112 FOUNDRY WORK iff I made excellent chargemen and foremen. They only survive in the ranks of the older men. Each department now employs its own sets of hands, producing the same classes of castings the year through. Moulders, like machinists, are specialists. Only in the general jobbing and repair shops do exceptions occur. Foundry Metal.—This includes cast iron in its numerous grades, the steels, malleable cast iron, the immense groups of brasses and bronzes, alloys of copper, aluminium and its alloys, and the varied die-casting alloys. Many of these are now graded by analysis and by the scleroscope, instead of, as of old, by the foreman estimating by the aspect of fractured surfaces, supplemented by test bar results. For melting, the cupola furnace occurs in many excellent designs, with its equipment of fan or blower, blast gauge, platform, weighing machine, receiver or ladles. Brass-melting furnaces are coke-fired, or oil- or electrically-heated, with provisions for utilizing the waste heat. Steels are melted in converters of large and small capacities; malleable cast iron in air furnaces. Sands.—In a foundry equipped with modern appliances, the prepara- tion of sands is done wholly with machinery. It takes charge of them at every stage, drying, crushing, grinding, mixing, sifting, and conveying. Suitable mixtures have to be graded for green, dry, core, and loam sands, and again for light and heavy moulds. They differ also for steel and iron, and facings for the moulds are varied. For this work, a complete mechanical plant is often now installed. The Treatment of Castings.—This, colloquially denoted by the terms " fettling " and " dressing ", engages, in the big advanced foundries, a large quantity of machinery and plant, doing work that was formerly all performed by hand methods. It includes: machines for severing the runners, with chisels or with saws; grinding wheels; pneumatic chisels for the removal of fin marks and roughnesses; tumbling barrels for smoothing castings by attrition; and, in the later plants, sand-blasting machines, now made in many designs to deal with castings of all dimensions. In the more complete plants, dust-exhausting systems of pipes with exhausters are installed. To deal adequately with all the aspects of foundry work outlined in the preceding paragraphs is obviously not practicable. Neither does it seem to be called for. Each single subject is now highly specialized. The foundry craftsman is only directly concerned with and responsible for the preparation of the moulds. The sands are prepared for his use, the metal is graded, suitably melted, and brought to him, the patterns are prepared to be moulded in a certain way, from which no essential departure can be made, and he has no further concern with the castings if they are turned soundly out of the moulds. Bearing these facts in mind, it is proposed to occupy the major portion of this article with the subject of the preparation of moulds required for the metals and alloys, leaving the collateral matters to be dealt with in a summary fashion.