ANTIMONY. 193 



These data, reduced to a common standard, give the fol- 

 lowing quantities of ox3^gen needed to oxidize 100 parts of 

 SbaOs to SbjOg. Each cubic centimetre of the K^CrgO; 

 solution corresponds to one milligramme of : 



10.985 

 10.939 

 10.951 

 10.936 



Mean, 10.953, =t: .0075 



In the second series of experiments pure antimony was 

 dissolved in hydrochloric acid with the aid of an unweighed 

 quantity of potassium chlorate. The solution, containing 

 both antimonious and antimonic compounds, was then re- 

 duced entirely to the antimonious condition by means of 

 stannous chloride. The excess of the latter was corrected 

 with a strong hydrochloric acid solution of mercuric chlo- 

 ride, then, after diluting and filtering, a weighed quantity 

 of potassium chlorate was added, and the titration with an- 

 hydrochromate was performed as usual. Calculated as 

 above, the percentages of oxygen given in the last column 

 correspond to 100 parts of antimony : 



Sd. KCIO.,. K\Cr^0^sol.cc. Per cent. O. 



1.636 grm. 0.5000 grm. 18.3 13.0S8 



3-0825 " 0.9500 " 30.2 13.050 



4.5652 " . I. 4106 " 45.5 13.09S 



Mean, 13.079, =fc .0096 



This series gave Kessler Sb = 122.34. 



The third and fourth series of experiments were made 

 with pure antimony trichloride, SbClg, prepared by the action 

 of mercuric chloride upon metallic antimony. This prepa- 

 ration, in the third series, was dissolved in hydrochloric 

 acid, and titrated. In one experiment solid KoCr^.O^ in 

 weighed amount was added before titration : in the other 

 two estimations KClOg was taken as usual. If, according 

 to Siewert's work, wo take Cr = 52.009, the percentages of 

 oxygen in the last column correspond to 100 parts of SbClj : 

 13 



