Scientific American Supplement, No. 620, page 49 by Various Authors
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volving furnace or cylinder:
Per cent. Carbonic acid, anhydrous 0.4 Sulphuric acid, anhydrous 0.26 Silica soluble 24.68 Silica insoluble 0.6 Alumina and oxide of iron 10.56 Lime 61.48 Magnesia, water, and alkalies 2.02 ------ 100
Again, fineness of the particles results in their being speedily heated to a uniform temperature, so that they do not serve as nuclei for the condensation of the moisture existing in the furnace gas. The calcined material, on reaching the lower end of the furnace, is discharged on to the floor or on to a suitable "conveyer," and removed to a convenient locality for cooling and subsequent grinding or finishing. It, however, is not in the condition of hard, heavy clinkers, such as are produced in the ordinary cement kiln, which require special machinery for breaking up into smaller pieces before being admitted between the millstones for the final process of grinding; nor does it consist of an overburnt exterior and an underburnt core or center portion; but it issues from the cylindrical furnace in a condition resembling in appearance coarse gunpowder, with occasional agglutinations of small friable particles readily reduced to fine powder in an ordinary mill, requiring but small power to work, and producing but little wear and tear upon the millstones. The operation is continuous. The revolver or furnace, once started, works on night and day, receiving the adjusted quantity of powdered material at the upper or feed end, and delivering its equivalent in properly burnt cement at the opposite end, thus effecting a great saving of time, and preventing the enormous waste of heat and serious injury to the brickwork, etc., incidental to the cooling down, withdrawing the charge, and reloading the ordinary kiln.
Cement, when taken from the furnace, weighed 110 lb. per bushel. Cement, when ground, leaving 10 percent. on sieve with 2,500 holes to the inch, weighed 121 lb. per bushel, and when cold 118 lb. per bushel. When made into briquettes, the tensile breaking strain upon the