A substance which has the properties of a base, especially a hydroxide or carbonate of an alkali metal, e.g., calcium.
Since all of these substances, when dissolved, increase the hydroxyl ion concentration, the term alkali is synonymous with base.
An aqueous alkaline solution is one with a pH value greater than 7.0. Alkalies are used in conservation work principally in adhesives, and in deacidifying and buffering paper.