J. M. Ordway on Waterglass. 339 
soda well shaken in a bottle partly full of air, and afterwards 
filtered, I have obtained a very deep blue solution. Waterglass 
saturated in the same way with zine, after a while deposits the 
zinc again, or even coagulates into a gelatinous mass. Zincate 
of soda mixed with cold silicate at first shows no change, but a 
precipitate forms very soon. In like manner aluminate and glu- 
cinate of soda speedily cause a precipitation. But manganate, 
stannate, and chromate produce no alteration. Bolley* observed 
some years ago that even lime, magnesia, and baryta are slightly 
soluble in waterglass. 
Thus we see that silica, though it has no neutralizing power, 
exhibits some reactions which go to vindicate its acid nature. 
But its chemical activity is more distinctly shown when earthy 
or metallic protoxyds in the state of hydrates are mixed, in 
equivalent quantities, with dissolved waterglass. ih most such 
: 
ve been given a priort and not after actual experiment. For 
is utterly impracticable. The extraction can be effecte only by 
drying nett the mixture and then lixiviating the dehydrated 
: Litharge, when ground exceedingly fine with water, coagulates 
silicate, but does not entirely destroy the toughness, especially 
of silicate of potash. 
ium. 
llic salts effect a double de- 
tes, and generally a 
thickeni soon ensues. But sulphate 
whether 
* Kopp and Will's Jahresbericht for 1858, p. 140. . ; 
iy: Palas says that even common glass on being boiled with ig pee — 
ioe no inconsiderable amount of sulphate of soda.—Leibig and Kopps v% 
ticht for 1856,—p. 355. 
