6 



SPECIFIC GEAVITY OF Vv-HEAT AND OTHER CEEEALS. 



NECESSITY FOR EXHAUSTING THE AIR. 



That it is necessary to exhaust the air from the picnometer con- 

 taining the wheat covered with toluene in order to free the wheat 

 from mechanically held air is shown in Table I, in which are given the 

 results of specific-gravity determinations made with and without 

 the use of the aspirator. This table further shows that the volume 

 of air so held is not the same in all cases. The specific gravity of a 

 number of samples determined without aspiration will therefore not 

 necessarily run parallel to the true specific gravity of the same samples. 



Table I. — Specific-gravity determinations made with and without the use of the aspirator. 



UNIFORMITY IN DUPLICATE TESTS. 



Table II shows the results of duplicate specific-gravity determina- 

 tions of 13 wheat samples, representing both hard and soft wheats. 

 The maximum variation from the average of the two determinations 

 amounted to 0.0039, the average variation behig 0.0009. Considering 

 the difficulty of securing two samples of 10 grams each wliich are 

 exactly alike from any given lot of wheat, tliis variation is very 

 slight and indicates a small unavoidable error in sampling rather than 

 an inaccuracy in the test. 



Table II. — Specific-gravity determinations showing uniformity in results of duplicate tests. 



Ma.ximum variation from average, 0.0039. Average variation from average, 0.0009. 

 ICir. 99] 



