326 Wells — Complex Chlorides containing Gold. 



loss was then 9.56%, while chlorine was still being given 

 off when the heating was stopped. The pure triple salt, 

 therefore, was not prepared in this way, but the intense 

 black color of the product makes it appear that it is prob- 

 ably formed to a considerable extent at least. 



Some potassium auric chloride, KAuCl 4 , was heated in 

 a similar manner, but, although the product became very 

 dark brownish-red, no intense black color was observed, 

 as in the case of the cesium salt, and hence it seems doubt- 

 ful that a potassium-aurous-auric chloride can be pre- 

 pared in this way. 



Summary. — It has been shown in this and the preceding 

 article on Pollard's salt: 



That the ammonium triple chloride (NH 4 ) 6 Ag 2 Au 3 Cl 17 

 does not correspond in its type of formula to the cesium 

 salt Cs 4 Ag 2 Au 2 Cl 12 . 



That no corresponding potassium triple chloride could 

 be prepared. 



That a series of cesium triple chlorides, Cs^AgoAusCl^, 

 Cs 4 Au' 2 Au'" 2 GL 12 , Cs 4 ZnAn 2 Cl 12 , i Cs 4 HgAu 2 Cl 12 , and Cs, 

 CuAu 2 Cli 2 can be prepared, which show evident isomor- 

 phism where two univalent silver or aurous atoms are 

 replaced by a bivalent atom. 



That two of these new salts, Cs 4 Ag 2 Au 2 Cl 12 and Cs 4 

 Au' 2 Au'"Cl 12 possess an astonishingly black color in com- 

 parison with the salts containing bivalent metals. 



That the double salt CsHgCl 3 is isomorphous with 

 Cs 4 HgAu 2 Cli 2 and with Cs 4 Au' 2 Au'" 2 Cl 12 , thus indicating, 

 perhaps that the multiple formula Cs 4 Hg 4 Ch 2 should be 

 ascribed to the former. 



That no cesium-calcium-auric salt could be prepared. 



Note: The next article in this series will describe a new 

 cesium-auric chloride, and this will be followed by one dealing 

 with a general discussion of triple salts, as well as another on a 

 chromophore grouping, suggested by the black salts described 

 here, and a consequent theoiy of the cause of the colors of 

 substances. 



New Haven 3 Conn., March, 1922. 



