Knight's cyclopædia of the industry of all nations, 1851 / [edited by George Dodd].

Date:
[1851]
Catalogue details

Licence: Public Domain Mark

Credit: Knight's cyclopædia of the industry of all nations, 1851 / [edited by George Dodd]. Source: Wellcome Collection.

    964/1000
    1755 WALNUT TREE. WARMINa J. VENTILATION. I75C The nnnual averages of the trade with this country per head of the population were about as follows:— Imports Exports per nead. per head. 1844-46 \ (Al. 12s. .. 61. 17s. 1847-49 J P^''^°'^™(5Z. 13s. .. 6/. 16s, Tlie value of articles the produce or manu- facture of New South Wales exported in the three years 1844-46, was 3,335,200/.; the value of those articles exported in the last three years was 4,971,600/., being an increase of 1,636,400/., or more than 39 per cent. WALNUT-TEEE. The uses of the walnut-tree ai-e various. Before the introduc- tion of mohogany and other foreign woods, the wood of the walnut-tree was held in higher estimation than that of any other European tree; and many specimens of furnitm-e and carving stiU exist, to testify the beauty (some- what sombre) of the wood. In almost every stage of its growth the fruit of the walnut- tree is used. When young, green, and tender, walnuts are pickled and preserved with the husks on. About the end of Jime they may be preserved with or without the husks. When the nuts are fully ripe, Avhich is gene- rally at the end of September or the beginning of October, the kernel, deprived of its investing sldn, is eaten in great quantities. As long as the sMn can be easily removed, they are a nutritious and healthy article of diet; but when they get dry, so that their skins stick to them, they become indigestible. A great num- ber of the walnuts consumed in England are of foreign growth. The albumen which constitutes the bulk of the seed of the walnut contains an oil, which is used in large quantities, especially on the Continent. It is obtained by reducing the seeds to a pulp by means of a stone wheel and basin, and then expressing the oil, first without heat, and then by the application of heat. The oil obtained by heat is used by artists, and also for lamps, AU parts of the walnut-tree, excepting the albumen of the seed, possess a bitter principle, which acts as a tonic and anthel- mintic, and was formerly much esteemed as a medicine. WARMING AND VENTILATION. Under the headings Aunott's Stove, Cooking Appaeatus, and Stove, descriptions are given of various gratos, xtoves, and Jire-places; other modes of warming buildings call for a little notice here. The emplojTnent of steam-boilers in large establishments where steam-engines are worked, is one of the circumstances which have led to the very extensive adoption of the method of wanning by steam. A marked difference is observable in the principle of this method, as compared mth that of hot- air warming. The steam is not permitted to mingle with the air of the room wliich is to be wai-med, but acta through the medium of the metallic tube which confines it, and which it raises to a temperature sufficient to wai-m the room. The efficacy of this mode of heating depends on the great capacity for heat which steam possesses, a capacity equal to 1000° J that is, a pound of water at 212° Avill absorb a thousand degrees of heat in becoming a pound of steam. Mr, Scott RusseU calcu- latea that a room containing 500 cubic feet of air, and exposing 400 feet of surface, may be maintained at a temperature of 20° above that of the air without—that is to say, at 60° in the inside of the room when the atmos- phere is at 40° without—for a space of twelve hours, by the evaporation of two gallons of water, and at the expense of about three pounds of coal. This mode of heating buildings is adopted to a very large extent in the steam-power factories. The method of heating by hot water, though not so much adopted in factories as the steam method, is perhaps of more ex- tensive appUcation in other buildings. Where all the apartments to be warmed are on one level, an open boiler may be used; but where it is necessary to carry the pipes to different floors of a building, some of them much above the level of the boiler, the boiler must in that case be closed, Wlien an open boiler is employed, a pipe branches out from the upper part of the side, extends horizontally through the rooms to be warmed (without in any case rising above the level of the water in the boiler), and returns again to the boiler, which it enters at a lower level than the other. Under this arrangement a current of heated water wiU flow from the boiler at the upper orifice, and, after traversing the tube, return to the lower orifice. The closed boiler is however more extensively useful, since it enables all tlie stories of a building to be warmed by one appai-atus. The whole system, including both tubes and boiler, is filled with water at a valve at the highest point; mix when heat is applied to the boiler, a circu- lation ensues which speedily causes the whole length of tubing to become hot. Vai-ious modifications of this hot-water system are adopted in the new Houses of Parliament, in the British ]\Iiiseum, and otlier pubhc buildings. Ventilation.—There is an important but often neglected circumstance attending the artificial warming of buildings, viz. that the