140 M. Stas's New Determination of the Atomic Weights. 



tate washed, dried, and fused in hydrochloric acid. From 100 

 of silver there were obtained 132-848 and 132*8417 of chloride 

 of silver. 



The synthesis of nitrate of silver was effected by dissolving 

 pure silver in nitric acid, evaporating to dryness in a Bohemian- 

 glass vessel, heating in a current of dry air, and fusion till con- 

 stant. The mean of eight experiments gave for the relation 

 between silver and nitrate of silver 



100:157-492. 



Sulphuret of silver was prepared by heating a known weight 

 of silver, either in the vapour of pure sulphur or in sulphuretted 

 hydrogen gas. In the mean of five experiments, 100 parts of 

 silver gave 114-8522 of sulphuret. 



The method for estimating the relation between the equivalents 

 of silver and of the chlorides of sodium, ammonium, and potas- 

 sium, was that of Gay-Lussac. It consisted in dissolving a known 

 weight of silver in nitric acid, and adding an equivalent of the 

 chloride in question; the equivalents being calculated according 

 to Prout's law. The excess of silver after precipitation, estimated 

 by standard solutions, gave the required relations. 



The chloride of potassium was prepared cither from carefully 

 purified chlorate of potash, from platinochloride of potassium, 

 from nitrate of potash, or from tartrate of potash. The mean 

 of 19 experiments with quantities of pure silver varying from 3 

 to 32 grms., gave for the relation, 



Ag:K CI =100: 69-103. 



Fourteen similar experiments with chloride of sodium led to 

 the relation 



Ag:NaCl = 100: 54-2078. 



The relation between the equivalent of silver and that of chlo- 

 ride of ammonium, as obtained from ten experiments, was 

 Ag:NH 4 Cl = 100: 49-5944. 



For the relation between nitrate of silver and chloride of po- 

 tassium the numbers were 



AgO NO 5 : K Cl = 100 : 43-8758; 

 and for the relation between nitrate of silver and chloride of am- 

 monium, 



AgO NO 5 : NH 4 Cl= 100 : 31-488. 



The preparation of pure lead was attended with greater diffi- 

 culties even than that of pure silver. It was effected by digest- 

 ing solution of acetate of lead in a leaden vessel with thin lead- 

 foil until all copper and silver were precipitated. Sulphuric 

 acid was then added so as to form sulphate of lead, which was 



