GRADES FOR COMMERCIAL CORN. 5 



distance from center to center. The thickness of the metal should 

 be from 0.025 to 0.035 of an inch. 



Round sieves from 10 to 12 inches in diameter or rectangular sieves 

 9 by 11 inches have been found very satisfactory and easy to manipu- 

 late. For the most efficient work, the two sieves with the bottom 

 pan should be made to nest, so that all screening can be done at one 

 operation. 



It is recommended that the sieves be made of brass, aluminum, or 

 other suitable metal, pressed from one piece, although sieves made 

 by soldering or nailing the perforated metal to any suitable frame 

 will give satisfactory results if kept in good repair. 



If made to nest, as shown in figure 3, the depth of the first sieve 

 should be 1 J inches, the second 2 inches, and the bottom pan 2\ inches. 



Fig. 1.— Section of sieve with perforations one- Fig. 2. — Section of sieve with perforations nine 



fourth cf an inch in diameter, the distance from sixty-fourths of an inch in diameter, the distance 



center to canter of holes being approximately from center to center of holes being approxi- 



eleven thirty-seconds of an inch. mately thirteen sixty -fourths of an inch. 



If made of metal, at least the bottom pan should be of aluminum, 

 to reduce the weight, thereby facilitating the ease of handling. 



MOISTURE TESTS. 



In determining the moisture content, it is desirable that all im- 

 portant samples be tested in duplicate whenever practicable and the 

 final result based on the average of the two tests. Results of tests 

 need not be expressed closer than one-tenth of 1 per cent, and the 

 grain should be given the benefit of the doubt in computing aver- 

 ages. For example, in taking the average of two tests, one showing 

 19.3 per cent and the other 19.4 per cent, the true average would be 

 19.35 per cent, but when used in connection with these grades the 

 moisture content should be recorded as 19.3 per cent and not 19.35 

 per cent. Likewise, in single tests any reading in the second decimal 

 place may be ignored in moisture determinations. 



Owing to the numerous methods of making moisture determina- 

 tions and the wide variations in the results obtained by the different 

 methods, the tester and method described in Circular No. 72 of the 



