12 



PROCEEDINGS OP THE AMERICAN ACADEMY 



of the chlorine in chloride of antimony ; in both cases precipitating 

 with nitrate of silver the chlorine from a solution of the chloride of 

 antimony in tartaric acid and water with the usual precautious. But, 

 while in the first series the precipitated chloride of silver was washed 

 with boiling hot distilled water to about the xo ckT)?tt7 according to Bun- 

 sen's scheme ; in the second series, although hot water was also used 

 in washing, one decigramme of nitrate of silver per litre was added to 

 each successive portion of the wash-water poured upon the precipitate, 

 until the last two portions, which were poured on cold. By this 

 simple device, the advantages of washing with hot water may be 

 secured, while its solvent action is prevented. The results are given 

 in the following table : — 



First Series. 



No. 



1 

 2 

 8 

 4 



Weight of SbCls 

 taken. 



2.3856 gram. 

 3.1300 

 3.4207 

 5.0031 



Weight of AgCl 

 obtained. 



4.4784 gram. 

 5.8712 

 6.4243 

 9.3790 



Per cent of CI 

 calculated. 



46.441 



46.407 



46.462 



46.377 



No. 



1 

 2 

 3 

 4 



Mean value, 46.634 



Max. difif. from mean, 0.017 



Difference between means of two series, 0.212 



It is evident from these results that when great accuracy is required, 

 the solubility of chloride of silver may become a very serious source 

 of error in determinations of chlorine, and in our first paper on the 

 atomic weight of antimony, this was the chief cause of the discrepancy 

 between the analyses of chloride of antimony on the one hand, and 

 the bromide, iodide, and sulphide of antimony — analyses of which 

 closely agreed among themselves — on the other hand. It was shown 

 in the paper just referred to that, although the greatest care was taken 

 in purifying the material, the chloride of antimony used actually left 



