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CHEMICAL AND PHYSICAL PROPERTIES OF CAST IRON.
Without chemistry we could not define elements causing physical effects or be able to scientifically and intelligently direct mixtures. The physical test tells us what is obtained. The chemical test tells us the metalloids we must use to effect results, and each property is essential to an attainment of the desired end. The first to be noted is carbon, as its influence in the form of graphite or combined carbon is the greatest in determining the character or '' grade '' of cast iron.
The amount of carbon which iron will absorb depends upon the working conditions of a furnace and the amount of silicon, phosphorus and manganese taken up by the iron. Much silicon reduces the power of iron to absorb carbon. The greater the percentage of manganese the more carbon can iron absorb, as is shown by *' Spiegel' * iron, which contains carbon as high as six per cent. When iron is below .75 in manganese, about 3.50 of carbon is all it contains, although it may possess as much as 4.50 per cent, of carbon in rare cases. It is claimed that chromium, when substituted for manganese, will cause iron to absorb carbon as high as 12 per cent. The carbon in iron is ob- division of elements among iron workers is more generally understood in being classed as metals and metalloids, the latter being limited to inflammable non-metallic elements, and which as a rule are lighter, bulk for bulk, than metals. With this conception of the elements, we can consider iron, "manganese, and silicon as being metals, while the carbon, sulphur and phosphorus would be classed as metalloids. While this classification may be accepted, it is for convenience, with founders especially, considered that the term. about 5 per cent, shop scrap, the pig rangingan-