OF ARTS AND SCIENCES. 3 



wholly overlooked by Schneider, the effect would only have been to 

 raise the mean result about 0.26. So far, however, from neglecting 

 these very small errors, Schneider in every case accurately collected 

 and determined both the sulphide of antimony volatilized and the sul- 

 phur retained by the regulus, and with these amounts, never exceeding 

 a few milligrammes, he corrected his observed data. In the paper re- 

 ferred to, Schneider gives the detail of eight separate determinations, 

 the mean of wiiich gives for the atomic weight of antimony the value 

 120.30, and this differs from the extremes on either side by only 0.23. 

 In tills determination, the atomic weight of antimony is referred to that 

 of sulphur, which is taken as 32.* 



In the next number of PoggendorfF's " Annalen " to that in which 

 the paper of Schneider appeared, Heinrich Rose published the result 

 of a previous analysis of Sb CL, made under his direction by Herr 

 Weber, which gives for the atomic weight of antimony the value 120.7 

 when chlorine is 35.5 ; and, although we have only the evidence of a 

 single analysis, yet this one was thought by Rose to be of especial 

 value as confirming the subsequent determination of Schneider. This 

 confirmation he regarded as the more satisfactory, since by Weber's 

 analysis the atomic weight of antimony is referred to chlorine, and not 

 as before to sulphur or oxygen. The process was this : A weighed 

 amount of Sb CI3. purified by repeated fractional distillation, was dis- 

 solved in an aqueous solution of tartaric acid. From this solution the 

 metal was precipitated by H2S, and in the filtrate the chlorine was 

 determined by precipitation with AgNOg in the usual way. 



Next in order in this series of investigations comes the admirable 

 work of Mr. W. P. Dexter. He adopted the same process as Ber- 

 zelins, but conducted it with all the refinement which ingenuity, guided 

 by the increased chemical knowledge of the time, could devise. Espe- 

 cial care was taken to secure pure metallic antimony; and a compari- 

 son of the results obtained with different specimens — purified by the 

 processes he describes — shows conclusively that, even if the metal 

 was not absolutely pure, the error resulting from this cause was wholly 

 inappreciable. The agreement between the results of the several 

 experiments is wonderfully close, but for the details we must refer to 

 the original paper.f It is only important to state here that Dexter 

 obtained for the atomic weight of antimony, as the mean of ten deter- 

 minations, the value 122.34, and that the extremes on either side were 



* PoggendorfTs Annalen, xcviii. 455, June, 1856. 

 t Ibid., c. 563, April, 1857. 



