In making castings, dry sand or loam moulds well coated with charcoal blacking are preferable to green sand moulds; the metal should be well skimmed before pouring, and it should be cast at as low a heat as possible, so long as it is attached to the thickest part of the casting, which, if possible, it should exceed in bulk, so as to solidify the last, and act as a feeder while the cast is cooling. If metallic moulds are employed, the alloy is rendered closer in texture and somewhat harder. Parson's manganese bronze was recently subjected to a series of tests at Woolwich Arsenal, with the following results:-On fracturing an ingot of the alloy, the broken surfaces present a fine and close grain, resembling more nearly the fracture of the best qualities of steel than the coarsely granular appearance of the broken surface of ordinary bronzes. The alloy may be cast or forged, the latter. operation being conducted at a red heat, and haying the effect of considerably increasing its strength and toughness. When cast, the alloy is quite equal in ultimate strength to fair quality wrought-iron, and much superior to best gun-metal. Under the hammer, however, it acquires such qualities that it is virtually a new and valuable metal.

Of the 6 specimens tested, 3 were cast and 3 forged-each series representing 3 different degrees of hardness. The first cast specimen, representing the tough quality, exhibited an ultimate strength of 24 tons per sq. in., an elastic limit of 14 tons, an elongation of 8} per cent. A second specimen of harder quality broke under a load of 22 tons, had an elastic limit of 14 tons, and the elongation amounted to 5 1/2 per cent. The third, of harder quality still, brake at 23 1/2 tons, had an elastic limit of nearly 17 tons, while the elongation was reduced to less than 4 per cent. The extra-ordinary changes produced by the operation of forging will be apparent from an inspection of the following figures, the specimens tested being forged samples of the same quality as the 3 specimens cast above mentioned. The first, or tough quality, when forged, had an ultimate strength of 29 tons, an elastic limit of 12 tons, and the elongation amounted to nearly 32 per cent. The forged specimen of the harder quality had an ultimate strength of nearly 29 tons, the elastic limit being over 13 tons, and the elongation more than 35 1/4 per cent.

With the hardest quality, forging brought the ultimate strength to more than 30} tons, the elastic limit being 12 tons, with an elongation, of 20} per cent.

Some years ago Berthier made several alloys of manganese protoxide and metallic copper in the proportions of 1 to 8, 1 to 4, 1 to 2, and with the manganese slightly in excess of the copper. These alloys were all ductile, the first being perfectly so, while the last, still very ductile, was also very tenacious and capable of taking a fine polish.

Experiments have been made in Paris with a new alloy having a white colour, yet containing no nickel. It is said to be very strong and malleable. It is made of copper and ferro-manganese, the proportions being varied according to the purpose to which the alloy is to be employed. An alloy of 40 parts copper and 60 of ferro-manganese, with a suitable quantity of some appropriate flux, produces a metal of such tenacity that it surpasses the best steel armour-plates. The melted mixture is cast in blocks, and is perfectly malleable. To obtain a white metal that can be rolled out in sheets, the above alloy is melted again, and 20 or 25 per cent. of zinc or white metal added, which imparts to it the desired quality. A plate of the first-named alloy, 2 in. thick, was found by experiment to offer more resistance to a cannon-ball than a steel armour-plate of the same thickness. This new kind of " white bronze " is not to be confounded with the alloy used in America under the same name for gravestones and monuments, and which consists principally of zinc. (Polyt. Notiz.)

While most.experimenters have succeeded in combining manganese and copper in statu nascendi-that is, by simultaneous reduction from their respective oxides-Heusler Brothers, of Dillenburg, recognised a greater advantage in reducing metallic manganese from pure pyrolusite for itself, and afterward alloying it in any required proportion with other metals. The reduction takes place in large plumbago (graphite) crucibles, with an admixture of carbon and of very basic materials, by which, after 6 hours' smelting in a powerful coke fire, " crude manganese " is obtained, this containing 90 to 92 per cent. manganese, 6 to 6.5 carbon, 0.5 to 1.5 iron, and 0.5 to 1*2 silicon. The crude metal can be refined to contain 94 to 95 per cent. manganese when it is remelted with a suitable flux, and this metal contains only combined carbon, while in its crude state graphitic carbon also is almost always present. The refined metal is white, with crystalline fracture, and it oxidizes slowly when exposed to damp air; it is, therefore, soon combined with copper, thus forming " manganese copper," with 70 parts copper and 30 manganese.

The alloy is cast either in ingots or shot, and becomes a commercial article in this state; its fracture is of steel-grey colour and very close, and it is not difficult to combine it in any proportion with other metals or alloys, such as brass, bronze, gun-metal, bell-metal, yellow-metal, and others. The same combination has been found a very powerful "physic" in refining copper, because the manganese will take up all oxygen which is absorbed by the bath of refined copper in the refining furnace before it is made tough, either by an addition of lead or by an insertion of a pole of green wood.

" Manganese German silver" was made from 70 copper, 15 manganese, and 15 zinc; but as this alloy proved rather brittle in the rollers, the proportions were altered to 80 copper, 15 manganese, and 5 zinc, when a beautiful white and ductile metal was obtained, which would take a high polish.