Wells — Complex Chlorides containing Gold. 325 



black precipitate is instantly formed, while metallic gold 

 is also deposited. The black compound is the triple salt 

 under consideration. It is not easy to obtain it in a pure 

 condition, free from metallic gold and the yellow double 

 salt CsAuCl 4 , but occasionally it can be recrystallized sat- 

 isfactorily. 



A good crop was obtained by treating 5 g. of aurous 

 chloride, made by heating HAuCl 4 , with 30 g. of cesium 

 chloride dissolved in a little 1:1 hydrochloric acid, then 

 diluting with the same acid to about 400 cc, heating to 

 boiling, filtering and cooling. Another satisfactory crop 

 was prepared by evaporating on the steam-bath, until 

 crystallization took place, a similar, but somewhat more 

 concentrated solution. The first product was simply 

 dried by pressing on paper, but the second one was 

 washed to a considerable extent, before drying, by largely 

 diluting the last part of the mother-liquor with hydro- 

 chloric acid. 



The salt forms very minute black crystals which are 

 rapidly decomposed by water with the formation of 

 cesium-auric chloride and metallic gold, but they appear 

 to be very stable with strong hydrochloric acid. 



The results of the analyses of the two crops that have 

 been mentioned are as follows : 



Calculated for 

 I II Cs 4 Au' 2 Au"' 2 Cl 12 



CsCl 38.83 37.89 38.56 



An 44.86 45.92 " 45.19 



CI 16.31 16.19 16.25 



The analyses were made by heating the substance 

 (dried at 100° ) in a Rose crucible in a stream of hydrogen. 

 The loss in weight gave the chlorine, while the residue 

 consisting of gold and cesium chloride, was treated with 

 water and the gold was collected and weighed. 



An attempt was made to prepare this triple salt, the 

 simplest formula for which is CsAu"Cl 3 , by heating the 

 double salt CsAu'"Cl 4 . The latter became intensely black 

 at about 320°, but the loss in weight at this temperature 

 was only 1.68% instead of the theoretical 7.51%, so that 

 the change, if it did take place, was only superficial or 

 partial. Upon heating to the melting-point without 

 measuring the temperature, a reddish liquid was formed 

 which became intensely black upon solidification, but the 



