PROPERTIES OF SILEX.

isg

PROPERTIES OF SILEX.

Silex when perfectly pure exists in the form of a white powder.It is insipid and inodorous. It is rough to the touch, cuts glassyand scratches or wears away metals. Its specific gravity is about2.66. It is unalterable by the simple combustible bodies. Whenmixed with water it does not form a cohesive mass. Its mole-culae when diffused in water are precipitated with the utmostfacility. It is not acted on by any acid, except the fluoric.When in a state of extreme division it is soluble in alcalies; fusedwith them it forms glass. It melts with the phosphoric and bo-racic acids. It is unchangeable in the air and unalterable by ox-igen and the rest of the gazeous fluids. It has been consideredas insoluble in water, but it appears when in a state of extremedivision to be soluble in a minute quantity.

METHOD OF OBTAINING SILEX.

Silex may be obtained, tolerably pure, from flints, by the fol-lowing process: Procure some common gun-flints; exposethem in a crucible to a red heat, and then plunge them into coldwater; by this treatment they will become brittle, and easily re-ducible to powder. Mix them, when pulverized, with three orfour limes their weight of carbonate of potash, and let the mix-ture be fused, in a dull red heat, in a silver crucible. We shallthus obtain a compound of alcali and silex, called siliceous potash.Dissolve this compound in water, filter the solution, and add toit diluted sulphuric or muriatic acid. An immediate precipita-tion now ensues, and as long as this continues, add fresh portionsof acid. Let the precipitate subside; pour off the fluid thatfloats above it; and wash the precipitate with hot water till itcomes off tasteless. This powder when dry is silex.