ANTIMONY. 219 



hydrochloric acid, and titrated with dichromate solution. Six experi- 

 ments were made, but Kessler rejects the first and second as untrust- 

 worthy. The data for the others are as follows : 



S 2 <9 3 . KCIO*. K.jCr.jO^ sol. in cc. 



1,7888 grm. .4527 grm. 19.200. 



1.6523 " .45 6 " 3-9 " 



3.2998 " .8806 " 16.5 " 



1.3438 " .3492 " 10.2 " 



From these figures Kessler deduces Sb = 122.16. 



These data, reduced to a common standard, give the following quanti- 

 ties of oxygen needed to oxidize 100 parts of Sb 2 3 to Sb 2 O 5 . Each cubic 

 centimetre of the K 2 Cr 2 7 solution corresponds to one milligramme of : 



10.985 

 10.939 

 10.951 

 10.936 



Mean, 10.953, - OO 75 



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 reduced 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 chloride, then, after 

 diluting and filtering, a weighed quantity of potassium chlorate was 

 added, and the titration with dichromate was performed as usual. Cal- 

 culated as above, the percentages of oxygen given in the last column 

 correspond to 100 parts of antimony: 



Sb. KClO y A" 2 O a <9 7 sol. cc. Per cent. O. 



1.636 grm. 0.5000 grm. 18.3 13.088 



3.0825 " 0.9500 " 30.2 i3-5 



4.5652 " 1.4106 " 45.5 13.098 



Mean, 13.079, .0096 



This series gave Kessler Sb = 122.34. 



The third and fourth series of experiments were made with pure 

 antimony trichloride, SbCl 3 , prepared by the action of mercuric chloride 

 upon metallic antimony. This preparation, in the third series, was dis- 

 solved in hydrochloric acid, and titrated. In one experiment solid 

 K 2 O 2 7 in weighed amount was added before titration; in the other two 

 estimations KC10 3 was taken as usual. The third column gives the 

 percentages of oxygen corresponding to 100 parts of SbCl 3 . 



