soap (redirected from medicated soap)

soap, a cleansing agent. It cleanses by lowering the surface tension of water, by emulsifying grease, and by absorbing dirt into the foam.

Ancient peoples are believed to have employed wood ashes and water for washing and to have relieved the resulting irritation with grease or oil. In the 1st cent. A.D., Pliny described a soap of tallow and wood ashes used by Germanic tribes to brighten their hair. A soap factory and bars of scented soap were excavated at Pompeii. Soap fell into disuse after the fall of Rome but was revived in Italy probably in the 8th cent. and reached France c.1200; Marseilles became noted as a soapmaking center. Although soap was known in England in the 14th cent., the first English patent to a soapmaker was issued in the 17th cent. The industry was handicapped in England from 1712 to 1853 by a heavy tax on soap. In the American colonies soap factories appeared at an early date, and many housewives made soap from waste fats and lye (obtained by leaching wood ashes).

The manufacture of soap was stimulated by Chevreul's discovery of oleic and stearic acids in the early 19th cent. and by Leblanc's method (1791) of preparing soda from salt. Chemically, soaps are metallic salts of fatty acids. The manufacture of soap is based on a chemical reaction (saponification) in which an alkali acts upon a fat to form a metal salt (soap) and an alcohol (glycerol). A number of methods may be employed to make soap, but all are based on the same principle of operation. Fats and oils (often blended) are heated in a large vessel, then enough alkali to react with all the fat is stirred in. Salt is added, and the soap then forms a light curd that floats to the surface. Glycerol, a valuable byproduct, can be distilled from the liquid residue.

To produce a purer soap, the curds are washed with salt solution, water is later added, and the solution is allowed to settle; the upper of the two layers thus formed is the pure soap, called settled soap. It is thoroughly churned, poured into huge frames, cut with wires, shaped, and stamped. Hard-milled soap is run over chilled rollers and is scraped off as chips which are rolled into ribbons, cut, and shaped. Soap is marketed also as chips, flakes, and beads and in powdered form. Soap powders, as distinguished from powdered soap, contain builders that assist in rough cleaning. Soaps differ according to the lathering properties of the fat or oils and according to the alkali employed. When sodium hydroxide is used as the alkali, hard soaps are formed; potassium hydroxide yields soft soaps.

Aluminum, calcium, magnesium, lead, or other metals are used in place of sodium or potassium for soaps used in industry as paint driers, ointments, and lubricating greases and in waterproofing. Fillers are added to many soaps to increase lathering, cleansing, and water-softening properties; the sodium salt of rosin is commonly used in yellow laundry soap to increase lathering. Soap substitutes include saponin-containing plants such as soapwort and shagbark and the modern soapless detergents (usually sulfonated alcohols), which may be used in hard water and even in saltwater without forming curds.

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soap

Any of a group of organic compounds that are salts of fatty acids, usually stearic acid (with 18 carbon atoms) or palmitic acid (with 16 carbon atoms). The source may be any vegetable oil or animal fat. Soaps are emulsifying agents commonly used for cleaning; they have long been made from lye and fat. Detergents are entirely synthetic and may or may not be soaps. Soaps of metals heavier than sodium are not very soluble; the curdy precipitate made by soap in hard water is the calcium or magnesium salt of the fatty acid in the soap. Heavy-metal soaps are used in lubricating greases, as gel thickeners, and in paints. Napalm is an aluminum soap.

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(Simple Object Access Protocol) A message-based protocol based on XML for accessing services on the Web. Initiated by Microsoft, IBM and others, it employs XML syntax to send text commands across the Internet using HTTP. SOAP is similar in purpose to the DCOM and CORBA distributed object systems, but is lighter weight and less programming intensive. Because of its simple exchange mechanism, SOAP can also be used to implement a messaging system. SOAP is supported in COM, DCOM, Internet Explorer and Microsoft's Java implementation. See UDDI, .NET and REST.

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1.	(protocol)	SOAP - Simple Object Access Protocol.
2.	(language)	SOAP - Symbolic Optimal Assembly Program.