Although very widely disseminated, since it is found in ocean water, bromine is nowhere an abundant element. It is a constituent of some silver ores from Mexico and South America; it is very generally found in strong saline springs, as well as associated with deposits of salt; and it is present in many marine plants. The waters of the Atlantic, according to Von Bibra, contain 24 grains per gallon; while Here-path’s analysis gives Dead Sea water a strength of 121*5 grains per gallon. It is only from the waters of certain saline springs in America that bromine is prepared as a direct product. At several places in western Pennsylvania and West Virginia the manufacture is carried on extensively, 125,000 lb having been extracted in 1870. In Europe bromine is only obtained as a secondary product of the preparation of potash and other alkaline salts, its chief source being the mother-liquors of the kelp manufacture, brine springs, and especially the Stassfurth saline deposits, near Magdeburg, Prussia. The produce at Stassfurth in 1873 amounted to about 10,000 lb; and it is estimated that the yield of English and French works was, taken together, about the same.

On the commercial scale bromine is prepared at Stassfurth from the liquids which have been exhausted of all their crystallizable soda and potash salts, and from which also a deposit of chloride of magnesium has been obtained. This final mother-liquor is found to contain from 0 ’ 3 to 0 ’ 5 per cent, of bromine, in the form of bromide of potassium. To separate the bromine the liquor is introduced into a sandstone apparatus similar to that used for the evolution of chlorine from common salt,—the process and reaction being similar in both cases. In this it is mixed with black oxide of manganese and sulphuric acid in definite proportions, and heated by a current of steam. The red vapour of bromine is given off and led by a pipe into a condensing worm of earthenware, and received into a series of three Woulfe’s bottles, the first of which contains water, and the others alkaline ley and iron filings. The reaction which takes place is thus represented—

2KBr + MnO 2 + 3H 2 SO 4

= 2KHSO 4 + MnSO 4 + 2 H 2 O + 2Br,

-—sulphates of potash and manganese, water, and free bromine being produced from bromide of potassium, manganese dioxide, and sulphuric acid. Pure bromine vapour distils over at first, but as the distillation proceeds chlorine is gradually evolved, and from this the bromine may be freed by shaking up with a solution of bromide of potassium, which yields up its bromine to combine with chlorine. On account of its peculiarly irritating action on the organs of respiration, very great precautions have to be taken to protect workmen from the fumes of bromine, and it is indispensable that those engaged in the industry should abstain from all alcoholic liquors.

The chief industrial application of bromine and its compounds is in medicine, for which it is used in the form of bromide of potassium, bromide of ammonium, and bromide of sodium, besides in various combinations with alkaloids and organic substances. It is, however, most largely employed as bromide of potassium, a salt prepared on the large scale by the decomposition of potassium carbonate by the bromide of iron. It is also prepared by passing the vapour of bromine into a solution of caustic potash, when a mixture of bromide and bromate of potassium is produced. The mixed salts are reduced to a uniform bromide by burning with coal dust. Bromide of silver is employed to some extent in photography, and, according to the experiments of Vogel, it possesses a peculiar sensitiveness for the red, green, and yellow colours, which are not acted on by other photographic agents. During the American Civil War (1861-5) bromine came into use as a disinfectant in military hospitals, a purpose to which it was also applied in the Franco-German War in 1870-1. For such purposes it was found to possess several advantages over chlorine, which, however, has the recommendation of cheapness and abundance. It has long been hoped that bromine might be substituted for iodine in the preparation of the several coal-tar colours, but hitherto the attempts in that direction have not been successful. Eosine, a tetrabromated potassium salt, is the only dye into which bromine at present enters. The use of bromine has been suggested by Dr Rudolf Wagner in several metallurgical operations, in which he anticipates it might be of great service. He proposes, in place of the present wasteful method of reducing mercury from cinnabar, to digest the ere in an aqueous solution of bromine, whereby a bromide of mercury would be formed. He also suggests that bromine might be advantageously applied to the extraction of gold from poor auriferous ore, in a manner analogous to Plattner’s chlorination process. Further, it is recom mended for the refining of gold by the formation of a bromide; and it is thought that bromine vapour might be used with advantage for toughening brittle gold.