Downloaded from PORTLAND CEMENT MANUFACTURE. 47 into large reservoirs or "backs," and allowed to settle; it is then dried, and afterwards calcined a t a high temperature, and eventually ground between millstones to the requisite fineness. In Fig. 10 , Plate 6, is shown a general plan of works erected to turn out 360 tons of Portland cement per week. Wash Xilk aBd Elevatms.-The wash mill, shown in Fig. 1 , Plate 2, is a circular pan about 18 ft. diameter and 4 ft. deep, usually built of brick,

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... th a brick bottom, sunk into the ground and puddled on the outside. On one side of the pan is an opening,