lS4 METALLURGY OF CAST IRON.
reason, a well-known writer has aptly said that the establishing and maintaining of a central standardizing agency is properly foundrymen's work. As the making of these castings involves principles of founding interesting to many, we illustrate the plan used, which is as follows: A mold of dry sand, for the outer body and a dried core for the inner, are made as seen in the plan and section view of Figs. 44 and 46. The construction of the mold explains itself. The secret of getting a clean, solid casting lies mainly in the method of gating and pouring it. At A is a gate leading down to the bottom of the mold at an inlet at D. The round gates B, seen at the top of the mold, are placed about four inches apart and are one-half inch in diameter. A riser is seen at E. In starting to pour the mould, the molten metal is directed to drop from the ladle into the basin at the point marked W, in a way that will allow it to flow gently down the gate A and enter the mould at D to prevent the bottom being cut by the top gates. When from thirty to fifty pounds of metal has entered the mould, a quick turn of the ladle empties a large body of the metal into the pouring basin, quickly filling all the gates at B; this then drops the metal down upon that which is rising from the stream flowing in at D. This action is kept up until the mould is filled and the metal runs out at the riser E. After this point is attained, the pouring is slackened and a steady stream maintained until from three hundred to five hundred pounds of metal has flown through the riser E to run down the incline seen at S into the scrap hole X. The effect of allowing such a large body of metal to flow through the mould by making it enter the gate at A is to keep up an agita-ing only open or close grained iron in connection with exacting any certain specified analyses from blast furnaces, as the slight difference possible in the most radical cases of open and close grained iron can be regulated by a slight variation in silicon when making a mixture, and which anyone can easily do, if they so desire, "