1813.] On the Cause of Cfiemical Proportions. 443 



Article VII. 



Essay on the Cause of Chemical Proportions, and on some Cir- 

 cumstances relating to them : together with a short and easy 

 Method of expressing them. By Jacob Berzelius, M.D. 

 F. R. S. Professor of Chemistry at Stockholm. 



I. On the Relation between Berthollet's Theory of Affinities 

 and the Laws of Chemical Proportions. 



Some chemists have affirmed that the existence of chemical 

 proportions is contrary to the principles of the theory of affinities 

 with which the illustrious Benhollet has enriched chemistry. On 

 that account they have refused to adopt it. But if, on the one 

 hand, the knowledge of chemical proportions, which we at 

 present possess, does not accord with all the applications made 

 by Benhollet, and by other chemists, of his theory ; on the 

 other hand, it is incontestable, that these principles have never 

 h en refuted, but are more and more confirmed, the more they 

 are examined. Chemists, before Berthollet, were misled by con- 

 sidering the weakest of the two chemical forces, or affinities, 

 opposing each other as null. Berthollet pointed out that error, 

 and showed the effect which the chemical mass produces. 



Berthollet himself, far fromjjdenying the possibility of chemical 

 proportions, has contributed a good deal to prove their existence, 

 although the numbers resulting from his analytical experiments 

 be not always very accurate. He has proved that when the 

 elements cease to oppose each other, in consequence of their 

 chemical mass, their combinations always take place in definite 

 and invariable proportions. The doubts entertained by some 

 chemists of the truth of Berthollet's principles originate certainly 

 from the conduct of some of his zealous supporters, who have 

 extended his doctrine to cases to which it does not apply, and 

 have maintained the existence of indefinite combinations even 

 when the action of the chemical mass cannot interfere. This 

 opinion no doubt occasioned the line experiments of Proust, 

 whose object was to sh o w that, when the metallic oxides absorb 

 more oxygen, they pass at once from one degree of oxidation to 

 another, without passing through the intermediate steps ; and that 

 uhat had been considered as an intermediate step was merely a 

 mixture of a perfect oxide with an Imperfect one. 



The effects of the chemical mass are produced when, for 

 example, three bodies, A, B, and C, exist together in the same 

 Solution; that is to say, in mutual contact; and when both A 

 and B have an affinity for C, and endeavour to form the new 

 combinations, A C and H C, which still remain in solution, 

 and of course preserve their contact with the surplus of A and 



