I J.' t 



luction or 



USES OF CEREALS 549 



ual reduction of the endosperm and the elimination of the branny 

 coat and^the germ. The cleaned and tempered grain is passed 

 through between pairs of chilled iron rolls, which gradually reduce 

 the particles to smaller sizes. The first pairs of rolls used contain 

 fine grooves on the surface and are called corrugated rolls. There 

 are usually from 3 to 5 pairs of these, and they are referred to as 

 the "break" rolls. One roll of each pair turns about two and one 

 half times faster than the other, consequently this gives a sort of 

 tearing motion instead of simply crushing or squeezing the particles. 



Scalping and grading. Each time after passing between a pair 

 of rolls the "stock" (partially ground product) is sent through spouts 

 to a sifter, where sieves of different meshes separate the particles 

 according to size. This is called scalping and grading. The largest 

 particles are "scalped off " ; that is, do not go through the top sieve, 

 but pass over the lower end to the next pair of rolls. After the 

 coarser branny particles have passed through several pairs of corru- 

 gated rolls, usually from 3 to 5, the endosperm is practically all 

 removed and the finished flakes of bran scalp off. 



Purifying. The smaller particles from the inner portion of the 

 kernel are separated according to size by the other sieves, and those 

 small enough to go through the fine silk bolting cloth are called flour, 

 while those larger and granular, more closely resembling corn meal, 

 are separated out and called "middlings." These are passed through 

 machines, called purifiers, where light suction currents of air lift 

 off the light branny particles and fluffy cellulose matter, until we 

 have left "purified middlings." 



Reducing. Next comes the gradual reduction of these middlings 

 until they become fine enough for flour. This is done by passing 

 the stock between pairs of smooth rolls, each pair being set a little 

 closer together so as to grind a little finer, and every time the stock 

 is ground by a pair of rolls it is conveyed to a machine which sepa- 

 rates out the fine flour. This may be done on what are called reels 

 or flour dressers, hence the last step, "flour dressing." 



593. Illustrating the process. The accompanying 

 diagram (Fig. 169) of a typical mill is inserted to make 

 more clear, perhaps, the arrangement of apparatus and 

 the passage of the grain from one machine to another 

 through the different steps. Such a diagram, showing the 



