COLONEL P. YOEKE’S EESEAECHES ON SILICA. 
541 
Two crystallized hydrates of silicate of soda have been described by Fritzsciie*, one 
of which crystallizes in rectangular prisms, and contains 56 '6 per cent, of water, the 
other 47 per cent. HERMAANf has also described a salt of this kind crystallizing in 
rhombohedi’ons and containing 54'4 per cent, of water. In all these salts the proportion 
of acid to base is the same as in the one I have described above, and the number of 
equivalents of water contained in them respectively is 9, 6 and 8. Lately M. Fremy J, 
in a communication on the Silicates, has described a silicate which he states he obtained 
in large crystals, to which he assigns the formula 4NaO, 26HO, which would 
give 48’ 6 per cent, of water. I regret that I have not been able to determine the cry- 
stalline form of the salts I have obtained ; but the point to which I wish to direct attention 
is, that in the process of obtaining a crystalhzed hydrate from the fused anhydrous salt 
a portion of soda is extruded. I found that this extrusion also took place when the 
salt was formed by dissohdng hydrated silica in such a quantity of a solution of caustic 
soda, as that the soda should be in the same proportion to the sihca as in the fused salt 
before described, \iz. as 31 : 23. 
A specimen of a crystallized salt, formed in this manner, of which the solution had 
been exposed to the atmosphere during crystallization, yielded, on analysis, — 
Silica 22-38 
Soda 24-44 
Carbonate of soda . 2-41 
AVater 50-55 
I also obtained a crystallized salt by dissolving sihca in a solution of caustic soda in such 
proportion that the oxygen in the silica should be double that in the soda. The crystal- 
lized salt was redissolved and recrystallized, the crystallization in both instances taking 
place out of contact with the atmosphere. 
Analysis gave the following composition of this specimen (c ) : — 
Silica . 
. 24-45 
2SiO j r30-2 . 
in 100. 
. 24-193 
Soda 
. 25-276 
NaO give 31 
. 25-00 
Water . 
. 50-374 
7HoJ 163 
. 50-80 
As it appeared to me desirable to ascertain if any portion of the water in these salts 
should be considered as basic, I made some experiments on specimens (a) and (c) with 
this -view. I found however no decided difference in the comportment of the two 
specimens ; and further, that all the water, with the exception of less than 1 per cent., 
was expelled at a temperature of 300° Fahr. 
With regard to the silicate of lithia (LiO, SiO), I have not yet been able to examine 
it particularly ; but when treated with water it appears, like the soda compound, to split 
into different combinations, as a substance which remained when more than one-half of 
* PoGOENDOEvr’s Armalen, xliii. 135. t Eedmaxn’s Journal fur prakt. Chemie, xiv. 275. 
J Comptes Eendus, December 1856. 
MDCCCLVII. 4 B 
