Rubidium Cliloraurates and Bromaurates. 



159 



Methods of analysis : — The crystals were prepared for analy- 

 sis by quickly pressing them between smooth filter-papers and 

 finally allowing them to become air-dry. The hydrous csesium 

 chloraurate, however, loses its water and becomes opaque on 

 exposure. It was therefore dried as rapidly and thoroughly 

 as possible on paper and was put into a weighing-tnbe as soon 

 as some of the fragments began to lose their transparency. 



Gold was determined by precipitation with ammonium oxa- 

 late or with sulphurous acid. The filtrate from the metallic 

 gold was used either to determine the alkali-metal as normal 

 sulphate or the halogen by the usual gravimetric method. 

 Water was determined by the method used in the combustion 

 of organic compounds, the halogens being held back by a mix- 

 ture of lead chromate and lead oxide. The absence of water 

 in the anhydrous compounds was established by the use of the 

 same process. 



Analyses. 



Found. 



Caesium 28*11 



Gold 41-61 



Chlorine 29-91 



Calculated 

 for CsAqCIj 



28-16 

 41-77 

 30-06 





99-63 





Calculated 





Found. 





for 2CsAuCl 4 . H 2 



Csesium 



. .. 27-23 





27-63 



Gold 



... 40-23 



„ 



40-99 



Chlorine 



... 29-07 





29-50 



Water .. 



2-32 



2-37* 



2-20* 1-87 





98-86 











Calculated 





Found. 





for CsAuBr 4 



Caesium 



... 20-73 







20-45 



Gold 



... 30-32 



30-26 



30-34 



Bromine . 



49-31 







49-21 



100-36 



Found. 



Rubidium 



Gold... 45-53 



Chlorine. 32-98 



* From a separate product. 



Calculated 

 for RbAuCl, 



20-14 



46-46 



33-40 



