10 PHILOSOPHICAL TRANSACTIONS. [ANNO \7Q6. 



and the solution was colourless. 1 . From this solution I precipitated sulphate of 

 lead by the means of sulphuric acid. 2. With prussiate of pot-ash I obtained a 

 brown precipitate of molybdaena ; and 3. Muriate of tin turned another portion 

 of it blue. 



From these experiments it appears that the 1st solution contained iron, with 

 some molybdic acid dissolved in muriatic acid ; and the 2d solution contained 

 molybdic acid and lead. 



Molybdate of lead sublimed with muriate of ammonia. — Exper. 1. 125 grs. of the 

 ore were mixed with 2 oz. of muriate of ammonia, and put into an earthen matrass, 

 to which a head of stone-ware was fitted. The matrass was then exposed to a 

 sufficient degree of heat, and when all was sublimed the vessels were separated. 

 The black powder which remained was mixed with 2 oz. of muriate of ammonia, 

 and again sublimed. This operation was repeated 3 times, after which nothing re- 

 mained in the matrass. The sublimate, as before, was yellow, green, and blue. 

 a. Distilled water was poured on the sublimate, so as to dissolve all of the saline 

 part ; but as the solution was turbid, it was poured on a filter, which collected a 

 precipitate of a pale bluish-grey colour. . 



b. This precipitate after it had been edulcorated was boiled with distilled water, 

 which was afterwards filtrated. 1. Prussiate of pot-ash precipitated some iron. 

 2. Muriatic acid was added to another portion, after which the prussiate produced 

 a brown precipitate of molybdaena. 3. Muriate of silver was precipitated when 

 nitrate of silver was dropped in. 



c. I then boiled lixivium of carbonate of pot-ash on the undissolved part of the 

 residuum, by which the greatest part was dissolved. The alkali was then satu- 

 rated with muriatic acid, and prussiate of pot-ash being added, precipitated some 

 molybdaena. On the small portion of the residuum which remained I poured 

 diluted nitric acid. The solution was then filtrated, and I obtained a small quan- 

 tity of sulphate of lead by the means of sulphuric acid. These experiments show 

 that the residuum was composed of molybdic acid, iron, lead, and a small quan- 

 tity of muriatic acid, which was produced from the muriate of ammonia during the 

 sublimation. 



d. I now took the solution a and divided it into 2 portions, to 1 of which I 

 added 3 oz. of concentrated sulphuric acid, and evaporated the liquor to half the 

 quantity. When cold it deposited a white saline matter, which for the greater 

 part dissolved in water, leaving a small residuum which appeared to be muriate of 

 lead. Pot-ash expelled some ammonia from a portion of the dry salt ; and a pre- 

 cipitate was produced when muriate of barytes was added to the solution. This 

 white saline matter was therefore a mixture of sulphate of ammonia with a small 

 portion of muriate of lead. 



The solution to which the sulphuric acid had been added was again evaporated to 

 a considerable degree, and when cold it resembled a very thick mucilage of a pale 

 yellow colour. It readily dissolved in water, and contained sulphuric acid in great 



