a Mineral not hitherto described, 1 33 



The excess of nitrate of silver having been separated by 

 hydrochloric acid, the solution was tested with chloride of 

 barium, but no precipitate was produced. Hydrosulphuric 

 acid was then passed through for a considerable time. The 

 precipitate was digested with fuming nitric acid. Sulphuric 

 acid was added, and the whole evaporated until the excess of 

 sulphuric acid was completely expelled. The dry product 

 was washed with water. The insoluble white residue, washed, 

 dried and ignited, weighed 3*90. Heated in the inner flame 

 on charcoal with carbonate of soda, a large bead of malleable 

 lead was obtained. 



The last solution was boiled with excess of potass. The 

 dark brown precipitate, washed, dried and ignited, weighed 

 0*97. Heated in the inner flame on charcoal, a bead of mal- 

 leable copper was obtained. 



The solution through which hydrosulphuric acid had been 

 passed, contained iron with a minute quantity of alumina and 

 silica. 



The residual matrix, after treatment with nitric acid, was 

 boiled with hydrochloric acid. The red-brown matter was 

 entirely dissolved, and consisted of sesquioxide of iron. Frag- 

 ments of quartz with adhering particles of metallic gold re- 

 mained. The acid solution was filtered hot. On cooling, a 

 small quantity of white matter subsided, which became slate- 

 coloured by exposure to light, and by fusion with carbonate 

 of soda on charcoal in the inner flame, gave a minute bead of 

 silver. 



The Restdts Tahdated. 



-Chloride of silver . . . 3-4.0 = Cl 0*84. 

 Sulphate of lead . . . 3-90 = Pb 2*66 

 Oxide of copper . . , 0*97 =Cu 0*77 



Dividing by the respective atomic weights, the chlorine, 

 lead, and copper are found to be in the exact ratio of one 

 equivalent of each. Thus, — 



0-84. ^^ 2-66 ^^ 0-77 



^=-°23' To?=-"^^' ^='02*- 



A minute quantity of chloride of silver was also present. 



Now the preceding results of themselves would lead to the 

 formula (Pb^ Cl + Cu^ Cl) + aq; but, it must be remembered, 

 that they merely indicate the quantitative relations between 

 the three elements, chlorine, lead and copper. As a given 

 weight of the mineral could not be analysed, the evidence is 



possible, the former with adherent chloride was incinerated on the cover 

 of a porcelain crucible. The residue was added to the chloride, and the 

 whole moistened with aqua-regia and dried. 



