J. M. Ordway on Waterglass. 35 
hearer we get to an entire precipitation of the silica, the more 
apt is the remaining liquid to exhibit such alternations of opac- 
ity and clearness. 
The silicates containing less than 170 eq. of silica to 100 eq. 
of alkali, are usually thrown down in the liquid state; those 
more silicious yield solids of greater and greater firmness as the 
relative proportion of silica increases. But all these hard pro- 
ucts belong to the same class of solids as pitch,—that is, heaped 
up fragments will, in the course of time, flatten themselves out 
and form one united cake. 
_It is obvious from the above examples that the more any 
given waterglass solution is diluted before adding alcohol, the 
greater will be the relative amount of silica in the precipitate. 
And thus by mere precipitation under varied conditions, we may 
get an unlimited number of differently constituted silicates. 
But while the ratio of acid and base admits of an infinite diver- 
sity, the quantity of water in the principal products appears to 
nearly constant, generally amounting to not far from 
r cent. 
In this respect waterglass differs from the proper salts, many 
of which alcohol throws down combined or associated with an 
amount of water varying according to the proportion of spirit 
used. Thus 100 parts of a solution containing 10 p. ¢. 
carbonate of potash, on being treated with alcohol of sp. gr. 
0'820, gave with 
60 of alcohol no precipitate. 
70 “ lieht “ 
a 
100 . 17°8 p’ts of a liquid containing 26 p. c. K6 
20'8 “ ws “ 99 
120 % . 
140 “ 21°7 bs “ 6 30 &“ 
190 «“ 23-2 “ “ a 32 e 
200 s 231 “ bad bed 33 - 
400 “ 3 “ “ “ 38 = 
8: 
Carbonate, sulphate, and stannate of soda afford liquid pro- 
ducts with a certain amount of alcohol, but with a larger quan- 
lity they yield crystals. . 
fice Soke nine even as much as ten per cent of any of 
the salts commonly occurring in the crude alkaline silicates, are 
not immediately affected by a moderate addition of alcohol. 
Hence it is not at all strange that the greater part of these salts 
