- 3 - 



Since the density of wheat is fairly constant it seemed logical 

 that infested kernels could be separated from sound kernels by using 

 the weight factor. The imnersion of wheat in a solution or solutions of 

 controlled specific gravity appeared to offer the most feasible method 

 of separating the wheat kernels of different weights. 



There were two objectives in this study. The first was to deter- 

 mine whether the range of the density of sound kernels of wheat over- 

 lapped the range of the density of kernels infested iiriLth the rice weevil. 

 The second objective was to determine whether, in case the first phase 

 of the study showed an overlapping of the ranges, a multiple separation 

 might be accomplished by the use of two solutions of different specific 

 gravities, 



TECH^IIQUES Aim mTERIALS 



The density of hard red winter wheat, the type most common in the 

 Kansas area, is about I.I4., After some experimentation, sodium silicate 

 solution (Na2Si30Y) was selected as a material that could be easily ad- 

 justed to specific gravities below l.U. This material, commonly known 

 as water glass, is readily available. The specific gravity of the solu- 

 tion is adjusted by the addition of water. Doubtless there are other 

 materials also suitable for use, 



VJhen a second solution was needed which co\ild be adjusted to speci- 

 fic gravities below l.li^ and which would not be miscible x-ri-th sodium 

 silicate and water, a solution of methyl chloroform and deodorized kero- 

 sene was selected. Hydrolysis at room temperatures was negligible so 

 that mixtures of sodium silicate and methyl chloroform remained nearly 

 stable. Further testing is necessary to determine whether hydrolysis 

 or specific gravity changes occur after prolonged use of these solu.tions. 



An X-ray unit especially designed for the radiographic inspection 

 of grain samples was used to check the exact percentage of internal in- 

 festation of all the grain samples, and also of the kernels separated 

 by flotation, 



PROCEDURE 



In the first phase of the study, solutions of sodium silicate were 

 prepared, their specific gravity ranging from 1,0^0 to 1,350 in steps 

 of 0.05 between 1.0^0 and 1.100, of 0,01 between 1,100 and 1,200, and 

 of 0.05 between 1,2^0 and 1.350, Samples of hard red -winter wheat with 

 a 12-percent moisture content and infested with all stages of the rice 

 weevil ( Sitophilus oryza (L,)) were immersed in solutions at each desig- 

 nated specific gravity. Each sub sample was then washed, dried, and 

 X-rayed, and an exact count of the infested kernels in each part was 

 made. Only kernels of normal size and shape were considered in making 

 the determinations in the surface (floating) layer. 



