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Preparations and Compositions. Part III.

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Lond.

Take of

Liquor of potass, three pints;Fresh lime, one pound.

Boil down the liquor to one pint, then add the lime previous-ly slaked, and mix them intimately.

Kali causticum cum calce. Dub.Caustic Kali with Lime.

Evaporate solution of caustic kali to one-third, then add asmuch fresh burnt lime, in powder, as will form a sufficient-ly thick mass, which is to be kept in a well-closed vessel.

The addition of the lime in these preparations rendersthem less apt to deliquesce, more easily managed, and milderin their operation than fused potass.

Carbonas potassje. Ed.Carbonate of PotassLet impure carbonate of potass (called in English pearl ashes)be put into a crucible, and brought to a low red heat, thatthe oily impurities if there be any, may be burnt out:then triturate it with an equal weight of water, and mixthem thoroughly by agitation. After the feces have subsid-ed, pour the liquor into a very clean iron pot, and boil todryness, stirring the salt towards the end of the process, toprevent its sticking to the vessel.

PoTASSiE SUBCARBONAS. Lo7ld.

Subcarbonate of Potass.

Take ofImpure potashes, in powder, three pounds;Boiling water, three pints and a half.

Dissolve the potashes in the water, and filter, then pour it in-to a bright iron vessel, and evaporate the water by a gentleheat until the liquor become thick; then, having removedit from the fire, stir it constantly with an iron spatula untilit become a granulated salt.

A purer subcarbonate of potass may be prepared in the samemanner from Tartar, previously burnt till it becomes of anash colour.