Emily Dickinson Lexicon

A-CID'I-FI-ER, n.

A simple or compound principle, whose presence is necessary for acidity. The elementary acidifying principles are oxygen, chlorine, bromine, iodine, flourine, sulphur, selenium, and tellurium. Cyanogen may be named as an example of a compound acidifying principle, and probably there is one or two more. No acid is known which does not contain one of these substances.