(1,000 words)

1. Terminology and history

As commonly understood, an acid is a substance, usually liquid, that has a sour taste and a caustic effect. The basis of the modern chemical definition of acids goes back to the Swedish scientist Svante Arrhenius, who defined acids in 1887 as substances that produce protons or hydrogen ions (H+) when added to water and bases (alkalis) as substances that produce hydroxyl ions (OH--). The term alkali derives from the Arabic word for sodium carbonate (Na2…

Cite this page
Priesner, Claus, “Acid”, in: Encyclopedia of Early Modern History Online, Executive editor of the English edition: Graeme Dunphy. Consulted online on 21 March 2018 <>
First published online: 2015
First print edition: 20160321

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