2 BULLETIN 574, U. S. DEPARTMENT OF AGRICULTURE. 
Because of the time involved, it is impracticable to make the 
mechanical separations on the entire 2 J or more pints, and it there- 
fore becomes necessary, in most cases at least, to divide the sample 
in order to obtain a smaller representative portion for the determi- 
nation of the factors mentioned. 
Experiments have shown that the sample upon which the deter- 
minations for the factors mentioned are based should be approxi- 
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Fig. 
1.— A vertical cross section of the sampling device, showing the paths taken by the material in 
passing from the hopper to the containers. 
mately 40 grams in weight for wheat and approximately 250 grams 
in weight for corn. After the mechanical separations and weighings 
have been made, mathematical calculations are involved in order to 
convert these weights into terms of percentage, and the accompany- 
ing tables enable the analyst to accomplish these results without any 
calculations. 
