52 EARTH COLOURS entailing increased motive power, not inconsiderable wear, and a higher prime cost; but in this instance the object is achieved, without extra power or wear, by very simple means. The dust-proof shell enclosing the runners and screen is provided with large doors and charging… … FIG. 7. The motive power required to drive edge-runner mills depends on the dimensions of the mill and on the class of material to be treated; the larger the mill and the coarser the material, the more power needed to drive it. This type is the more suitable for raw materials that are of an earthy…
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Internet Archive · Gerstein - University of Toronto · Public domain (published before 1931). Free to use for anything.
