540 
COLONEL P. TOEKE’S EESEAECHES ON SILICA. 
the proportions I have mentioned. The fused substance readily dissolved in water, 
affording a perfectly colourless transparent solution. The solution was evaporated at 
atmospheric temperatures in vacuo with sulphuric acid; after some days it began to 
crystallize, and eventually formed a mass of crystals with veiy little liquid remaining. 
Analysis. 
I. 17‘62grs. of the salt, dried by pressure in filtering paper, was treated with hydro- 
chloric acid, effervescence was produced. It yielded 3’72 grs. of ignited silica. The 
filtrate evaporated and residue ignited, gave 8' 33 grs. chloride of sodium =4-41 soda. 
II. I6'24grs., dried as before, heated on a sand-bath, melted into a clear liquid, which 
soon became viscid and opaque; ignited, it weighed 7'78grs. ; loss =8’46. 
III. 22T7 grs. of the salt, dried as before, heated red in a platinum crucible =I0'66 ; 
loss =11-51. 
To expel the carbonic acid, a little silica was added to the remaining substance, the 
whole =13-78. 
This was heated by the gas-flame, urged by bellows for ten minutes, and! ]^ 3 . 9 g 
then weighed J 
Loss = carbonic acid = 0-50 
These experiments would give as the constituents of 100 parts of the salt (a), — 
Silicic acid 
I. 
21-11 
II. 
III. 
Soda .... 
25-02 
Carbonic acid and] 
water by loss ,J 
■ 53-87| 
52-1 
2-25 
51-90 
and as 2-25 carbonic acid would combine with 3-15 soda, 100 parts would contain — 
Silicic acid . . . . 2 1- 1 1 
Soda 21-87 
Carbonate of soda . 5-40 
Water 51-90 
100-28 
If the carbonate of soda be the ordinary ten-hydrated salt, and this be considered as 
mixture and subtracted, we obtain — 
SiO, . , 
. . 30-2 
By Theory, 
in 100 pts. 
24-19 
By Experiment, 
in 100 pta. 
24-61 
Soda 
. . 31-0 
25-01 
25-49 
7HO . 
. . 63-0 
50-80 
49-90 
124-2 
