Page:The New International Encyclopædia 1st ed. v. 02.djvu/874

BENZIDINE without the aid of mordants, and are at present manufactured in very large quantities.

BEN'ZINE (for derivation see ). One of the products of the fractional distilla- tion of crude petroleum. It is a mixture of volatile hydrocarbons of the marsh-gas series, containing chiefly hydrocarbons that are rep- resented by the two formulæ, C„H„ and CiHk,. It is often used as a cleaning fluid for household purposes, as well as for removing ink from printing-presses. It is a very good solvent for fats, gums, and resin, and is employed in mak- ing many varnishes. It also finds employment for enriching coal-gas, and for certain other purposes. At ordinary temperatures it is a limpid, colorless liquid, much lighter than water, with which it does not mix, and readily catching fire. It boils between the tempera- tures of 70° and 90° C. (158° and 194° F.), its vapor forming with air a highly explosive mixture. It should not be confounded with the much more important substance called benzene (q.v.) that is obtained as a product of the fractional distillation of coal-tar. See also.

BENZO'IC ACID (for derivation see ), C„IIr,COOH. An organic substance used in medicine and the arts, and largely for sci- entific purposes. It may be manufactured by one of the following three methods: (1) From benzoin, by subliming or boiling the gum with caustic soda solution. (2) From the urine of herbivorous animals, by evaporating to a small bulk, filtering and adding hydrochloric acid to acid reaction; on standing, crystals of hippuric acid separate out; these crystals are transformed into benzoic acid by boiling with strong hydro- chloric acid, the hydrochloride of amido-acetic acid (glycine) being formed at the same time, according to the following equation:

C„H;CONHCH,COOH + HCl + HjO = Hipijuric Acid Hydrochloric Water .icid

CeH^COOH + CH=(NH,)C00H.HC1 Benzoic Acid Hydrochloride ol Glycine

Finally, (3) benzoic acid may be made from benzyl chloride by oxidizing the latter with nitric acid, the transformation taking place according to the following chemical equation:

CeH„CHXl -f 20 = C,H,COOH + HCl Benz.Tl Benzoic Hydrochloric Chloride Acid .4-cid

The crude benzoic acid obtained by one of these methods may be purified by recrystallization from water. The pure acid melts at 120° C. and boils at 250° C. It readily sublimes, however, long before melting. Though but sparingly soluble in cold water, it dissolves readily in hot water, as well as in alcohol, ether, and other organic liquids.

The acid employed for medicinal purposes is obtained exclusively by subliming gum benzoin, and retains the balsamic odor of the gum. When introduced into the body, it is converted (probably in the kidneys) into hippuric acid, which appears in the urine, of course increasing its acidity. For this reason, benzoic acid, or its salts, are administered whenever the urine undergoes alkaline decomposition — for instance, in cystitis and pyelitis. Benzoic acid is also used as a disinfecting expectorant in phthisis and bronchitis, when the expectoration is foul.

In the arts, benzoic acid is employed in making the dyes known as aniline blue, anthracene brown, etc.

Among the benzoates, or salts of benzoic acid, may be mentioned the benzoate of ammonium and the benzoate of sodium, both of which are used in medicine. They are prepared by adding benzoic acid, respectively, to solutions of ammonia and of sodium carbonate. These benzoates are much more readily soluble in cold water than the free acid.

Benzoic acid has been known since the beginning of the Seventeenth Century. In 1824 Wöhler discovered the relationship between benzoic and hippuric acids, and in 1832 Liebig and Wöhler determined the true chemical composition of benzoic acid and established its relation to the other benzoyl compounds.

BENZOIN (ben-zoin') GUM, or (earlier benjoin, Fr. benjoin, Ger. Benzoe, Sp. benjui, from Ar. luban-jawa, incense of Java, which is the Arabic name for Sumatra, as the syllable lu was lost through mistaking it for the Arabic definite article al, el). A fragrant resinous substance, the drj- juice of a large tree, Styraæ benzoin, a native of Sumatra and Java. The tree was introduced into Siam and other places in the East, and the finest gum to be found in the market comes from Siam. Gum benzoin yields a pleasant odor when burned, and is used as incense in the Roman and Greek churches; very large quantities of it are used for a similar purpose in the East. It is used, to some extent, in perfumery, and is sometimes administered medicinally, owing to its properties as a stimulant and emetic: as a good antiseptic it is one of the ingredients of court plaster. Druggists sometimes add a little benzoin to pomade, to prevent the fat of the latter from becoming rancid. A little of the tincture of gum benzoin added to washes imparts to them a milk-white color and an odor resembling that of vanilla. Benzoin conies to us in reddish- yellow transparent pieces. It is obtained by making longitudinal or oblique incisions in the stem of the tree, the liquid which exudes soon hardening by exposure to the sun and air. Dif- ferent products, the quality of which depends mainly on the age of the trees from which they are obtained, differ considerably in price. The gum yielded by trees from 5 to 8 years old is supposed to be of the finest quality; it is al- most white, and possesses a particularly strong odor. The gum of trees 16 to 18 years old is almost worthless. Chemically, gum benzoin is a mixture of three different resinous substances soluble in alcohol and alkalies; it contains, be- sides, a considerable quantity of benzoic acid, and often some cinnamic acid.

BENZOIN O'DORIF'ERUM. See.

BEN'ZOL. See.

BENZOYL, ben'zoil, C„H,CO. An organic radical, i.e. a group of atoms that forms part of the molecules of many compounds, but that can- not exist independently.

BEOTHUK, ba'6-thuk. A mysterious tribe formerly inhabiting the interior of Newfoundland. The name is of Micmac origin, and is said to signify 'red people,' in allusion to their custom of painting their bodies with red ochre.