38 
BULLETIN 102, U. S. DEPARTMENT OF AGRICULTURE. 
of a mechanical analysis. Directed only by his judgment in a mechan- 
ical separation of l 'damaged kernels" from "sound kernels" in any 
given sample, the analyst is entirely without means of expressing in 
any standard way the quality and soundness of the sample as a 
whole. He is, furthermore, entirely without means of confirming 
his judgment or opinion in his discrimination between sound and 
damaged kernels by any standard test or criterion. 
The results of these corn-acidity investigations indicate that the acid 
test is such a criterion, and it is offered as an aid to any analyst or 
inspector who desires to determine in a uniform, standard, and scien- 
tific way the quality and soundness of corn. 
In order to classify corn as to quality and soundness by means of 
the acid test, it is necessary to fix certain limits in the degree of 
acidity, above which limits the corn may be said to be unsound as 
compared to corn below such limits. It is only in a general, broad 
way that these limits are suggested. Corn which is to the eye 
unquestionably of poor quality and unsound shows invariably a high 
degree of acidity between limits of 30 and 50 c. c. Corn showing 
above 50 e. c. in degree of acidity is in a very advanced stage of 
deterioration, and its quality does not need to be tested in any other 
way than by inspection. 
As a result of these and other investigations of the acidity of corn 
in this country x and abroad, a limit of 30 c. c. seems most appro- 
priate in discriminating against wholly bad or unsound corn. Any 
corn with a degree of acidity more than 30 c. c. is unquestionably 
unsound and of very poor ejuality. 
Of samples representing approximately 2,450 cars of corn received 
at a principal terminal market from December, 1911, to May, 1913, 
inclusive, 87 were found to have a degree of acidity greater than 
30 c. c. The results of analyses, together with the commercial grade 
and the remarks of the inspector who graded the samples, are shown 
in Table XIX. 
Table XIX. — Quality and condition of corn which shoued a degree of acidity greater 
than 30 c. c, as found in representative samples at a principal terminal market. 
Labo- 
ratorv 
No. 
Month. 
Grade. 
Mois- 
ture. 
Cob 
rot. 
Heat 
dam- 
aged. 
Ger- 
mina- 
tion. 
Acid- 
ity. 
Inspector's remarks. 2 
Per 
Per 
Per 
Per 
cent. 
cent. 
cent. 
cent. 
C.c. 
38496 
July 
3 
13.0 
4.00 

8 
30.1 
Too much damage. 
3S665 
do 
3 
14.7 
22.60 

2 
30.3 
35498 
do 
Sample . 
15.2 

15. 10 
4 
37.6 
Subject; heating. 
38520 
do 
...do.... 
15.7 
11.00 

6 
33.0 
Heating; one end hot. 
3S.531 
do 
...do.... 
14.6 
22. 25 

2 
35.7 
Heating. 
38572 
do 
...do.... 
14.6 
1.85 
5.70 

33.4 
Slightly heating. 
3S619 
do 
...do.... 
14.^ 
15. 85 


32.8 
Heating. 
38748 
do 
...do 
14.4 
44.00 


41.5 
Do. 
3S495 
.....do 
4 
14.0 
15. 65 


3S. 7 
Subject; too much damage for 3. 
i Black, O. F., and Alsberg, C. L. The determination of the deterioration of maize, with incidental 
reference to pellagra. XJ. S. Department of Agriculture, Bureau of Plant Industry Bulletin 199, 16 p., 1910. 
2 Explanation of terms: Subject=grade subject to change upon reinspection; mahosanv^badlv heat 
damaged. 
