found in the Red Lead of Siberia. 28* 



Exp. IV. The two nitric folutions united and evaporated, 

 produced 92 parts of nitrate of lead, cryflallifed in o&aedra, 

 perfectly white and tranfparent. Thefe 92 parts of nitrate 

 of lead, diflblved in water, were precipitated by a folution of 

 the fulfate of foda. This produced 8 1 parts of the fulfate 

 of lead, which were equivalent to 56,68 of metallic lead. 



Exp. V. The alcaline liquors united, had an orange-yel- 

 low colour. They depofited at the end of fome days two 

 parts of a yellow powder which contained no more lead. 

 Thefe liquors, fubjetted to evaporation until a faline pellicle 

 was formed on their furface, produced, on cooling, yellow 

 cryftals ; among which there was carbonate of potafh, not 

 decompofed. Thefe cryftals diiToIved in water, and the 

 folution united with the mother water, the whole was 

 mixed with weak nitric acid until the carbonate of potafh 

 was faturated. The liquor then had a very dark orange- 

 red colour. Being united with a folution of the muriate of 

 tin, newly made, it firft afiumed a brown colour, which af- 

 terwards became grcenifh. Mixed with a folution of the 

 nitrate of lead, it immediately produced the red lead. Laft- 

 ly, evaporated fpontaneoufly, it produced ruby-red cryftals, 

 mixed with cryftals of the nitrate cf potafh. Ninety-eight 

 parts of this mineral, decompofed as above mentioned, hav- 

 ing produced 81 parts of the fulfate of lead, 100 parts 

 would have given 82.65, which are equivalent to 57.1 of 

 metallic lead. But admitting, as experiment proves, that 

 100 parts of lead abfoib, in combining with acids, 12 parts 

 of oxygene, the 57.1 of metallic lead ought to contain in 

 the red lead 6.86 of this principle, and we ought to have 

 for the mineralifing acid 36.4. 



Exp. VI. To verify by fynthefis the proportions of the 

 principles of the red lead found by anaiyfis, I diflblved 50 

 grains or about 2.654 grammes of metallic lead in the nitric 

 acid j and the folution having been divided into two equal 

 parts, the one was completely precipitated by the neceffary 



quantity 



