92 PROCEEDINGS OP THE AMERICAN ACADEMY 



and an excess of sodic bicarbonate. It will be found advantageous 

 to standardize the solution of iodine by means of pure crystallized 

 antimouio-potassic tartrate, — of course, after addition of an alkaline 

 dicarbonate. 



The determination of tungstic oxide may be effected by first separat- 

 ing the antimony as sulphide, and then precipitating the hot solution 

 with baric chloride, after adding ammonia in small excess. The baric 

 tungstate may be weighed upon an asbestos filter. It is better, how- 

 ever, to precipitate the tungstic oxide by means of mercurous nitrate ; 

 only, in case this method is to be applied, the antimony must be pre- 

 cipitated as sulphide after the addition of dilute sulphuric acid, and 

 chlorhydric acid must not be employed. 



11:3 Baric Antimonoso-tungstate. — A solution of sodic antimo- 

 Doso-tungstate, obtained as above, gives with baric chloride a heavy 

 pale j^ellow curdy or indistinctly crystalline precipitate. This salt 

 melts under hot water to a thick yellow oily liquid, which dissolves 

 very slowl}^, requiring a large quantity of water for solution. The 

 solution has a yellow color and an acid reaction. It gives pale yellow 

 flocky precipitates, with mercurous, argentic, and thallous nitrates. 

 Of this salt, 



1.0722 gr. lost on ignition with W04Na2 0.0858 gr. = 8.00 % 

 1.2057 gr. gave 0.3318 gr. SbgSg = 21.78 % Sb^Og 



1.36G8 gr. " 0.3371 gr. " = 21.17 cf^ " 



1.2543 gr. " 0.U40 gr. SO^Ba = 7.54 %BaO 



1.4895 gr. " 0.1709 gr. " = 7.53 r^^ « 



1.9450 gr. " 1.6599 gr. oxides (WOg-f Sb204) = 85.34 % 



The analyses lead to the formula 



11 WO3 . 3 SbgOs . 2 BaO -f 18 aq, 

 which requires : 



4046 100.00 



The salt may be reduced to the type 



6 WO3 . SbsOg . BaO + 9 aq, 



