192

PROOFS OF THE PROPERTIES OF SILEX.

made of wax; let it stand for a few days and agitate it frequently.On examining the contents the silex will be found to be dis-solved in the acid.

Experiment IV.

Silex is dissolved by alcalies in the humid way, when in astate of extreme division.

This may be proved by boiling one part of pure silex, minutelydivided, in a silver vessel with 20 parts by weight of a concen-trated solution of potash or soda. The earth will be dissolved,and may be separated again by the addition of an acid.

Experiment V.

Silex is soluble in alcalies by fusion.

The method of obtaing silex, as mentioned before, furnishes aproof of this.

Experiment Vi.

Silex is fusible with the phosphoric and boracic acids.

Place a few grains of silex and glacial acid of phosphorus orborax, on a bit of charcoal, and urge it by means of the blow-pipe ; the mixture will melt and form a globule of transparentglass.

The other properties of this earth may be investigated withoutany description.

FORMATION OF GLASS.

Glass Is obtained by mixing silex with a proper proportion ofsoda or potash, and exposing this mixture to a violent heat.