19& METHOD OF OBTAINING ALUMINE.

pounds decomposable by acids. It dissolves slowly in all acids.It possesses a powerful attraction for lime. The most intenseheat of our furnaces is not able to melt it, but it becomes fusiblewhen lime is added, Lavoisier has proved that it is capable ofentering into a kind of fusion like paste, by the action of oxigengas; it then cuts glass and resists the file. It absorbs water andcarbonic acid from the atmosphere. By its mixture with waterand silex it acquires great solidity. It does not unite with anycombustible substance, but becomes fused into coloured frits withmetallic oxids. Its specific gravity is 2. It is employed in amultitude of arts.

' METHOD OF OBTAINING ALUMINE.

Take any quantity of alum of commerce, dissolve it in sixparts of boiling distilled water, and add to this solution, whencold, liquid ammonia, till no further precipitate ensues. Thenheat the whole nearly to the boiling point for a few minutes, andtransfer it on a filter. In proportion as the fluid passes off, pourmore water over the precipitate, until it passes tasteless. Letthe precipitate obtained, while yet in a pasty state, be transferredinto a glass or Wedgwood's bason, and add to it muriatic acid insmall quantities at a time, until the whole is dissolved. Thenevaporate the solution, till a drop of it, when suffered to cool ona plate of'glass, yields minute crystals: on letting it now cool,crystals of alum will be deposited. Remove these crystals bydecanting the fluid, and renew the evaporation, until, on fur-ther cooling, no more crystals are formed. Nothing now butpure alumine remains in the solution; the fluid may thereforebe decomposed by adding to it gradually liquid ammonia till nofurther precipitate ensues. The precipitate thus obtained whenwell Washed and dried, is pure alumine.

Remake...T he process recommended in general by systematicwriters for obtaining alumine differs from this; it consists in de-composing a solution of alum of commerce by an excess of a carbo-