156 J. M. Ordway on Waterglass. 
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excludes silicated alkali or ‘liquor silicum,’ the “ kieselfeuchtig- 
keit” and ‘‘kieselsaft” of the Germans. Yet the two things 
are confounded by many. Thus while writing this, I have be- 
fore me the printed directions given by an English manufacturer 
for dissolving his “soluble glass to produce liquor silicis;” and 
of two specimens of his glass, one proves to be a sesquisilicate 
of soda, and the other a bisilicate. 
Still though the extremes are unlike enough, there can be 
only an arbitrary line of distinction drawn on the middle ground. 
Anything more alkaline than NagSi, is prone to deliquescence, 
and is too poor in silica for most uses, and it would perhaps be 
but just to consider ‘ waterglass’ as including nothing more basi¢ 
than the sesquisilicates. Again with regard to this last term it 
may be remarked that as silica in combining with the alkalies 1s 
regardless of precise atomic ratios, ‘silicate’ without a limiting 
prefix, conveys no more definite idea than ‘hydrate;’ and the 
world being still divided respecting the atomic constitution of 
silicic acid, a limiting prefix has to be itself interpreted, unless 
the context makes its meaning apparent. In this paper silica 18 
taken as SiO,, merely because custom has made this the more 
equivalents, of silica, and therefore should properly be rather 
hard to dissolve. ae 
Manufacture.—It was discovered some years ago that flint oF 
quartz enters into solution when boiled with caustic alkalies 
under strong pressure; and this method has sometimes beet 
resorted to for manufacturing the silicates of potash and soda. 
sas 
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