104: PROCEEDINGS OF THE AMERICAN ACADEMY 



The analyses lead to the formula : 



22 WO3 . 5 SbPg . 6 P2O. . 12 K2O -I- 48 aq, 

 which requires : 



9393 100.00 



ANTIMONIO-TUNGSTATES. 



As already stated, these compounds are formed by the direct oxida- 

 tion of antimonoso-tungstates, one molecule of oxygen being absorbed. 

 I shall hereafter show that, in place of oxygen, platinous cliloride and 

 other divalent compounds may serve as complex replacing molecules. 

 Antimonio-tungstates are also formed when andmonic hydrate in excess 

 is boiled with an acid tuugstate,. and when tungstic teroxide is digested 

 or boiled with an alkaline antimonate. The salts of this series are, as 

 a whole, not so well detiiied as the phospho-tungstates, vanadio-tung- 

 states, and arsenio-tungstates, and are much more difficult to prepare 

 in a state of pu)ity. 



Analytical Methods. — These are essentially the same as those 

 which I have given in the ease of the antimonoso-tungstates. Anti- 

 raonic and tungstic oxides may be precipitated together by mercurous 

 nitrate and mercuric oxide. In the ignited precipitate it must be 

 assumed that the antimony is in the form of tetroxide, Sb^O^, and the 

 proper correction applied, after a special determination of the antimony, 

 as sulphide or as metal. 



6 : 2 Antimonio-timgstate of Potassium. — This salt was prepared by 

 boiling potassic di-antimonate for a long time with a solution of 12 : 5 

 acid potassic tungstate. After filtration from a small quantity of the 

 antimonate in excess, the filtrate, on standing twenty-four hours, 

 deposited colorless granular crystals, which were washed with cold 

 water and dried upon woollen paper. The salt was not very soluble 

 in water : the crystals were soft and packed togetlier between the 

 fingei's. In this salt, 



