32 Klaproth on the Chemical Analysis 



' Copper . . Ag 41 



Silver . . . e 40 



Arsenic 24.10 



Iron . . . f 22.50 



Sulphur 10 



Loss . . 2 



100 



Analysis of an Antimonial Sulphur et of Copper , ( Graugiiltigerz,) 

 from Kapnik. 



a. 300 grains of this ore in picked and clean crystals were 

 reduced to powder and digested in a mixture of three ounces of 

 nitric acid, (sp. gr. 1.230,) and an ounce and a half of water. 

 There was some evolution of nitrous gas, which was increased 

 by heat, and when the action ceased the liquid was poured off, 

 and the residue again digested in two ounces of nitric acid di- 

 luted with one of water ; the insoluble portion was then col- 

 lected and washed upon a filter. 



b. To the pale blue nitric solution concentrated by evaporation 

 muriatic acid was added, which produced a slight turbidness, 

 and the mixture being heated, afforded only half a grain of a 

 precipitate, which did not behave like pure muriate of silver. 



c. The solution was next divided into three equal portions. 



1. One-third was evaporated nearly to dryness, and the green 

 saline mass moistened with sulphuric acid which presently 

 formed a clear solution, indicative of the absence of lead ; the 

 solution was supersaturated with caustic ammonia, which left 

 an insoluble portion of precipitate, which being collected and 

 ignited weighed 3.5 grains. It was dissolved in muriatic acid, 

 and the solution decomposed by prussiate of potassa. After 

 the separation of the blue precipitate, carbonate of potassa occa- 

 sioned a slight brown deposit which weighed 0.25 grains, and 

 examined by the blow-pipe appeared to be oxide of manganese, 

 so that the proportion of iron may be assumed at about 3.25 

 grains. The dark-blue ammoniacal liquor was now super- 

 saturated with sulphuric acid, and the copper being separated 

 by the immersion of a plate of clean iron weighed 37.5 grains. 



2. Another third of the nitric solution was mixed with excess 



