90 THE ATOMIC WEIGHTS, 



navy gravimetric process was employed. The following results represent, 

 respectively, material thrice, four times, and five times purified : 



I.3S35 grm. CsCl gave I.1781 gini. AgCl. Ratio, 117.435 

 1.36S2 " 1. 1644 " " 117.503 



1.2478 " 1.0623 " " 117.462 



Mean, 1 17.467, =b .013 



Godeff'roy's work* was, in its details of manipulation, sufficiently 

 described under rubidium. In three of the experiments upon ciesium 

 the silver chloride was washed by decantation, and in one it was col- 

 lected upon a filter. The results are subjoined : 



I.5S25 grin. CsCl gave 1.351 grm. AgCl. Ratio, 117.135 



1.3487 " I.1501 " " 117.265 



I. 1880 " I.0141 " " 117. 148 



1.2309 " I. 051 " " 117. 107 



Mean, 1 17.164, i .02j 



We may now combine the three series to form a general mean : 



Johnson and Allen .... 117.499, ±: .025 Cs = 132.007 



Bunsen 1 17.467, =t .013 " =131.961 



Godeffroy 1 17. 164, dr .023 " ^ 131 560 



General mean. . . 117.413,^.010 



Hence, if AgCl == U2.2S7, ± .0J37, and CI = 35.179, ± .0048, Cs = 

 131.885, ±: .0142. 

 If 0= 16, Cs = 132.890. 



* Ann. Cheni. Pharm., iSi, 1S5. 1S76. 



