AERATED WATERS. Waters impregnated with carbon dioxide gas, and frequently con taining mineral salts. Such waters are exten sively used to quench thirst, and are commonly called soda waters. The carbonic acid lased in making the common artificial nitrated waters is prepared by treating a mineral eart,dmate. as chalk or lime-stone, with dilute sulphuric acid. The cal thus obtained is forced into bottles or siphons containing water, yielding a brisk, sparkling liquid with a pungent hut pleasant acidulous taste. Artificial waters, similar to seltzers, vichy, and other well known mineral waters, are produced by dissolving the known ingredients of the mineral water in distilled water and then impregnating them with carbon dioxide gas. The carbonic acid water mixed with fruit syrups is the ordinary soda water of the pharmacy. Formerly carbonic acid water was made on a small scale in an apparatus called a gazogene or seltzogene (see accompanying within the cell, and being already dissolved, they pass off into the air. In water plants the free inward or outward migration of dis solved gases depends on the relative amounts inside and outside the body. (See AnsontmoN.) In the larger land plants the greater number of cells and the more Compact structure make it impossible for the cells more distant from the surface to confine', the necessary- changes at an adequate rate. Such plants have therefore devel
oped an extensive aerating system (lig. 1), con figure), in which sodium bicarbonate was decom posed by tartaric acid in the presence of water. A recent invention is the use of capsules contain ing liquefied carbon dioxide. The liquid which it is desired to impregnate with the gas is placed in a specially constructed bottle, the top of which is provided with a receptacle for the capsule containing the liquefied gas: the covering of the capsule is then ruptured, setting free the acid, which is absorbed by the liquid in the bottle. Aitrated waters may also be said to occur natu rally, for water taken from a spring contains gases, such as oxygen. nitrogen, and carbon diox ide, dissolved in it. Similarly, running waters, such as rivers and rain waters. absorb gases from the atmosphere, which may be expelled by boiling. See .1 Treatise on Brreragcs, by C. II, Sulz, and the articles, CARBoNATED OR ACID UL(cUS WATERS, and AILNERAL WATERS.