372 O. D. Allen on Caesium and Rubidium. 



J-5 parts of boiling 



II. 17-535 grms. of solution saturated at 25° C. gave a residue of 

 0-205 grm. 



III. 16-094 grms. of solution saturated at 25° C. ffave a residue of 

 0-188 grm. ^ 



One part of the salt tlius required respectively Si-oS, and 84'6 

 parts of water at 25° C. for solution. 



The hitartrate of caesium forms crystals closely resembling the 

 rubidium salt, but in my experiments they were usually of 

 smaller size. 



The salt obtained by concentrating the solution from which 

 all the rubidium had" been separated, was to all appearance 

 pure. It was recrystallized, and after drying at 100° C, at which 

 temperature it suffered no loss of weight, was analyzed in the 

 same manner as the bitartrate of rubidium. 



I. 0-4718 grm. gave \ ^'^Jf grm. water, and 



^ ^ ( 0-294 " carbonic acid. 



II. 0-5966 grm. gave \ ?"^2^ ^"''- "^^^f ' ^"'^ 



*= (0-372 " carbons « 



III. 1-3086 grm. gave 0-7708 grm. chlorid of ( 



bonic acid. 



Assuming the combining proportion of caesium to be 123'35, 

 as determined by Bunsen, the following statement exhibits the 

 composition of the salt, according to the formula, 

 Cs H, O3 I ^ 

 H Cs [ ^* 



48-00 



17-62 



500 



1-83 



88-00 



32-31 



231-35 



48-24 



272-35 



100-00 



The discrepancy between the composition as calculated and 

 found is perhaps due to a slight admixture of the neutral tar- 

 trate which might possibly have been present, owing to the use 

 of insufficient tartaric acid. 



The solubility of bitartrate of caesium was determined for 

 the same temperature and by the same methods as were em- 

 ployed in case of the rubidium salt. 



I. 2-998 grms. of solution saturated at the boiling point gave a residue 

 of 1-483 srrras. 



