WATER

n. Wat'u6r. Gr.,v . Lat.,a<?Mrt. Fr.,eau. Ger., Wa er. It., acqua. Sp., agua. 1. A transparent, colorle liquid, H2O. devoid of odor or taste and neutral in reaction. It is found everywhere in nature, constituting, in the form of seas, rivers, lakes, and springs, about three quarters of the earth's surface, forming also one of the constant constituents of the atmosphere, in which it appears under the forms of invisible aqueous vapor, mist, clouds, rain, hail, and snow; and, lastly, constituting the important element of all animal and vegetable fluids and entering into the composition of every one of the liquid and solid animal and vegetable ti ues. As occurring in nature, w. is never perfectly pure, but contains solid, liquid, or gaseous admixtures, either suspended or di olved. Hence different varieties of w. are recognized and named according to their source or their contained constituents (river-water, sea-water, lake-water, spring-water, rain-water, hard water, soft water, mineral-water, chalybeate water, sulphurous water, etc.). Pure w. may be obtained by distillation. It freezes at C. (32 F.) to form ice, and boils at 100 C. (212 F.), forming invisible aqueous vapor. Steam is aqueous vapor a ociated with particles of liquid vrater in a very fine state of subdivision. Above the temperature of 4 C. water expands on heating and contracts on cooling; below that temperature the reverse is the case. Hence water at 4 C. occupies a minimum amount of space and consequently po e es its maximum degree of density. As w. is taken as a standard of density for solids and liquids, its sp. gr. is reckoned, at the temperature of maximum density, or 4 C., as 1. W. is a poor conductor of heat. It po e es very great solvent powers, di olving a large number of solid, liquid, and gaseous substances. Aqueous solutions of non-volatile solids are usually called simply solutions (Lat., liquores); solutions of liquids are designated as dilutions, and solutions of gases or of volatile substances are called waters (Lat., aquce). Partial aqueous solutions of many substances are also employed in pharmacy, and are prepared by boiling or steeping vegetable substances in w. (infusions, decoctions). In certain crystalline compounds w. appears to enter into a weak chemical combination with salts (w. of crystallization), and its presence appears to define and maintain the crystalline form. A similar weak chemical combination perhaps takes place in the formation of an aqueous solution (see CRYOHYDRATE). 2. In pharmacy, a solution of a gas, a solid, or a liquid in w. [B.] See also WATERS. 3. A familiar term for urine. Aerated w. E, he; E2, ell; G, go; I, die; I2, in; N, in; N2, tank; [s. 726]