ELUTRIA′TION. Cleansing by washing. The term is commonly applied to the operation of washing insoluble powders with water, to separate them from foreign matter, or the coarser portion. It is usually performed by grinding or triturating the mass with a little water until reduced to a very fine powder, and this paste is suddenly diffused through a large quantity of water, contained in a deep vessel, from which, after the subsidence of the grosser portion, the liquid is poured into another vessel, and allowed to deposit the fine powder it still holds in suspension. When this has taken place, the clear supernatant liquor is decanted, and the sediment drained and dried. The coarse sediment deposited in the first vessel is now submitted to a fresh grinding and diffusion through water, and the entire operation is repeated until the whole of the pulverisable portion is washed over. The proper length of time for the liquid to remain in the first vessel depends solely on the density of the powder and the degree of fineness required in the product; heavy powders subsiding almost immediately, while light ones often take several minutes to deposit the coarser portion. Sometimes three or more vessels are employed, and the muddy liquor, after remaining a short time in the first, is poured into the next one, and this, in a short time longer, into the third, and so on, until the last vessel is filled, by which means powders of different degrees of fineness are obtained, that deposited in the last vessel being in the minutest state of division. The elutriated paste or moist powder is then drained, and dried. On the small scale the trituration is performed with a stone and muller, or in a mortar; on the large scale, in a mill, driven by either horse or steam power. Antimony chalk, bistre, and other pigments, as well as various other substances insoluble in or unacted on by water, are commonly obtained in the state of an impalpable powder by elutriation,
or ‘washing over,’ as it is called by amateurs and operatives.
ELYDOR′IC PAINTING. A method of painting invented by M. Vincent, of Montpetit, in which the pigments are mixed up with an emulsion of oil and water. It is said to add the fresh appearance of water colours, and the finish of miniature painting, to the mellowness of oil colours.
EMBALM′ING. Syn. Mummification. The preservation of the dead bodies of animals. See Putrefaction.
EMBOS′SING. The formation of ornamental figures in relief on cloth, leather, paper, and wood, has now been brought to such perfection as to place this species of decoration within the reach of almost every class of society. Embossed cloth and PAPER are now employed by the bookbinder to cover even the low-priced volumes that pass through his hands; whilst the EMBOSSED LEATHER that encloses the album or ornaments our furniture frequently bears the richest patterns of the arabesque or moresque. Cloth and paper are usually embossed by machinery; leather and wood more frequently by hand labour.
EMBROCA′TION. Syn. Embrocatio, L. A fluid medicine for external and local use. Embrocations do not differ, materially, from liniments and lotions, and are applied in the same manner. (See those preparations, and below.)
Embrocation, Guestonian. Syn. Embrocatio terebinthinæ cum acido L. Prep. (Dr Paris.) Oil of turpentine and olive oil, of each 11⁄2 oz.; dilute sulphuric acid, 3 fl. dr.; agitate together until mixed. Used in rheumatism, &c.
Embrocation, Lynch’s. Olive oil (coloured with alkanet root), 5 fl. oz.; oils of amber, rosemary, and turpentine, of each 1 dr. In bruises, rheumatism, &c.
Embrocation, Roche’s. Prep. 1. (Dr Paris.) Olive oil, mixed with half its weight of the oil of cloves and amber.
2. Olive oil, 2 oz.; oil of amber, 1 oz.; oils of cloves and lemons, of each 1 dr. For hooping-cough.