10 
BULLETIN 1460, U. S. DEPARTMENT OF AGRICULTURE 
high, low, and medium intensities of heat. Data from this study are 
given in Table 4. 
These data show that heat is the most important factor to be con- 
sidered in digesting wheat samples. As great an oxidation can be 
obtained in 30 minutes with a high degree of heat as can be obtained 
in 90 minutes at low heat. 
At all intensities of heat with the two samples tested, over 90 per 
cent of the protein nitrogen was in the form of ammonia within 30 
minutes. In 90 minutes 94.25 per cent of the protein nitrogen was 
in this form at high heat, 93.2 per cent at medium heat, and 92.6 per 
cent at low heat. 
These data also indicate that samples of low protein content digest 
at a slower rate than those of high protein content. 
By increasing the heat 50 per cent above the maximum used in the 
above discussion it was found that over 99 per cent of the protein 
nitrogen in samples of wheat could be transformed into ammonia in 
less than 15 minutes. The flasks at this temperature were too hot to 
handle. 
Table 4. — Influence of heat and acid on protein test results 
Sample 
No. 
Time 
Intensity of heat 
30 minutes 
60 minutes 
90 minutes 
Protein 
found 
Digested 
Protein 
found 
Digested 
Protein 
found 
Digested 
High 
6 
8 
6 
8 
6 
8 
Per cent 
14.03 
10.49 
14.02 
10.26 
13.91 
10.20 
Per cent 
91.55 
92.02 
91.15 
90.00 
90.44 
89.47 
Per cent 
14.42 
10.66 
14.31 
10.49 
14.19 
10.36 
Per cent 
93.76 
93.51 
93.04 
92.02 
92.33 
90.87 
Per cent 
14.53 
10.72 
14.36 
10.60 
14.26 
10.54 
Per cent 
94.47 
Do 
94.04 
Medium 
93.37 
Do 
92.98 
Low 
92.78 
Do 
92.45 
In studying the effect of catalytic agents on the oxidation process, 
a shorter period of time was chosen than was necessary to complete 
the oxidation of the wheat samples, so that the heat factor would 
not mask the effects of the reagent studied. Two samples of wheat 
were used, one of high, the other of low protein content, and the re- 
sults from each sample were averaged. The studies were made at 
low and medium intensities of heat. A 1-gram sample and 20 cubic 
centimeters of concentrated acid were used throughout, the catalyst 
being changed to suit the occasion. These data are shown in Table 
5. In this table a value of 100 has been given to the results when 
the sample was digested with acid alone and when catalysts were 
used the results are expressed in terms of this value. 
These data show that there is no advantage in choosing between 
red and yellow oxide of mercury in any quantity. The best quan- 
tity to use seems to be 0.5 gram. No advantage is gained by doub- 
ling the quantity of these reagents. Mercuric sulphate as a catalyst 
gave slightly lower results, 
