Analysis of Tartarized A7itimo7iy, 397 



D. I dissolved ^5'6 grains of protoxide of antimony in a so- 

 lution of bitartrate of potash, and then precipitated it by sul- 

 phuretted hydrogen : after washing and drying in the same 

 mode as before, the precipitate weighed 52-8 grains ; and, as 

 it had the appearance of being an hydrosulphuret of antimonj', 

 I suspected that it was subhydrosulphuret consisting of 1 atom 

 of sulphuretted hydrogen, and 2 atoms of oxide of antimony, 

 on which supposition I ought to have obtained 53-05 of preci- 

 pitate instead of 52-8 ; and it will be observed that supposing 

 this to be the true constitution of this substance, the results of 

 B will agree with those of C as nearly as 43*46 to 44-04, for 

 subhydrosulphuret of antimony must consist of 52 x 2 + 17 

 = 121, and 121 : 104 :: 51-25 : 44-04. 



E. Further to examine this view of the subject, I dissolved 

 100 grains of sulphuret of antimony and 100 grains of the pre- 

 cipitate in question in separate and equal quantities of muriatic 

 acid, and decomposed the solutions with similar portions of 

 water; the precipitate from the sulphuret weighed 86-7 grains, 

 and that from the hydrosulphuret 87 grains ; and as in 1 atom 

 of subhydrosulphuret, 17 of sulphuretted hydrogen, and 16 of 

 oxygen = 33, would supply the place of 2 atoms of sulphur 

 = 3'2 in 2 atoms of sulphuret of antimony, it is evident that 

 equal weights of these compounds should yield nearly equal 

 quantities of precipitate by solution in muriatic acid and the 

 affusion of water. 



F. The nature of this precipitate was then examined by heat- 

 ing 50 grains in a small flask by a spirit-lamp, and I found to 

 my surprise, that it was readily converted into black sulphuret 

 of antimony, losing only 1-2 grain of water. It appears, there- 

 fore, that instead of a subhydrosulphuret as I had suspected, 

 the precipitate was sulphuret, containing a small quantity of 

 hydrosulphuret, but yet sufficient to give so much colour as to 

 conceal the nature of the sulphuret. The difficulty of the case 

 was increased by the fact already alluded to, viz. that 2 atoms 

 of oxygen and 1 atom of sulphuretted hydrogen are so nearly 

 equal in weight. 



G. As then 50 of the precipitate contain 48-8 of sulphuret 

 of antimony, 51-25 the whole quantity obtained, C must con- 

 tain 50-02 = 43-35 of protoxide of antimony, which is the 

 (juantity contained in 100 grains of crystallized emetic tartar. 



We have tluis obtained 7-4 as the quantity of water, and 

 43*35 as the weight of the protoxide of antimony ; and having 

 found, as already mentioned, that crystals of tartarized anti- 

 mony are obtained even from the last portions of the solution 

 in preparing the salt, the remainder of 49-25 will give the 



weight 



