42 
BULLETIN 102, U. S. DEPARTMENT OF AGRICULTURE. 
a limit which would be practical from the standpoint of commercial 
grading. In the same sense that corn with an acidity of 20 c. c. is of 
poorer quality than corn with an acidity of 15 c. c, an acidity of 27 
c. c. denotes poorer quality and a further advance toward wholly 
bad corn than an acidity of 25 c. c. 
In the commercial classifying of corn according to quality and 
soundness by means of the acid test, this investigation would recom- 
mend but one limit 
between the limits of 
22 and 30 c. c, and 
that it be placed at 
26 c. c. 
The results of this 
investigation show 
that corn with a de- 
gree of acidity below 
22 c. c. is normally 
sound and of first- 
class quality from 
the commercial 
standpoint; that 
corn with a degree 
of acidity between 
22 and 26 c. c. is in- 
ferior in quality and 
soundness, due to de- 
terioration of the 
germ : that corn with 
a degree of acidity 
between 26 and 30 
c. c. has deteriorated 
sufficiently to be con- 
sidered unsound; 
and that corn with a 
degree of acidity 
greater than 30 c. c. 
is badly damaged 
and of a very low 
quality. It must be 
remembered in the application of the acid test that the sample as a 
whole must be considered and not individual kernels. 
The question will perhaps arise in the minds of some why the 
degree of acidity of corn was taken as the one important chemical 
factor in establishing its condition or quality. The answer to this 
question will be found in carefully studying Table XX, comparing 
the change in the different factors throughout the experiment. This 
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1 
Fig. 31.— Curves comparing the monthly average degree of acidity 
of sound corn with the monthly average degree of acidity of 
damaged corn as determined by mechanical analyses of corn 
arriving at a principal terminal market. 
