=AL′DEHYD-AMMO′NIA= (-hĭd-). An ammonia-compound of aldehyd, discovered by Döbereiner and Liebig. _Prep._ (Liebig.) Aldehyd (of process No. 1, above) is mixed with an equal volume of ether,[16] in a flask surrounded with ice, or (what is better) a freezing-mixture; and is then saturated with dry gaseous ammonia. The crystals which soon form, after being washed with ether, and dried by means of bibulous paper and a short exposure to the air, are pure aldehyd ammonia. [Footnote 16: Some authorities recommend the use of twice this quantity of ether.] _Prop., &c._ It smells like a mixture of turpentine and ammonia; melts at 165° to 170°; volatilises, unchanged, at 212° Fahr.; decomposed by exposure to the air; very soluble in water; soluble in alcohol, and more or less so in most other menstrua, except ether; acids decompose it. With sulphuretted hydrogen it forms thialdine.——_Use._ Chiefly to make pure aldehyd (which _see_). =AL′DER= (awl′-). _Syn._ AL′DER-TREE; AL′NUS (ăl-), L.; A. GLUTINO′SA (Gaertn.); BETU′LA ALNUS, Linn.; AUNE, AULNE, Fr.; ERLE, Ger. A well-known English tree, chiefly growing in moist grounds near rivers. Its wood is used for hurdles, for various articles of turnery and furniture, and when converted into charcoal, for making gunpowder; it possesses considerable durability under water; but is otherwise of little value. Bark and leaves very astringent, and reputed vulnerary; decoction used as a gargle in sore throat, and, in double the dose of cinchona, as a febrifuge in agues; bark and sap used in dyeing and tanning. The following belong to different nat. orders and genera to the preceding:—— =Alder, Black.= _Syn._ WIN′TER-BERRY; PRI′NOS VERTICILLA′TUS, Linn. A tree growing in the United States of America. Bark febrifuge, tonic, and astringent; berries tonic and emetic. (Bigelow.) It has been much recommended in dropsies, diarrhœa, intermittents, &c. _Dose_ (of the dried bark), 1/2 to 1 dr., 3 or 4 times a day. =Alder-tree, Black.= _Syn._ BERRY-BEARING ALDER-TREE; RHAM′NUS FRAN′GULA, Linn. A large shrub found in the woods and thickets of England, &c. Wood, BLACK DOG′WOOD; bark, bitter, emetic, purgative; used to dye yellow; root-bark, a drastic purgative; berries, purgative, emetic; unripe berries yield SAP-GREEN; charcoal of the wood esteemed the best for gunpowder.