M. Wohler on Crystallized Silicon. 103 
ning the quantity of gold which is reduced from a solution of 
aurochloride of gold by a known weight of pure metallic anti- 
mony. But this method gave very unsatisfactory results. 
Wohler* describes an improved method of preparing the 
crystallized silicon discovered by him+. It consists in fusing 
aluminium with five times its weight of soluble glass, and ten 
times its weight of cryolite. The soluble glass he uses is that 
made by Kuhlmann of Lille. This is powdered and mixed 
with the powdered eryolite ; a Hessian crucible is half-filled with 
the mixture, and the piece of aluminium laid on it, and then 
filled up with the rest of the mixture. The crucible is then 
heated, and the mixture kept melted for about half an hour. On 
cooling, black reguli are obtained, quite saturated with silicon, 
and the surface is generally covered with 3- and 6-sided plates 
of silicon. 
It is remarkable that these reguli cannot be remelted at the 
temperature at which they are formed. They can be heated to 
redness in any open crucible without melting and without being 
oxidized. Ifa red-hot globule be thrown into cold water, half 
the volume of aluminium flows out, and the silicon remains in 
the form of the globule as a crystalline mass filled with hollow 
spaces. In preparing silicon, it is better therefore to treat the 
regulus in this manner before treating it with hydrochloric acid ; 
some aluminium is obtained in this way, which can be used for 
a fresh preparation of silicon. 
The same chemist has, in conjunction with Bufft, been en- 
gaged on some investigations of the relations of aluminium to 
the galvanic current. In the course of these they have dis- 
covered a gas containing silicon which is spontaneously inflam- 
mable in the air, and a new chloride of silicon with its corre- 
sponding oxide. When the galvanic current is passed through 
a solution of chloride of sodium, aluminium containing silicon 
being used as the electrodes, a gas is evolved at the positive pole 
which is spontaneously inflammable, and explodes when mixed 
with oxygen. It burns with a brilliant white light, producing 
white fumes of silica. Ifa piece of porcelain be placed in the 
flame, brown stains of amorphous silicon are deposited on it ; 
and if the gas be passed through a glass tube heated to redness, 
a brown mirror of amorphous silicon is deposited. The gas also 
takes fire when mixed with chlorine. The formation of this body 
is yery peculiar, occurring as it does at the positive pole, while 
there is a disengagement of hydrogen at the negative pole. 
* Liebig’s Annalen, June 1857. + Phil. Mag. April 1857. 
{ Liebig’s Annalen, April 1857; and Comptes Rendus, June 29, 1857. 
