ALUMINA. 
171 
855. Crclatinous Hydrated Si¬ 
lica, frdm a five per cent, solu¬ 
tion prepared by dialysis. 
did Hydrated Silica, 
856. 
prepared from the above solution 
by evaporation in vacuo. 
Nos. 855 and 856 prepared and pre¬ 
sented by Prof. Graham, F.R.S., Master 
of the Mint. 
Alumina. 
The Ri|by, the Sapphire, grey Corundum, and granular Emery are 
all of thein varieties of alumina, or the oxide of aluminium. The 
various tints exhibited by the crystalline kinds will be seen in the 
numerous specimens presented by Mr. Plennell. The manufacture of the 
metal aluminium dates only about ten years back, from a process dis¬ 
covered by the French chemist, M. Deville ; it is, however, made from 
other minerals than those contained in this case. 
857. Emeey, extensively used 
as a polishing material. 
I. of Naxos, Grecian Archipelago. 
858 and 859. Corundum, also 
used for polishing and grinding. 
East Indies. 
860. Corundum, crystallized. 
Namaqualand, S. Africa. 
861. Corundum, embedded in a 
matrix of granite. 
Eazlinsk, on R. Borsooha, Ekater- 
inhourg, Russia. 
862. Red Corundum. 
Warwick, Orange Co., N. Y. 
863. Varieties of Corundum, 
rough crystals, as imported from 
Ceylon. 
871. Sapphire, sliced. 
872 and 873. Star Sapphire, 
Asteria or Salemstein. 
874. Star Ruby. 
875. Ava Rubies, uncut. 
876. Ava Rubies, cut in India. 
877. Ava Rubies, cut in Eng¬ 
land, 
878. Ava Ruby, drilled by na¬ 
tives. 
879. Ava Ruby, 
natives. 
880. Ruby, cut. 
eimraved bv 
O */■ 
863a. Crystals of Sapphire, 
Ruby, and OrienTx4.l Topaz, pre- j 
cious varieties of Corundum, se¬ 
lected from the above. 
Nos. 863 and 863a presented by E. G. 
Hennell. 
864. Sapphire, crystal. 
865. Sapphire, rolled crystal. 
866. Sapphire, engraved. 
867. Sapphire, fine colour. 
868. Sapphire, light coloured, 
cut. 
869. Sapphire, dark coloured, 
cut 
870. Sapphire, exhibiting dif¬ 
fusion of colour from a small plane 
on the back. 
Nos. 869 and 870 presented by E. G. 
Hennell. 
881. Rubies, slightly opaque. 
Presented by E. G. Hennell. 
882 and 883, Oriental Topaz, 
yellow variety of Corundum, 
884. Diaspore {Hydrate of 
Alumina), embedded in Dillnite. 
Dilln, near Scliemnitz, Hungary. 
Presented by W. W. Smyth, F.E.S. 
885 to 887. Aluminium, ingot, 
wire, and foil. 
888. Medal struck in Alumi¬ 
nium. 
Presented by Prof. Graham, F.E.S., 
Master of the Mint, 
(A series of specimens illustrating the 
manufacture of Aluminium, presented by 
Messrs. Bell Brothers, is arranged in a 
table-case on the 'svestern side of this 
floor, near the entrance.) 
