12 
BULLETIN 1460, U. S. DEPARTMENT OF AGRICULTURE 
INFLUENCE OF SIZE OF SAMPLE DIGESTED ON PROTEIN-TEST RESULTS 
As 1 and 2 gram samples were used in this study, tests were made 
to note the influence of size of sample on results. Both 1 and 2 gram 
portions were digested for a time sufficient to afford complete oxida- 
tion. Samples were chosen having protein contents of from 8 to 18 
per cent in 1 per cent ranges. The data are given in Table 7. 
Table 7. — Influence of size of sample digested on protein test results 
Test No. 
Ranges in percentage of protein 
10 to 10.99 
11 to 11.99 
12 to 12.99 
13 to 13.99 
14 to 14.99 
15 to 15.99 
16 to 20 
One-gram sample: 
1 
10.26 
10.60 
10.15 
10.66 
10.32 
11.34 
11.00 
11.80 
11.97 
11.34 
11.97 
12.71 
12.77 
12.77 
12.90 
12.03 
12.60 
12.54 
12.37 
13.00 
13.11 
13.39 
13.45 
13.79 
13.51 
13.05 
13.39 
14.65 
14.19 
14.02 
14.60 
14.31 
14.82 
15.39 
15.10 
14.90 
14.90 
19.55 
2 
18 81 
3 
18.29 
4 
17.90 
5 . 
6 
7 
8 
10.39 
11.57 
12.58 
13.34 
14.43 
15.07 
18.64 
Two-gram sample: 
1 
10.22 
10.60 
10.15 
10.66 
10.32 
11.34 
10.94 
11.75 
11.91 
11.34 
11.97 
12.75 
12.77 
12.78 
12.94 
12.00 
12.60 
12.54 
12.40 
13.08 
13.12 
13.39 
13.40 
13.85 
13.62 
13.11 
13.45 
14.71 
14.25 
14.08 
14.65 
14.31 
14.83 
15.45 
15.28 
15.03 
15.10 
19.55 
2_ - 
18.81 
3 . - 
17.95 
4 . 
18.34 
5 
6 
7 
8 
Average __________ 
10.39 
11.54 
12.59 
13.37 
14.47 
15.21 
18.66 
Difference of average 
10.00 
-0. 03^ 
+0.01 
+0.03 
+0.04 
+0.14 
+0.02 
i Minus sign indicates a less quantity in the 2-gram sample. 
The data show, on the average, that there is a slight advantage 
in using a 2-gram sample, especially with wheats containing the 
higher percentages of protein. This advantage is not sufficiently 
great to warrant its use, as it takes approximately 30 per cent longer 
to digest a 2-gram sample completely. When this factor is con- 
sidered in the light of a laboratory making several hundred tests a 
day, the total additional time necessary to oxidize 2-gram samples 
will be considerable. 
INFLUENCE OF METHOD, TIME, AND SAMPLE ON PROTEIN-TEST RESULTS 
The time of digestion given to the samples by the various collab- 
orators varied from 25 to 180 minutes. Less time was consumed 
by those using electricity as a source of heat than by those using 
gas. Three distinct methods were used: The Kjeldahl method, the 
Gunning method, and the Kansas City Protein Referee Board 
method. Large variations were also obtained by many laboratories 
with some of the spring wheats. Experiments were planned, there- 
fore, to study the relation of these variables upon the protein test 
results. In this study the three different intensities of heat, de- 
scribed previously (see p. 5) were used. Three different methods 
