CONSTANT AND CHANGEABLE METALLOIDS, ETC. 133
tons or more of any certain grade of iron over 1.50 in silicon from a furnace that is trying to make it, and no stock of iron in that special furnace yard to draw from. Anybody placed in this position might soon be forced to realize by reason of waiting for the shipments they desired, that furnacemen cannot, as yet, always perfectly control a furnace to obtain the grade they desire at every cast.ccasions, of manganese and phosphorus varying to an effective degree from similar ores, and then again a change in the total carbon to alter the grade of an iron, it may often pay those who are manufacturing castings, where such changes as above would seriously affect their iron, to always have an analysis of the total carbon, manganese, and phosphorus in connection with the silicon and sulphur. There is one thing to be remembered and that is, that a furnaceman has far less difficulty in obtaining a uniform grade when making low silicon irons, or that under 1.50, than above this percentage; and also that there is much more difficulty in obtaining a uniform grade in very hot weather, due to humidity of the air, |