10 
BULLETIN 328, U. S. DEPARTMENT OF AGRICULTURE. 
sisting of 0.5 per cent of wild oats and 1 per cent of pigeon grass and 
other weed seed. This wheat was obtained from a farmer's wagon 
as the grain was unloaded at a country elevator. Because the grain 
buyer considered wild vetch an inseparable impurity which would 
injure the milling qualities of the wheat, the farmer was given a 
lower price for his grain than he would have received had the wheat 
been free from vetch seed. 
COMPARATIVE MILLING YIELDS OF WHEAT AND OF ITS IMPURITIES. 
Table III shows the yields of bran, shorts, and straight flour ob- 
tained in milling wheat in comparison with the yields of these products 
obtained in milling rye, corn cockle, kinghead, and hairy vetch as used 
in the milling and baking tests. Averages are given of three tests with 
wheat and corn cockle and of two tests with rye, kinghead, and hairy 
vetch. 
Table III.- — Milling tests of wheat, rye, corn cockle, Hnghead, and hairy vetch, showing 
comparative yields of straight flour, bran, and shorts. 
Ingredient. 
Bran. 
Shorts. 
Straight 
flour. 
Quantity 
milled. 
Machine used in milling. 
color of flour. 
Wheat 
Per cent. 
12.5 
13.6 
22.9 
52.3 
12.9 
Per cent. 
14.7 
31.3 
28.0 
31.9 
25.3 
Per cent. 
71. 4 
47.8 
47.6 
15.8 
57.8 
Pounds. 
120 
113 
20 
5 
5 
50-barrel mill 
White. 
Rye... .* 
do 
Gray. 
Bluish white. 
Dark grav. 
Yellow. 
Corn cockle . . 
Kinghead 
Hairy vetch.. 
Smal 1 experimental mill 
do 
do 
A relatively low yield of flour was secured when each impurity 
was milled by itself, especially in the test with kinghead seed, from 
which less than 16 per cent of flour was obtained. The presence of 
more than 1 per cent of this impurity in wheat as milled resulted in 
a noticeably decreased flour yield, as shown in Table IV. 
Although the flour from each impurity was difficult to bolt when 
milled alone, when the mixtures of rye, corn cockle, and hairy vetch 
with wheat were milled the yield of flour was not greatly reduced. 
In all probability the'wheat flour aided in bolting through a greater 
proportion of the flour from each of the impurities. On account of 
the decidedly different color of the flour of each impurity from that 
of wheat flour, the detrimental effects on the color of the bread made 
from such flour mixtures are very noticeable. (See Table IV.) 
MILLING AND BAKING TESTS OF WHEAT CONTAINING IMPURITIES. 
TESTS WITH ADMEXTURES OF VARIOUS PERCENTAGES OF EACH IMPURITY. 
Table IV gives the results of milling and baking tests with samples 
of wheat containing certain percentages of the so-called inseparable 
impurities — rye, corn cockle, kinghead, and hairy- vetch seed. These 
data are the averages of tests covering three years with rye, kinghead, 
and corn cockle, with the exception of the tests with 5 per cent and 10 
