40 
BULLETIN 102, U. S. DEPARTMENT OF AGRICULTURE. 
PERCENTAGE OF TOTAL SAMPLES 
&UOW 
8090100 
Assuming that 30 c. c. correctly discriminates in a general way 
between good and bad corn, it becomes necessary, in order to make 
the acid test a test of value, to establish limits below 30 c. c. which 
win relatively classify the good corn according to its degree of quality 
and soundness. 
Results of corn-acidity investigations show that theoretically 
quality and soundness vary directly in proportion to the degree of 
acidity of the corn. All corn shows acidity of a certain degree. 
The minimum degree of 
acidity is represented in 
the corn at the time of 
harvest, and is found to 
vary between the limits of 
9 or 10 and 15 or 16 c. c, 
having never been found 
to exceed 20 c. c. 
Covering a period of 
three years, approximately 
10,000 samples were tested 
for degree of acidity. 
These samples included 
seed corn as well as corn 
from the harvest field, corn 
as stored on the farm and 
as found through all stages 
of commercial handling, 
including transportation 
and storage, and showed 
ranges in the degree of 
acidity from 9 to 10 c. c. 
to over 100 c. c. Of the 
corn arriving at terminal 
Fig. 29.— Curve showing the percentage of samples of corn markets throughout the 
tested for degree of acidity which fell below 15, below 16, ° 
below 17, and so on up to and including 32 c. c, representing COUUtrV, between 75 and 
approximately 8,000 cars received at four principal termi- gQ -p er cerL ^ f ^q cars as 
nal markets. " c . . c 
sampled showed acidity 
below 22 c. c, about 90 per cent was below 26 c. c, and approxi- 
mately 4 or 5 per cent was above 30 c. c. (Figs. 29 and 30.) 
From the results of mechanical analyses of samples representing 
cars arriving at terminal markets (fig. 21) the average degree of 
acidity of the separations shows as follows: 
Sound kernels 19. 5 
Broken kernels 22. 5 
Damaged kernels, exclusive of heat damage 41. 2 
Slightly heat-damaged kernels 41. 8 
Badly heat-damaged kernels = , , . 50. 8 
Beam 
