of Mineral Substances. 269 



tion ; this was again evaporated to dryness, and the residue, 

 treated by very dilute muriatic acid, left 45 grains of silica. 



b. The liquid was mixed with caustic ammonia, and the pre- 

 cipitate separated by filtration ; carbonate of soda was then 

 added, by which 33.5 grains of carbonate of lime were thrown 

 down equivalent to 18.5 grains of Hme. 



c. The precipitate thrown down by caustic ammonia was 

 boiled in caustic potassa, which dissolved it, with the excep- 

 tion of some brown residuary matter. This residue, dissolved 

 in nitric acid, and precipitated by ammonia, afforded 3 grains 

 of oxide of iron ; carbonate of ammonia, subsequently added 

 to the washings, furnished an additional precipitate of carbonate 

 of lime, equal to 2.5 of lime. 



d. To obtain the ingredient dissolved by the caustic potassa, 

 tlie solution was slightly supersaturated by sulphuric acid, and 

 precipitated by carbonate of potassa; the precipitate was 

 washed, and boiled in distilled vinegar, which being again 

 saturated with ammonia, and the precipitate washed, dried 

 and ignited, gave 29 grains of pure alumina. 



Hence 100 parts of crystallized zoisit consist of 



Silica a ^ 45 



Alumina d 29 



Lime , b 



18.50| 

 2.50J 



Oxide of iron c 



21 



98 



Analysis of the foliated Augite of Carinthia. 



A. 



This mineral is diflficultly fusible in small fragments ; it runs 

 before the blow-pipe into an opaque olive-colourjed slag. Its 

 powder is greenish grey ; heated to redness, it becomes paJe- 

 brown, without loss of weight, 



B. 

 a. IQQ ^t^if^ ^tj[fi jii'i:f.fid yf'flh iji Bolutioii coulaiuing 200 of 



