Steam, denotes the visible, moist vapour ascending from hot or boiling liquors; and also from substances containing humidity, which is easily evaporated by a degree of heat, that is insufficient for their combustion.
Steam being one of the most powerful agents in Nature, is an object of great importance to manufactures, as well as to horticulture. Hence several machines, known under the names of steam-engines, have been invented, with a view to facilitate the operations of extensive iron-works, and also to expel noxious exhalations from mines. Among these contrivances, that by Mr. James Watt, of Birmingham, first deserves honourable mention for its ingenuity; next in order of time, is Mr. Jonathan HoRnblower's machine, for raising water or other liquids by means of fire and steam, for which a patent was granted in 1781 ; then Mr. James Sadler's engine for diminishing the consumption of steam and fuel, as well as gaining a considerable effect in time and force; in consequence of which, he obtained a patent in June, 1791; and I lastly, the Rev. Mr. Edmund Cartwright's improvements in constructing, working, and applying steam-engines; for which a patent was granted to him in November, 1797- As, however, a description of these respective inventions would be unintelligible, without the aid of numerous engravings, the curious reader will consult the 4th, 7th, and 10th vols, of the Repertory of Arts, etc. where full specifications are inserted, and illustrated with plates.
Farther, steam may be made subservient to the purpose of promoting vegetation; by means of flues and other contrivances, conducted beneath hot-houses : - with this economical design, various successful experiments have been made under the inspection of the Earl of Derby, and also by Thomas Wakefield, Esq. of Northwich. Our limits, however, being circumscribed, we cannot specify the machinery invented by Mr. W.; because such account would necessarily be deficient without an engraving. We shall therefore only remark, that during the last five years, the steam has been used in his vine-house, with the best success ; the plants vegetating with uncommon luxuriance throughout the summer ; and producing "the. greatest abundance of large and well - flavoured fruit." - Another advantage attending this new method of raising fruit is, that it prevents the depredations of the red spider ; because, if a sufficient volume of steam be applied, that destructive insect never appears. For a more minute account of the numerous trials made with Mr. Wakefield's field's flues, the reader Is referred to the 18th vol. of the Transactions of the Society for the Encouragement of Arts, etc.
Steam may, with equal advantage, be employed in domestic economy, and particularly in cooking. Thus, steamed potatoes are always more wholesome and nutritious, than such as are boiled in water ; and Dr. Darwin observes, that if the heat of the steam could be increased after it has left the water, the art of boiling all vegetables might be considerably improved; and thus the mucilage, abounding both in potatoes and flour-puddings, and also in the roots, seeds, stems, leaves and flower-cups of plants, may be rendered more nutritive, and, probably, more palata--See also the article Cooking,