Bromine

Bromine (Gr. bromos, 'disagreeable smell': sym. $\backslash text\{Br\}$; atomic weight, 80), one of the elements, occurs in combination in sea-water to the extent of about 1 grain to the gallon. It is found more abundantly in certain saline springs, especially those at Kreuznach and Kissingen in Germany. It is also present in marine and land plants and animals. In the extraction of bromine from concentrated sea-water, from which common salt has been separated in quantity, and which is then called Bittern (q.v.), or from salt springs, the liquor—which contains the bromine, as bromide of magnesium, $\backslash text\{MgBr\}\_2$—has a stream of chlorine gas, $\backslash text\{Cl\}\_2$, passed through it, which forms chloride of magnesium, $\backslash text\{MgCl\}\_2$, and liberates the bromine. The liquid thus becomes of a more or less yellow tint, and if it be then agitated with ether, and allowed to settle, the latter floats up the bromine. The ethereal solution is then treated with potash, which principally forms bromide of potassium, $\backslash text\{KBr\}$, and fixes the bromine, so that the ether may be distilled off. The residue is then treated with oxide of manganese and sulphuric acid in a retort with heat, which results in the liberation and distillation of pure bromine. Bromine is a deep red liquid of density 2.98 at $59^\backslash circ$ ($15^\backslash circ$ C.), which readily evolves red fumes of a very irritating and suffocating nature. It is very poisonous, acting by destroying the animal tissues. When even a little of its vapour is inhaled, there is danger of spasm of the glottis and consequent suffocation. In medicine it has been found of service internally in scrofulous diseases, and as an application to ulcers or in hospital gangrene. It is sparingly soluble in water, more so in alcohol and ether, and its watery solution possesses great bleaching properties. When raised to the temperature of $145^\backslash circ$ ($63^\backslash circ$ C.) it boils, and when reduced to $9^\backslash circ$ ($-12^\backslash circ$ C.) it becomes a red crystalline solid. Treated with sulphur-urated hydrogen, bromine yields hydrobromic acid, $\backslash text\{HBr\}$, which is the analogue of hydrochloric acid, as bromine is of chlorine.