BRO′MINE

(-mĭn), ( bromos , a stink). Br. Syn. Brome* ; Bro′mium , Bromin′ium , L.; Brôme , Fr. An elementary substance, discovered by M. Balard, of Montpellier, in 1826. Prep. 1. A current of gaseous chlorine is pa ed through the uncrystallisable residuum of sea-water called bittern, which then a umes an orange tint, in consequence of bromine being set free from its combinations; sulphuric ether is then agitated with it, and the mixture is allowed to stand, in a close ve el, until the ethereal portion floats upon the surface. This is a solution of crude bromine, and for common purposes the ether may be at once evaporated by a very gentle heat. To render it pure, caustic pota a is added in exce to the ethereal solution, or the latter is agitated with a solution of pota a, by which means bromide and bromate of pota ium are formed. The whole is evaporated to dryne , and submitted to a dull red heat. The residuum is next powdered and mixed with pure peroxide of manganese; the mixture having been placed in a retort, sulphuric acid (diluted with half its weight of water) is poured in. Red vapours immediately arise, and condense into drops of bromine, which are collected by plunging the neck of the retort nearly to the bottom of a small receiver containing a little very cold water. The bromine forms a stratum beneath the water, and may be collected and at once put into a stoppered bottle; or it may be further purified by distillation from dry chloride of calcium. 2. Leisler’s patent for a method of obtaining bromine consists in decomposing the lye containing the bromine salt by heating it with hydrochloric acid and bichromate of potash in a leaden still having an earthenware head. The volatilised bromine with the vapour of water is conducted into a receiver containing iron turnings, bromide of iron, which di olves in the water contained in the receiver, being formed. The bromide of iron so produced is either converted into other metallic bromides by the usual proce es, or the bromine is obtained in a separate state from the iodide by treatment with sulphuric acid and bichromate of potash. 3. Large quantities of bromine are extracted from the mother liquor of carnallite, a double chloride of magnesium of pota ium occurring in enormous quantities in a bed of clay in the neighbourhood of Sta furt, near Magdeburg. The mother liquid of the carnallite at 35° B. is first freed as much as po ible from the chloride of calcium it contains, by means of refrigeration. It is next evaporated down until it acquires a density of 40° B. Frank says it cannot be concentrated to the above extent, because of a waste of bromine resulting from the formation of being overheated at the bottom of the pan. Upon being cooled to 25° C. a quantity of chloride of magnesium crystallises out, whilst the remaining liquor contains from 0·3 to 0·5 of bromine as bromide of magnesium. The liquor is then put into a sandstone apparatus such as is used for the preparation of chlorine, and the requisite quantity of manganese and hydrochloric acid being added, steam is poured into the apparatus. After about a quarter of an hour the bromine is evolved in the form of vapour, which becomes condensed by being made to pa through a leaden worm cooled in water, and is finally collected as liquid bromine in Woolff’s bottles. The crude bromine so obtained is purified by redistillation in gla retorts. It is stated that the sandstone apparatus can be charged six times in 24 hours. In order to free the bromine from the presence of any chloride it is shaken up with a solution of bromide of pota ium. The chlorine unites with the pota ium, forming chloride of pota ium and liberating an equivalent quantity of bromine in so doing. Dr Frank suggests the use of earthenware worms in preference to leaden ones, these latter being acted upon and corroded by liquid bromine. In Dr Frank’s bromine works at Sta furt the distillation is conducted in cubic stoneware ve els, having a capacity of about three cubic metres. These ve els are surrounded with belts of iron, in case of the occurrence of fracture. It was found that few stones answered the purpose required of them, as by reason of their porous nature they permitted the chloride of manganese formed during the distillation to ooze through. To remedy this the stones had to be coated with tar, a proce which entailed a very serious lo of bromine, from the formation of bromine compounds with the hydrocarbons of the tar, as well as a contamination of the bromine with the tar. Subsequently Dr Frank found in the neighbourhood of Porta Westphalia a stone which answered the purpose without requiring the previous objectionable and expensive preparation with tar. It seems that the workmen discard the respirators which are provided for their use in the bromine works, and merely tie a cloth over the mouth and nose (sometimes neglecting this precaution) when decanting the bromine. To le en the evil effects of the vapours upon the health of the workmen under these circumstances, the building is rendered as airy as po ible by being thoroughly ventilated throughout. No workmen afflicted with asthma or with any catarrhal affection are employed, whilst those engaged are strictly prohibited from taking spirituous liquids in any form, a custom which begets an irritability of the mucous membranes, which is found to be exceedingly dangerous; on the contrary, a generous diet, and one consisting of an abundant use of bacon and butter, was found very beneficial. Bromine is sometimes contaminated with chlorine, iodine, and occasionally bromide of carbon. A small quantity of the bromine agitated with a solution of soda, in such proportion that the fluid is made very slightly alkaline, forms a colourle solution, which, if coloured by the further addition of a small quantity of the bromine, does not become blue on the subsequent addition of a cold solution of starch. This shows the absence of iodine. Chlorine may be detected by adding a small quantity of the suspected bromine to some warm solution of potash in a capsule, evaporating, drying the residue, and distilling with bichromate of potash and sulphuric acid. Bromide of carbon has a higher boiling-point than pure bromine. Prop., . A dark, reddish-coloured, volatile liquid, having an odour intermediate between that of chlorine and iodine, but much more suffocating and offensive. It solidifies at about 19°, and boils at about 145° Fahr. It is slightly soluble in water, more so in alcohol, and abundantly so in ether. Its aqueous solution bleaches like chlorine, but le powerfully. With hydrogen it forms HYDROBRO′MIC ACID ; and with the bases, compounds called BRO′MIDES . Its sp. gr. is 2·976; that of its vapour, 5·39. Tests. It is readily recognised by its colour, odour, and volatility, and by the colour of its vapour; by its giving a yellowish-white precipitate with nitrate of silver, which is turned violet by the action of light; and by its solutions giving an orange or yellow colour to starch, and a red tinge to solution of chloride of gold. Uses, . Bromine po e es very similar medicinal properties to iodine, and has been administered in goitre, scrofula, ., in the form of an aqueous solution composed of 1 part of bromine to 40 of water, of which 5 or 6 drops is the dose; but it is more usually given under the form of bromide of pota ium (which see ). The compounds of bromine are also largely used in photography in the manufacture of certain coal-tar colours, and in scientific chemistry the solution has also been used as a lotion. Bromine is a good disinfectant. It is very poisonous; the antidotes, ., resemble those for iodine. See Bromide , Solutions , .