Sodium

a widely distributed and well known chemical element. In combination with chlorine it forms common salt. In plant life sodium seems to bear somewhat the same relation to plants on the seashore that potassium does to inland plants, but common salt is not a requisite of plant growth. The stalks and leaves of saline plants store up salt, but their seeds contain little of it. In its pure form sodium resembles potassium in weight and appearance. When laid on water, it acts like it, only not so energetically. Several compounds of sodium are important. Sodium chloride, or salt, has been mentioned. Sodium nitrate is the saltpeter of Chile from which common saltpeter is made. Sodium sulphate, or Glauber's salt, is the medicinal principle of Carlsbad and other mineral waters. Sodium carbonate or soda is essential to the manufacture of glass and of soap. It was obtained formerly from the ashes of sea plants, but processes have been devised for getting a commercial supply from salt. Soda is used in the manufacture of baking powder, in sodawater, and as a medicine. Sodium borate is common borax. Alkali water is impregnated commonly with sodium. See Potassium; Salt; Borax; Baking Powder