The bromine in the Woulfe's bottle ia always more or less contaminated with chlorine, bromide of lead (formed in the oondensing worrn), and other substances; it must, therefore, be refined or rectified before it is fit for use. This rectification is effected by redistilling the bromine in large, glass, tubulated retorts, the necks of which are luted into glass receivers; the ineondensable portion is carried from the receiver into a Woulfe's bottle, containing caustic potash or soda solution, and thence into a vessel containing moist irou filings. The retorts are heated by means of sand baths ; these have double sides, between which steam is passed. The first products of the several retorts contain much chlorine ; they are, therefore, mixed together, and redistilled in the sarne manner. When this portion has been removed, pure bromine distils over, and is collected in other receivers. From these, the bromine is run off into glass cylinders, having a cock near the bottom, by means of which it is transferred into the final receptacles—strong glass bottles, fitted with ground glass stoppers, and holding from 4 to 5 lb. of bromine. The stoppers are coated on the outside with rosin, over which is placed a layer of c!ay luting secured with parchment paper. Four of these bottles are packed in a wooden box of four compartments. For the transport of bromine by sea, Frank evaporates a, solution of ferrous bromide to dryness, and packs the dried salt in bottles. When required for use, the salt is dissolved in water, and chlorine gas is passed through the solution in order to liberate the bromine. By this means, all danger of leakage or of loss frorn broken bottles is avoided. The bromine made in this way at Stassfurt has an advantage over all ether kinds of commercial bromine in that it is entirely free from iodine.
In 1866, a patent xv,,s taken out by Leisler for obtaining bromine from the mother-liquer left by operations with kainite or earnallite, or from the water of the Dead Sea, which contains, according to an analysis by Lartet, in 1 litre, taken from a depth of 300 metres, 7'093 grm. (0'7 per cent.) of bromine. In this process, bichromate of potash and an acid are added ; heat is applied, the bromine is volatilized, and is collected in a condenser filled with iron or steel filings. The means employed is a distilling apparatus ; the acid used is hydrochloric, diluted with four times its volume of water. To 100 parts by bulk of the mother-liquor, 1 part of the acid is added, the bichromate being intro duced as a saturated aqueous solution. The bromide of iron formed is dissolved by the aqueous vapour, and is condensed in the receiver. From it, bromine or any of its compounds may be obtained.
The mother-liquor of varee contains iodine and bromine in about the proportions of 8 parts of the former to 1 part of the latter. In order to obtain bromine from this source, the iodine must first be separated. This may be effected by throwing down the iodine, either by passing chlorine gas through the liquor till a sample taken out gives no precipitate with chlorine water or iodide of potassium ; or it may be separated as flee iodine and iodide of copper by adding sulphate of copper. The liquor, after this treatment, is mixed with peroxide of manganese and strong snlphuric acid, the pmportions being first determined by experiment with srnall quantities, and the mixture is distilled precisely in the same way as in Frank's process, already described.
Another method of purifying commercial bromine consists in saturating it with baryta, or hydrate of barium. By this means, the chlorine contained in the impure bromine is converted into chloride and hydroehlorite of baryta, and the bromine itself into bromide and brornate of baryta. The mixture is evaporated and ignited, in order to decompose the oxygen salts, and the residue is treated with alcohol, which dissolves the bromide of baryta and ltaves the chloride. The pure bromide is then distilled with manganese and sulphuric acid in order to obtain bromine.
Bromine in the form of bromide of potassium is used as a medicine, its medicinal properties being very similar to tl.ose of iodine. It is also administered in the form of an aqueous solution, composed of 1 part of bromine to 40 parts of water, in cases of serofula and similar diseases ; five or six drops is the common dose. The solution is used also as a lotion. Bromide of potassium is ex tensively used in photography. Bromine itself is sornetimes employed as a disinfectant. Its use in the preparation of aniline dyes, in the form of bromides of ethyl, amyl, -and methyl, has now been almost superseded. According to Reichardt, bromine may with advantage be substituted for chlorine in the manufacture of potassium ferrieyanide.
The total annual production of bromine in Europe and America amounts to about 1150 ewt., of which 400 cwt. are made at Stassfurt, and 300 cwt. in Scotland, from the mother-liquor of varee.
(Sorghwre dura.) Broom-corn is a species of grass whicli is largely cultivated in the United States, for the manu facture of brooms. It is closely allied to the Sorghum sacch,aratum, a sugar-yielding grass, which is another variety of the same species. Broom-corn WRS originally brought to the United States from the East Indies, and its cultivation has since rapidly extended in North America. It is cultivated for its " brush," tbe dried panicles cleared of the seed. The grain is used for feeding cattle and poultry. The stalks make a good manure, and are sometimes employed as fodder. Large quantities of the brootn-corn " brush " are imported into this country, chiefly for making carpet-brooms and clothes-brushes.
The corn used in this manufacture is grown principally in the valleya of the Mohawk and the Connecticut. The soil of the bottoms along theae rivera posaesses certain characteriatics highly favourable to the growth of thia agricultural product Although the labour attending ita cultivation ia gredt, it is considered a valuable crop, being More hardy than maize, and less liable to injury from frost. It was a good deal cultivated in the Geneaee Valley some yeare ago, and is still to some extent ; but the product goea to supply western and local markets. The crop has become one of the most decided importance, and it will no doubt attract the attention of farmers more generally than it has done; while to its manufacture into brooma, mechanical ingenuity and capital will be turned. In 1860, 2585 tona of broom-eorn, worth 85 dollars a ton, were sent away from Chicag,o.