ATOMIC WEIGHTS 



Mean, 74.064, ± .003 



Corrected for weighing in air the mean becomes 74.077. 



Much more elaborate determinations of this ratio are due to Stas.^ 

 In one experiment a known weight of silver was converted into nitrate, 

 and precipitated in the same vessel by pure hydrobromic acid. The 

 resulting bromide was washed thoroughly, dried, and weighed. In four 

 other estimations the silver was converted into sulphate. Then a known 

 quantity of pure bromine, as nearly as possible the exact amount neces- 

 sary to precipitate the silver, was transformed into hydrobromic acicl. 

 This was added to the dilute solution of the sulphate, and, after precip- 

 itation was complete, the minute trace of an excess of silver in the clear 

 supernatant fluid was determined. All weighings were reduced to a 

 vacuum. The data are as follows : 



Mean, 74.0810, ± .0006 



In his paper on the atomic weight of cadmium,^ Huntington give^ 

 three syntheses and three analyses of silver bromide. The data are as 

 follows, with the usual ratio given in the last column : 



1.4852 grm. Ag gave 2.5855 AgBr. 

 1.4080 " 2.4510 " 



1.4449 " 2.5150 " 



4.1450 grm. AgBr gave 2.3817 Ag. 

 1.8172 " 1.0437 " 



4.9601 " 2.8497 " 



74.084 

 74.077 

 74.060 

 74.035 

 74.111 

 74.057 



Mean, 74.071, ± .0072 



Similar synthetic data are also given by Eichards, incidentally to his 

 work on copper.^ There are two sets of three experiments each, which 

 can here be treated as one series, thus : 



^ Oeuvres Completes, 1, 587, 603. 



2Proc. Amer. Acad., 17, 28. 1881. 



sproc. Amer. Acad., 25, 199, 210, 211. 1890. 



