^4 Attaints of the Sydney Earth. 



This however did not appear to me to be a precipitate caufed by a change in the cKennical 

 affinities, but rather an earthy matter which had been fufpended in the concentrated acid, 

 "and afterwards depofited, when the Hquor was rendered lefs denfe by the addition of wa- 

 ter. To afcertain this, I poured the remaining portion of the concentrated liquor on a 

 •filter of four folds : it paffed perfedlly tranfparent, and, although diluted with twenty-four 

 parts of water, it remained unchanged, and as pellucid as before. 1 now filtrated the for- 

 mer portion, and added it to that already mentioned. 



It was then evaporated to drynefs, and left a pale brownifh mafs, which was diflblved 

 again, by digeftion, in the fmallefl polTible quantity of muriatic acid. 



Water was added, in a very large proportion, to this folution, without producing any 

 effe<ft ; I then, by pruffiate of potafli, precipitated a quantity of iron, which was feparated 

 by a filter. 



The clear folution was then faturated with lixivium of carbonate of potafli, and a white 

 precipitate was produced, which was colleded and edulcorated. This, when digefted 

 with diluted fulphuric acid, was diflblved ; and the fuperfluous acid being driven off" by 

 heat, boiling water was poured on the refiduum, and completely diflblved it. 



To this folution fome drops of lixivium of potafli were added, and, by repeated evapora- 

 tions, the whole formed cryftals of alum. 



From the above experiment it appeared, that the muriatic acid had only diflblved fome 

 alumine and iron ; but, in order to fatisfy myfelf more completely in refpeft to the com- 

 ponent parts of this fubfl;ance, I made the following analyfis. 



Jnalyfts. A. 400 grains were put into a glafs retort, which was then made red-hot 

 during half an hour. Some water came over, and the earth afterwards weighed 380.80 

 grains, fo that the lofs amounted to 19.20 grains. The greater part of this lofs was occa.- 

 fioncd by the diflipation of the water imbibed by the earth ; to which muft be added, the 

 lofs of weight caufed by the conibufl;ion of a fmall portion of vegetable matter. 



B. The 380.80 grains were rubbed to a fine powder, and being put into a glafs retort, 

 1470 grains of pure concentrated fulphuric acid were added. The retort was then placed 

 in a fmall reverberatory, and the fire was gradually increafed, till the acid was difl.il!ed 

 over : it was then poured back on the matter in the retort, and diftilled as before, till a 

 mafs nearly dry remained. 



On thisjboiling diftilled water was repeatedly poured, until it no longer changed the colour 

 of litmus paper, and was devoid of tafte. The undiflblved portion was then dried, and made 

 red-hot; after which it weighed 281 grains. 



C. I now mixed the 281 grains with 300 grains of dry carbonate of potafli, and expofed 

 the mixture ^o a ftrong red heat, in a filver crucible, during four hours. The mafs was 

 loofe, and of a greyifli white : it was foftened with water, and, being put into a re- 

 tort, fulphuric acid was added to a eonfiderable excefs. The whole was then diflilled 

 to drynefs; and when a fuflicient quantity of boiling water had been added, it was 

 poured on a filter, and the refiduum was well waflied : it was then made red-hot, and 

 aften\'ards weighed 274.75 grains. 



D. The folutions of B and C were added together, and were much reduced byevapora- 

 tion. Pure ammoniac was then employed tg faturatc the acid, and a copious loofe preci- 



" ' pitate 



