182 



THE SMALL GRAINS 



181. Specific gravity method. In this method the 

 seed is immersed in a liquid of such density that the 

 kernels of average weight will just sink, while the lighter 

 kernels, chaff, and many foreign seeds will float and may 

 be skimmed off. Grading and also a certain amount of 

 cleaning are effected by differences in specific gravity. 



FIG. 60. Apparatus for cleaning and grading seed grain by the specific 

 gravity method. 



As the medium for cereals, water can usually be employed, 

 to which salt may be added to increase the density as 

 required. 



A simple arrangement for separating cereal seeds is the 

 following : The apparatus consists only of two tubs or 

 half barrels. A hole is bored through the side of each 

 at the bottom, and wire netting tacked over the hole 



