2; BULLETIN 788, U. S. DEPARTMENT OF AGRICULTURE. 
(flour, feed, and other mill products), the method used was that of 
drying to constant weight a small portion of the sample in a water- 
bath oven, at the temperature of boiling water. 
MOISTURE REQUIREMENTS OF WHEAT FOR MILLING PURPOSES. 
At the beginning of the process of milling, the miller gives much 
consideration to the question of the moisture content of his raw ma- 
terial. He knows that in order fo secure the highest yields of flour 
and to insure its greatest purity, the pericarp or outer coatings of the 
wheat kernel at the time of grinding must be of a certain toughness, 
and the endosperm, or inner parti, of a certain mellowness. The de- 
sree to which these properties are possessed by the different parts 
of the kernel is influenced largely by the amount of moisture present. 
Wheat when received at the mill is seldom, if ever, in the best 
condition for milling, its moisture content being too high, too low, 
or not properly distributed throughout the kernel. To acquire the 
right moisture content for the outer and inner parts of the kernel, 
thereby insuring the best possible milling condition for different 
wheats, requires the application of various methods of tempering. 
These methods may consist of a single, or successive, or of com- 
bined applications of water, heat, or steam, working through a period 
of time, ranging from a few minutes to as much as 36 hours, in order 
that the moisture may be properly distributed within the kernel. 
Dry climates and dry seasons naturally produce wheat of low 
moisture content, and damp climates and wet seasons produce wheat 
of high moisture content. There is, moreover, often considerable 
range in the moisture content of wheat during any given season and 
in any one locality. Moisture determinations of samples obtained 
from more than 5,000 cars of wheat, which were made by this depart- 
ment at Kansas City, Mo., during the years 1910 to 1914, inclusive, 
showed a range in the content of that factor from 7.4 per cent to 22 
per cent. The fact that the moisture content of wheat may vary so 
greatly is evidence that the problem of properly tempering wheat is 
a complicated one. 
AMOUNT OF MOISTURE ADDED TO WHEAT DURING TEMPERING. 
In Table I is shown the percentage of moisture contained in wheat 
before and after cleaning and tempering as found from moisture 
determinations made on a series of samples secured from five dif- 
ferent mills. The wheat of each mill was of similar class (hard red 
winter) and grade, and contained, at the beginning of the tempering 
process, approximately the same percentage of moisture. Different 
amounts of water, however, were added by each mill. The difference 
in moisture content of tempered and untempered wheat as shown in 
this table indicates the change in that factor which resulted from 
So 
