Indeed, the mechanical appliances for finishing and adjusting different parts, comprise one of the most interesting departments of the works, with their planting machines, lathes, punches, screw-cutting tools, grinding and polishing stones, and drills which allow of the drilling of several holes in the same piece at the same time, and at various angles.

The pig iron used preferably for malleable castings is a white charcoal pig, and is melted in cupolas, or in a reverberatory furnace (picture below).

This latter furnace, of which A is the fire-place, B the hearth, 0 the tap-hole, D the flue towards the stack, and E the door through which the impurities are removed from the top of the molten metal, consumes more fuel, and produces more waste than the cupola. On the other hand, the metal is purer, because it is not melted in direct contact with the fuel, and does not absorb its impurities, sulphur especially. There is also the advantage that, should the metal contain too much carbon, part of it may be removed by the oxidizing action of the flame.

Most of the castings are made in green sand, from metallic patterns, which insure constancy of shape and of smooth surfaces.

The castings, which are as brittle as glass, are then put into "tumblers," which are revolving cylinders of cast-iron with ribs inside, in which the articles are deprived of adhering sand, and become polished by mutual friction.

The cleaned castings, intended for conversion into malleable iron, are next packed close, with alternate layers of powdered iron scales from rolling-mills, into rectangular cast-iron boxes D (engraving below), which become of a rather elliptic shape, after a certain length of use, and which can be placed one upon top of the other, if need be, and closed at the top by a mixture of sand and clay which prevents contact with the air, and follows the settling of the mass.

Engraving above represents the disposition of the annealing furnace, which resembles those employed for making the bone-black of sugar refineries. A is the fire-place, B a flue conducting the flame into the annealing chamber C; and D D D are the cast iron boxes filled with the iron scales and the articles to be softened.

Leaving aside the time necessary for raising the temperature, and the cooling off, the articles are subjected for about a week to a white heat, not sufficient, however, to melt what may still remain of cast-iron.

After a proper annealing, the castings are covered with a film of oxide of iridescent colors - the yellow and azure blue predominating - which resembles that kind of Champlain iron ore called peacock, on account of its coloration.

Any adherent oxide is removed by another passage through the "tumblers," and the process of malleable iron making is finished. Any further grinding, polishing, boring, and adjusting which may be needed, is made in the same works.

The oxide of iron, or scales, employed, have parted with a portion of their oxygen during the annealing process, and the loss is made good by grinding the scales, and rusting them with a solution of sal ammoniac (hydrochlorate of ammonia).

It seems to us possible to do without the expense of sal ammoniac, by wetting the powdered scales several times with water, stirring and drying them on the top of the annealing furnace.

Among the products manufactured by the above mentioned firm, we have noticed hinges, entirely of cast-iron, and others with wrought iron pivots; patent elastic washers for railroad fish-plates, which prevent the nut from unscrewing, and keep it tight; castors for furniture, bolts, pulleys for cords of window sashes, keys, padlocks, screw presses, carriage parts, saddlery hardware, &c. &c. In fact, it would be necessary to make a catalogue with an index, of all of the patterns which were shown to us.

It is difficult to state the cost of malleable iron castings, since it depends to a great extent upon the size and the quantity of the articles. We may say, however, that being given a certain pattern, the malleable iron castings will cost from 70 to 80 per cent, more than ordinary castings from the same pattern. This increase of price is necessitated by more labor, the consumption of fuel for annealing, greater cost of pig metal employed, &c. &c.

To sum up, malleable iron castings are useful, whenever equal strength of material being not needed, the cost in labor, if made of wrought iron, would be too great; or when a casting is needed without the brittleness of common cast iron.

Scissors, sewing-machine parts, the butt-ends and guards, and many other parts of gun locks, ornaments, &c. &c, are made in quantities from malleable iron castings. Even nails, of all sizes, are thus manufactured in England, and we are disposed to believe that, if made of good metal and well annealed, they may be at least equal to certain cut-nails produced from inferior plate, and the fiber of which has been broken by the concussion of the cutting machine.

Oxide of zinc has been proposed as a substitute for oxide of iron, under the plea that the operation is more rapid.