A dictionary of chemistry, on the basis of Mr. Nicholson's: in which the principles of the science are investigated anew, and its applications to the phenomena of nature, medicine, mineralogy, agriculture, and manufactures, detailed (Volume 2).

  • Ure, Andrew, 1778-1857.
Date:
1821
Catalogue details

Licence: Public Domain Mark

Credit: A dictionary of chemistry, on the basis of Mr. Nicholson's: in which the principles of the science are investigated anew, and its applications to the phenomena of nature, medicine, mineralogy, agriculture, and manufactures, detailed (Volume 2). Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    EME ENA * Emerald. This genus contains two species, the prismatic and rhomboidal. 1. PrismnUc Emerald, Euclase of Haiiy. Its colours are green, of various shades, and sometimes sky-blue. It is found only crystallized. The primitive form is a prism of 133® 24*. Its secondary forms are, an oblique four-sided prism, variously modifi ed by accumulations and truncations The lateral planes are more or less longitudi- nally streaked, giving the prisms a reed- like appearance. Lustre splendent. Cleav- age perfect, in the direction of the smaller diagonals of the prism. Fracture small COnchoidal. Fragments tabular. Transpa- rent. Refracts double. Haider than quartz, but softer than topaz. Easily frangible. Sp. gr. 2.9 to 3.3. Loses transparency, and then melts before the blow-pipe. Its con- stituents are 35 to 36 silica, 18 to 19 alu- mina, 14 to 15 glucina, 2 to 3 iron, and 27 to 31 loss. The last is chiefly water, and in some measure alkali. Found in Peru and Brazil. It is a beautiful mineral, but too brittle for jewelry. 2. Ithombnidul Emerald, of which there are two sub-species, the precious emerald and the beryl. Precious emerald is well characterized by its emerald-green colour, of various depths. It is generally crystal- lized. The primitive form is an equiangu- lar six-sided prism, on which various trun- cations are found. The lateral planes are smooth; the terminal planes rough. Lustre splendent. Cleavage straight and four fold. Fracture imperfect conchoidal. Transpa- rent. Moderate double refraction. Nearly as hard as topaz. Sp. gr. 2.6 to 2.77. Heat- ed to a moderate degree, it becomes of a blue colour, but recovers its tint on cool- ing. At a high heat, it fuses into a white vesicular glass. Its constituents are, silica C4..5, alumina 16, glucina 13, oxide of chrome 3.25, lime 1.6, water 2. Klaproth found 1. of oxide of iron. It occurs in drusy cavities, along with iron pyrites, calcareous spar, and quartz, in veins that traverse clay- slate. The most beautiful emeralds come from Peru. As a gem, it is valued next to the ruby. See Beryl, in its alphabetical place.* * Emery. A sub-species of rhomboidal corundum. Its colour is intermediate be- tween grayish-black, and bluish-gray. It occurs massive and disseminated, and also in granular concretions. Lustre glistening and adamantine. Fracture fine grained un- even. Translucent on the edges. So very hard as to scratch topaz. Difficultly fran- gible. Sp. gr. 4.0. Its constituents are 86 alumina, 3 silica, 4 iron, and 7 loss. In Saxony, it occurs in beds of talc and stea- tite. It occurs abundantly in the Isle of Naxos, and also at Smyrna. It is used for polishing hard minerals and metals. Us fine powder is obtained by trituration and elutrialion.* ♦ V.mktiv. Digest ipecacuan root, first in ether and then in alcohol. Evaporate the alcoholic infusion to dryness, redissolve in water, and drop in acetate of lead. Wash the precipitate, and then diffusing it in wa- ter, decompose by a current of sulphuretted hydrogen gas. Sulphuret of lead falls to the bottom, and the emetin remains in solu- tion. By evaporating the water, this sub- stance is obtained pure. Emetin forms transparent brownish-red scales. It has no smell, but a bitter acrid taste. At a heat somewhat above that of boiling water, it is resolved into carbonic acid, oil and vinegar. It affords no ammo- nia It is soluble both in water and alcohol, but not in ether; and uncrystallizable. It is precipitated by proto-nitrate of mercury and corrosive sublimate, but not by tartar emetic. Half a grain of emetin acts as a powerful emetic, followed by sleep ; six grains vomit violently, and produce stupor and death. The lungs and intestines are inflamed. Pelletier and Magendie, Ann. de Chitnie et Physique, it. 172.* Ei/PYRMTMA. 1 his term is applied to de- note the peculiar smell produced by a con- siderable heat upon vegetable or animal sub- stances in closed vessels, or when burned under circumstances which prevent the ac- cess of air to a considerable part of the mass, and consequently occasion an imperfect com- bustion, or destructive distillation of the parts so covered up by the rest of the mass. Emulsion. An imperfect combination of oil and water, by the intervention of some other substance capable of combining with both these substances. The substances are either saccharine or mucilaginous. E.vamel. There are two kinds of enamel, the opaque and the transparent. Transpa- rent enamels are usually rendered opaque by adding putty, or the white oxide of tin, to them. The basis of all enamels is there- fore a perfectly transparent and fusible glass. The oxide of tin renders this of a beautiful white, the perfection of which is greater when a small quantity of manganese is like- wise added. If the oxide of tin be not suf- ficient to destroy the transparency of the mixture, it produces a semi-opaque glass, resembling the opal. Yellow enamel is formed by the addition of oxide of lead, or antimony. Kunckel likewise affirms, that a beautiful yellow may be obtained from silver. Red enamel is afforded by the oxide of gold, and also by that of iron The former is the most beautiful, and stands the fire very well, which the latter does not. Oxide of copper affords a green; manga- nese, a violet; cobalt, a blue, and iron, a very fine black. A mixture of these diffe- rent enamels produces a great variety of in- termediate colours, according to their na- ture and proportion. In this branch of the art, the coloured enamels are sometimes mixed with each other, and sometimes the