200 METALLURGY OF CAST IRON.
In purchasing pig irons for any new class oi work,
or such as founders are inexperienced with, and that others may be making, it is often a good plan to find out and deal with the furnace which can show dealings with founders making the same class of work which they desire to manufacture if they can. This starts a founder, in making a new class of work, to use brands of iron that have been tested and found suitable for the class of work he desires to produce, and may be the means of preventing some experimenting and loss of capital. IT WAS ADVANCED IN THE FOUNDRY, Nov., 1901, that buyers of foundry pig iron should consider the fracture of pig in being open or close grained in connection with specified analyses. How practical this proposition is will be found by reference to page 179. Methods for computing averages of silicon, sulphur, etc., that exist in different furnace casts or piles of iron, in making mixtures of any special 'brands or different grades, are given in Chapter XXXVI., Tables 39 to 42, pages 256 and 257. The net weight of sand and chill cast pig iron per ton of 2,268 Ibs. and 2,240 Ibs. respectively is given in the first two tables at the close of this work.n. Graphitic Carbon. Phosphorus. Manganese.