ATOMIC WEIGHT OF JAPANESE TELLURIUM. ^35 



had been prepared by him and Mr. Shimose years ago. They had 

 obtained this tellurium from the sediment removed from the lead- 

 chambers of a sulphuric-acid factory, by a method the particulars of 

 which they communicated to the Chemical Neivs in 1883. The 

 tellurium, which I thus received, had already been carefully freed from 

 selenium and distilled in hydrogen. 



Before I had made very much progress in preparing for the 

 determination of the atomic weight, a preparation which has taken a 

 very long time, Staudenmaier's memoir came to hand, but its contents 

 did not deter me from finishing my investigation, though they can 

 leave no reasonable doubt, I think, that the atomic weight of the 

 element is really 127*6. 



Long ;is the work has occupied me, there is now no occasion to 

 describe it in detail, since it was purposely the closest copy I could 

 make of Brauner's operations, so far as these seemed to be material to 

 the point. The tellurium, already so pure, was tested for impurities, 

 and was again distilled in hydrogen. 



Excellent commercial bromine was distilled from potassium 

 bromide, zinc oxide, and water (Stas). It was dehydrated first by 

 means of anhydrous calcium bromide left in it for some days, and 

 then by baryta, from which it was filtered through asbestus in vessels 

 closed from the air. It was then distilled into a receiver sealed on to 

 the distilling flask. 



The silver was first precipitated by Stas's well-known sulphite 

 method, fused under borax and nitre, then kept for a time in fusing 

 potassium-sodium carbonate, washed with water, hydrochloric acid, 

 and ammonia, melted again in a lime crucible, and granulated in 

 distilled water. 



The distilled water of the laboratory was fractionally redistilled, 

 and the nitric acid was treated in the same way. 



