COINS. See Medals and Electrotype.
COKE. Charred or carbonised coal. The principle of its manufacture is similar to that of charcoal. There are three varieties of coke:—
1. Kiln-made coke; STIFLED COKE. Made by burning pit-coal in a pile, kiln, or stove. It has a dull-black colour, and produces an intense heat when used as fuel. By condensing the bituminous vapours which are given off during the process, about 3% of tar may be obtained from common coal, and from some strong coal, by careful treatment fully 10% of its weight. The screenings of dust coal, separated from the better kinds of bituminous coal, is the sort commonly used for making coke in ovens.
2. Gas coke; DISTILLED COKE. The cinder left in the gas retorts. Grey; produces a weak heat, insufficient to smelt iron.
3. Shale Coke; MINERAL CARBON. From bituminous shale, burnt in covered iron pots, in a similar way to that adopted for making bone-black; or in piles. Black and friable. Used to clarify liquids, but is vastly inferior to bone-black, and does not abstract the lime from syrups. See Fuel, Pit-coal, &c.
COLCHICIN′A. Syn. Col′chicine. Colchicia. A peculiar principle discovered by Gieger and Hesse in the seeds of the Colchicum autumnale or common meadow saffron. It also exists in the corms or bulbs.
Prep. Macerate the bruised seeds in boiling alcohol, add magnesia, to throw down the alkaloid, digest the precipitate in boiling alcohol, and filter. By cautious evaporation colchicine will be deposited, and maybe purified by re-solution and crystallisation in alcohol.
Prop., &c. Odourless; bitter; soluble in water and alcohol; form salts with the acids. It is very poisonous. 1⁄10th of a grain, dissolved in spirit, killed a cat in 12 hours. It differs from veratria in being soluble in water and crystalline, and in the non-production of sneezing when cautiously applied to the nose. Strong oil of vitriol turns this alkaloid of a yellowish-brown; nitric acid turns it of a deep violet, passing into indigo-blue, green and yellow. It is not used in medicine.
COL′CHICUM. Syn. Mea′dow saf′fron; Colchicum autumnale (Linn.), L. The recent and dried corms or bulbs (colchici cormus), as well as the seeds (colchici semina), are official in the British Pharmacopœia. The corms are ordered to be dug up in the month of July, or before the autumnal bud has projected. The dry coatings having been torn off, cut the corms transversely in thin slices, and dry, at first with a gentle heat, but afterwards slowly increased to 150° Fahr.
Dose (of the corms), 2 to 8 or 9 gr.; (of the seeds), 2 to 7 gr., made into a pill or bolus with syrup or conserve; chiefly, as a specific in gout, to alleviate or check the paroxysm. This drug forms the base of almost all the advertised gout nostrums. It is, however, an active poison, and its administration requires care. “After all that has been said respecting colchicum in gout, and admitting that it rarely fails to allay pain and check a paroxysm, I would record my opinion that he who would wish to arrive at a good old age should eschew it as an ordinary remedy, and consider that he is drawing on his constitution for a temporary relief, with a certainty of becoming prematurely bankrupt in his vital energies.” (Collier.)