*l(58 Inquiry into the Laws of Affinity. 



" On talcing the folid flate, the force of cohefion in a body obliges a part of the caloric 

 .to feparate; in the fame manner as when a fait cryftallifes, it abandons part of the folvent, 

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



lO. It might be affirmed, that the affinities would be really reprefented by the tables of 

 capacity; fince they would afford the meafure of the aftion of fuch fubftance upon an- 

 other, when a common term of faturation Was found, fuch as neutralifation for the acids 

 and the alkalis, and thermometric temperature for caloric ; but nothing could poffibly be 

 concluded for chemical action at another term of faturation, and more particularly for an- 

 other conftitution, and for all the circumftances in which the forces of clafticity and cohe- 

 fion might not be introduced. 



• II. After having confidcred all the affinities which may jointly produce chemical aftion, 

 r examined how, in the compounds, they may refult from their conftituent parts, in order 

 to acquire a conception how the varied powers which produce all the chemical phenomena, 

 can be derived from one fingle property of fimple bodies. 



The obfervations prefented on this fubjed have fliewn, that what principally diftln- 

 guiOies compound fubftances, whofe adlion 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 poffefs in the elaftic ftate : the elementary affinities are modified by 

 the ftate of faturation, by the force of cohefion, or by the variations of elafticity : the re- 

 fulting affinity may undergo, by combination, a new degree of faturation which tends to 

 fupport the compoCtion, or may be weakened by other tendencies to combination with one 

 of the conftituent fubftances. 



12. All the confiderations which I have prefented refpe£ling the modifications of che- 

 mical aftion, do not prevent us from ufing the term affinity to denote the whole chemical 

 power of a body exerted in a given fituation, either by its prefent conftitution, its propor- 

 tion, or even by the concurrence of other affinities ; but we muft avoid confidering this 

 power as a conftant force which produces compofitions and decompofitions. By fo doing 

 we fliould erroneoufly infer from its prefent effects in any inftance, what it would be under 

 other conditions which may indeed give it a very different degree of force ; by fo doing wc 

 fliould negleft all the modifications it may experience from its initial adlion to that in which 

 it obtains its equilibrium. 



13. In this effay I have pointed out an uniform proceeding for the cultivation of che- 

 mical fcience. I have confidered all the forces which unite in the combinations and phe- 

 nomena on which it is employed ; I have endeavoured to determine the influence of each 

 in different circumftances. If the reader fliould regret the lofs of all expe£tation of claffing 

 the chemical power of bodies, independently of the conditions which modify it, it will rea- 

 dily be granted, that the tables of affinity contained fimple notes of fadls nearly fterile, and 

 that they deprived us of the advantage of employing in our deduftlons the knowledge of 

 the moft fruitful properties, by means of which a great number of the refults of chemical 

 aftion may be anticipated; and the fadts may be interpreted and direded without having 

 lecourfe to fuppofitions, or rec[uiring any particular principles to explain anomalies. 



' 4. . V.—^ 



