POTASSII BROMIDUM - BROMIDE OF POTASSIUM, KBr,=119.

Preparation

By adding bromine in slight excess to liq. potassae, and afterward heating with charcoal, dissolving, and crystallizing. In the first part of the process a mixture of bromide and bromate of potash is formed, 6KHO + Br6 = 5KBr + KBrO3 + 3H10, and in the second part the bromate is deoxidized, the bromide remaining unaffected.

Characters And Tests

It occurs in cubical crystals, resembling those of the iodide, but smaller. When well kept they are transparent or white, but commonly have a tinge of yellow from some free bromine. They have a saline, bitter taste, and high diffusion power. They contain 66 per cent. of bromine. Chlorine water added to the crystals liberates bromine, which will impart an orange-red color to chloroform, ether, or sulphide of carbon. The starch-test would detect iodine, which used to be a frequent adulteration.

AMMONII BROMIDUM - BROMIDE OF AMMONIUM, NH1Br,=98.

Preparation

By saturating hydrobromic acid with ammonia - HBr x NH1HO = NH1Br + H1O.

Characters And Tests

It occurs in white, colorless crystals, which gradually become yellowish; is rather more disagreeable to the taste than the potassium salt; answers to the tests mentioned, but effervesces with acids.

Sodii Bromidum - Bromide of Sodium, NaBr (not officinal). Crystallizes like the analogous salt of potassium; it is less bitter in taste; contains more bromine (78 per cent.).

Lithioe Bromidum - Bromide of Lithia (not officinal) is crystalline, white, soluble, and contains a larger proportion of bromine than any other compound (92 per cent. Weir Mitchell).

Calcii Bromidum - Bromide of Calcium (not officinal) is white, very soluble, in fact deliquescent. Readily decomposes on exposure, becoming brown in color; occurs in Kreuznach and Vals water; is less stable than the potassium salt, and therefore more active (Hammond).