"by the assistance of hartshorn and water "

Harts' horns are the horns of the male red deer.  Various remedies were prepared from shavings of the horns.  These included oil of hartshorn, prepared by distilling the bones or horns, salt of hartshorn (ammonium carbonate), obtained by dry distillation of the oil, and spirit of hartshorn, an aqueous solution of ammonia. Salt of hartshorn was used for treatment of fevers, and as a smelling salt.

Male red deer
Creative Commons Attribution Share AlikeMale red deer - Credit: Lviatour