264 Disulphuret of Bismuth. 



XI. Solubility of bitungstate of Ammonia. 



(a) Fifty grains of crystallized bitungstate of ammonia were 

 boiled with 200 of water. A part only was dissolved, and more wa- 

 ter was added at intervals until the solution was complete, and the 

 boiling was continued until nascent precipitation. The flask was 

 then found to contain 800 grains of water. 



(b) 100 grains of the same, required for its perfect solution 1600 

 grains of water, at 212° F. 



(c) 50 grains of crystallized bitungstate of ammonia were repeat- 

 edly agitated with 900 grains of water, at a mean temperature of 

 60° F. 17 grains only of the salt were dissolved. 



Hence the bitungstate of ammonia requires 16 parts of water at 

 212° F., and 53 parts of water at 60° F., for solution. 



The bitungstate of ammonia was made by digesting moist recently 

 prepared tungstic acid, with caustic ammonia, evaporating the solu- 

 tion to dryness, at a regulated temperature, then dissolving in hot 

 water and crystallizing. Thomson, in his Elements of Chemistry, 

 Vol. II, p. 66, in speaking of the action of reagents on bitungstate 

 of ammonia, mentions that metallic tin and a drop of muriatic acid 

 cause white flocks at first to separate, which gradually become blue, 

 and a deep blue color covers the tin. I find tin to act more distinct- 

 ly as a reagent without the acid, on the bitungstate of ammonia. 

 The tin becomes almost instantly of a splendid blue, like that of a 

 fine sword blade, and a blue precipitate soon begins to form, finally 

 concealing the tin. The precipitate, by long standing, becomes white 

 on the surface. 



Muriate of cobalt is a good test of bitungstate of ammonia. It 

 gives a voluminous precipitate of a lilac color, and a lilac colored 

 solution, which, when dry, becomes blue, and when heated to drive 

 off the muriate of ammonia, it changes to a green. 



XII. DisuJphuret of Bismuth. 



A notice of this compound was published in this Journal, Vol. 

 XXIV, page 189, with its synthesis. Afterwards the experiment 

 was repeated : 720 grains of pulverized bismuth were well mixed 

 with 240 grains of flowers of sulphur, and put in a covered crucible 

 weighing 1706 grains. The crucible had been recently ignited to 

 drive off hygrometric moisture. It was at first moderately heated, 

 and after half an hour the heat was raised, first to a dull red, and 



