Vanadium, a metal, first recognized as distinct in 1801 by Del Rio, who found it in the brown lead ore (now known as vanadinite) of Zimapan in Mexico, and called it erythronium. But it was generally considered by chemists to be chromium, an opinion afterward adopted by Del Rio himself. In 1830 Sefstrom found the iron made from the magnetic ore of Taberg in Sweden, as well as the cinder produced in its conversion, to contain a peculiar metal, which he called vanadium, from Vanadis, one of the names of the Scandinavian goddess Freyja; and the Zimapan lead ore was afterward found by Wohler to contain the same metal. It has also been discovered in the iron slag of Staffordshire, and recently by Roscoe in larger quantity in the copper-bearing beds at Alderley Edge and Mottram St. Andrews, Cheshire, by Dr. Bolton in pitchblende, by Dr.
Hayes in many rocks, and by Bottger in pea iron ores. The metal is obtained by prolonged ignition of the dichloride in a stream of pure dry hydrogen gas. It is a grayish white powder, which has the appearance under the microscope of a silver-white crystalline mass. It does not tarnish in the air, burns with brilliant scintillations when thrown into a flame, burns vividly when quickly heated in oxygen, forming a pentoxide, and takes fire in a current of chlorine gas, forming a tetrachloride. It is insoluble in hydrochloric acid. It has until recently been regarded as a hexad metal, analogous to tungsten; but Roscoe has shown, by a comparison based upon the composition of the oxides and oxychlorides, and upon the isomorphism of the vanadates with phosphates, that it is a pentad, belonging to the arsenic and phosphorus group. Vanadium forms five oxides: V20, V202, V203, V204, and V206; compounds analogous to the oxides of nitrogen, V205 being called vanadic anhydride, and sometimes pentoxide of vanadium. The monoxide, V20, is a brown substance formed by prolonged exposure of the metal to the air at ordinary temperatures, or more quickly at a dull red heat. The dioxide, V2O2, is produced by continued heating of the monoxide.
The trioxide, V203, is formed by igniting the pentoxide, V206, in hydrogen gas, or in a crucible lined with charcoal. When exposed to warm air it absorbs oxygen, glows with a dull red light, and passes again into pentoxide. Vanadious oxide or anhydride, or vanadium tetroxide, V204, is formed by further oxidation of the dioxide or trioxide, or by partial reduction of the pentoxide. It forms with acids vanadious salts, which have a bright blue color. Vanadium pentoxide, or vanadic anhydride, may be prepared from the native lead vanadate. The mineral is dissolved in nitric acid, and the lead and arsenic precipitated by sulphuretted hydrogen, which also reduces the vanadium pentoxide to tetroxide. The blue filtered solution is then evaporated to dryness, which reconverts the tetroxide to pentoxide. It is then digested in aqua ammonia, which dissolves the pentoxide. A lump of sal ammoniac (chloride of ammonium) is put into the solution, and as the salt dissolves ammonium vanadate is precipitated, being only very slightly soluble in a saturated solution of the chloride of ammonium. A temperature below redness expels the ammonium. It is a reddish yellow powder, which dissolves in 1,000 parts of water, forming a light yellow solution.
With stronger acids it forms vanadic salts, but it unites with bases more readily than with acids, forming salts called vanadates of various constitution, as orthovanadates, having the general formula (3MO),V205; pyrovanadates, (3MO),V205; metavanadates, MO,V205, analogous to metaphosphates; divanadates, MO,2V2O5; and trivanadates, MO,3V206. In the United States the principal localities of vanadium minerals are at the Wheatley mine, Phoenixville, Pa., where several vanadates of lead occur, and at the Cliff mine, Lake Superior, where a chocolate-colored mineral is found containing vanadic acid. Vanadic acid is used in the manufacture of a permanent black ink.