The remainder was mixed > with about three hundred grains of 

 recently distilled Sulphuric Acid, and evaporated to dryness in a 

 vessel of platina. This operation was twice repeated ; the resulting 

 dry mass was -washed with: boiling- water, until all the soluble 

 sulphuric compounds had been separated fi-om a gritty Avhite inso- 

 luble powder.- This was dried and heated to redness. It weighed 

 fifty graiiis, and had the properties of Silex. (B.) 



The washings containing tlie substances dissolved by the Sul-> 

 phuric acid were evaporated to the consistence of a syrup nearly,- 

 and set aside; crystals in the form of the octohedrou or its modifi-> 

 cations gradually appeared ; these, when separated from the liquor, 

 had all the properties of Alum, and v/hen dry weighed 49.75 grs. 

 indicating very nearly 5 grains of Potash. (C.) 



From the liquor remaining after the separation of the alum 

 crystals, oxide of Iron was obtained, which, purified from Alumine 

 by the solvent action of caustic alkali^ and dried, amounted to 

 2.49 grs. (D). This was united with 1.62 grs. of Silex (Bb) and 

 the fluid from which the Iron and Silex had been separated by 

 means of subcarbonate of Potash, yielded 0.75 grs. of black oxide of 

 Mcngaticse (E), together with 0.87 grs. of Silex. (Be). Traces of 

 Lime and Magnesia, in combination with oxide of Iron, were alsa 

 observed, which were estimated at 0.50 grs. (F). 



By the preceding method the quantity of Alumine was not de- 

 termined with exactness ; for this reason, as well as further to con- 

 firm the other results of that analysis, the following process was 

 employed. One hundred grains of the mineral reduced to fine 

 powder, together with three hundred grains of caustic pot- 

 ash, were heated to redness in a silver crucible. The mixture as- 

 sumed a dark green colour, and aflTorded, with diluted muriatic acid, 

 a perfect solution of a greenish yellow colour. This, when evapo- 

 rated sufficiently, and suffered to cool, formed a Jelly, and ott 





