Sulfuric Acid, a compound containing hydrogen, oxygen, and sulfur; concentrated sulfuric acid is sometimes called oil of vitriol. Sulfuric acid is a heavy, oily liquid with little odor or color. Very active chemically, the acid dissolves most metals and reacts strongly with many other substances. It mixes readily with water in all proportions and will absorb water from materials such as wood or cloth, leaving only a charred residue. Sulfuric acid can cause severe burns to the skin and other body tissues, and must be handled with great care.

The ability to take part in many different chemical reactions makes sulfuric acid one of the most important and widely used commodities in the chemical industry. Its principal uses are in the manufacture of fertilizers, in petroleum refining, and in the production of many chemicals, including sulfates, dyes, and drugs. Large amounts of sulfuric acid also are used in the iron and steel industry for cleaning newly manufactured metal. The lead-acid storage battery (used in automobiles and other vehicles) contains a solution of sulfuric acid and water.

Most commercial sulfuric acid is made by the contact process. In this method, sulfur dioxide formed by the burning of sulfur is converted to sulfur trioxide, which is then dissolved in previously made sulfuric acid to create a more concentrated acid. The finished product then can be diluted with water to any required strength. Commercial sulfuric acid is available in a number of standard strengths ranging from about 30 per cent to nearly pure concentrations of 98 per cent.

Chemical formula: H2SO4. A 98 per cent solution of sulfuric acid has a specific gravity of 1.84 (nearly twice that of water), a boiling point of 640 F. (338 C.) and a freezing point of 37 F. (3 C.). The figures for weaker concentrations are generally lower: for a 50 per cent solution, for example, the values are 1.40, 225 F. (124 C.), and -31 F. (-35 C.) respectively.