Professor Gmelin's Analysis of Helv'inc. 271 



b. The Silica being removed, the sulphuric acid, formed by 

 the action of nitro-muriatic acid, was thrown down by nitrate 

 of barytes. The sulphate of barytes weighed after ignition 

 0.7063 gr. =g 0.097442 gr. of sulphur = 5.057 per cent, of sul- 

 phur. 



c. The barytes in excess being precipitated by sulphuric 

 acid, and the sulphate of barytes removed by the filtre, the 

 liquid was evaporated in a porcelain dish. It became first 

 red, then green, whereby nitrous vapours were disengaged. 

 Having been evaporated almost to dryness, a white powder 

 separated by addition of water, which was entirely dissolved 

 by an additional quantity of sulphuric acid. The sulphuric 

 acid solution was now decomposed by ammonia, and the pre- 

 cipitate put upon a filtre. The liquor, which had passed 

 quite clear, became troubled by degrees, and assumed a brown- 

 ish hue ; it was concentrated by evaporation, whereby the ex- 

 cess of ammonia was expelled, and the oxide of manganese 

 collected upon a filtre. It weighed after ignition 0.0604 gr. 

 =r 2.824 p. c. Oxalate of ammonia afforded no precipitate in 

 the filtered solution, a proof of the absence of lime ; hydro- 

 sulphuret of ammonia precipitated sulphuret of manganese, 

 which was dissolved in muriatic acid, and joined to the solu- 

 tion of manganese obtained below. The liquid was now 

 evaporated and ignited; but there remained in the crucible 

 nothing but a slight trace of manganese, which was dissolved 

 by oil of vitriol with red colour ; by muriatic acid with dis- 

 engagement of chlorine, and whose solution likewise was join- 

 ed to the solution of manganese obtained below. 



d. The precipitate is still to be examined, which was thrown 

 down by caustic ammonia (in c). It was dissolved in muria- 

 tic ncid, the solution evaporated, in order to expel the acid in 

 excess, then boiled with a solution of pure potash. The brown 

 residue left was dissolved in muriatic acid with disengagement 

 of much chlorine ; from this solution the iron was thrown 

 down by succinate of ammonia. 0.119gr. of oxide of iron 

 were obtained = 8.564 p. c. of protoxide. 



e. The liquor from which the iron had been removed, joined 

 with that (in c.) obtained by the decomposition of sulphuret 

 of manganese, was thrown down by boiling with a solution o£ 



