A Chemical Analyjis of Three Species ofWhinJtoiit, and Two of Lava. 409 



3. The.folutio;i, after being freed from this precipitate, was perfe£lly colourlefs and 

 tranfparent. I dropt into it a fmall quantity of fulphuric acid, which produced no cloudy 

 confequcntly the folution contained neither barytes nor ftrontian. It was then evaporated 

 to a fmall quantity, and treated with carbonate of ammonia. Some white earth was thrown 

 dowu, apparently carbonate of lime, which after being waflied, dried, and heated red hot 

 a few minutes, weighed 6\ grains. 



4. The iiifoluble refiduum, No. i. which weighed 675 grains, I mixed in a filver cru- 

 cible with a folution of cauftic pot-afli, containing as much alkali as was equal to twice 

 the weight of tlie 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 wartied out of the crucible with boiling diftilled water, it was fuper- 

 faturated with muriatic acid, by which the greater part was diflblved. This mixture, being 

 then evaporated to a fmall quantity, became gelatinous. It was next diluted with water, 

 digcfted, and filtered. Some fikx remained on the filter, which, after proper wafiiing 

 being dried, and heated red hot a quarter of an hour, weighed 43 grains, and was per- 

 feftly white. To learn whether this filex was free from every other earth, I mixed a part 

 of it with four parts of carbonate of foda, and melted the mixture in a filver crucible. 

 Water, being poured on the melted mafs, diflolved it entirely into a liquor Glicum, which 

 was diluted largely, and faturated exa£Hy with an acid. No precipitate appeared, even 

 after fix or eight days ; therefore thefe 43 grains were pure filex. 



5. The folution, No. 4. (from which the filex had been leparated), was of a light 

 greenifti colour. Cauftic ammonia, when poured into it, threw down a browniih precipi- 

 tate. Having carefully feparated this precipitate, and wafhed it on a filter, I dropt into 

 tlie remaining folution, which was now colourlefs and tranfparent, a fmall quantity of 

 fulphuric acid, in order to detedl barytes or ftrontian. No precipitate was formed. The 

 folution was then evaporated to a fmall quantity, and treated with carbonate of ammonia, 

 by which a fecond portion of carbonate of lime was obtained. Its weight, after being 

 heated red hot, was 9^ grains. 



6. Tb*- ^rownifii precipitates, thrown down from the folutions No. 2. and 5. by cauftic 

 ammonia, had the appearance of argil mixed with iron. To feparate the argil, thefe pre- 

 cipitates were mixed together, and boiled, while ftill moift, in a folution of cauftic pot-alh, 

 in a filver crucible. A part was diflblved ; but a fpongy matter remained, of a darker 

 brown colour than at firft, which was collefted on a filter. 



7. Into the cauftic-alkaline folution I poured fulphuric acid, till flightly in excefs, and 

 neutralifed it again by carbonate of foda. The argil was precipitated ; which being fuffi- 

 ciently waflied, was re-diflblved in diluted fulphuric acid. This folution was then mixed 

 with fome acetite of pot-afli, and gave, by fuccefiive evaporations, fmall regular cryftals 

 of alum. At laft it became gelatinous ; and being evaporated to drynefs, and diluted again 

 with water, one grain of filex was left. The remaining folution produced, to the laft drop, 



VoL.lV.— December 1800. 3G cryftals 



