8 Grain Screenings. 



Composition of Screenings. 



Elevator screenings are so variable in composition that to get 

 an idea of what on the average constitutes screenings, a composite 

 sample representing thousands of tons should be examined. 



Following is the analysis of such a sample representing 6,000 tons 

 of screening from the 1912 crop, as shipped from various elevators 

 at two or three different periods of the year from Fort William and 

 Port Arthur to Buffalo, Chicago, and Duluth: — 



37 per cent scalpings, 



7 per cent succotash flax. 

 18 per cent buckwheat screenings. 



38 per cent black seeds. 



Scalpings consist of the larger grains and weed seeds in the 

 screenings in the following proportions by weight; 65 per cent wheat; 

 25 per cent wild oats, oats, flax, and barley; 3 per cent weed seeds 

 (wild buckwheat, lamb's quarters, stickseed, ball mustard, prairie 

 rose, wolfberry, great ragweed, cow cockle) ; 7 per cent straw, chaff, etc. 



Succotash flax is made up of 30 per cent flax; 40 per cent broken 

 wheat; 15 per cent weed seeds (wild buckwheat, stickseed, lamb's 

 quarters, wild oats, false flax, American dragonhead, lady's thumb, 

 knotweed, sunflower, purple cockle, ball mustard, hare's-ear mustard 

 hemp nettle, roadside thistle, prairie rose) ; and 15 per cent chaff, etc. 



Buckwheat screenings consist of 58 per cent wild buckwheat; 

 29 per cent wheat, oats, and flax; 9 per cent weed seeds (ball mustard, 

 stickseed, wild oats, cow cockle, purple cockle, ragweed, stinkweed, 

 hare's-ear mustard, western false flax, Russian thistle, prairie 

 rose); and 4 per cent chaff, etc. 



Black seeds are composed of the finer weed seeds separated from 

 the screenings by the use of the 1-14 inch perforated zinc screen. 

 This material contains about 45 per cent lamb's quarters; 4 per 

 cent tumbling mustard; 2| per cent wild mustard; 62 per cent of other 

 mustards (western false flax, hare's-ear mustard, stinkweed, worm- 

 seed mustard, shepherd's purse, peppergrass) ; 8 J per cent other weed 

 seeds (American dragonhead, hedge nettle, stickseed, green foxtail, 

 Russian pigweed, sow thistle, catchfly, roadside thistle, Canada 

 thistle, wormwood, cinquefoil, evening primrose, pale plantain, witch 

 grass) ; and 33^ per cent dust and chaff. 



COMMERCIAL SEPARATIONS. 



The above separations were made by hand screens, but correspond 

 fairly closely to the commercial separations made by the screening 

 separators in use in most terminal elevators. 



The scalpings include everything that does not pass through 

 a zinc screen with triangular perforations nine-sixty-fourths of an 

 inch to the side. Sometimes in elevators only two separations are 

 made of the cleanings as taken from the grain, scalpings and black 

 seeds. The scalpings will then contain both the buckwheat screenings 

 and succotash flax. Moreover, scalpings are often further cleaned to 



