38a Sxientific Nem, Accounts of Books, Sc. 



That the black fclfpar which is found at Unkel in the Bafaltes, is compofed of 66.5 

 parts of alumine, 15.0 of filiceous earth. 6.5 of oxide of iron, and 4.0 of oxide of 

 manganefe. 



That the blue calcedony of Siberia contains only filiceous earth. 



That rock cryftal is the fame as pure filiceous earth. 



That the Holzftein of Bareuth contains 80.0 parts of filiceous earth, ii.oof alumine, 

 3.0 of oxide of iron, i.o of oxide of chrome; which proves that chrome is alfo found in 

 Germany, He fufpeiSts that it is likewife to be found in feveral other of the folTils of this 

 country. 



Lime in the Nut-gall. 



Prouft did not obtain lime from the nut gall ; TrommsdorfF afcertained the prefence of 

 this earth with precifion. 



The method which Prouft propofes to procure pure gallic acid is not advantageous ; at 

 beft it is good for feparating this acid from the tanning principle, but it does not difen- 

 gage it" from the extraftive matter, and when it is propofed to feparate the muriatic acid 

 by evaporation, the elevated temperature which is neceflary to efFecl it, refolves the gallic 

 acid into its principles, or at leaft carbonifes it. 



ExtraSlion of the Alkali of Sea Salt by Lime- 



The decompofition of fulphate of foda by lime in order to obtain that alcali canqot be 

 advantageous, becaufe this earth attacks the fait only in proportion as it is itfelf diflblved 

 In water. 



Method of obtaining Phefphorus by Phofphate of Lead. 



TrommsdorfF has made new attempts to render Giobert's procefs ufeful, by precipi- 

 tating urine by nitrate and acetite of lead ; but the phofphorus which he obtained was in 

 fuch fmall quantities, that it did not pay the expence of the fire. The chemift of Turin 

 would be juftified in affirming that his method is the beft, if his precipitate had been the 

 pure phofphate of lead. But the reduced lead which remains in the retort is the phof- 

 phuret of that metal. 



On the ATineral Kermes, and the golden Sulphur of Antimony, 



Several new experiments have alfo been made by the fame chemift, on the red and 

 orange coloured hydro-fulphurets of antimony, and he is perfedly fatisfied that the former 

 confifts of oxide of antimony and fulphurated hydrogen ; and that the latter is compofed 

 ssi the fame principles, and a portion of fulphur not hydrogenatcd. By direding a cur- 

 rent 



