330 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



Marignac's second method of determination was by conversion of the 

 oxide into the sulphate. The oxide was dissolved in nitric acid, and 

 then sulphuric acid was added in slight excess from a graduated tube. 

 The mass was evaporated to dryness with great care, and finally heated 

 over a direct flame until fumes of SO3 no longer appeared. The third 

 column gives the sulphate formed from 100 parts of oxide: 



2.6503 BLO3 gave 4.0218 Bu( 804)8. Ratio, 151.749 



151.775 

 151.734 

 151.G88 

 151.739 

 151.682 



Mean, 151.728, ± .0099 



Hence Bi = 208.16. 



This result needs to be studied in the light of Bailey's observation,' 

 that bismuth sulphate has a very narrow range of stability. It loses the 

 last traces of free sulphuric acid at 405°, and begins to decompose at 

 418°, so that the foregoing ratio is evidently uncertain. The concordance 

 of the data, however, is favorable to it. 



Two analyses of bismuth sulphate, rather vaguely stated, are given by 

 Bailey. The weights found, and the ratio derived from them are as 



follows : 



BuiSOJ^. BuOs. Ratio. 



2.2155 1.4615 151.591 



1.5635 1.0267 152.284 



Mean, 151.937, ± .231 



Hence Bi = 207.25. Combined with Marignac's series, the general 

 mean becomes 151.729, ±.0099. Bailey's figures practically disappear. 

 The next determination of this atomic weight was by Lowe." who 

 oxidized the metal with nitric acid, and reduced the nitrate to oxide by 

 ignition. Special care was taken to prepare bismuth free from arsenic, 

 and the oxide was fused before weighing. In the paper just quoted 

 Bailey calls attention to the volatility of bismuth oxide, which doubtless 

 accounts for the low results found in this investigation. The data are 

 as follows : 



Bi taken. B%Oa found. Per cent. Bi. 



11.309 12.616 89.640 



12.2776 13.694 89.656 



Mean, 89.648, ± .0040 



Hence Bi = 207.84. 



'Journ. Chem. Soc, 51, 676. 1887. Bailey deduces from his analyses Bi = 208.3.3 and 208.43. 

 There may be some error in his printed figures, for his deductions do not agree with the data 

 as given. 



= Zeit. anal. Chem., 22, 498. 



