The antler of a hart, once used as a source of ammonia.
An aqueous solution of ammonia; salts.
(RQ:Fielding Tom Jones)
{{quote-text|en|year=1777|author=Richard Brinsley Sheridan|title=The School for Scandal|section=V.ii
To revive with hartshorn salts.
(RQ:Dickens Barnaby Rudge)