60 J. L. Smith on determining the Alkalies in Minerals. 
58. This second fusion complicates the method but little, as 
the residue on the filter readily dries in a water-bath into a powder 
that is easily detached from the filter, and the small portion ad- 
hering to the latter may be disregarded, as the alkalies remaining 
rarely exceed more than =1, of the whole mass, and in most in- 
stances not more than ;,;';;. In many analyses made, one fusion 
sufficed for the entire extraction of the alkalies, but as a few 
tenths would occasionally remain behind, we preferred the ad- 
ditional fusion to get at that small quantity, and to entitle it to 
rank as a method by which all but the merest trace of the alkalies 
could be extracted from the insoluble silicates. 
59. The proportion of sal-ammoniac added to the carbonate of 
lime as here recommended, is arrived at after numerous expet- 
ing the amount of chlorid of calcium formed, the mass fuses 
more thoroughly, but the water does not disintegate it as com- 
pletely as when the ammoniacal salt is less ; also the accumulation 
of this latter at the end of the process is less, an object not to be 
disregarded. The advantage of thus estimating the alkalies in 
insoluble silicates is obvious ;—the long routine of separating 
silica, alumina, lime, &c., is done away with—the accumulation of 
chlorid of ammonium is very trifling,—and lastly, the alkalies 
are obtained directly in the form of chlorids. The method will 
course be all that is necessary, and the action of the water need 
61. There is nothing new in the attempt to dissolve out the 
alkalies by water, from a silicate that had been heated with lime. 
M. Fuchs used the method for procuring lithia from lepidolite, 
but of course his efforts were entirely directed to procuring the 
lithia from the mineral, and not to estimating its quantity, as the 
to decompose alkaline silicates, heating over a lamp and subse- 
quently treating the mass with water to extract the alkalies or 
ture may reduce the feldspars, it fails when tried on kyanite, 
zircon, micas and other silicates difficult of decomposition. This 
