Sand

ordinarily, a kind of soil, forming, with clay and mold, the surface of the agricultural portions of the earth. Vast stretches of country are covered with sand Pure sand consists of finely ground crystalline rocks, chiefly quartz. It is present in almost all soils and on careful examination shows all degrees of age. Some grains have sharp edges like newly fractured bits of glass, others are worn smooth and round by constant rubbing together. Sand varies in color, owing to tinctures of different minerals. Iron gives sand a reddish tinge. The term has passed into traditional use. "Sand in one's make-up" is another expression for true grit. No tie can be more worthless than "a rope of sand." The "sands of life" have reference to the running sand employed in hour glasses to denote the passing of time. "To sand one's track" means to render assistance. It is derived from the custom of locomotive engineers who dribble sand in front of their driving wheels to prevent them from slipping. The uses of sand in the industrial arts, as glass-making, plastering, concreting, molding, and the like, are numerous. Special articles may be consulted. See Silicon; Concrete; Glass, etc.