Intelligence und Miscellaneous Articles. 501 
firmed the suspicion, but has proved that it contains arsenic acid, per- 
oxide of iron and lime, and that it is a double arseniate, differing 
in its characters and composition from the previously known arse- 
niates. 
The proportions of its constituents are as follows :— 
Arsenic acid .......... 34°26 
/ Oxide ofaron Ye eeiioz : 41°31 
Oxide of manganese .. 1:29 
Rai C8 Sipe ene SAE a2 no ' 435 
Silica .. a PARA 4-04 
Potasbysa2ihe 4 Peete Beets 0-76 
Water. s220 3 SR Py oy 8°75 
98°84 
which may be represented by the formula 
3 F* Ar + C-Ar? + 3 Aq... +S. 
In this formula, I have considered the gelatinous silica as foreign 
to the mineral. The analysis of the limestone of Champigny, near 
Paris, which contains 10 of every 100 of silica soluble in acids, 
without the smallest admixture of alumina, that of the green grit of 
Vouziers, given by M. Sauvage in his important work on the Geo- 
logy of the Ardennes, which shows that this rock contains 56 of 
every 100 of silica soluble in a solution of potash, prove with cer- 
tainty that gelatinous silica is mechanically mixed with minerals, the 
definite proportions of which clearly show that they contain no com- 
bined silica. Silica frequently occurs in solution in the same waters 
that deposit carbonate of lime ; it appears that the same has occurred 
- with the mineral from Romanéche, which has all the characters of 
a concretion, intermixed with gelatinous silica. 
Arsenic and iron being the two elements of this new substance, 
Ihave given it the name of arsenio-siderite, which designates them. 
The arsenio-siderite forms concretionary fibrous masses, which 
adhere to the surfaces of the tubercles of manganese; these fibres, 
which are large and distinct, may be separated like those of hard 
asbestus : it is tender and readily yields to the fingers. Its colour is 
yellowish-brown, which deepens by exposure to the air. It is very 
fusible by the blowpipe, and exhibits the reactions of both arsenic 
and iron. Its specific gravity is 3°52.—Ann. de Chim. Mars 1843. 
ANALYSIS OF CHRYSOBERYL. BY M. AWDEJEW. 
The author of these analyses remarks, that few minerals have af- 
forded more variable results than the chrysoberyl. Klaproth and 
Arfwedson considered it to be a silicate of alumina; Seybert first 
proved it to contain glucina; he considered the chrysoberyl as con- 
taining silicate of alumina, and aluminate of glucina. ‘Thomson 
stated that it contained no alumina, which has been confirmed by the 
analysis of M. H. Rose. 
M. Awdejew examined two varieties of chrysoberyl, one from 
Brazil, and the other from Ural; the latter has been described by 
M. G. Rose. 
Chrysoberyl from Brazil.—This mineral was in the state of yellow 
