Bromine (βρωμος, a bad odour). Symbol, Br. Combining proportion, 80. Specific gravity, 2.966.
In a previous portion of this work, the connexion between chlorine, iodine, and bromine has been pointed out; and as we have to notice the colour of the element bromine, the chromatic union of the triad may be alluded to. These elements present very nearly all the colours of the spectrum:
| Bromine | red to orange. |
| Chlorine | yellow to green. |
| Iodine | blue, indigo, violet. |
These three elements also furnish examples of the three conditions of matter; iodine being a solid, bromine a fluid, chlorine a gas; the relation of their combining proportions is also curious: as might be expected, the fluid bromine takes an intermediate position, and (according to the axiom that half the sum of the extremes is equal to the mean) by dividing the combining proportions of iodine and chlorine, and adding them together, we have, as nearly as possible, the combining proportion of bromine:
| Chlorine | 35 | ÷ | 2 | = | 17.75 | |
| Iodine | 126 | ÷ | 2 | = | 63 | |
| ———— | ||||||
| 80.75 |
The combining proportion of bromine is 80, but 80.75 is so near, that it may reasonably be conjectured future experiments will reduce the number of the three elements, and may prove that they are only modifications of a single one. This is the only kind of alchemy which is tolerated in the nineteenth century, and any philosopher who will reduce the number of elements, and prove that some of them are only modifications of others, will achieve a renown that must transcend the éclat of all previous discoverers.
Bromine was discovered by Balard, in 1826, and, like chlorine and iodine, is a constituent of sea water. The chief source of bromine is a mineral spring at Kreutznach, in Germany. The process by which it is obtained offers a good example of chemical affinity; the water of the mineral spring is evaporated, all crystallizable salts removed, and a current of chlorine gas passed through the remaining solution, which changes to a yellow colour, in consequence of the liberation of the bromine by the combinations of chlorine with the bases previously united with the former; the liquid is then shaken with ether, which dissolves out the bromine. In the next place, the etherial solution is agitated with strong solution of potassa, and is thus obliged to part with the bromine which is converted into bromate of potassa; this is ultimately changed by fusion to bromide of potassium; and by distillation with black oxide of manganese and sulphuric acid, the bromine is finally obtained. Six processes are therefore necessary before the small quantity of bromine contained in the mineral spring-water, is separated.
First Experiment.
Bromine is a very heavy fluid, which should be preserved by keeping it in a bottle covered with water; when required, a few drops may be removed by means of a small tube, and dropped into a warm bottle, which is quickly filled with the orange-red vapour. If some phosphorus is placed in a deflagrating spoon, and exposed to the action of bromine vapour, it takes fire spontaneously.