ANTIMONY. 



223 



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



Kessler ............. ' ................ . ... 53.623, d= .015 



Cooke ............ ---- ............ ____ 53.o66, .0096 



General mean ................... 53.2311, .008 



The results thus obtained with SbCl 3 confirmed Dumas' determination 

 of the atomic weight of antimony as remarkably as the syntheses of Sb 2 S 3 

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

 series a constant error must be hidden, and much time was spent 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 s , was prepared by adding the finely powdered metal to a 

 solution of bromine in carbon disulphide. It was purified by 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- 

 mony of Sb = 120. Reduced to a common standard, the fifteen analyses 

 give the subjoined quantities of SbBr 3 proportional to 100 parts of silver 

 bromide : 



1.8621 grm. SbBr 3 gave 2.9216 grm. AgBr. 



.9856 

 1.8650 

 1.5330 

 1.3689 

 1.2124 



.9417 

 2.5404 

 1.5269 

 1.8604 

 1.7298 

 3-2838 

 2.3589 

 L3323 

 2.6974 



1.5422 

 2.9268 

 2.4030 



2.1445 

 1.8991 

 1.4749 

 3-9755 

 2.3905 

 2.9180 

 2.7083 

 5.1398 

 3.6959 

 2.0863 

 4.2285 



63-736 

 63.909 

 63.721 

 63.795 

 63-833 

 63841 

 63.848 

 63.901 

 63-874 

 63-756 

 63.870 

 63.890 

 63.825 

 63-859 

 63-791 



Mean, 63.830, .008 



The iodide of antimony was prepared like the bromide, and analyzed 

 in the same way. At first, discordant results were obtained, due to the 

 presence of oxyiodide in the iodide studied. The impurity, however, 



