Supplement to the American dispensatory / by John King and John U. LLoyd.

  • John King
Date:
1880
Catalogue details

Licence: Public Domain Mark

Credit: Supplement to the American dispensatory / by John King and John U. LLoyd. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    both Mr. Hanbury and Dr. Eichardson brought specimens before the English medical and therapeutical associations, and subseque'ntly its introduction to other countries soon followed. The word Chloral is derived from the first syllables of chlorine and alcohol. Chloral is a colorless fluid, oily in appearance, and of the sp. gr. 1.518, at 32° F. (0° C). At ordinary temperatures it evolves a pungent vapor that is very irritating to the eyes. It has a disagreeable taste, is soluble in less than its weight of water, and in four times its weight of chloroform. Chloral dissolves phosphorus, sulphur, bromine, and iodine, the latter solution giving a very rich purple color. Heat facilitates their solution. Anhydrous metallic oxides have no action upon it. It unites with water to form a hydrate. The formula for chloral is C2CI3OH, and its modern name is Trichloraldehyde. It is made by passing chlorine gas into anhydrous alcohol. The reaction which produces chloral is generally considered as very complex.' In practice, it is customary to first red'^uce the temperature of the alcohol through which the chlorine passes, then, as the solution thickens, to apply heat until hydrochloric acid gas ceases to be evolved and chlorine appears, when the flow of chlorine is discontinued.'^ The crude chloral alcoholate, together with other incidental products of the reaction, is now agitated with sulphuric acid, and then distilled ; it is now purified, by again distilling it, from a small portion of quicklime, being careful not to have an excess of lime, or the chloral will be de- stroyed. Chloral is decomposed by solutions of caustic alkalies, yield- ing a formate of the base, and chloroform. It is not employed in medicine, and is of interest only from the fact that it unites with one equivalent of water to form chloral hydrate. Chloral Hydrate, CjCigHgOa, or C2CI3OHH2O, is prepared by mixing chloral with the proper amount of water, and then pouring the solu- tion, in thin layers, into a porcelain or glass dish ; this is covered and placed in a cool situation. Heat is liberated, and the liquid solidifies, forming a mass of pure dazzling whiteness, composed of minute, trans- parent, or semi-transparent cr^^stals, or crystalline plates of chloral hy- drate. These have a sweet, ethereal odor, a greasy feeling when rubbed between the fingers, and a pungent taste. According to Versmann, one hundred parts of water dissolve three hundred and sixty parts of chloral hydrate. Chloral hydrate fuses, at about 58° C. (136° F.), boils at 95° C. (203° F.), with ])artial decomposition into chloral and water, and readily dis- tils at 120° C. (248° F.). It is soluble in very small quantities (less than its weight) of water, and equally soluble in ether or alcohol; soluble in four parts of cold chloroform ; but slightly soluble in carbon disulphide, and in spirits of turpentine. Its alcoholic solution is neu- tral, and, when the chloral is pure and recent, the aqueous solution is also, but with the chloral of commerce the latter solution usually ex- hibits a slight acid reaction. Chloral hydrate dissolves in glycerin, and this solution has the property of dissolving many alkaloids that are 'See Comptes Rendus, Ixxiv, for explanation by Wurtz and Vogt. '•^When the therapeutical use of chloral hydrate was; first agitated in this country, the writer was obliged to prepare the article in a limited way, until a supply could be obtained from abroad. Few persons can realize, without actual experiment, the care that is neces.sary, and the large amount of chlorine required for the production of even a limited quantity of this agent. It has been calculated that one pint of alcohol will require at least 316 gallons, or 73,233 cubic inches of chlorine, and there will be formed about 396 gallons or 91,542 cubic inches of hydrochloric acid gas.—L.
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