184 



ALUMINIUM. Al. 



166. METALLIC. 



a. In the form of sheet and wire. 



167. CHLORIDE. A1 2 C1 6 . 



a. Anhydrous, pure. 



168. OXIDE. A1 2 O 3 . 



a. Anhydrous, pure. 

 6. Hydrated, pure. 



c. Native. (Corundum.*) 



d. Files made of corundum. 



e. Ditto. (Emery.) 



169. SULPHATE. A1 2 3S 4 , 9H 2 0. 



a. Commercial, impure. 

 6. Pure. 



c. Crystals formed on an alum heap during combustion. 



170. AMMONIO-SULPHATE. A1 2 3S 4 , (N H 4 ) 2 S 4 , 24H 2 0. 



a. Crystallized. (Ammonia Alum.) 



* J. A large mass of 6ne crystals. (Presented by Messrs. 



Hopkin & Williams.) 



Note. Specimen b will be found in a special glass stand in the north 

 window of this Museum. For perfect crystals, see specimens in Case No. 9. 



171. POTASSIO-SULPHATE. A1 2 3S 4 , K 2 S 4 , 24H 2 0. 



a. Crystallized. (Potash Alum.) 



b. Ditto, coloured with Armenian bole. (Commercial Roche 



Alum.) 



c. Ditto. (True Roche Alum, Alum Rupellum, Roman 



Alum.) 



Note. The name Eoman Alum, is also applied to a white variety. See 

 Per. Mat. Med., vol. i., p. 664. On the same page will be found a figure 

 of the crystalline form of alum. In specimen c, the colouring is seen to 

 form part of the substance of the crystals, while it is only external, and 

 easily removed by washing in specimen b. 



GLUCINUM, OB BERYLLIUM. Be. 



172. CARBONATE. BeC0 3 . 



t a. In powder. 



173. OXIDE. BeO. 



t a. Iii powder. 



174. SILICATE. Be 2 Si0 4 . 



a. In powder. (Limoges Beryl.) 



CERIUM. Ce. 



175. METALLIC. 



f a. Small nodules. 



