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Preparations and Compositions. Part III

Soda tartarizata. Land.Tartarized Soda.

Take of

kubcarbonate of soda, twenty ounces ;Supertartrate of potass, in powder, two pounds ;Boiling water, ten pints.

Dissolve the subcarbonate of soda in the water, and gradual-ly add the supertartrate of potass. Filter the solutionthrough paper; evaporate until a pellicle be formed, andset it aside to crystallize. Pour off the liquor, and dry thecrystals on blotting paper.

The tartaric acid, in several instances, is capable of enter-ing into combination, at the same time, with two bases. Inthe present example, the superabundant acid of the super-tartrate of potass is neutralized with soda, and, in place of amixture of tartrate of potass and tartrate of soda, each pos-sessing their own properties, there results a triple salt, havingpeculiar properties.

The tartrate of potass and soda forms large and very regularcrystals, in the form of prisms with eight sides, nearly equal,which are often divided longitudinally, almost through theiraxis The principal form is a rhomboidal tetrahedral prismof 80° and 100°, with rhombic faces. It has a bitter taste.It is soluble in about five parts of water, and effloresces in theair. It is decomposed by the strong acids, which combinewith the soda, and separate supertartrate of potass, and bybaryta and lime. By heat its acid is destroyed'. It consistsof 54 tartrate of potass, and *6 tartrate of soda. Mr Phillipsfound that 1 • parts of subcarbonate of soda were sufficient toneutralize 24 of supertartrate of potass.

Medical use __It was introduced into medical practice by

M. Seignette, an apothecary at Rochelle, whose name it longbore, and is still very much employed as an excellent purga-tive salt.

Aqua ammonije, olim Aoua ammonia caustjos. Ed.

Water of Ammonia, formerly Water of Caustic Ammonia.Take of

Muriate of ammonia, one pound;

Quicklime, fresh burnt, oqe pound and a half;

Distilled water, one poundj

Water, nine ounces.Pour the water on the powdered lime, contained in an iron

or earthen vessel, which is then to be covered up until the