2 BULLETIN 328, XT. S. DEPARTMENT OF AGRICULTURE. 



given a lower commercial grade or by a reduction in price, as com- 

 pared with wheat that is free from such impurities. Special experi- 

 ments to determine the effects that these impurities have on the 

 milling and baking qualities of wheat were begun in 1912 by the 

 Office of Grain Standardization and were continued in 1913 and 1914. 

 The results of milling and baking experiments with wheat con- 

 taining various amounts of rye, corn cockle, kinghead, and vetch show 

 conclusively that these impurities have detrimental effects on the 

 quality of the flour. 1 Further experiments are planned with such 

 impurities as rye, barley, wild oats, kafir, and wild-rose seed, and also 

 with sprouted and bin-burnt wheat. 



FREQUENCY OF OCCURRENCE OF IMPURITIES IN WHEAT. 



A study of the analyses of samples of wheat secured from the crops 

 of 1911, 1912, and 1913, as grown and as marketed, shows that a 

 large percentage of the samples of spring and durum wheat contained 

 rye, barley, oats, wild oats, corn cockle, kinghead, and wild-rose seed, 

 and that wild vetch is sometimes found in appreciable amounts. 

 Rye was found in 83.1 per cent of the hard winter-wheat samples 

 secured. This information is given in Table I. 



Table I.- — Wheat samples from the crops of 1911, 1912, and 1913, which contained cer- 

 tain impurities, showing the percentage of each impurity found. 



Impurities found. 



Spring and durum wheat 

 (633 samples). 



Sam- 

 ples 

 con- 

 taining 

 impu- 

 rities. 



Per- 



cent- 



of 



total. 



Percentage of 

 impurity. 



Maxi- 

 mum. 



Hard winter wheat 

 (267 samples). 



Sam- 

 ples 

 con- 

 taining 

 impu- 

 rities. 



Per- 



cent- 



of 



total, 



Percentage of 

 impurity. 



Maxi- 

 mum. 



Rye 



Oats 



Wild oats . . 

 Corn cockie 

 Kinghead . . 

 Wild vetch 

 Wild rose . . 



590 

 562 

 375 

 124 

 42 

 209 



71.6 

 39.2 

 93.2 

 88.8 

 59.2 

 19.8 

 6.8 

 33.0 



0.23 

 .06 

 .33 



1.36 



.11 



.09 



.10 



Trace. 



12.9 

 14.3 

 6.8 

 28.5 

 6.0 

 3.8 

 3.8 



5 

 222 



63 

 

 

 

 



15 



1.87 

 83.1 

 23.6 



















5.6 



Trace. 



0.31 

 .03 

















 Trace. 



0.1 



4.1 



3.3 



















COMPARISON OF THE SPECIFIC GRAVITY OF WHEAT AND OF ITS 



IMPURITIES. 



The specific gravity of wheat varies with the type or class and 

 also with the quality. The average specific gravity of a number of 

 samples of soft wheat, determined in connection with investigations 

 with grain, was 1.3891, with a range between 1.3616 and 1.4133, 



1 The writer is indebted to Levi M. Thomas, assistant in charge of the milling and baking investigation 

 of the Office of Grain Standardization, who made all the baking and practical tests with the flour, assisted 

 by W. K. Marshall, aid in grain standardization, and to Thomas Sanderson, in charge of the experimental 

 mill of the North Dakota Agricultural College, who made the milling tests 



