90 PROCEEDINGS OF THE AMERICAN ACADEMY 



oxide which has been freshly precipitated from the correspondiug 

 chloride by sodic carbonate aud washed by decautatioa with cold 

 water. If the precipitated oxide is allowed to stand for some time, it 

 becomes crystalline, and is then no longer available. The solution of 

 antimonoso-tungstate obtained in this manner has a yellow color, and 

 there is no sensible reduction of tungstic teroxide. Instead of this 

 process, the following may be employed with advantage. Freshly 

 precipitated antimonious oxychloride, SbOCI, after washing with cold 

 water, dissolves very readily in boiling solutions of alkaline tungstates 

 of the metatungstic series. The solutions obtained in this way are 

 also yellow. The oxychloride, on standing for some days, also be- 

 comes highly crystalline, and then dissolves with great difficulty. The 

 solutions of sodic salts obtained as above become on evaporation thick 

 and syrupy, and finally yield yellow gummy masses. There is in 

 these cases also a tendency to supersaturation, as with the arsenoso- 

 tungstates, though by no means to the same extent, and crystals of 

 antimonious oxide (hydrate ?) are sometimes deposited. The concen- 

 trated solution of the sodic salt obtained as above gives yellow oils 

 with strong solutions of potassic or ammonic salts, which are but 

 slightly soluble in a lai-ge excess of the latter. After pouring off the 

 supernatant liquid, the oils may be redissolved in a small quantity of 

 water, and again precipitated by a large excess of a concentrated solu- 

 tion of a potassic salt. I prefer for this purpose the bromide. Two 

 or three repetitions of this process yield a nearly pure potassic anti- 

 monoso-tungstate, which may be advantageously used in the prepara- 

 tion of other salts. The alkaline salts of this series are either oily 

 liquids or gummy masses with a pale yellow color, and very easily 

 soluble. The solutions absorb oxygen rather slowly from the air, and 

 are not easily oxidized by bromine or chlorine unless in presence of 

 an excess of alkali, as, for example, sodic bicarbonate. They then 

 pass into an timonio- tungstates. Th^ general formula of the auti- 

 monoso-tungstates is 



m WO3 . n SboOg .p R,0. 



Aimlytical Methods. — The quantitative separation of antimony from 

 tungsten in these compounds may be effected by the following methods. 

 Hydric sulphide passed through the solution previously acidulated 

 with chlorhydric acid precipitates antimonious sulphide completely, 

 without any sensible reduction or precipitation of tungsten. An ali- 

 quot portion of the sulphide may then be heated in an atmosphere of 

 dry carbonic dioxide, in the usual manner. This method applies to the 



