Al′dan, a river of Eastern Siberia, a tributary of the Lena, 1200 miles in length. The Aldan Mountains run along parallel to it on the left for 400 miles.
Aldeb′aran, a star of the first magnitude, forming the eye of the constellation Taurus or the Bull, the brightest of the five stars known to the Greeks as the Hyades. Spectrum analysis has shown it to contain antimony, bismuth, iron, mercury, hydrogen, sodium, calcium, &c.
Aldeburgh (a¨ld′bu-ru), a municipal borough of England, on the coast of Suffolk, more important formerly than it is now, having suffered from encroachments of the sea. The poet Crabbe was born there in 1754. Pop. 2892.
Al′dehyde, in chemistry, the generic name given to the compounds of alcohol intermediate between the alcohols and the acids. Common aldehyde (C2H4O) is derived from spirit of wine by oxidation, and is a colourless, limpid, volatile, and inflammable liquid, with a peculiar ethereal odour, which is suffocating when strong; specific gravity, 0.79. Atmospheric oxygen converts it into acetic acid. It decomposes oxide of silver, depositing a brilliant film of metallic silver; hence it is used in silvering curved glass surfaces.
Alder (a¨l′dėr; Alnus), a genus of plants of the sub-ord. Betulaceæ (Birch), (nat. ord. Amentaceæ). Fourteen species are known as small trees or shrubs indigenous to temperate and colder regions of the globe; eight of these are found in Central and Western Europe. The only species indigenous to Britain is the common alder (Alnus glutinōsa), a tree growing in wet situations in Europe, Asia, and the United States. Its wood, light and soft and of a reddish colour, is used for a variety of purposes, and is well adapted for work which is to be kept constantly in water. Alder is still largely used in gunpowder manufacture, and the roots and knots furnish a beautifully-veined wood well suited for cabinet work; it is used for cigar-boxes in East Prussia and West Russia. The bark is used in tanning and leather-dressing, and by fishermen for staining their nets. This and the young twigs are sometimes employed in dyeing, and yield different shades of yellow and red. With the addition of copperas it yields a black dye.
Alderley Edge, a town of England, Cheshire, about 8 miles south-west of Stockport. Pop. (1921), 3072.
Al′derman (a¨l′dėr-; Anglo-Saxon ealdorman, from ealdor, older, and man), among the Anglo-Saxons a person of a rank equivalent to that of an earl or count, the governor of a shire or county, and member of the witena-gemót or great council of the nation. Aldermen played an important rôle already before the Constitution of Egbert, but reached their highest power during the reign of Alfred the Great, who had married the daughter of an alderman. Aldermen, at present, are officers associated with the mayor of a city for the administration of the municipal government in England and the United States.
Al′derney (Fr. Aurigny), an island belonging to Britain, off the coast of Normandy, 10 miles due west of Cape La Hogue, and 60 from the nearest point of England, the most northerly of the Channel Islands, between 3 and 4 miles long, and about 1¼ broad. The coast is bold and rocky; the interior is fertile. About a third of the island is occupied by grass lands; and the Alderney cows, a small-sized but handsome breed, are famous for the richness of their milk. The climate is mild and healthy. A judge, with six 'jurats', chosen by the people for life, and twelve 'douzainiers', representatives of the people, form a kind of local legislature. The French language still prevails among the inhabitants, but all understand and many speak English. The Race of Alderney is the strait between the coast of France and this island. Pop. 2561.