Azincourt. See Agincourt.
Azo Compounds, a class of substances which belong to the benzene series and contain carbon, hydrogen, and nitrogen. All azo compounds are highly coloured, and in some cases they are direct cotton dyes. The simplest azo compound is azobenzene, the chemical formula of which is C6H5—N = N—C6H5. It is prepared from nitrobenzene by reducing it with stannous chloride and sodium hydroxide. Azobenzene is
a highly-coloured crystalline substance, but it is not a dye; it forms, however, the basis of the dyes known as azodyes. The azodyes form one of the largest groups of dyes, and derive their name from the presence of the characteristic chemical group —N = N—, known as the azo group. Azo compounds may become exceedingly complicated in structure. They are divided into mon-azo, di-azo, tri-azo compounds according to the number of azo groups present. The well-known dyes Congo Red and Bismarck Brown are azo compounds of complicated structure. Azo dyes were discovered by Griess in 1856, but as a class did not come on the market until about 1876.
Azof. See Azov.
Azo´ic. See Pre-Cambrian.
Azoimide, or Hydrazoic Acid, N3H, is an acid liquid of disagreeable odour, producing headache if inhaled. The acid itself and its salts, with the exception of the alkali salts, are exceedingly explosive and dangerous to handle. Lead hydrazoate, PbN6, is one of the most stable of these salts. It is a more powerful explosive than mercury fulminate, and has been used instead, in the manufacture of detonators.
Azores (a-zōrz' or a-zō'res), or Western Islands, a group belonging to and 900 miles west of Portugal, in the North Atlantic Ocean. They are nine in number, and form three distinct groups—a N.W., consisting of Flores and Corvo; a central, consisting of Terceira, São Jorge, Pico, Fayal, and Graciosa; and a S.E., consisting of São Miguel (or St. Michael) and Santa Maria. The total area is 922 sq. miles; São Miguel (containing the capital Ponta Delgada), Pico, and Terceira are the largest. The islands, which are volcanic and subject to earthquakes, are of comparatively recent origin, and are conical, lofty, precipitous, and picturesque. The most remarkable summit is the peak of Pico, about 7600 feet high. There are numerous hot springs. They are covered with luxuriant vegetation, and diversified with woods, corn-fields, vineyards, lemon and orange groves, and rich, open pastures. The mild and somewhat humid climate, combined with the natural fertility of the soil, brings all kinds of vegetable products rapidly to perfection, among the most important being grain, oranges, pine-apples, bananas, potatoes, yams, beans, coffee, and tobacco. The inhabitants are mainly of Portuguese descent, indolent and devoid of enterprise. Principal exports: wine and brandy, oranges, maize, beans, pineapples, cattle. The climate is recommended as suitable for consumptive patients. The Azores were discovered by Cabral about 1431, shortly after which date they were taken possession of and colonized by the Portuguese. When first visited they were uninhabited, and had scarcely any other animals except birds, particularly hawks, to which, called in Portuguese açores, the islands owe their name. Pop. 242,613 (1911).
Az´ote, a name formerly given to nitrogen; hence substances containing nitrogen and forming part of the structure of plants and animals are known as azotized bodies. Such are albumen, fibrine, caseine, gelatine, urea, kreatine, &c. See Nitrogen.
A´zov, or Asov, a town in the Russian government of Ekaterinoslav, upon an island at the mouth of the Don, where it flows into the Sea of Azov; formerly a place of extensive trade, but its harbour has become almost sanded up. Pop. 31,111.
Azov, Sea of (ancient, Palus Moeōtis), an arm of the Black Sea, with which it is united by the Straits of Kertch or Kaffa; length about 170 miles, breadth about 80 miles; greatest depth not more than 8 fathoms. The W. part, called the Putrid Sea, is separated from the main expanse by a long sandy belt called Arabat, along which runs a military road. The sea teems with fish. The Don and other rivers enter it, and its waters are very fresh.