POTASH, Potashes, Pearl-Ash.
Shili-kien, Carbonate of potash, &vet.
Hwui kien, Klua, Jowkshar, . lion .
Potaske,. . DAN. Manu•uppu, . TAIL, Muir ka Nsmak, .
Potash is a commercial term commonly applied to an impure carbonate of potash, obtained by the incineration of wood, lixiviating the ashes in barrels, first with cold and then with hot water, filtering the ley, and evaporating it to dryness in an iron pot. Potash is of great importance in the arts, being used in the soap and gas manu factures. the rectification of spirit, bleaching, in medicine, and for other purposes. It is procur able in most Indian bazars. No manufacture of potash upon au extensive scale has ever been attempted in India. The common source of it is the ashes of land plants, and the English market is supplied from Russia and America. A source of pearl-ash, and one very interesting to us, seeing the enormous quantities of saltpetre all over the country, is nitrate of potash and charcoal. The Hindus of the Malabar coast, as well as the Singhalese, who do not use Over Munnoo, or im pure carbonate of soda, in bleaching and washing linen, employ for these purposes the ashes of burnt vegetables (chiefly cocoanut leaves), which can only in this way be of service from the potash they contain. Dioscorides describes it as ashes of vine-twigs Cineris lixivium (Pliny xxxviii. c. 51). The Arabs are usually supposed to have been the first to make known this alkali (al-kali). In countries where forests are abundant, as N. America, Russia, Sweden, Poland, wood is piled in heaps and burnt on the surface of the ground, in a place sheltered from the wind. The ashes
which are left consist of a soluble and insoluble portion. The soluble part is made up of the car bonate, together with the sulphate, phosphate, and silicate of potash, and the chlorides of potas sium and of sodium ; and the insoluble portion of carbonate and sub-phosphate of lime, alumina, silica, the oxides of iron and manganese, and a little carbonaceous matter that had escaped in cineration. In China, it is prepared by burning composite, polygonaceous, and other inland plants. The ash is made into a thick mass by the addition of some kind of meal, and is sold as an alkali for raising bread, cleaning clothes, etc.
The Bitartrate of Potash, or Cream of Tartar, must have been known ever since wine has been made from the grape, in the juice of which it exists. During the fermentation of wine, sugar disappears, and alcohol is formed, and the salt not being soluble in this, is deposited on the bottom and sides of casks, as a crystalline crust, which, according to the colour of the wine, forms either red or white tartar or argot. It is the Fiex vini of Diosc. v. c. 13. Its nature was determined by Scheele in 1769. It is largely purified both at Montpelier and at Venice. In commerce it is in white crystalline crusts formed of clusters of small crystals aggregated together, which are hard and gritty under the teeth, dissolve but slowly in the mouth, and have an acid and rather pleasant taste.—Royle ; Hindu Med. p. 97.