324 Wells — Complex Chlorides containing Gold. 



respond to the formula Cs 4 Au" 2 Au'" 2 Cl 12 it was possible 

 to calculate the composition of the mixtures obtained by 

 reduction with filter-paper. In the case where the prod- 

 uct showed the greatest variation from the orange-red 

 salt in its composition, the original solution was prepared 

 from 6 g. of the orange-red compound, 10 g. of cesium 

 chloride and about 300 cc. of water. Then a single 10 cm. 

 filter-paper was added and the whole was heated in a cov- 

 ered beaker upon the steam-bath for 24 hours. The filter- 

 paper and a considerable quantity of gold that had pre- 

 cipitated were then removed by filtration and a crop of 

 very black and opaque, apparently homogeneous crystals 

 was obtained by cooling. It is evident, from the composi- 

 tion of the original solution and the fact that gold was 

 removed by precipitation, that the product was formed in 

 the presence of an excess of mercuric chloride, and conse- 

 quently that it was likely to contain the salt CsHgCl 3 as 

 an isomorphous constituent. The results of the analysis 

 and the calculation are as follows : 



Calculated for 



A 



10 % 20 % 70 % 



Analysis Cs 4 Au' 2 Au'" 2 Cl 12 CsHgCl 3 Cs 4 HgAu'" 2 Cl 12 . Total 



Cs 33.23 3.04 6.04 23.96 33.04 



Hg 17.55 9.12 9.05 18.17 



Au 22.22 4.52 17.79 22.31 



CI 26.29 2.44 4.84 19.19 26.47 



The amount of the aurous compound was calculated 

 from the deficiency of chlorine, 0.78%, shown by the 

 analysis, below the amount required to give AuCl 3 with 

 the gold. Then the percentages of CsHgCl 3 and Cs 4 Hg 

 Au 2 Cl 12 were calculated by finding the proportions of 

 these that would bring the gold to the amount found. In 

 this calculation the required proportions of the constitu- 

 ent salts are given only approximately, but the fair agree- 

 ment of the total with the analysis is a satisfactory one. 

 The assumption, therefore, that this product was com- 

 posed of three isomorphous salts appears to be a plausible 

 one. 



. Cesium- Aurous- Auric Chloride, Cs 4 Au' 2 Au'" 2 Cl 12 . — 

 "When a concentrated solution of cesium chloride, best in 

 1 :1 or stronger hydrochloric acid, is mixed with solid aur- 

 ous chloride the result is very striking, for an intensely 



