Chloral, Camphorated. Hydrate of chloral and camphor, equal parts. Rub them together in a warm mortar until they liquefy. It forms clear mixtures with oil of turpentine and chloroform, but not with solution of ammonia. It is a counter-irritant, and applied externally it has been found to give relief in rheumatic pains and neuralgia. It should be painted on the affected part with a camel’s-hair brush.
Chloral, Hydrate. C2HCl3O. Aq. Syn. Hydrate of chloral. Prep. “Pass dry chlorine gas, for several days, through absolute alcohol, sp. gr. 0·795, until it becomes a thick viscid liquid of sp. gr. 1·57. At the beginning of the operation the alcohol is well cooled to prevent inflammation and explosion, but towards the end of the operation the alcohol is heated nearly to the boiling point. The resulting liquid, which after a day or two solidifies to a mass of crude chloral hydrate, is agitated with four times its bulk of concentrated sulphuric acid, and the anhydrous chloral which floats on the surface is separated and purified by fractional distillation. The purified anhydrous chloral is placed in a still, mixed with 11 per cent. of water, and distilled over chalk to remove any hydrochloric acid that may be present; the resulting solid distillate is then fused and poured out into shallow vessels to cast into cakes.” (Squire.) The purest chloral hydrate is said to be that which has been crystallised two or three times out of pure bisulphide of carbon.—Prop. White opaque solid, having a pungent odour resembling that of a ripe melon. Soluble in water, glycerin, and alcohol. Gradually volatilises in the air, and may be distilled without decomposition. From 100 gr. dissolved in 1⁄2 fl. oz. of water, well shaken with 1 fl. oz. of solution of potash (B. P.), and allowed to stand for several hours, at least 46 grain-measures of chloroform should separate.
Chloral hydrate may be obtained in crystals
by mixing the cake with about half its bulk of chloroform, and putting aside in a cool place. When the crystallisation is complete (which is generally in about 8 or 10 days) the crystals are freed from the mother liquor by a centrifugal machine, and afterwards dried at a gentle heat. The mother liquor may be utilised for future crystallisations.
Uses. An excellent sedative, antispasmodic, hypnotic, anodyne. It has done good service in hypochondriacal and other nervous affections, as well as in the insomnia of the insane, and of dipsomaniacs; also in asthma, hooping-cough, and scarlet fever. It has also the reputation of being an efficient preventive of sea-sickness, especially on short voyages, such as crossing the channel, which can be accomplished during the sleep occasioned by the agent.—Dose, from 10 to 60 gr.
It was introduced into medical practice by Dr Liebreich, of Berlin. Immense quantities are imported into this country from Germany.
CHLORALUM. An impure aqueous solution of chloride of aluminum, sp. gr. 1·15, 1 fl. oz. of the liquid contains 75 grains of anhydrous chloride. Introduced by Professor Gamgee as an antiseptic and disinfectant, for which purposes it is recommended to dilute the article as sold with four times its bulk of water.
CHLO′′RATE. Syn. Hyperoxymu′′riate†, Chlo′′ras, L. A compound in which the hydrogen of chloric acid, HClO3, is replaced by a metal or other basic radical, e.g. KClO3, chlorate of potassium. Chlorates may be prepared by dissolving the hydrate or oxide in chloric acid, and crystallising. The alkaline chlorates, however, are made by passing chlorine into solutions of the hydrate or carbonate of potassium or sodium, boiling the resulting liquid, and separating the chlorate from the chloride, which is also formed by crystallisation. They are very similar to the nitrates, both in their general properties and composition. They are all decomposed at a red heat, metallic chlorides being formed and oxygen gas given off. Like the nitrates, they deflagrate with inflammable substances, but with greater facility and violence. A mixture of this kind will detonate with a slight blow or friction. All the chlorates are soluble in water.
Char., Tests, &c. The chlorates are known by their deflagrating when placed on red-hot charcoal. By evolving a yellow gas when treated with concentrated sulphuric acid, in the cold, which gas also communicates to the liquid a red or yellow tinge. By evolving oxygen gas when heated alone in a test-tube. This test is not characteristic, unless carried a stage further, by dissolving the residual chloride out of the tube, and adding to the filtered solution a few drops of nitrate of silver; then the formation of a white precipitate, insoluble in nitric acid, will show that the salt treated was a chlorate, and not a nitrate. Pure chlorates give no precipitate with nitrate of silver.
CHLORHY′DRIC ACID. See Hydrochloric Acid.