SEfARATIGN OF ALUMINE. 2^1 



To prove what has been ftated before, let any quantity of The precipitate 



the obtained alutnine be heated in conta6t with charcoal pow- earth''^if he d 



der; introduce the mixture into a tabulated retort, connected with charcoal, 



wfth the pneumatic apparatus, and add to it muriatic or (ul-^"^ then treaied 



, "^ r 1 With an acid, 



phuricacid; the re(u!twill be fuiphuretted hidrogen gas in gives fulphuret- 



abundance, particularly if heat be applied to the mixture. ^'^ ^''^'^°e«n» 



The produdion of this gas will become evident on confidering 



the piiiofophy of the procefs, B^y means of the following 



method, aluniine may be obtained in a purer ftafe. • 



Take any quantity of alum of commerce, diflfolve it in four Method of 

 parts of boiling diftilled water, and mingle this folution with ^^jP^^^"^ P"''*'' 

 liquid ammonia till no further cloudinefs enfues. Then heat 

 the mixture nearly to the boiling point for a few minutes, and 

 transfer it on a filter. In proportion as the fluid palles ofF, Precipitate by 

 pour more water over the precipitate, and continue the ablu- ^|^°"g*j' ^^j^^ 

 tion till the water runs off taftelefs. Having done this, let the folve in muriatic 

 precipitate while yet in a party fiate, be transferred into a ba-*^'^*^ ^^^"'^^^^ 

 fon or flaflv, and add to it muriatic acid, in fmall quantities at for a contami- 

 a time, until tiie whole is diffolved; then evaporate the folu- "J''"S portion 

 tion till a drop of it, when fuffered to cool on a plate of glafs, dilute and pre- 

 yields minute cryftals. If it now be fuffered to cool, cryftals ^ipiiate a^ain bj- 

 of alum v\ill bedepofited. Remove thefecryflals, by decant- 

 ing the fluid, and renew the evaporation, until on further cool- 

 ing, no more cryflals are formed. Nothing now but nearly 

 pure alumine remains in folution; the potafli and fulphuric 

 acid being got rid of, at the expence of a little alumine in the 

 cryftals. The fluid rpay therefore be diluted with water, and 

 then decompofed by liquid ammonia, taking care to add this 

 alcali in excefs. The precipitate thus obtained, when waflied 

 and dried, will be aluniine in a (late pf confiderable purity. 



The alumine thus obtained does not yield fuiphuretted hidro- The earth that 

 gen when heated with charcoal power; it emits ?Jo odour "°w falls is 

 when breathed upon, it is fumevv'hat unduous to the touch, in- pur^ 

 fipid, and white as fnow. 



S/igrt 



