Dr. Percy on the Composition of Beudantite. 165 



was added, and the whole evaporated to dryness and ignited. 

 The product weighed 2'05 grs. 



The solution from which the lead had been separated was 

 boiled with chlorate of potash. Ammonia in excess was 

 added. The precipitate, washed, dried and ignited, weighed 

 2 62 grs. 



Second Analysis. 



The particles of crystals were carefully selected under a lens. 



Weight 6*64- grains. 



The mineral was digested in hot hydrochloric acid. Excess 

 of ammonia was added to the solution, and afterwards excess 

 of hydrosuiphate of ammonia, when the whole was exposed to 

 a gentle heat during many hours. The precipitate was washed 

 on a filter with water containing a little hydrosuiphate of am- 

 monia, and afterwards treated with hot hydrochloric acid. 

 Decomposition was complete. Through the solution, after 

 filtration, sulphuretted hydrogen was passed for a considerable 

 time. The precipitate was digested with the strongest nitric 

 acid, and after the addition of a i'ew drops of sulphuric acid, 

 evaporated to dryness and ignited. The product weighed 

 2*66 grains, 



The solution from which the lead had been separated by 

 sulphuretted hydrogen was left in a warm place until the 

 odour of that gas ceased to be detected. It was filtered, 

 boiled with nitric acid, and treated with excess of ammonia. 

 The precipitate, washed, dried and ignited, weighed 2*50 grs. 



The hydrosuiphate of ammonia solution was digested with 

 excess of hydrochloric acid in a warm place for more than 

 twenty-four hours. The precipitate, washed and dried at 100° 

 C, until it ceased to lose weight, weighed 3*72 grs. The 

 arsenic was determined indirectly in the usual way. The 

 analytical data obtained are as follow: — 



Sulphur and sulphuret analysed, weighed . . . 3*1«1 



Ditto ditto, adherent to filter .... 0*31 



Globule of free sulphur 1*27 



Sulphate of baryta 11-60 



The solution from which the arsenic had been separated as 

 sulphuret by hydrochloric acid, was reduced by evaporation, 

 and treated with excess of chloride of barium. The preci- 

 pitate, washed, dried and ignited, weighed 2*40 grs. 



Of another portion of crystalline fragments selected under 

 a lens, 5'34< grains were weighed. 



The mineral was digested in hot hydrochloric acid. The 

 solution was poured into a hot solution of chloride of ba- 



