Hartshorn, (spirits of:) A volatile alkali, originally prepared from the horns of the stag or hart, but now procured from various other substances. It is known by the name of ammonia or spirits of ammonia.
Hemlock: see _Cicuta.
Horticulturist: One skilled in horticulture, or the art of cultivating gardens: horticulture being to the garden what agriculture is to the farm, the application of labor and science to a limited spot, for convenience, for profit, or for ornament—though implying a higher state of cultivation than is common in agriculture. It includes the cultivation of culinary vegetables and of fruits, and forcing or exotic gardening as far as respects useful products.
Hydrogen: A very light, inflammable gas, of which water is in part composed. It is used to inflate balloons.
Hypochondriasis: Melancholy, dejection, a disorder of the imagination, in which the person supposes he is afflicted with various diseases.
Hysteria or hysterics: A spasmodic, convulsive affection of the nerves, to which women are subject. It is somewhat similar to hypochondriasis in men.
Ingrain: A kind of carpeting, in which the threads are dyed in the grain or raw material before manufacture.
Ipecac: (An abbreviation of ipecacuanha) an Indian medicinal plant, acting as an emetic.
Isinglass: A fine kind of gelatin or glue, prepared from the swimming-bladders of fishes, used as a cement, and also as an ingredient in food and medicine. The name is sometimes applied to a transparent mineral substance called mica.
Jams: A side-piece or post.