MAGNE'SIUM AND THE MAGNESIIIII LIGHT. Although the discovery of the metal magnesium was made by Sit H. Davy in 1808, it was looked upon 83 little more than a chemical curiosity for about half a century. In 1830 a French chemist, Bussy, obtained globules of the metal by fusing. globules of potassium, in a glass tube, with anhydrous chloride of magnesium. Bussy's labors were followed by somewhat improved methods, adopted by Bunsen, and subsequently by Mattliiesseu, who succeeded in pressing some grains of the metal into wire. The first great advance on Bussy's labors was in 1856, when Deville and Caron effected the reduction of the pure chloride of magnesium by °nixing it with fused chloride of sodium in clay crucibles, using fluoride of calcium as :a flux, and throwing in fragments of sodium; they thus obtained magnesium on a !larger scale than any of their predecessors. The most important part of their investi gations was the discovery of the volatility of the metal. All these were, however, mere laboratory experiments. In 1859 Bunsen of Heidelberg, and Roscoe (now of Manches tel.), published a memoir on the great importance of magnesium for photographic pur poses, owing to the high refrangibility and the great actinic power of the light emitted by burning magnesium-wire. The study of this memoir led 3Ir. Sonstadt to consider whether, the magnesian salts being so abundant, the metal might not be obtained, on a comparatively large scale, at a moderate price. After a prolonged series of expensive 4experiments he succeeded, in 1862, in producing specimens of the metal varying from the size of a pin's head to that of a hen's egg. Although it burned freely enough, it -was still wanting in ductility and malleability, in consequence of the presence of certain dinpurities; but by May, 1863, these difficulties were overcome by a process of purifica .tion by distillation; and by the close of that year he considered it safe to begin mann lacturing. The magnesium metal company was consequently organized, and operations •commenced at Manchester, where magnesium is now made on a considerable scale, as well as by an American magnesium company at Boston. One great advantage of Son -stadt's method is its simplicity; it can be accomplished by the hands of ordinary work men ignorant of all chemical knowledge. The process of manufacture may be thus described: 1. An anhydrous chloride of magnesium is prepared by saturating lumps of lock-magnesia (carbonate of magnesia) with hydrochloric acid, and then evaporating the solution to dryness. 2. One part of metallic sodium cut in small pieces is placed in an dron.crucible, and covered with five parts of the chloride. The crucible is covered, and
dieated to redness, when the chlorine leaves the magnesium and unites with the sodium, lor which it has a stronger affinity. When the crucible has cooled, and its contents are iremoved eamasse, and broken, the magnesium—in that state known as crude magne sium—is seen in nuggets of various sizes, varying from granules to masses as large as a hen's egg. 3. The distillation of the crude metal is effected in a crucible through which a tube ascends to within an inch of the lid. The tube opens at the bottom into an iron placed beneath the bars of the furnace, where, on the completion of the opera tion, magnesium is found in the form of a heap of drippings, which may be melted :and.cast into ingots or any desired form. The difficulty of obtaining a metal with so .little ductility in the form of wire—the only form that was originally used for yielding light—had still to be overcome; and after various partially successful attempts to press :small quantities into wire by Matthiessen and others, Mr. Mather of Salford devised a ipiece of machinery by which the metal is pressed into wire of various thickness. Mr. _Mather also was the first who obtained the metal in ribbons, in which form, from the ilarger exposed surface, corabustion takes place more completely. The apparatus for imaking the wire and ribbon is very ingenious. " The chief feature of it is a small 'hollow cylinder, adapted to receive a ram at one end, and covered at the other by an iron screen perforated with two or more holes opposite the chamber. This press, as the cylinder is called, is subjected to the action of gas from a blow-pipe, and the heat ,employed is only- sufficient to soften the metal in the press. The pieces of magnesium .are thrust into the chamber, the ram is placed in the mouth of the press, and a pressure .of between two and three tons—obtained by hydraulic apparatus or by steam—forces ithe ram against the softened metal, and the latter oozes in continuous strings of wire through the perforations already named. To make ribbon, the wire thus obtained is ;passed between two hollow heated rollers, and is received in a flattened state upon a .reel."—Richardson, & Watts's Chemical 7echnology. To Mr. Mather is also due the credit •of having constructed the first magnesium lamp, in which the end of the wire or rib ibon is presented to the flame of a spirit-lamp. A concave reflector sent the light for ward, and protected the eyes of the operator.