ANTIMONY. •- 223 



This mean may be combined with that of Kessler's series, as follows: 



Kessler 53-623, ± .015 



Cooke 53-o66, ± .0096 



General mean 53.2311, ± .008 



The results thus obtained wdth SbCl3 confirmed Dumas' determination 

 of the atomic weight of antimon}' as remarkably as the syntheses of Sb.^Sj 

 had sustained the work of Schneider. Evidently, in one or the other 

 series a constant error must be hidden, and much time was sjDent by 

 Cooke in searching for it. It was eventually found that the chloride of 

 antimony invariably contained traces of oxychloride, an impurity which 

 tended to increase the apparent atomic weight of the metal under con- 

 sideration. It was also found, in the course of the investigation, that 

 hydrochloric acid solutions of antimonious compounds oxidize in the air 

 during boiling as rapidly as ferrous compounds, a fact which explains 

 the high values for antimony found by Kessler. 



In order to render " assurance doubly sure." Professor Cooke also 

 undertook the analysis of the bromide and the iodide of antimony. The 

 bromide, SbBr,, was prepared by adding the finely powdered metal to a 

 solution of bromine in carbon disuli^hide. It was purified b}^ repeated 

 distillation over pulverized antimony, and by several recrystallizations 

 from bisulphide of carbon. The bromine determinations resemble those 

 of chlorine, and gave, if Ag = 108 and Br = 80, a mean value for anti- 

 mon}^ of Sb = 120. Reduced to a common standard, the fifteen analyses 

 give the subjoined quantities of SbBr^ proportional to 100 parts of silver 

 bromide : 



1. 8621 grm. SbBrj gave 2.9216 grm. AgHr. 63.736 



.9856 " 1.5422 " 63.909 



1.8650 " 2.9268 " 63.721 



1.5330 " 2.4030 " 63.795 



1-3689 " 2.1445 ". 63.833 



1. 2124 " 1. 8991 " 63 841 



.9417 , " 1.4749 " 63.84S 



■ 2.5404 " 3-9755 " 63.901 



1.5269 " 2.3905 " 63.874 



1.8604 " 2.9180 " 63.756 



1.729S " 2.7083 " 63.870 



3.2838 " 5-1398 " 63.890 



2.3589 " 3-6959 " 63.825 



1.3323 " 2.0S63 " 63.859 



2.6974 " 4-2285 " 63.791 



Mean, 63.830, dr .008 



The iodide of antimony was prepared like the bromide, and anah^zed 

 in the same way. At first, discordant results w'ere obtained, due to the 

 presence of oxyiodide in the iodide studied. The impurit}^ however, 



