Assay. See Alkalimetry.
Uses, &c. Barilla is chiefly used in the manufacture of soap and glass; but the gross quantity imported, though annually increasing, only reached 54,608 cwt. in 1856; whilst the exports of soda in the same year reached to about 1,500,000 cwt., and in 1859 to above 2,000,000 cwt. This enormous quantity was chiefly furnished by our home manufactories.
Barilla is chiefly imported from Spain, Sicily, Teneriffe, and the Levant; but since the introduction of Le Blanc’s process for obtaining soda from common salt, its importance and value has considerably lessened. See Kelp, Soda, &c.
BARIUM. Ba. A metallic radical or element, of which baryta is the chief oxide, and somewhat extensively distributed. First obtained in 1808 by Sir H. Davy. Prepared from baryta by strongly heating it in an iron tube, through which the vapour of potassium is conveyed; the reduced barium being subsequently extracted from the mixed residuum by quicksilver, which is afterwards driven off in a small green-glass retort, in a vapour of mineral naphtha.
Prop., &c. Greyish-white, approaching silver in colour and lustre; decomposes water, and gradually oxidises in the air, with the formation of the ordinary oxide (BARYTA). It is malleable, fusible under a red heat; burns in contact with air with a deep red light, and has the sp. gr. 4·70.
Salts. Barium forms numerous salts, which are all either colourless or white, except a few, whose acids are coloured, as the chromate, manganate, &c. Some of them are soluble in water; one or two only are soluble in alcohol, and that very sparingly; and (with the exception of the sulphate) they are all extremely poisonous. They may be prepared by saturating solutions of the acids with either baryta-water, or carbonate of barium; and some of them may be prepared by double decomposition.
The various soluble barium salts are known by the following reactions, and they are all (except the sulphate) soluble either in water or in dilute hydrochloric acid, except the nitrate and chloride, which are not soluble in aqueous solutions of their respective acids. Their solutions give an immediate heavy white precipitate with dilute sulphuric acid, and with solutions of the sulphates, which is insoluble in dilute acids and solutions of the alkalies and of the salts of ammonia, that with a solution of sulphate of lime being very sensitive, and characteristic:—Hydrofluosilicic acid gives a very characteristic colourless crystalline and quickly subsiding precipitate, only slightly soluble in hydrochloric acid and nitric acid; alcohol, in equal volume, being added, so hastens and completes the reaction, that the filtrate is unaffected by sulphuric acid:—Chromate of potassium gives a bright yellow precipitate in neutral solutions, soluble in hydrochloric acid and in nitric acid, but insoluble in acetic acid:—Caustic potassa or soda (when quite free from carbonate), and caustic ammonia, cause no precipitate, except in highly concentrated solutions:—Alkaline carbonates give a heavy white precipitate with baryta-water or a solution of baryta, and which is all but insoluble in water, and freely soluble in dilute hydrochloric acid:—Heated with proof spirit, or pyroxilic spirit, the barium salts give a greenish-yellow tinge to the flame:—The barium salts, and particularly the chloride, when exposed on a platinum wire to the inner flame of the blowpipe, colour the outer flame yellowish-green:—Insoluble sulphate of barium may be mixed with powdered charcoal, and exposed for a short time to a full red heat, when sulphide of barium will be formed, which is freely soluble in water, and which, after being neutralised with hydrochloric acid, or acetic acid, will yield a solution suitable to the application of the usual tests. The carbonate, and the salts of barium with the organic acids, are all convertible into pure baryta by exposure to a bright red heat.
Baryta is distinguished from lime and from magnesia by its great solubility in hot water, and by the entire insolubility of its sulphate; from strontia, by being precipitated by hydrofluosilicic acid, and by not giving a red colour to the flame of alcohol; from alumina, by its
causticity and alkaline reaction, and by not being precipitated from its solution in water by ammonium sulphydrate.
Pois., &c. The sulphate, owing to its insolubility, is the only salt of barium which is not poisonous.—Symp. Nausea, vomiting, pains in the head, ringing in the ears, vertigo, and intermitting cramps and convulsions; the respiration is frequently suspended for several moments, and the pupil is generally dilated. The symptoms, however, often vary, and are not very distinctive.—Treatm., Ant., &c. Vomiting, followed by copious draughts of water soured with sulphuric acid, or sulphate of soda (Glauber-salt) or sulphate of magnesia (Epsom-salt), dissolved in a large quantity of water. When carbonate of barium has been swallowed, a mixture of one of the above sulphates and weak vinegar should be taken after the vomiting, in order that a soluble barium salt may be first formed, on which the alkaline sulphate will act more readily. Subsequent irritation may be soothed by opium or morphia, and antiphlogistics.