process is applicable only to the hardest wheats, and is partially supplanted by roller-milling.
In roller-milling, wheat is subjected to action of a pair of steel or chilled-iron horizontal rollers, having toothed surfaces. They revolve in opposite directions, at different rates of speed, and have a cutting action.
Porcelain rollers, with rough surfaces, are sometimes employed. In this system, grinding is accomplished by cutting rather than crushing.
"The disintegrator consists of a pair of circular metal disks, set face to face, studded with circles of projecting bars so arranged that circles of bars on one disk alternate with those of the other. The disks are mounted on the same centre, and so closely set to one another that projecting bars of one disk come quite close to plane surface of the other. They are inclosed within an external casing. The disks are caused to rotate in opposite directions with great rapidity, and the grain is almost instantaneously reduced to a powder."
After grinding comes bolting, by which process the different grades of flour are obtained. The ground wheat is placed in octagonal cylinders (covered with silk or linen bolting-cloth of different degrees of fineness), which are allowed to rotate, thus forcing the wheat through. The flour from first siftings contains the largest percentage of gluten.
Flour is branded under different names to suit manufacturer or dealer. In consequence, the same wheat, milled by the same process, makes flour which is sold under different names.
In buying flour, whether bread or pastry, select the best kept by your grocer. Some of the well-known brands of bread flour are King Arthur, Swan's Down, Bridal Veil, Columbia, Washburn's Extra, and Pillbury's Best; of pastry, Best St. Louis. Bread flour should be used in all cases where yeast is called for, with few exceptions; in other cases, pastry flour. The difference between bread and pastry flour may be readily determined. Take bread flour in the hand, close hand tightly, then open, and flour will not
