ATOMIC WEIGHTS 



329 



Next in order are the results obtained by Dumas.' Bismuth tri- 

 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 : 



= 3.545 grm. Ag. 

 1.168 

 1.629 

 2.225 

 3.144 

 2.470 

 1.752 

 3.6055 

 5.361 



3.506 grm. BiCIs 



1.149 



1.5965 



2.1767 



3.081 



2.4158 



1.7107 



3.523 



5.241 



98.900 

 98.373 

 98.005 

 97.829 

 97.996 

 97.806 

 97.643 

 97.712 

 97.762 



Mean, 98.003, d= .090 



Hence, with Ag=108 and CI = 35.5, Bi = 311.03. 



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 

 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 BioOo added : 



1 Ann. Chim. Phys. (3), 55, 176. 1859. 



2 Arch. Sci. Phys. Nat. (3), 10, 10. Oeuvres Completes, 2, 717. 



