used, and some of them are covered by patents. Some of the advantages claimed for patent ovens are in the recovery of by-products and in saving labor and obtaining a greater yield of coke from the same amount of coal.
The main principle in coking lies in admitting the air to support combustion at or over the surface, instead of causing it to pass through the coal as in burning fuel for firing boilers, etc., thus being an action of distillation more than -of combustion. This prevents destruction of the coal while burning, and causes it to " cake '' and become the coke of industrial commerce.
The kind of ovens generally used In America is the bee-hive oven, as illustrated in Fig. i, page 8. Ovens are generally built from ten and one-half to twelve feet in diameter and from five to eight feet in height. The standard size is twelve feet in diameter and from six to eight feet high. Some are built on the plan seen in Fig. i. The interior of the oven is fire-brick, and the space between the ovens is packed with clay or loam. Pillars, as at K, are used for the support of the larries on the track B, so as to take their weight from the arch, of the ovens. The outside of the ovens, as at S, are built of stone and made very strong. The filling is clay or loam, and the floor X is composed of tile fire-brick.
Coal is sometimes coked in mounds, heaps, or piles similar to the method used for making charcoal of wood. It was by such method that coke was first made. By such methods of coking the coal must be chiefly in lumps, and piled in such a manner as to leave all the air space that is practical through theron ' which cannot fail to interest foundrymen r and engineers, touching, as it does, upon every stage | from melting to the test bar. The work is of a kind |. that can come only from the practical founder about matters seldom found in print, because practical foun- I dry men of Mr. West's attainments are, as yet, a rarity/" v<Ľundrymen*:. Association's Test:"., . . ... 539