1^ ANALYSIS OK A MINERAI,, &C. 



The filtrated folution, by gradual evaporation, afforded 

 cryllais of muriate of lead ; and the lead which afterwards 

 lemained in the liquor, was feparated by a few drops of ful* 

 phuric acid. 



The folution was nowofabright green colour, and, as before, 

 was found only to contain copper, and a minute portion of iron; 

 the former was therefore precipitated in the metallic flate, by a 

 plate of zinc. 



Thefe experiments, with others which I have not thought 

 neceHTary to mention, prove, that the conftituent parts of this 

 ore are lead, antimony, copper, and a little iron, combined with 

 fulphur; and, when the fpecific gravity, the external and in- 

 ternal colour, fradure, grain, and other characters are confi- 

 dered, there can be no doubt but that at leaft the three firfl 

 metals exift in the ore, in, or nearly in, the metallic ftate, 

 combined with fulphur, fo as to form a triple fulphuret ; to af- 

 certain the proportions of which, the following analyfis was 

 made. 



V. Analyfis. 



Analvfis. Pul- A. 200 grains of the ore, reduced to a fine powder, were put 

 Ycrizing- Jnto a glafs matrafs, and, two ounces of muriatic acid being 



added, the veffel was placed in a fand-bath. As this acid, even 

 when heated, fcarcely produced any effefl, fome nitric acid was 

 gradually added, by drops, until a moderate effervefcence began 

 to appear. 

 Digcftionwith The whole was then digefled in a gentle heat, during one 

 nitro-mur. acid,j,Qyf . ^^^^ ^ green coloured folution was formed, whilft a 

 quantity of fulphur floated on the fur face, which was colledted, 

 and was again digefled in another veflel, with half an ounce of 

 muriatic acid. 

 ydtfuipbur. The fulphur then appeared to be pure, and, being well waflied 



and dried on bibulous paper, weighed 34- grains : it was after- 

 wards burned in a porcelain cup, without leaving any other 

 refidium than a flight dark ftain. 

 The green fohi- B. The green folution, by cooling, had depofited a white 

 tion afforded, by fj^jj^^e (ediment ; but this difappeared upon the application of 

 iilution, w ^ */ j^g^. g^ J ^|jg addition of the muriatic acid in which the fulphur 

 had been digefled. 



The folution was perfe6lly tranfparent, and of a yellowifti 

 green: it was made to boil, and in this llate was added to three 



quart* 



