Density

in physics, the amount of mater in a body, compared with its size. Judging by the heft, a piece of iron contains seven or eight times as much as a piece of ice of the same size, while cork is about one-fourth as heavy as ice. Water is taken as the standard. A pound of cork and a pound of water weigh the same, and contain the same amount of matter; but a cubic inch of cork contains only about one-fourth as much matter as a cubic inch of water. Scientists have agreed to use a cubic centimeter as the unit of volume and the amount of matter in a cubic centimeter of water as the unit of matter. Under standard conditions a cubic centimeter of water weighs 1 gram, a cubic centimeter of cork weighs .24 grams, and a cubic centimeter of cast iron weighs 7 grams. We say that the density of water is 1; of cork, .24; of iron, 7. By weighing with care, we may build up

A TABLE OF DENSITIES.