11 June, 1917.J The Milling of Wheat. 353 



on rubbing the grind througli the fingers and thumb. The object to be 

 attained here is to have as big a release of flour as possible without 

 impairing its quality, and the settiug of the first two reductions should 

 be made with this purpose iu view. 



After C roll, no fixed method of treatment can be laid down, the flow 

 sheet in every mill varying more or less. A detailed examination would 

 to a great extent be similar for the stock and the working of the 

 rolls. It should bo borne in mind that the stock should be kept as 

 sharp as possible, although it will not l)e practicable to avoid a certain 

 amount of flaking after passing the C roll. As F and I rolls deal with 

 stock of a fibrous and germy nature, aiiy undue pressure, instead of 

 making the yield from the tails better, will cause flaking, which will not 

 only lessen the quantity of flour obtained, but will also lower the colour 

 and affect the keeping quality of the flour. The X or scratch roll is 

 specially designed to treat semolina with pieces of bran adhering. If 

 such were allowed to pass to the smooth rolls without further treatment, 

 it would lower the colour of the flour. This roll has about 32 grooves 

 to the inch, and is run at a differential speed of 2 to 1. This roll 

 requires careful adjustment, for, if set too close, both the pure and the 

 impure stock will be cut up The scratch roll is a valuable addition to 

 the reduction system. By its use the percentage of flour may be in- 

 creased approximately by 2 per cent., and its colour is much better. 



Scalping, Purifying, and Dressing. 



The grind from the bleak rolls are subjected to scalping, purifying, 

 and dressing, in order to prepare the stock for further treatment at the 

 breaks or reductions, as the case may be. 



Scalping is the method by which the semolina, middlings, and flour 

 are separated from the broken wheat, and the separation should be as 

 complete as possible. 



The old method of reels, rotary and centrifugal, have all been found 

 to have shortcomings. In some mills they are still being used, but the 

 tendency is growing of replacing them by the plansifter, largely on 

 account of the more gentle treatment given to the stock and the number 

 of separations it is possible to make on one machine 



The purifiers are nearly all of the sieve pattern. The stock 

 travelling over sieves of different mesh is purified by a current of air 

 drawn up through the sieves. Careful adjustment and attention are 

 necessary to make for good work during the operation. Centrifugals 

 are probably the best all-round flour-dressers. Thev have a tendency 

 to break up flakes, and, where pure stock is used, will dress out more 

 flour. 



The plansifter may be used with advantage on stock from A reduction 

 grind. Througli allowing a greater number of separations, the stock 

 will go to P roll ill a more uniform condition. 



On the breaks the aim should be to separate the endosperm from the 

 bran in as uneontaminated a condition as possible. The chop, on reach- 

 ing the scalpers, is separated at the first operation by means of wire 

 covers, the tailings passing over to the next break for further reduction. 

 The endosperm is graded by means of grit gauze of different mesh into 

 coar.se and fine .semolina, coarse and fine middlings, and flour, .\fter 



5625.-2 



