J. L. Smith’on determining the Alkalies in Minerals. 237 
14. Carbonate of lime I have used for more than six years 
for decomposing certain of the alkaline silicates, and more suc- 
cessfully than carbonate of baryta; still, in numerous instan- 
ces, the decomposition was far from complete, and the method 
unsatisfactory. Notwithstanding these failures, I felt convinced 
that lime was the most powerful decomposing agent that could 
be conveniently employed for this purpose, as it could be used 
i it$-caustic state in a platinum crucible, without injuring the 
Various methods resorted to, it will suffice to state that the object 
In view 
> and lime, which would render the mixture fluid at a bright 
heither of which have any marked decomposing action on | 
silicates; in fact their action is simply that of fluxes, which ena- 
ble the lime and silicate to come in contact in a liquid state, ef- 
fecting nothing beyond that. It is with the fluorid of caletum 
that we have to do in this part of the paper, leaving the details 
on the use of the chlorid of calcium until farther experiments 
we made to test fairly its value. ; 
16. The manner in which I proceed is as follows: = 
Palverize the silicate to a sufficient degree of fineness—it is 
~. Tequired that the levigation be carried to any great extent; 
Mix intimately, in. a glazed porcelain mortar, a weighed portion 
ren mineral With one part of pure fluor 8 and four to 2 
ecipitat of lime,* introduce it into a piati- 
© 9Sth ag pitated carbonate ey | 
lhe Boor cia iety, free fi all impurities ; it is 
, is the transparent variety, free trom imp j 
many and abundantly procured in an as well as in all other countries, The carbo- 
(the of lime is made by dissolving cale spar or pure marble in hydrochloric acid, 
milk of7: acid may be used,) adding an ex é ; lime water or 
oxy yd lime is then poured on the solution until it is alkaline. By this means any 
Henle alumina, or magnesia will be thrown down. To th 
times in of earbonate of ammonia is added, and the precipitate washed seve 
% wet distilled water, Tt is best to prepare one’s own carbonate of lime, for as 
tia, be “Tule, little reliance can be placed on the carbonates of lime, baryta, stron- 
tttange Fe being recipitated by carbonate of ammonia, for in more than one 
he Belt TaN tetiads “OF beryta sold va bonate of 
‘> Srnms, Vol. XV, No. 44,—March, 1853. 31 
