A Grammatical Dictionary of Botanical Latin

Vaporarium,-ii (s.n.II), abl. sg. varporario: “in botanic gardens, a stove or formerly a “Bark-stove” (Jackson); (in horticulture) “a glazed structure for keeping tropical plants, having a bed of tanner’s bark (called a bark bed) or other fermentable matter which produces a moist heat” (Wikipedia Dec. 2016) [> L. vaporarium,-ii (s.n.II) “a steam-pipe in the Roman baths, which conveyed the heat to the sweating-room” (Lewis & Short).

Tanner's bark was used in hot beds instead of dung: "It was a by-product of leather manufacture, a rough powder made of oak bark which generated a constant heat of about 25 degrees centigrade. Unlike manure, which produced lower temperatures that were exhausted after a few weeks, tanner's bark kept it's warmth for up to six months." (from The Brother Gardners: Botany, Empire, and the Birth of an Obsession by Andrea Wulf. Note by Sophie Gale, on line).

Vaporarium,-i (s.n.II), abl.sg. vaporario: (pharm.) a vapour bath (Bennitt).

Hypocaustum,-i (or hypocauston,-i) (s.n.II), abl. sg. hypocausto: a heated bathing-room, the heat comes from below; a sweating-chamber, ‘pure Latin = vaporarium” (Lewis & Short).