230 



THE ATOMIC WEIGHTS. 



chloride was prepared by the action of dry chlorine upon bismuth, and 

 repeatedly rectified by distillation over bismuth powder. The product 

 was weighed in a closed tube, dissolved in water, and precipitated with 

 sodium carbonate. In the filtrate, after strongly acidulating with nitric 

 acid, the chlorine was precipitated by a known amount of silver. The 

 figures in the third column show the quantities of BiClg proportional to 

 100 parts of silver : 



.090 



Hence, with Ag = 108 and CI = 3-5.5, Bi = 211.03. 



The first three of the foregoing experiments were made with slightly 

 discolored material. The remaining six percentages give a mean of 

 97.791, whence, on the same basis as before, Bi = 110.79. Evidently 

 these results are now of slight value, for it is probable that the chloride of 

 bismuth, like the corresponding antimony compound, contained traces 

 of oxychloride. This assumption fully accounts for the discordance be- 

 tween Dumas' determination and the determinations of Schneider and 

 of still more recent investigators. 



In 1883 Marignac * took up the subject, attacking the problem by two 

 methods. His point of departure was commercial subnitrate of bismuth, 

 which was purified by re-solution and reprecipitation, and from which 

 he prepared the oxide. First, bismuth trioxide was reduced by heating 

 in hydrogen, beginning with a moderate temperature and closing the 

 operation at redness. The results were as follows, with the percentage 

 of Bi in Bi.^Os added : 



2.6460 grm. Bi^Oj loit 0.2730 grm. O. 89.6S3 per cent. 



Mean, 89.682, =h .0036 



Hence, if = 16, Bi = 208.60. 



* Arch. Sci. Phys. et Nat. (3), 10, 10. 



