STONE CONTAINING POTASH. ] g^ 



into a crucible of filver, and fiifed for half an hour. The fufed Analyfis of a 

 mafshad rather apa% appearance, and could not be rendered °"^"°**'°'"^ 

 perfeclly fluid. 



Exp. If. — As foon as the crucible was nearly cold, it was 

 removed from the furnace, its contents were foftened by 

 water, and the afFufion of this fluid renewed from time to time, 

 till all the fufed mafs was detached from the crucible : about 

 18 times its quantity of water were expended for that purpofe. 



Exp. in. — Into the obtained alkaline imperfeft folution of 

 muriatic acid was gradually poured, and the whole evaporated 

 to drynefs, 



Exp. /r.— The mafs was then transferred into a fla(k con- 

 taining dilute muriatic acid, the whole was fuffered to boil 

 for a few minutes, and the infoluble part feparated by the 

 filtre. The filiceous earths thus obtained had a greyilh ap- 

 pearance, but it acquired a white colour after having beea 

 again digefted in muriatic acid, dried and ignited. It weighed 

 58 grains. 



Exp. V. — The fluid from which this quantity of filex had 

 been feparated, together with the muriatic acid employed for 

 purifying it, and the water expended for ablution, were con- 

 centrated to about 20 cubic inches, and then mingled, boilincr 

 hot, with a folution of carbonate of foda ; the precipitate de- 

 pofited was collected, and wafhed as ufual. 



Exp. VI. — As foon as the precipitate was fo dry that it could 

 be removed from the filtre without lofing part of it, it was 

 transferred into a folution of potafh, and the mixture boiled 

 for about half an hour. On futFering the alkaline folution to 

 fland undiflurbed for twentj-foar hours, a powder was depo- 

 fited, which, on being again boiled in a more concentrated 

 folution of potafli, remained unaltered. It was therefore col- 

 lefted, waftied, dried, ignited, and put afide for further exa- 

 mination. 



Exj). VII. — Into the alkaline folution, freed from this pow- 

 der, I now dropt muriatic acid, till the precipitate which firft 

 appeared again vaniflied, and then decompofed it by the ad- 

 dition of carbonate of ammonia. The precipitate obtained in 

 this experiment, after repeated ablutions and ignition, amount- 

 ed to 28 grains. Experiments not efi!ential to be ftated here, 

 convinced me that it was alumine. • 



Vol. VIII.— June, 180k K &xyr 



