Tartarum vini albi vel rubri. Tartar: an acid concrete salt thrown off from wines, after complete fermentation, to the sides and bottoms of the casks; of a red or white colour, and more or less drossy, according to the colour and quality of the wine. The white is generally purer than the red: both kinds, when purified, are exactly the same.

This salt is one of those which are most difficultly dissoluble in water, being scarcely affected by it in the cold, and requiring ten or twelve times its own weight when assisted by a boiling heat. From this saturated solution the tartar begins to separate almost as soon as the boiling ceafes: if the quantity of water is greater, as about twenty times the weight of the salt, it continues long enough suspended to be passed, with due care, through a woollen strainer or a filter. The filtered liquor appears nearly colourless, whether the tartar made use of was red or white: if hastily cooled, the salt separates in small grains like sand, but if the vessel is closely covered, and the heat very leisurely diminished, it shoots into semitran-sparent whitish crystals: if the filtered liquor be kept boiling, a thick skin forms on the surface, which, being taken off with a perforated wooden skimmer, is succeeded by fresh cuticles, till the whole of the salt is thus formed into what is called creme of tartar. The refining of tartar is practised, in the way of trade, chiefly about Montpellier, from whence the shops are generally supplied both with the crystals and creme; the process being so troublesome, and requiring so large conveniences, that it is scarcely ever attempted here. A certain earth, of the argillaceous kind, is added in the process, the chief use of which seems to be, to promote the sepa-ration of the colouring matter; for the salt extracted from the coloured tartars by water only is seldom of perfect whiteness. It is said that the earth generally contains some small portion of chalky matter, soluble in acids, which of consequence will be taken up by the tartar; I have sometimes observed solutions of the cryftals to deposite an earthy precipitate on adding alkaline lye. The purer sort of white tartar, unrefined, especially that of Rhenish wine, is, for many purposes, particularly for combinations with other bodies, not inferiour either to the creme or crystals.

*(a) Alcohol, distilled from tansy, proved, after (landing for upwards of fifteen years, richly impregnated with the flavour of the plant, and sufficiently grateful. M. S. of Dr, Lewis*

Crystalli tar-tari Ph. Land. & Ed.

Cremor tar-tari.

Pure tartar, in doses of half a dram or a dram, is a mild cooling aperient: two or three drams gently loosen the belly; and six or eight prove moderately cathartic. Its acidity and laxative power are its medical characters.

* The difficult solubility of creme of tartar being an objection to its medical use, some experiments were made by Dr. Peter Jonas Berg, for rendering it more soluble by certain additions, without altering its medicinal qualities. Borax was found to answer best for this pur-pose. To four parts of creme of tartar, one of borax was added. These were dissolved in a sufficient quantity of water, and the liquor {trained. About a sixteenth part of impurities were left behind. The pure solution evaporated yielded an acid and extremely soluble white salt (a).

Tartar, diffolved in water, efffervesces with fixt alkaline salts, and saturates, of the vegetable alkalies, near one third its own weight. The compound salt, resulting from their union, is a neutral one, more purgative than the tartar itself, and far easier of solution, whence its name soluble tartar. This salt is prepared, either by boiling the refined tartar in a sufficient quantity of water till it is difffolved, and then dropping in strong alkaline lye; or by dissolving the alkali in boiling water in the proportion of a pound to a gallon†, or to fifteen pounds‡, and then adding the tartar, till a fresh addition occasions no further effervescence; which generally happens before triple the weight of the alkali is thrown in: the liquor is then filtered while hot, and either crystaiiized or evaporated to dryness. As this salt difficultly crystallizes, infpiflation to dryness is the molt convenient method; and in this case, to secure the neutralization of the salt, the tartar may be made to prevail at first, and the liquor suffered to cool a little before filtration, that the redundant tartar may concrete and separate from it; or the neutralization may be more perfectly obtained by means of stained papers, as mentioned at the end of the article Acetum,

(a) Nova Acta Physico-Medica Academiae Caesareae Leopol-dino-Caroliriae Nature Curiosorum, tom, quart, alkali tartari-fat. † Ph. Lend.

Alcali hxum vegetabile tartarifatum vulgo tart.

solub. ‡ Ph. Ed.

Sal. vegetabilis guibusd.

Of the mineral fixt alkali or soda, this acid saturates, according to the faculty of Paris, four fifths its own weight. The London college directs six parts of the acid to five of the alkali. The neutral salt resulting from its coalition with this alkali, is somewhat less dissoluble than that with the vegetable; and shoots much more easily, into pretty large, hard, multangular cry-stals, some columnar and flattish, others more irregular. It is milder in taste, and said to be less purgative, requiring to be given to the quantity of an ounce or an ounce and a half to purge effectually: eight drams are reckoned by some to be equivalent, in cathartic power, to six of the soluble tartar.

Tartar forms likewise soluble compounds with all the absorbent earths, and with some metallic bodies, but with thefe last it is difficultly made to satiate itself completely, the part that is first saturated seeming to impede the action of the reft; for after long boiling, a very considerable part of the tartar separates on cry-stallization unchanged.

It is observable, that if any of these combinations or tartar, with alkalies, with earths, or with metals, be dissolved in water, and any other acid added, the pure tartar separates and falls to the bottom, as acid, and as difficult of solution, as at first; the substance, that was combined with it, being absorbed by the acid superadded. As the acids of the vegetable kingdom, whether native or fermented, vinegar, lemon juice, etc. have this effect of disuniting tartar from all the bodies that are combinable with it, equally with those of the mineral kingdom; it follows, that the tartareous acid, is of a kind effentially different from all the other known vegetable ones, and that no acid, unless it be tartar itself, can be joined in prescription to the tartarum solubile, the sel de Seignette, or the combinations of tartar with earths of metals. *In the Swedish Transactions, part iii. for the year 1770, was published an analysis of creme of tartar by Mr. Scheele. By this it appears, that creme of tartar is not a pure acid, but a compound salt, containing the fixed vegetable alkali united with a superabundance of the tartareous acid. It differs, therefore, from solu-ble tartar, only in the proportion of acid it contains.

Natron tar-tarifatum Ph. Lond.

Soda tartari fata vulgo fal rupellenfis Ph. Ed.

Sel de Seig-nette, Ro-chelle salt.