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 beryllium fluoride. It is a malleable metal, of specific gravity 1·64 (Nilson and Pettersson) and a specific heat of 0·4079. Its melting-point is below that of silver. In a fine state of division it takes fire on heating in air, but is permanent at ordinary temperatures in oxygen or air; it is readily attacked by hydrochloric and sulphuric acids, but scarcely acted on by nitric acid. It is also soluble in solutions of the caustic alkalis, with evolution of hydrogen a behaviour similar to that shown by aluminium. It combines readily with fluorine, chlorine and bromine, and also with sulphur, selenium, phosphorus, &c.

Considerable discussion has taken place at different times as to the position which beryllium should occupy in the periodic classification of the elements, and as to whether its atomic weight should be 9·1 or 13·65, but the weight of evidence undoubtedly favours its position in Group II., with an atomic weight 9·1 (O＝16) (see Nilson and Pettersson, Berichte, 1880, 13, p. 1451; 1884, 17, p. 987; B. Brauner, Berichte, 1881, 14, p. 53; T. Carnelley, Journ. of Chem. Soc., 1879, xxxv. p. 563; 1880, xxxvii., p. 125, and W. N. Hartley, Journ. of Chem. Soc., 1883, xliii. p. 316). The specific heat of beryllium has been calculated by L. Meyer (Berichte, 1880, 13, p. 1780) from the data of L. F. Nilson and O. Pettersson, and appears to increase rapidly with increasing temperature, the values obtained being 0·3973 at 20·2° C., 0·4481 at 73·2° C. and 0·5819 at 256·8° C.

Beryllium compounds are almost wholly prepared from beryl. The mineral is fused with potassium carbonate, and, on cooling, the product is treated with sulphuric acid, the excess of which is removed by evaporation; water is then added and the silica is filtered off. On concentration of the solution, the major portion of the aluminium present separates as alum, and the mother liquor remaining contains beryllium and iron sulphates together with a little alum. This is now treated for some days with a hot concentrated solution of ammonium carbonate, which precipitates the iron and aluminium but keeps the beryllium in solution. The iron and aluminium precipitates are filtered off, and the filtrate boiled, when a basic beryllium hydroxide containing a little ferric oxide is precipitated. To remove the iron, the precipitate is again dissolved in ammonium carbonate and steam is blown through the liquid, when beryllium oxide is precipitated. This process is repeated several times, and the final precipitate is dissolved in hydrochloric acid and precipitated by ammonia, washed and dried. It has also been obtained by J. Gibson (Journ. of Chem. Soc., 1893, lxiii. p. 909) from beryl by conversion of the beryllium into its fluoride.

Beryllium oxide, beryllia or glucina, BeO, is a very hard white powder which can be melted and distilled in the electric furnace, when it condenses in the form of minute hexagonal crystals. After ignition it dissolves with difficulty in acids. The hydroxide Be(OH)2 separates as a white bulky precipitate on adding a solution of an alkaline hydroxide to a soluble beryllium salt; and like those of aluminium and zinc, this hydroxide is soluble in excess of the alkaline hydroxide, but is reprecipitated on prolonged boiling. Beryllium chloride BeCl2, like aluminium chloride, may be prepared by heating a mixture of the oxide and sugar charcoal in a current of dry chlorine. It is deliquescent, and readily soluble in water, from which it separates on concentration in crystals of composition BeCl2·4H2O. Its vapour density has been determined by Nilson and Pettersson, and corresponds to the molecular formula BeCl2. The sulphate is obtained by dissolving the oxide in sulphuric acid; if the solution be not acid, it separates in pyramidal crystals of composition BeSO4·4H2O, while from an acid solution of this salt, crystals of composition BeSO4·7H2O are obtained. Double sulphates of beryllium and the alkali metals are known, e.g. BeSO4·K2SO4·3H2O as are also many basic sulphates. The nitrate Be(NO3)2·3H2O is prepared by adding barium nitrate to beryllium sulphate solution; it crystallizes with difficulty and is very deliquescent. It readily yields basic salts.

The carbide BeC2 is formed when beryllia and sugar charcoal are heated together in the electric furnace. Like aluminium carbide it is slowly decomposed by water with the production of methane. Several basic carbonates are known, being formed by the addition of beryllium salts to solutions of the alkaline carbonates; the normal carbonate is prepared by passing a current of carbon dioxide through water containing the basic carbonate in suspension, the solution being filtered and concentrated over sulphuric acid in an atmosphere of carbon dioxide. The crystals so obtained are very unstable and decompose rapidly with evolution of carbon dioxide.

Beryllium salts are easily soluble and mostly have a sweetish taste (hence the name (q.v.), from , sweet); they are readily precipitated by alkaline sulphides with formation of the white hydroxide, and may be distinguished from salts of all other metals by the solubility of the oxide in ammonium carbonate. Beryllium is estimated quantitatively by precipitation with ammonia, and ignition to oxide. Its atomic weight has been determined by L. F. Nilson and O. Pettersson (Berichte, 1880, 13, p. 1451) by analysis of the sulphate, from which they found the value 9·08, and by G. Krüss and H. Moraht (Berichte, 1890, 23, p. 2556) from the conversion of the sulphate BeSO4·4H2O into the oxide, from which they obtained the value 9·05. C. L. Parsons (Journ. Amer. Chem. Soc., 1904, xxvi. p. 721) obtained the values 9·113 from analyses of beryllium acetonyl-acetate and beryllium basic acetate.

For a bibliography see C. L. Parsons, The Chemistry and Literature of Beryllium (1909).

 BERYLLONITE, a mineral phosphate of beryllium and sodium, NaBePO4, found as highly complex orthorhombic crystals and as broken fragments in the disintegrated material of a granitic vein at Stoneham, Maine, where it is associated with felspar, smoky quartz, beryl and columbite. It was discovered by Prof. E. S. Dana in 1888, and named beryllonite because it contains beryllium in large amount. The crystals vary from colourless to white or pale yellowish, and are transparent with a vitreous lustre; there is a perfect cleavage in one direction. Hardness 5-6; specific gravity 2·845. A few crystals have been cut and faceted, but, as the refractive index is no higher than that of quartz, they do not make very brilliant gem-stones.

 BERZELIUS, JÖNS JAKOB (1779–1848), Swedish chemist, was born at Väfversunda Sorgard, near Linköping, Sweden, on the 20th (or 29th) of August 1779. After attending the gymnasium school at Linköping he went to Upsala University, where he studied chemistry and medicine, and graduated as M.D. in 1802. Appointed assistant professor of botany and pharmacy at Stockholm in the same year, he became full professor in 1807, and from 1815 to 1832 was professor of chemistry in the Caroline medico-chirurgical institution of that city. The Stockholm Academy of Sciences elected him a member in 1808, and in 1818 he became its perpetual secretary. The same year he was ennobled by Charles XIV., who in 1835 further made him a baron. His death occurred at Stockholm on the 7th of August 1848. During the first few years of his scientific career Berzelius was mainly engaged on questions of physiological chemistry, but about 1807 he began to devote himself to what he made the chief object of his life—the elucidation of the composition of chemical compounds through study of the law of multiple proportions and the atomic theory. Perceiving the exact determination of atomic and molecular weights to be of fundamental importance, he spent ten years in ascertaining that constant for some two thousand simple and compound bodies, and the results he published in 1818 attained a remarkable standard of accuracy, which was still further improved in a second table that appeared in 1826. He used oxygen—in his view the pivot round which the whole of chemistry revolves—as the basis of reference for the atomic weights of other substances, and the data on which he chiefly relied were the proportions of oxygen in oxygen compounds, the doctrines of isomorphism, and Gay Lussac’s law of volumes. When Volta’s discovery of the electric cell became known, Berzelius, with W. Hisinger (1766–1852), began experiments on the electrolysis of salt solutions, ammonia, sulphuric acid, &c., and later this work led him to his electrochemical theory, a full exposition of which he gave in his memoir on the Theory of Chemical Proportions and the Chemical Action of Electricity (1814). This theory was founded on the supposition that the atoms of the elements are electrically polarized, the positive charge predominating in some and the negative in others, and from it followed his dualistic hypothesis, according to which compounds are made up of two electrically different components. At first this hypothesis was confined to inorganic chemistry, but subsequently he extended it to organic compounds, which he saw might similarly be regarded as containing a group or groups of atoms—a compound radicle—in place of simple elements. Although his conception of the nature of compound radicles did not long retain general favour—indeed he himself changed it more than once—he is entitled to rank as one of the chief founders of the radicle theory. Another service of the utmost importance which he rendered to the study of chemistry was in continuing and extending the efforts of Lavoisier and his associates to establish a convenient system of chemical nomenclature. By using the initial letters of the Latin