82 THE ROYAL SOCIETY OF CANADA 



The Manufacture of Mixed Feeds. Another use that is made of 

 elevator screenings is in the manufacture of mixed feeds, chiefly 

 molasses feeds. Usually it is only the finest weed seeds and smaller 

 pieces of broken wheat and fîax that are used in these feeds. Mills 

 that make a specialty of handling screenings are equipped with clean- 

 ing machinery which separates all the whole kernels of wheat, barley, 

 oats, or flax that the elevators have failed to remove. Straw and chafï 

 are taken out of the screenings at the same time as this separation is 

 made. The material left after these grains are removed is separated 

 into two grades by means of one-fourteenth inch perforated zinc sieve. 

 The material passing over this screen consists largely of wild buck- 

 wheat and broken wheat, but there is often a considerable sprinkling 

 of broken flax and of the larger weed seeds, such as purple cockle, 

 ball mustard, etc. Most of the buckwheat screenings so separated 

 are used with cracked corn, Kafifir corn, barley, wheat, sunflower 

 seed, etc., as chicken feed, although some of it is used in other ways. 

 The seeds of wild mustard and other species of Brassica are separated 

 from the other weed seeds by taking advantage of the fact that they 

 are spherical and will roll if placed on an inclined surface. Before 

 the remaining fine seeds are ready for grinding they have to be put 

 through a reel to remove the fine sand which would otherwise injure 

 the rolls. 



The exact method and the thoroughness with which these seeds 

 are ground varies in the different mills. The grinding is usually done 

 by a combination of one or more rolls such as are used in flour mills, or 

 by an attrition mill. After each "break" {i.e., passage through the 

 roll or attrition mill) the material passes to a reel, which removes the 

 fine material and sends the coarse material on to the next "break" to 

 be still further pulverized. To reduce to a minimum the possibility 

 of the final product containing vital weed seeds, the mesh of the wire 

 gauze used in these reels should be sufficiently fine to prevent the 

 passage through it of the smallest weed seeds found in screenings. 



These ground and bolted screenings are used in the manufacture 

 of molasses feeds, mixed with various other ingredients, such as 

 cottonseed meal, linseed meal, gluten feed, and molasses. Other mills 

 which handle screenings make only the above separations and grind 

 the fine black seeds to sell for use in molasses feeds, in medicinal stock 

 foods, and occasionally for feeding in its natural condition. In its 

 natural condition it does not make a palatable feed because of the 

 presence of certain seeds having a pungent or otherwise disagreeable 

 taste. The mixture of molasses with the feed tends to overcome this 

 difficulty, besides increasing greatly the carbohydrate content of the 

 ration. 



