SULPHUR BLEACHING OF COMMERCIAL OATS AND BARLEY. 5 



As practiced com- 

 mercially, sulphur is 

 burned in a furnace 

 or oven located some 

 distance from the 

 bleach in<y tower as a 

 precaution against 

 tire. The burning 

 sulphur coming in 

 contact with the oxy- 

 gen of the air forms 

 sulphur-dioxid gas, 

 which is forced into 

 th'e bleaching tower 

 8 or 10 feet from its 

 base through a pipe 

 leading from the fur- 

 nace. 



In order that the 

 bleaching may be ac- 

 complished this sul- 

 phur-dioxid gas must 

 come in contact with 

 water and unite with 

 it, in which case it 

 forms sulphurous 

 acid, which is the 

 bleaching agent. 

 For this reason the 

 grain, as it passes 

 into the bleaching 

 tower at the top, 

 is dampened with 

 either a jet of steam 

 or small spra3^s of 

 water. The sulphur- 

 dioxid gas, circulat- 

 ing upward, unites 

 with the moisture 

 adhering to the out- 

 side of the down- 

 ward-moving grain, 

 thereby making the 

 bleaching possible. 



[Cir. 74] 



Fig. 1.— A common type of tower or chimney grain bleacher. 



A, Elevator leg which conveys grain from elevator to bleacher; 



B, steam jets which moisten grain; C, first break for stream of 

 grain; V, deflecting shelves; E, pipe wliich conveys sulphur di- 

 oxid to bleacher; F, steam jet which creates suction draft in sul- 

 phur pipe; G, glass gauge through which height of grain in the 

 tower is observed; H, regulator for grain outlet; /, screw con- 

 veyor which returns grain to elevator; J, landing on tower; A', 

 door opening into tower for purpose of cleaning grain break; 

 L, sulphur furnace in which the sulphur dioxid is generated; 

 M, pocket in which grain accumulates, allowing better action 

 of sulphur dioxid. 



