M. Rose on the Pyroxenes and Aniphiboles. SI 
one of high importance, as it explains the objections which the 
results of the analyses of certain minerals form to the Theory 
of Definite Proportions, v 
3. Account of the Analyses of the Pyroxenes and Amphiholes, 
by MM. Rose^ Nordenshold^ and Bohnsdorff. 
MM* Rose, Nordenskold, and Bohnsdorff, three young che- 
mists, who are at present working in the laboratory of M . Ber- 
zelius, have undertaken to verify by analyses the application of 
the ideas of M. Mitscherlich to mineralogy. With this view, 
they have begun a series of analyses of the Pyroxenes and the 
Amphiholes. It results from this inquiry, which is still far 
from being finished, that the mineral called Pyroxene, when it 
is uncoloured, is a double bisilicate of lime and magnesia, con- 
taining an atom of each ; but that when it is coloured, it then 
consists of a mixture of bisilicate of lime, of bisilicate of mag- 
nesia, of bisilicate of the protoxide of iron, and, less frequently, 
of the bisilicate of the protoxide of manganese ; without these 
bases being combined in proportions conformable to the theory 
of definite proportions. The only thing constant is, that all the 
bases belong to the same isomorphous class, and that they are 
all in the form of bisilicates. 
One of these pyroxenes, analysed by Mr Rose, was found to 
be a double bisilicate of lime, and of protoxide of iron, contain- 
ing an atom of each of these bases. This pyroxene is the one 
which has been called Hedenhergite, and which has been con- 
sidered, after the analysis of M. Hedenberg, as a bisilicate of 
the protoxide of iron. Another has been found to be composed 
almost entirely of the bisilicate of the protoxide of manganese, 
with a very little of the bisilicate of lime, 
4. Account of M. Rose's Analyses of several Species of Mica^ 
containing Fluoric Acid. 
M. Rose has lately analysed several species of mica, in which 
he has discovered Flitoric Acid in considerable quantity. The 
Mica of granites contains more of it than that of primitive car- 
bonate of lime, which contains only traces of it. We may easi- 
ly discoveir if any species of Mica is more or less rich in fluoric 
