After the pots are taken out, they are dumped, the castings taken from the scale and the former sent to the soft tumbling room. Here they are packed with small pieces of an nealed malleable castings, or with wood and leather, such as old shoes, etc., so that the adhering scale is removed, and a fine coat of graphite is given them. They come out shining black, and can be shipped direct, or else coated with asphalt, as required. Sometimes the cast ings must be straightened which should always be done cold, either by drop hammer or hydrau lic press. Test plugs are usually cast on the important work, so that breaking these off on inspection the quality of the metal in the par ticular casting is revealed at a glance. Test bars for physical test should also be taken off with the first and last portion of every heat, so that all work from that heat can be traced and its quality known. The test bar has the further advantage of showing up the condition of the furnace, poor working on the part of which is immediately detected by a white rim on the casting.
The production of malleable castings in this country runs up to the enormous figure of 1, 000,000 tons annually. In Europe about 75,000 tons are made in the same time. Most of the large companies now make steel castings in ad dition, as malleable cast iron, though most ex cellent for shock, is not strong enough to stand under the terrific strains that are now put on the structures where this work is used. Thus the 100,000-pound cars now require steel couplers, as the malleable ones tear apart, yet the latter will stand all the bumping that comes along while steel will not. The principal use for malleable castings is for railroad work. Next comes agricultural machinery. After that a great variety of work, such as pipe fittings, hardware, machine parts, chain links, tools, etc. The demand is constantly growing, and while steel was supposed to be replacing the malleable casting, this has not turned out to be the case.