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A general term now used for any basic material (PH greater than 7). Historically, 'alkali' referred to hydroxides and carbonates of sodium and potassium. Before the composition of materials were known, compounds were named based on their sources and reactivity. For example, Sodium carbonate was called fixed alkali and mineral alkali, while Potassium carbonate was called effervescent alkali or vegetable alkali. Caustic alkali referred to both sodium and potassium hydroxides. After 1800, the term 'alkali' was extended to refer to water soluble compounds of all alkali metals and ammonium. In general, alkali compounds will react with fatty acids to form soaps, turn Litmus paper blue and dissolve in water to form alkaline solutions. These solutions taste bitter and are irritating to the skin. Alkaline solutions are used in deacidifying and buffering paper. Alkalis also act as fluxes in ceramics and glass production.

Synonyms and Related Terms

base; basic; alcali (Fr.); álcali (Esp.);

Resources and Citations

  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 25
  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • Susan E. Schur, Conservation Terminology: A review of Past & Current Nomenclature of Materials, Technology and Conservation, Spring (p.34-39); Summer (p.35-38); Fall (p.25-36), 1985
  • Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982
  • The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998