Alkali

al'ka-li, a compound resulting from the decomposition of water by any one of the alkali metals, as potassium, sodium, or lithium. Ammonia has the characteristics of an alkali, and is known as the volatile alkali. The alkalies are all very soluble in water, forming soapy, caustic solutions. They unite with oils and fats to form soaps, neutralize acids forming alkaline salts, change some of the vegetable yellows to brown, and reddened litmus to blue. Common lye, obtained by leaching wood ashes, is an alkaline solution consisting largely of potassium salts. It is used in a number of factories and by the housewife in making soft soap, and for hulling corn. The alkali waters of the Western States contain considerable quantities of alkali salts, chiefly in the form of carbonates or sulphates of potassium and sodium. Large areas of soil, both in the Old World and in the New, are so impregnated with alkali salts as to be practically barren; but recent experiments in irrigation have demonstrated that water and drainage will leach out the salts and convert deserts into fertile plains.

Among the useful plants which subsist on certain proportions of alkali salts in the soil are barley, rice, millet, beets, rape, sunflower, celery, asparagus, spinach, onion, alfalfa, clover, and grape. To this list may be added the date palm of the Old World. Plants require variable small amounts of alkali salts. Water, however, containing ten per cent of alkali material is destructive to vegetation.

So called spent lye is the liquid which remains after the combination of the alkali and grease in the manufacture of soap. It is of great value for plants. Before its application to the land it is mixed sometimes with peat or turf, or diluted with water. Besides containing potash or soda, this lye contains a large quantity of nitrogenous material.--JULIUS HORTVET.