Diuretic salt; acetated kali, sal Sennerti, tartarus regeneratus, and arcanum tartari; terra foliata tartari; essentiale sal. It is a fixed vegetable alkaline salt, saturated with the acetous acid, and evaporated to dryness: when the process is carried no further, it is of a brownish colour, somewhat oily, and is called tartarum regeneratum. When purified to perfect whiteness, it is sal diureticus.

Acetated kali is prepared by boiling one pound of kali with four or five pints of distilled vinegar over a gentle fire: when the fermentation ceases, more distilled vinegar must be added, and when the fermentation subsides, still more. When the vinegar is nearly all evaporated, fresh vinegar will not excite any fermentation, which usually happens when about ten quarts have been used: then gently evaporate to dryness. The impure salt is to be melted for a time with a gentle heat, dissolved in water, and filtered through paper. If the melting hath been duly performed, the filtered liquor will be colourless: if otherwise, of a brown colour. The water is then to be evaporated with a very gentle heat, in a shallow glass vessel; the salt, as it dries, being frequently stirred, that the humidity may the sooner and more completely be discharged. It should be kept in a vessel close stopped, or it will dissolve by the moisture of the air. If, on dissolving a little of it in water, or the spirit of wine, any faeces are observed in either of these liquids, the whole must be dissolved in spirit, filtered, and again evaporated. Pharmac. Lond. 1788.

To succeed completely, the salt must be perfectly saturated with the acid, properly calcined, and at last dried, without too much heat. - The first is ascertained by dipping a coloured paper into it, as directed in the article Spt. minder. The degree of calcination may be judged of, by dropping a little in water, and observing when it begins to part with its blackness readily: if, after this, the calcination is continued, the salt will be brownish. In the last drying, care must be taken not to melt it; for thus its whiteness will be lessened, in consequence of a decomposition of a portion of the acetous acid, and a deposition will take place on dissolving it in spirit, as the carbonate of potash is insoluble in alcohol.

The only use of rendering this salt white by depriving it of its oil, or carbone-for it is uncertain to what the colour may be owing-is, that it may rest more easily on weak stomachs; but if the process was carried on no further than to saturate the alkaline salt, if the evaporation of the liquor was performed in a water bath, the oily part of the salt would not have an empyreumatic flavour, so as to become offensive; the remaining trouble would be spared, and a medicine of equal goodness obtained.

Dr. Lewis directs the salt of tar to be dissolved in cold water, and filtered, and then this solution to be saturated with distilled vinegar: after which the evaporation is to take place over a very gentle fire, so that the liquor may not boil, until a pellicle appears on its surface: the process must be finished in a water bath; the pellicle, as it whitens, must be taken off, and the fluid continually stirred, until the whole is taken away in the form of a white scum, which may be dried in an oven.

In making this salt, care should be taken to use a pure alkali, in which no neutral is mixed; but, in general, a mixture of the salt of tartar with vinegar, to a point of saturation, without evaporation, or any other trouble, is very little, if at all, inferior. Two drachms of the alkali saturated with vinegar, it is said, have been very successful in dropsies.

Some chemists have proposed making this salt by a decomposition of acetite of lead by carbonate or sulphate of potash. It may be very readily prepared by using the acetous acid separated from an acetated kali, made with common vinegar, by means of sulphuric acid.

In doses of about twenty or thirty grains, this salt is a mild, cooling aperient and diuretic; from a drachm to half an ounce it is purgative. As a purgative it is mild and easy, and as it is diuretic also, it is a peculiarly proper purgative in dropsies. In the jaundice and similar complaints this salt may be given to advantage, and preparations of steel afterwards employed. See Lewis's Mat. Med. Neumann's Chem. Works.