6 SULPHUR BLEACHING OF COMMERCIAL OATS AND BARLEY. 



The base of the tower bleacher forms a pocket in which the grain 

 is allowed to accumulate to a point underneath the inlet for the sul- 

 phur dioxid. Owing to the accumulation of the grain in this pocket, 

 better action of the sulphurous acid upon the stained and discolored 

 grain is afforded by lengthening the time it is confined in the bleacher. 

 With this method of bleaching, the grain is in the tower about two or 

 three minutes. 



After treatment in the bleaching tower the grain is returned to the 

 elevator bins, where it is customarily left from 24 to 48 hours, and 

 where a large part of the actual bleaching takes place. If one bleach- 

 ing fails to produce the desired result, the process is repeated. 



Before loading for shipment, the grain thus treated is "run" or 

 "handled" in the elevator for the purpose of cooling it and also to 

 remove the sulphurous-acid odor, which is only partly accomplished. 

 More or less moisture is lost during the handling, but the operator 

 aims to remove no more moisture than is necessary, because the addi- 

 tion of moisture is one of the sources of profit in the bleaching process. 



RESULTS OF SULPHUR BLEACHING. 



APPEARANCE IMPROVED BY BLEACHING. 



As shown in figure 2, the oats subjected to sulphur bleaching are 

 the lower grades of white oats, the commercial grades of No. 3, No. 4, 

 and "Sample" or "No grade" white oats usually being used. The 

 reason that such oats receive low grades may be due to several causes, 

 such as stain, field or mold damage, bad odors, or a low-test weight 

 per measured bushel. When the damage is stain or mold the outward 

 appearance of the grain is greatly changed by sulphur bleaching, and 

 it is often difficult to distinguish between the sulphur-bleached grain 

 and that which is naturall}^ bright and sound, without subjecting it to 

 a chemical test. 



For the purpose of determining to what extent the outward appear- 

 ance of oats is changed through sulphur bleaching, samples represent- 

 ing 9 lots of oats before and after bleaching were submitted to several 

 experienced grain inspectors for grading in the regular manner, with 

 the exception that they did not take into consideration the odor of 

 sulphurous acid on the samples of bleached oats. 



The results of this test were that 6 of the sulphur-bleached samples 

 were classed the eciuivalent of a full grade higher than the samples 

 representing the corresponding lots of oats before bleaching and 3 of 

 the samples were raised from the average to the top of the same grade.'* 



a In the trading upon the grain exchanges there is at times a range of 1 to 3 cents 

 or more per bushel in the market price of a single grade of oats, depending on the 

 apparent quaHty and condition of the grain, and in order to compare values more 

 definitely than can be done by the present specifications for grades, the terms "top" 

 and "bottom" of the grade are used. 

 [Cu-. 74] 



