50 HISTORY OF CHEMISTRY. [LECTURE IV. 



of the taking up of phlogiston, Lavoisier only needs to assume 

 the giving up of oxygen, and vice versa : the inverse ratio of the 

 quantities of the precipitated metal A and of the dissolved one 

 B gives Lavoisier the relations of the quantities of oxygen com- 

 bining with equal weights of A and B ; or otherwise, and more 

 clearly expressed, the quantities of the precipitated and of the 

 dissolved metal respectively, which the experiment furnishes 

 directly, have the property of being able to combine with the 

 same quantity of oxygen. The generalisation, in the latter 

 form, was not emphasised, however, either by Bergman or by 

 Lavoisier, otherwise it would probably have led to the notion 

 of equivalence. This result did not follow, and even the ex- 

 periments of both these chemists were but little heeded. It 

 did not fare much better with the investigations of Richter, 

 which were carried out between 1791 and 1802, and were sup- 

 ported by far more observations. Richter was the first to state 

 the law of neutrality, and to deduce accurate conclusions from 

 it. 4 This merit was formerly attributed erroneously to Wenzel, 

 who arrived, however, at exactly the opposite result. The 

 error which passed into many of the older text-books appears 

 to have been caused by Berzelius, 5 and was pointed out by 

 Smith, 6 and others. 7 



Richter observed that upon mixing solutions of two neutral 

 salts, the neutrality is maintained, even when double decom- 

 position takes place, and- from this he concluded that the 

 quantities a and b of two bases, both of which are neutralised 

 by the same quantity c of an acid, are both likewise neutralised 

 by the same quantity d of another acid ; and, conversely, that 

 the weights of two acids which are neutralised by the same 

 quantity a of a base, require for neutralisation the same quantity 



4 Richter, Ueber die neueren Gegenstande der Chemie. 5 Berzelius, 

 Essai sur la theorie des proportions chimiques et sur 1'influence chimique 

 de 1'Electricite, Paris (1819), 2. 6 Memoir of John Dalton, etc., 160. 

 7 Wenzel determined the proportions in which base and acid combine 

 to form salts. He found, however, exactly the opposite of what Berzelius 

 makes him say. Compare Wenzel, Ueber die Verwandtschaft der Korper, 

 Dresden (1782), especially 450 et seq. 



