Dr. Gorham’s analysis of sulphate of Barytes. 239 
6. The 15 grains were lastly mixed with 40 of sub-carbonate of 
potass and water and repeatedly boiled to dryness. After filtration 
the residuum was thrown into muriatic acid and there remained un- 
dissolved 4 grains, which exhibited all the characters of silex. 
7. By accident a small portion of a solution of carbonate of pot- 
ass was added to the muriatic solution and a partial precipitation took 
place. I therefore added the former to the latter, till no more precip- 
itate would form ; the whole was then poured on a filter and the pre- 
cipitate, collected and dried, weighed 77 grains. 
8. A solution, accompanied with effervescence, was made of these 
77 grains in muriatic acid, and the solution, spontaneously evaporated, 
produced only crystals of muriate of Barytes. Previous however to 
the evaporation, liquid ammonia was poured into the solution, a precip- 
itate formed, which, when collected and dried, weighed 2 grains, and 
consisted of alumina. Barytic water produced no effect. 
9. These were redissolved in water and sulphuric acid added to the 
solution, a copious epee ers took place, which weighed on drying 81 
grains. 
10. The alkaline solution, which had been boiled on the powder, 
was saturated with sulphuric acid and evaporated. A small quantity 
of silex and a dark coloured substance was separated. The latter 
gave a white curdy precipitate with muriatic, and appeared to be ox- 
ide of silver, doubtless derived from the vessel. 
I endeavoured in experiment 9, to obtain in a direct way the quan- 
tity of real sulphate in this mineral, but in the process cf evaporating 
and redissolving the muriate, a portion of it was accidentally lost, and 
itwas necessary therefore to arrive at the proportion by an indirect 
method, 
The substance precipitated in experiment 7, may be colidicelied as 
carbonate of Barytes, containing 78 parts of the pure earth. The 
