AFkali

[Arab.] The name applied in chemistry to a cla of bodies po e ing the following common properties:—(1) They have the power of turning vegetable blue colors green, and vegetable yellows brown (2) they restore the color to a blue solution which has been reddened by an acid (3) they have a strong affinity for acids, combining with them to form salts which po e neither acid nor alkaline properties— hence an acid and an alkali are said to neutralize one another (4) they are all soluble in water. The alkalies proper are four in number—potash, soda, lithia and ammonia. They exert a power¬ fully corrosive action on animal and vegetable substances. As bicarbonates they are often used along with carbonic acid to correct acidity of the stomach.