2SG HISTORY OF CHEMISTRY. 



other compounds, assumed, as the basis of this process, that the ele- 

 ments in different specimens had the same propoition. Wenzel, in 

 1777, published his Lchre ion der Verwandschaft der Korper or, 

 Doctrine of the Affinities of Bodies ; in which he gave many good and 

 accurate analyses. His work, it is said, never grew into general 

 notice. Berthollet, as we have already stated, maintained that chemi- 

 cal compounds were not definite ; but this controversy took place at a 

 later period. It ended in the establishment of the doctrine, that then 

 is, for each combination, only one proportion of the elements, or at 

 most only two or three. 



Not only did Wenzel, by his very attempt, presume the first law ot 

 v nemical composition, the definiteness of the proportions, but he was 

 also led^ by his results, to the second rule, that they are reciprocal. 

 For he found that when two neutral salts decompose each other, the 

 resulting salts are also neutral. The neutral character of the salts 

 shows that they are definite compounds ; and when the two elements 

 of the one salt, P and s, are presented to those of the other, B and n, 

 if P be in such quantity as to combine definitely with , B will also 

 Combine definitely with s. s 



Views similar to those of Wenzel were also published by Jeremiah 

 Benjamin Richter 3 in 1792, in his Anfangsgrilnde der Stockyometrie, 

 oder Messkunst Chymischer Elemente, (Principles of the Measure of 

 Chemical Elements,} in which he took the law, just stated, of recipro- 

 cal proportions, as the basis of his researches, and determined the 

 numerical quantities of the common bases and acids which would 

 saturate each other. It is clear that, by these steps, the two first of 

 our three rules maybe considered as fully developed. The change of 

 genera 1 views which was at this time going on, probably prevented 

 chemists from feeling so much interest as they might have done other- 

 wise, in these details ; the French and English chemists, in particular, 

 were fully employed with their own researches and controversies. 



Thus the rules which had already been published by Wenzel ami 

 Richter had attracted so little notice, that we can hardly consider ^Jr. 

 Dalton as having been anticipated by those writers, when, in 1803, he 

 began to communicate his views on the chemical constitution of 



2 I am told that Wenzel (whose bo.ok I have not seen), though he adduces 

 many cases in which double decomposition gives neutral salts, does not express 

 the proposition in a general form, nor use letters in expressing it. 



* Thomson, Hist. Ghent vol. ii. p. 283. 



