198 METALLURGY OF CAST IRON.
gating, pouring, etc. The grand point about all this is the practicability of its achievement by any ordinary mind that will make any effort to master this new science of founding.
A description of the methods followed at our foundry in Sharpsville, Pa., for delivering pig iron to the cupola and keeping a record of our heats, etc., may serve many well in giving them ideas to form plans for such work. Our pig iron, in being loaded from cars or iron piles in the yard, is placed on buggies and then pushed to the elevator by a locomotive or hand power, after which it is carried to the cupola stage and stored in piles after the plan described on pages 141 and 142. A record of the silicon, sulphur, etc., contents of each pile is kept by the cupola tender, so that he knows just what iron to charge. We make a specialty of castings that now require heats ranging from seventy to one hundred tons weight. Our castings are of such -a character as to exact certain physical qualities. To know that they are right in our castings before leaving our shop, we have analyses of the silicon and sulphur, and occasionally of the other metalloids made for every heat; and when first starting to make these analyses we also conducted physical tests. A plan for obtaining both combined is shown by Tables 28 and 29. We largely dispense now with the physical test, owing to our experience being such as to enable us to judge of the physical properties by reason of chemical analysis and an examination of the castings. The tests given in Tables 28 and 29 were obtained from four round test bars cast on end at about equal divisions of the heat. The mixture for the heat here recorded was all pig iron, excepting about 5 per cent, shop scrap, the pig rangingan-