536 
COLOKEL P. TOEKE’S EESEAECHES OX SILICA. 
I. Fused a second time by gas-flame, urged by bellows for fifteen') 
minutes, crucible open / 
II. Fused a third time by gas-flame, urged by bellows for fifteen') 
minutes, crucible open J 
On the following day, — 
III. Fused a fourth time by gas-flame, urged by bellows for fifteen"! 
minutes, crucible open / 
IV. Fused a fifth time by gas-flame, urged by bellows for fifteen') 
minutes, crucible open j 
grs. diff. 
= 78-29 0-21 
= 78-26 0-03 
= 78-20 0-06 
= 78-14 0-06 
The carbonate of soda had acquired a slight brown tint ; on examination I found that 
this was owing to its containing a very minute portion of oxide of platinum denved from 
the crucible. From these experiments, it will be evident that the results I had obtained 
by the fusion of carbonate of soda with silica could not be accounted for by the action of 
heat alone. 
The carbonates of potash and soda having afforded me such different results, I now had 
recourse to carbonate of lithia. 
Experiments with Silica and Carbonate of Lithia. 
The carbonate of lithia, as purchased, was purified by dissohdng it hi 100 pai-ts of 
boiling distilled water, filtering the liquid from small portions of lime and other matters 
which remained undissolved, and evaporating the filtrate in a porcelain basin until a 
small portion of liquid only remained ; the carbonate of lithia was obtained as a crystal- 
line crust deposited on the basin. The mother-liquor contained potash. 
The carbonate of lithia thus obtained was fused in a covered crucible. It lost very 
little weight. I found that although carbonate of lithia by itself fused at a temperatm-e 
below a red heat, visible by daylight, yet that when any considerable proportion of silica 
was added, the fusing-point rose so much that I was obliged to conduct the experiments 
in a platinum crucible. 
Experiments with Carho^iate of Lithia. 
Carbonate of Litbia. 
Silica. 
Loss= Carbonic 
Equivalent of 
No. 
grs. 
grs. 
Acid. 
Silica deduced. 
I. 
34-46 
10-33 
14-9 
15-2 
II. 
26-87 
8-24 
12-09 
14-99 
III. 
42-74 
15-84 
23-24 
14-99 
IV. 
31-28 
9-14 
13-61 
Mean . 
14-77 
. 14-99 
Experiments III. and IV. were made with a different specimen of carbonate of lithia 
from Nos. I. and II. 
Hence it appears that the equivalent for silica, deduced from experiments with car- 
