196 METALLURGY OF CAST IRON.
with the drillings. To prevent this the pigs should be thoroughly cleaned with a wire "brush before being taken to the drill press, where they should be drilled with a flat drill, as a twist drill gives a large variation in the size of borings according as the hardness of the iron varies. Some drill six to ten holes to obtain samples as at A, others drill three holes as at B, while others drill but -one hole in the center as at C. Where it is desired to obtain the best possible average of the composition of a piece of pig in securing drillings, the plan seen at A is followed. It may be said that, as a rule, the majority of samples are taken as at C, unless analyses of the carbons are required, when it is very essential to follow the plan at A or B. In drilling as at A or B the material from each hole should be kept separate, and after the drilling is completed the same weight of drillings from each hole should be taken, and the whole mixed together as thoroughly as possible to obtain an average of the composition of the pig. For each analysis about a large teaspoonful of drillings is ample, and such are best passed through a 20- or 4o-mesh sieve before being used. To do this it may often be necessary to pulverize the drillings in an iron mortar. It is very important to properly sample a car or pile of iron and take proper precaution in obtaining a clean and thoroughly mixed sample of drillings, where one wishes an accurate analysis to show the average composition of a car or pile of pig iron.
The small foundry finds this method, necessary to check furnace reports of analyses, objectionable. This is on account of such founders not being in a position to support a laboratory. However, many small shops would find that it would pay them, in the end, toovidence, R. I."e Co., Wisconsin Malleable Iron Co,, VWstin-house Air 13rakc Co,, Votingstown Steel Co., Vale University. & Sons, Hecla Works, England; R. C. Hindiey, M. Hoskins, Harvard College, Havemeyer University, Henry Hiels Chemical Co., Isabella Furnace, Iron Gate Furnace, Iroquois Iron Co., Illinois Steel Co., Jefferson Iron Co., Kittan-ning Iron & Steel Co., C. A. Kelly Plow Co., Lebanon Furnace, Longdale Iron Co., Lackawanna Iron & Steel Co., Logan Iron........................ 16,720 " t-