Xiv THE ATOMIC THEORY 311 



separated as a white precipitate of gypsum, but the 

 neutrality of the solution was not affected by the double 

 decomposition and the liquid above the precipitate con- 

 tained nothing but perfectly-formed common sal-ammoniac 

 (Angus Smith, p. 207). No free acid or alkali was produced 

 because the relative weights of alkali and of earth required 

 to saturate one acid could be shown to be the same as those 

 required to saturate the other ; the lime and sulphuric acid 

 combining to form gypsum, therefore, liberated ammonia 

 and muriatic acid in exactly the right proportions to form 

 a neutral solution of sal-ammoniac. 1 



Richter's observations were collected by one of his con- 

 temporaries 2 into a table which shows the weight of base 

 which will neutralise 1,000 parts of sulphuric acid or a tab- 

 ulated quantity of any other acid. A part of this table is 

 reproduced below. 



EQUIVALENT WEIGHTS OF 



1 Wenzel, who studied (Theory of Affinity, Dresden, 1777) the mixing 

 of copper sulphate with lead acetate to produce lead sulphate and 

 copper acetate, concluded from his analyses that the acetic acid set free 

 from the acetate of lead was not sufficient to dissolve the copper set free 

 from the sulphate of copper ; he calculated that 9^ out of 124 parts of 

 copper would remain undissolved in the precipitate of sulphate of lead. 

 There is therefore no justification for the circumstantial statement of 

 Berzelius, which attributes to Wenzel the discovery of the law 

 enunciated fifteen years later by Richter. 



2 Fischer, in German translation (1802) of Berthollet's Researches on 

 the Laws of Affinity ; quoted by Berthollet, Chem. Statics, tr. 1804, 

 I. 402. 



