222 THE ATOMIC WEIGHTS. 



rected syntheses gave Sb = 120.295. In these eleven experiments the 

 following percentages of S in Sb^S.^ were established : 



28.57 

 28.60 

 28.57 



28.43 

 28.42 

 2S.53 

 28.50 

 28.49 

 28.58 

 28.50 

 2S.51 



Mean, 28.5182, rh .0I20 



These results, confirmatory of the work of Schneider, were presented 

 to the American Academy in 1876. Still, before publication, Cooke 

 thought it best to repeat the work of Dumas, in order to detect the cause 

 of the old discrepancy between the values Sb = 120 and Sb = 122. Ac- 

 cordingly, various samples of antimony trichloride were taken, and puri- 

 fied by repeated distillations. The final distillate was further subjected 

 to several recrystallizations from the fused state ; or, in one case, from a 

 saturated solution in a bisulphide of carbon. The portions analyzed 

 were dissolved in concentrated aqueous tartaric acid, and precijiitated 

 by silver nitrate, many precautions being observed. The silver chloride 

 w^as collected by reverse filtration, and dried at temperatures from 110° 

 to 120°. In one experiment the antimou}^ was first removed by H.^S. 

 Seventeen experiments were made, giving, if Ag = 108 and CI = 85.5, a 

 mean value of Sb = 121.94. If we reduce to a common standard, Cooke's 

 analyses give, as proportional to 100 parts of AgCl, the quantities of SbCl. 

 stated in the third column : 



1-5974 g™- SbClg gave 3.0124 grm. AgCl. 53-02S 



53.061 

 52.978 

 53-'84 

 53-148 

 53-IOI 

 53.0S8 



52.999 

 53-025 

 53-048 

 53.081 



53.175 

 53-072 

 53.020 

 53-030 

 53.028 

 53-053 



Mean, 53 066, ^t .0096 



