APPENDIX TO CHAPTER LIV.----SHRINKAGE, ETC. 413 ing nearly eight pounds, a shrinkage in the chilled iron of about six ounces, and in the gray about two ounces. This means a shrinkage of about four and a half pounds per hundred for all chilled iron, and nearly two pounds per hundred for all gray iron. In larger FIG. 86.- -CONTRACTION TEST WITH CHILL AND SAND MOLDS, AND PATTERNS. figures, for example, with a twenty-ton casting, Table 86, would imply a shrinkage of about 1,800 pounds for all chilled iron were it possible for all of its body to be as thoroughly chilled as is the section of rolls seen in Fig. 62, page 337, and 800 pounds for the gray iron if the total body of the casting does not get up in graphite any higher than the rolls hold it,-as seen in Fig. 61, page 333.hrinkage, which takes place as the metal is being poured, and the portion at E, which is irregular in outline, is that created by the shrinkage of the molten metal in cooling to a solid, to leave a cavity in the main body of the roll as seen at the right of Fig. 63, page 338, after the moulds have been poured and are released by splitting the end of the roll at K. The piece at E is the other end up from that shown before being removed from the roll K. A little study of the sections E and H will show that their total weight (by fine apothecary scales), minus any thin wafer sheets of iron that might be found sticking to the walls of the dry sand mould, that had not run out as metal to test the shrinkage, would be the shrinkage of that iron under the conditions in which it had been poured.