the degrees of tem- 

 perature. 



When caloric afts upon fubftances not equally dilatable, it produces feparations andf 

 new combinations, independent of the affinity peculiar to fubftances; in the fame mannet 

 as the folvents when they a£l upon fubftances not equally foluble. 



(To he continued.} 



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