90 THE ATOMIC WEIGHTS, 



nary gravimetric process was employed. The following results represent, 

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



1.3835 grm. CsCl gave 1.1781 grm. AgCl. Ratio, 117.435 

 1.3682 " 1.1644 " " 117.503 



1.2478 " 1.0623 <l " 117.462 



Mean, 117.467, .013 



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

 described under rubidium. In three of the experiments upon caesium 

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

 lected upon a filter. The results are subjoined : 



1.5825 grm. CsCl gave 1.351 grm. AgCl. Ratio, 117.135 



1.3487 " 1.1501 " " 117.265 



1.1880 " 1.0141 " " 117.148 



1.2309 " 1.051 " " 117.107 



Mean, 117.164, =b .023 



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



Johnson and Allen 117.499, .025 Cs = 132.007 



Bunsen 117.467,^.013 " =131.961 



Godeffroy 117.164,1^.023 "=131.560 



General mean.. . 117.413, dz .010 



Hence, if AgCl = 142.287, .0037, and Cl = 35.179, .00-48, Cs = 

 131.885, .0142. 



If 0=16, Cs 132.890. 



* Ann. Chem. Pharm., 181, 185. 1876. 



