Bromine (Gr. a stench), a chemical element discovered by Balard in 1826 in the bittern or mother liquor of the salt works of Montpellier, France, and so named in consequence of its disagreeable odor. The fact that chlorine water, when added to the lye from fucus ashes, after the addition of starch paste, gave besides the usual blue color an orange-yellow zone at the top of the liquid, was the immediate occasion of Balard's discovery. Since the announcement of the discovery, many chemists have occupied themselves with investigating the occurrence, properties, and uses of bromine, and it has now attained a position of the first importance in medicine and the arts. Bromine has been found in the mineral kingdom in combination with silver and zinc, and in the salt deposits of Stassfurt; it has also been detected in urine, coal beds, Chili saltpetre, and fucus ashes. According to Von Bibra, the amount of bromine in the Atlantic ocean is 24 grains per gallon; in the Dead sea, examined by Herapath, 121.5 grains; in the dried residue of the Mediterranean, 1.15 per cent.
In the mineral springs of Kreuznach Ure found 10.8 grains; in Kissingen water, determined by Kastner, there is 0.44 grain; in Tenbury, Worcestershire, examined by Ure, as much as 12'5 grains; and at Arnstadt, according to Har-tung, 13.6 grains. In the United States, bromine has been detected in various saline springs, for the first time in the brines of Onondaga in 1830, by Hayes and Silliman. The quantity in one of the artesian wells of Saratoga, determined by Dr. Chandler, is 3.63 grains; in the brine of Saginaw valley Dr. Chilton found 7.65 grains; at Tarentum, Penn., 6 grains; in the Salina brine, analyzed by Dr. Goessmann, 1.36 grain per gallon is reported. Many mineral waters in all parts of the world have been shown to contain bromine, and for a long time the chief commercial supply was from these sources. Since the opening of the Stassfurt salt mines the chief product is derived from this source. As much as 300 grains per gallon has been obtained from the mother liquors of Stassfurt. Only two or three of the manufactories at this place have economized this substance, as the unprecedented supply has reduced the price below profitable manufacture; the decrease in price has also been hastened by the large production in the United States. At Tarentum, Sligo, and Natrona in western Pennsylvania, at Pomeroy, Ohio, and at Kanawha, West Virginia, the manufacture of bromine has become of considerable importance.
The production in 1870 was 126,000 lbs. In 1867 the production at Stassfurt was 20,000 lbs. The cost in the United States in 1870 was $1 50 a pound. - The preparation of bromine is conducted, according to Professor Miller, in the following manner: The mother liquor from the brine, after all the salts separable by crystallization have been removed, is subjected to a current of chlorine, care being taken to avoid an excess of this gas, which would occasion inconvenience by forming a compound with the liberated bromine. All the bromides are readily decomposed by chlorine, the attractions of chlorine being more powerful than those of bromine. In the foregoing operation chloride of magnesium is formed, and bromine is set free: MgBr2 + Cl2=MgCl2 + Br2; the bromine shows itself by giving to the liquid a beautiful and characteristic yellow color. This yellow liquid, when agitated with ether, parts with its bromine, which is dissolved by the ether. If the mixture is allowed to stand in a glass globe closed at the bottom, the ether rises to the surface, where it forms a beautiful golden yellow layer.
The mother liquor is drawn off by opening the stopcock, and the ethereal solution is agitated with a solution of hydrate of potash; the yellow color immediately disappears; bromide and bromate of potassium are formed and dissolved in the water: 3Br2 + 6KHO = KBrO3 + 5KBr + 3H2O; while the ether, after repose, rises again to the surface despoiled of its bromine, and may again be employed in a repetition of the process upon a fresh quantity of bittern. When the solution of potash has, by repeated charges of bromine, been nearly neutralized, the liquid is evaporated to dryness; the saline mass is gently ignited, to decompose the bromate; after which it is mixed with peroxide of manganese, and distilled in a retort with sulphuric acid. Dense red vapors of bromine pass over, which may be collected in a receiver containing water, and kept cool by ice. The decomposition is of the same nature as that attending the liberation of chlorine from sea salt by means of oxide of manganese and sulphuric acid: 2KBr+Mn02 + 2H2S04==K2S04+MnS04 + 2H20 + Br2. In this operation a small quantity of chlorine passes over with the bromine, since, from the manner in which the bromide of potassium is formed, it is always contaminated with a portion of chloride of potassium.
The chlorine unites with part of the bromine, forming chloride of bromine, which is partially decomposed and dissolved by the water in the receiver, while the bromine is condensed in red drops. In order to obtain bromine free from chlorine, it must be saturated with hydrate of baryta, which produces a mixture of bromide and chloride with bromate of barium; this mixture must be heated to redness in order to convert the bromate into bromide of barium, and the residue digested in alcohol, which dissolves nothing but the bromide; the bromide of barium is obtained by evaporation of its alcoholic solution, and when heated with black oxide of manganese and sulphuric acid, it yields pure bromine. - Bromine forms a red liquid, so deep in color as to be nearly opaque. It has a specific gravity of 2-966 at 60°; it is very volatile, and emits dense red vapors resembling peroxide of nitrogen in color. It resembles chlorine in smell, and is extremely irritating to the nose and fauces when respired, even if largely diluted with air. When swallowed it operates as a powerfully irritating poison; it acts rapidly on all the organic tissues, and renders the skin permanently yellow. Bromine boils at 145.4° F.,and when exposed to a temperature of 9.5° it forms a red crystalline solid.
The properties of bromine greatly resemble those of chlorine, though they are less strongly developed. It bleaches many vegetable colors. Its vapor will not support the flame of a burning taper. Bromine is slightly soluble in water, and gives to it a yellow color; it also forms with it a hydrate (Br5H20) which crystallizes in octahedra at 32° F. This aqueous solution of bromine is decomposed by sunlight into hy-drobromic acid ancl oxygen. Alcohol dissolves bromine freely, and ether does so still more abundantly. Olefiant gas is rapidly absorbed by liquid bromine, and a liquid compound (C2H4Br2), bichromide of ethylene, is formed. Bromine combines directly with phosphorus, and with many of the metals, forming compounds termed bromides, the act of combination being often attended with ignition, as in case of antimony and of tin; even gold combines with it, though slowly; its compound with silver furnishes a material of considerable value in photographic operations. Bromine resembles chlorine in its power of combining with hydrogen and forming with it a very powerful acid. The oxyacids of bromine are, with the exception of bromic acid, nearly unknown, and this compound even has never been obtained in the form of anhydride.
Bromide of nitrogen is an oily-looking liquid, resembling chloride of nitrogen in its explosive properties. Bromine is employed in the manufacture of aniline colors, and its compounds are extensively used in medicine and photography. Bromoform, analogous to chlo-rofprm, has been prepared by chemists, and used to a slight extent as an anaesthetic. The hydrate of bromal has also been experimented upon as a hypnotic.