M. Arfwedson on the Composition of Mineral Substances. IS 
or of lead, and afterwards decompose the acetate of lithidn by 
heat. 
M. Arfwedson has also verified the assertion of M. Gmelin, 
of Tubingen, that there does not exist an Alum with a base 
of lithion and alumine, as he had at first believed. He finds 
that the error was owing to the presence of potash in the alu- 
mine, even in that which he had completely edulcorated. ” The 
sulphate of lithion contains two atoms of water, that is 14.^7 
hundredths. 
M. Arfwedson has analysed the following minerals ; 
a. The Disthene, or Cyanite of St Gothard and 
of Norway. 
Disthene of St Gothard. 
of Norway. 
Theory. 
Silex, • 34.33 
36.4 
32.00 
Alumine, - 64.89 
63.8 
68.00 
99.22 
100.2 
100.0 
Hence he concludes that the disthene is a subsilicate of alu- 
mine, in which the last contains twice as much oxygen as si- 
lex A^S. The difference between the theory and the experi- 
ment may be owing to a variable mixture of a silicate of alumine 
with the subsilicate. 
h. The Nepheline of Somma. M. Vauquelin found in this 
mineral only silex and alumine. The following is M. Arfwed- 
son’s analysis : 
Silex, - - - 44.1 1 
AlumiDe, - - - 33-73 
Soda, ... - 20.46 
Loss in the Fire, - » 0.62 
98.92 
This composition gives the formula NS-fSAS. 
c. The Sodalite (f Vesuvius, which is known from the ana^ 
lysis of M. Dunin Borkowsky. M. Arfwedson found that this 
stone contains muriatic acid like that of Greenland, in which it 
was discovered by M. Ekeberg. M. Arfwedson’s analysis is as 
follows : 
Silex, - - - 35.99 
Alumine, - • - 32,59 
Soda, — • « » • 26.55 
Muriatic Acid, - - - 5.30 
100.43 
