12 PHILOSOPHICAL TRANSACTIONS. [ANNO 17Q6. 



by Mr. Klanroth, I shall not repeat them, but shall only observe, that it does not 

 appear possible to decompose the ore completely by means of this acid. 



^ 9. Molybdale of lead with muriatic acid. — 240 grs. of the purified ore in fine 

 powder were put into a glass matrass, with 3 oz. of pure muriatic acid. The matrass 

 was then placed in a sand bath ; in about an hour the whole was dissolved, excepting 

 some muriate of lead, which I dissolved by pouring water on it. After this there 

 only remained a very small residuum of siliceous earth. 



a. The solutions were then added together, and formed a liquor which was trans- 

 parent, and of a greenish-yellow colour. 1. Prussiate of pot-ash produced a co- 

 pious precipitate of molybdaena, in the form of a reddish-brown flocculent matter. 

 b. Lixivium of carbonate of pot-ash precipitated a yellowish-white matter, and 

 turned the liquor to a deep blue. c. Carbonate of soda had the same effect, d. 

 Solution of carbonate of ammonia produced a similar precipitate, and caused 

 the liquor to become blue. 



These precipitates were separately collected and washed on filters. When ex- 

 amined by the blow-pipe, all of them afforded a yellowish-green glass, with phos- 

 phate of ammonia and soda. These precipitates dissolved in diluted nitric acid 

 with effervescence, and sulphuric acid precipitated sulphate of lead, after which 

 Prussian blue was precipitated by prussiate of pot-ash, and the liquor became brown. 



je. The blue solution, which consisted of the muriatic and molybdic acids com- 

 bined with soda, was evaporated. When the liquor became hot, the colour changed 

 from blue to pale yellow, and the evaporation was continued without any other 

 perceptible alteration till the whole was become a dry concrete salt. I dissolved 

 this salt in distilled water, and added muriatic acid, so as to be in a small excess. 

 The liquor was then evaporated to half, and was set in a cool place. The fol- 

 lowing morning I found a quantity of crystallized muriate of soda at the bottom of 

 the basin, covered with a white flocculent precipitate, which I collected and edul- 

 corated on a filter. The rest of the liquor was repeatedly evaporated, till I had 

 separated the greatest part of this white matter from the muriate of soda. The 

 last portion of the liquor however still contained some molybdic acid, combined 

 with the muriate of soda ; for after it had been several times evaporated and again 

 dissolved, it became blue when muriate of tin was added ; or if muriatic acid was 

 first poured in, prussiate of pot-ash produced a reddish-brown precipitate of 

 molybdaena. 



Experiments on the ivhite precipitate. — 1. It was not dissolved when water was 

 boiled on it. 2. When digested with sulphuric or muriatic acid, the greatest part 

 was dissolved, and prussiate of pot-ash produced a precipitate of a greenish-brown 

 colour. 3. A small part became yellow when nitric acid was distilled from it. 

 4. The solutions of carbonate of pot-ash, soda, and ammonia, dissolved the 

 greater part; and when these solutions were saturated with muriatic acid, prus- 

 siate of pot-ash produced precipitates like those of the acid solutions. 



f. I next examined the blue solution, which consisted of the muriatic and 



