Analyfn of the SpineU 2ji 



D. The powder thu$ extra£led by muriatic acid, was put into the lllver cru.cible, with ten 

 times its weight of a folution of cauftic potafli, of which the alkali conftituted half the weight. 

 The mixture was evaporated to drynefs- on a fand bath» and afterwards ignited for an hour. 

 The mafs difFafed in boiling water, left on the filtre a refidue of a fawn colouf. which, dried 

 in the air, weighed. 54 grains. ' • 



E. Thefe 54 grains again treated with cauftic potafh, and the mafs difFufed in water, left a 

 refidue in very fine powder, which dried in the air weighed 43 grains. 



F. The alkaline folutions D and E, which were of a yellow colour, were mixed together, 

 faturated with fulphuric acid, and the precipitate which was formed rediflblved w'th a flight 

 excefs of acid. The carbonate of potafh occafioned, in this folution, a very voluminous pre- 

 cipitate, which, after having been well wafhcd, was rediflblved in the fulphuric acid. The 

 folution refembled a mucilage : by expofure to heat, it was perfectly liquified, and (Jepofited a 

 white powder, which coIle(Sled, walhed, and dried in the air, weighed 95 grains. The acid 

 which had been feparated was fet afide. , 



G. I flightly ignited thefe 95 grains, with three times their weight of cauftic potafh. The 

 whole being afterwards diluted with water and filtered, a very fmall portion of refidue was 

 left, which, after walhing, was diffblved in the fulphuric acid, except a few flocks. ^ _, ,. ^^^ 



H. The part diflblved by the potafli G, was precipitated by fulphuric acid, and rediffblvedo 

 in excefs of acid, and afterwards precipitated hot by carbonate of potafh. The precipitate 

 being well wafhed, was again diiTolved in fulphuric acid. ^ 



I. The fulphuric folutions F, G, H, were evaporated. The liquor ha^ng aflTumed the 

 gelatinous form, indicated that filex had been feparated. It was therefore diluted with much 

 water, then concentrated, and the filex collected on the filtre. 



K. I evaporated the acid folution of the fulphate. After having added the acetite of potafh 

 to obtain cryftals*, a perfedlly pure alum was formed; but the folution having afTumed a 

 greenifh colour towards the end, I added pruffiate of potafh. A flight blue precipitate was 

 afforded, in which the oxide of iron might be eftimated at one fourth of a grain. The fo- 

 lution, cleared of iron, was decompefed by the carbonate of potafh. The precipitate being 

 again difTolved in fulphuric acid, afforded to the end perfectly pure cryftals of alum, which 

 were added to the former. / 



L. I then undertook the decompofition of the 43 grains, E, and which remained infoluble in 

 the potafh. Having put them into diluted nitrous acid, they were diflolved, and left only a 

 fmall portion of filex. The folution, after having been feparated from this laft, was mixed 

 with a fmall portion of the acetite of potafh, and left to fpontaneous evaporation Some more 

 fmall cryftals of alum were formed, after which the folution afforded only cryftals of fulphate 

 of magnefia. 



• In order to add to the fulphate of alumine the quantity of p6tafli neccflary for its cryftallitation, I at 

 prefent employ the acetite of potafh. By this means I avoid decompofiing part of the alum (which might ' 

 ii)c already formed) by adding more potafh than neceffary. 



Zzz M, To 



X 



