Of WHINS'TONE and LAVA. 79 



about 1200 grains of muriatic acid; and a receiver being adapt- 

 ed, the mixture was gradually heated till it boiled. It was at 

 firft of a brownifh-yellow colour, but afterwards became brown- 

 ifh. Part of the powder was difTolved, To diflill off the un- 

 combined acid, the heat was continued till the mixture began 

 to grow thick. It was then diluted with boiling diftilled water, 

 and poured on a filter ; and the undifTolved part, after proper 

 edulcoration, being dried and heated red hot a few minutes, 

 weighed 6y\ grains, and was greyifh-white. 



2. The filtered folution was of a faint yellowifh-brown co- 

 lour. Being faturated with cauflic ammonia, a bulky precipi- 

 tate was thrown down, which was carefully feparated by filtra- 

 tion. It had at firft a dirty greenifh-colour, which was after- 

 wards changed to brown by the action of the air. 



3. The folution, after being freed from this precipitate, was 

 perfectly colourlefs and tranfparent. I dropt into it a fmall 

 quantity of fulphuric acid, which produced no cloud ; confe- 

 quently the folution contained neither barytes nor ftrontian. It 

 was then evaporated to a fmall quantity, and treated with car- 

 bonate of ammonia. Some white earth was thrown down, ap- 

 parently carbonate of lime, which after being warned, dried, 

 and heated red hot a few minutes, weighed 6~ grains. 



4. The infoluble refiduum, No. 1. which weighed 677 grains, 

 I mixed in a filver crucible with a folution of cauflic potafh, 

 containing as much alkali as was equal to twice the weight of 

 the refiduum. This mixture, being evaporated to drynefs, was 

 expofed for one hour to a red heat, in which it melted. When 

 cold, the mafs was green. After being foftened, and wafhed 

 out of the crucible with boiling diftilled water, it was fuperfatu- 

 rated with muriatic acid, by which the greater part was difTol- 

 ved. This mixture, being then evaporated to a fmall quantity, 

 became gelatinous. It was next diluted with water, digefled,. 

 and filtered. Some filex remained on the filter, which, after 



proper 



