122 Chemical Examination of Algerite. 
dualistic school, this close correspondence establishes beyond 
a doubt the type of the compound. 
I have deducted the carbonate of lime and determined 
the composition of the mineral for 100 parts, and then in 
accordance with the above formula calculated its composition 
according to theory. The two results are subjoined. 
Found. Calculated. 
Silica, : , . 59:28 . 52:08 
Alumina, i s 26:08 - : 26°11 
Potash, - $ = 10:69 : - 10:88 
Peroxyd of iron, > 1:93 : 2-45 
Magnesia, à 434 FRO 11:05 10:78 
Water, : - 1.92 S 833 
100-10 99-85 
'The attempts to represent the composition of the natural 
silicates in accordance with the dualistic system, have tended 
perhaps more than any thing else, to show its inadequacy to 
the wants of the science. The unnatural complications of 
atoms which present themselves to the chemist in the usual 
mineralogical formulas, suggest that we are yet far from the 
simplicity of nature. In accordance with the unitary system 
on the contrary, M. Laurent has shown, that by considering 
the ratio between the oxygen of the silica and that which is 
contained in the bases present, and keeping in view two 
simple principles ; first, that in their peroxyds, the metals re- 
place hydrogen in two-thirds their ordinary equivalent, and 
second, that the molecules of a compound are divisible to an 
unlimited extent, we may reduce all the mineral silicates to a 
few simple forms.! 
In the calculation of a formula like the above, it is neces- 
sary to keep in view this divisibility of molecules and also the 
fact that H, Mg, Alé, Fe, Fe?, K, and other metals, may re- 
place each other to any extent. The FeSO and MgO, which 
in the calculation are for convenience represented together, 
of Science, v 
ON 
! Compt. sende l'Acad., t. xxiii. p. 1050, et t. xxiv. p. 94. See also Am, Jour. —— 
p. 405. vac 
