=ALCORNO′CO.= _Syn._ A.-BARK; ALCORNOQUE, Fr.; ALKORNOC, A.-RIND, Ger. The bark of an unknown tree of South America. It is astringent and bitter, and has been highly extolled as a specific in phthisis; but appears to possess little medicinal virtue. The bark of the young branches of the cork tree (_quercus suber_), used in tanning, is also sometimes called alcornoco-bark; but possesses none of the characters of the former article. =AL′DECAY.= The galls on the leaves of _myrobalanus chebula_ (Gaertn.), a forest-tree of Bengal. Equal to the best oak-galls. =AL′DEHYD= (-hīd). [_al_-(cohol)-_dehyd_ (rogenatus).] C_{2}H_{4}O. Syn. HYDRATED OXIDE OF ACETYLE; HYDRATE OF OTHYLE*; HYDROXIDE OF O.* Literally, dehydrogenated alcohol. In _chemistry_, a peculiar ethereal liquid, first obtained in a pure form by Liebig, from alcohol. It is produced under various circumstances, particularly during the destructive distillation of certain organic matters, and in several processes of oxidation. The following are the most convenient methods of preparing it:—— _Prep._ 1. (Liebig.) Sulphuric acid, 3 parts; is diluted with water, 2 parts; and as soon as the mixture has cooled, alcohol of 80%, 2 parts, is added; and, subsequently, peroxide of manganese (in fine powder), 3 parts. The whole, after agitation, is then distilled at a very gentle heat, from a spacious retort into a receiver surrounded with ice, the connection between the two being perfectly air-tight. The process is continued until frothing commences, or the distillate becomes acid which generally occurs when about one third (3 parts) has passed over. The distillate is next agitated in a retort, with about its own weight of fused chloride of calcium, in powder; after which about one half only is drawn over at a very gentle heat (85° to 90° Fahr.), by means of a water bath. This rectification is repeated in a precisely similar way. The last distillate is ANHYDROUS ALDEHYD only slightly contaminated with foreign matters.