30 THE ATOMIC WEIGHTS. 



Now, combining all four series, we get the following re- 

 sults : 



Dumas 114.8234, zh .0029 



Stas 114.8522, ±z .0007 



Cooke's 2d 114.888, ± .0012 



" 3d 114.8165, zfc .0044 



General mean 114.8581, d= .0006 



Here again we encounter a curious and instructive com- 

 pensation of errors, and another evidence of the accuracy of 

 Stas. 



The percentage of silver in silver sulphate has been de- 

 termined by Struve and by Stas. Struve* reduced the sul- 

 phate by heating in a current of hydrogen, and obtained 

 these results : 



5.1860 grm. AgjSO^ gave 3.5910 grm. Ag. 69.244 per cent. 



Mean, 69.203, =fc .0012 



Combining this mean with that from Struve's series we 

 get a general mean of 69.205, ± .0011. 



* Ann. Cham. Pharm., 80, 203. 1851. 

 f Aronstein's Translation, pp. 214-218. 



