Cream of Tartar

Cream of Tartar exists naturally in grape juice, but being insoluble in alcohol, it is gradually deposited, in the form of argol, as the sugar of the juice becomes converted into alcohol by fermentation. In the preparation of cream of tartar the argol is dissolved in hot water, to which charcoal or fine clay is added, to take up the colouring matter; by boiling and filtering a clear colourless solution is obtained, from which, on cooling, the cream of tartar separates as crystals. These crystals, after being exposed on linen for several days, become whiter and constitute the crystals of tartar, or, when ground to powder, the cream of tartar. Although cream of tartar is, practically speaking, the bitartrate of potash, $\backslash text\{KHC\}\_4\backslash text\{H\}\_4\backslash text\{O\}\_6$ (see TARTARIC ACID), yet it usually contains from 5 to 10 per cent. of tartrate of lime, while adulterants, properly speaking, may also be present. The tartrate of lime is derived from the clay added to purify it, and is more or less present in all commercial samples. In 1888, however, cream of tartar was offered in the market containing 99 per cent. of bitartrate of potash, so that it may be assumed that in future a purer article will be forthcoming. Cream of tartar is readily soluble in hot water, though it takes 60 parts of cold water to dissolve one part of it. Soluble cream of tartar is prepared by dissolving together 2 parts of Borax (q.v.) and 5 parts of cream of tartar, evaporating to dryness and powdering. Cream of tartar has an acid taste and gritty feel. When taken repeatedly in small doses of a scruple to a drachm, it acts as a refrigerant and diuretic; in doses of one to two drachms, it is useful as an aperient; and in larger doses of from two to three drachms it acts as a purging agent, accompanied by flatulence and griping. Imperial liquid is prepared by dissolving about a drachm of cream of tartar in a pint of boiling water, and adding a little lemon-peel and sugar to flavour it; when an agreeable refrigerant drink is obtained, which is highly serviceable in allaying thirst in feverish cases. Cream of tartar whey is obtained by adding two drachms of the salt to a pint of milk.