2 BULLETIN 328, U. 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 mining 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. 
Spring and durum wheat 
(633 samples). 
Hard winter wheat 
(267 samples). 
Impurities found. 
Sam- 
ples 
con- 
taining 
impu- 
rities. 
Per- 
cent- 
age, 
of 
total. 
Percentage of 
impurity. 
Sam- 
ples 
con- 
taining 
impu- 
rities. 
Per- 
cent- 
age 
of 
total. 
Percentage of 
impurity. 
Aver- 
age. 
Maxi- 
mum. 
Aver- 
age. 
Maxi- 
mum. 
B arley 
453 
249 
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 
.8 
5 
222 
63 
1.87 
83.1 
23.6 
Trace. 
0.31 
.03 




Trace. 
0.1 
Rye 
4.1 
Oats 
3.3 
Wild oats 


Corn cockle 


c 
15 



5.6 


Wild vetch 

.1 
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- 
