Harts' horns, are the horns of the male red deer. Various substances were made from the shavings of the animals' horns.
The oil of hartshorn is a crude animal oil obtained from the destructive distillation of the deers' bones or horns.
The salt of hartshorn actually refers to two distinct substances, sal ammoniac (ammonium chloride), and ammonium carbonate, which have been obtained from oil of hartshorn by dry distillation.
The spirit of hartshorn (or spirits of hartshorn) is an aqueous solution of ammonia. Originally this term was applied to a solution manufactured from the hooves and horns of the red deer, as well as those of some other animals. The aqueous solution was a colorless and pungent, consisting of about 28.5 percent ammonia. It was used chiefly as a detergent, for removing stains and extracting certain vegetable coloring agents, and in the manufacture of ammonium salts. Later the term was applied to the partially purified similar products of the action of heat on nitrogenous animal matter generally, and finally the term was applied to any aqueous solution of ammonia.