18 
BULLETIN 1460, U. S. DEPARTMENT OE AGRICULTURE 
Table 12 — Influence of size of sample ground on protein test results 
PART A 
(Results are on the basis of the moisture as present in sample) 
Laboratory No. 
Size of sample ground (grams) 
Maxi- 
mum dif- 
ference 
8 15 
30 
60 
125 
11998 . . 
Per cent 
10.94 
12.08 
13.00 
12.94 
13.22 
15.39 
12.37 
13.05 
14.31 
10.15 
10.66 
11.11 
Per cent 
10.60 
11.86 
13.11 
12.82 
12.88 
15.28 
12.25 
12.77 
14.48 
10.20 
10.66 
11.11 
Per cent 
10.77 
11.86 
13.11 
12.82 
12.94 
15.28 
12.20 
12.84 
14.53 
10.20 
10.60 
11.06 
Per cent 
10.72 
11.86 
13.05 
12.77 
12.82 
15.33 
12.20 
12.82 
14.53 
10.15 
10.54 
11.06 
Per cent 
10.66 
11.86 
13.05 
12.75 
12.88 
15.10 
12.20 
12.77 
14.53 
10.20 
10.60 
11.06 
Per cent 
0.34 
11999 
.22 
12000 
.11 
12001 
.19 
12002 - ■ _ 
.40 
12003.. . 
.29 
12004 _ __ • .__ 
.17 
12005 
.28 
12006 
.22 
12007 
.05 
12008... ... . 
.12 
12009. ... 
.05 
PART B 
(Results are on the basis of 13. 5 per cent moisture) 
11999 
12000 
12001 
12002 
12003 
12004 
12005 
12006 
12007 
12008 
12009 
10.55 
10.35 
10.50 
10.48 
10.50 
11.69 
11.69 
11.61 
11.58 
11.65 
12.61 
12.66 
12.67 
12. 63 
12.62 
12.51 
12.50 
12.51 
12.42 
12.44 
12.60 
12.46 
12.52 
12.58 
12.46 
14.71 
14.76 
14.82 
14.89 
14.79 
11.81 
11.71 
11.75 
11.79 
11.83 
12.45 
12.35 
12.39 
12.44 
12.44 
13.96 
14.13 
14.25 
14.21 
14.21 
9.62 
9.83 
9.89 
9.79 
9.83 
10.25 
10.35 
10.31 
10. 29 
10.38 
10.90 
10.80 
10.76 
10.78 
10.78 
.20 
.11 
.14 
.18 
.12 
.10 
.29 
.27 
.13 
.14 
From the data in part B of Table 12, it is seen that there were 
some differences in the protein test results due to size of sample 
ground, even when the moisture factor was considered. The smaller 
the size of the sample ground, the larger were these differences. 
That is to say, grinding only 8 to 15 grams of sample introduced an 
appreciable error even if moisture conditions were controlled. The 
differences in protein results when 30 grains or more were ground 
were very small, being in most cases well within the usual limit of 
error, 0.1 per cent. It is believed, however, that these grindings 
were carried out much more carefully than is the case in the average 
protein laboratory. 
CARE OF GRINDING APPARATUS 
At present most laboratories are equipped with small burr flour- 
ing mills. These give satisfactory grinding service. The only pre- 
caution to be pointed out is to be sure the burrs in the mill are 
cleaned thoroughly before additional samples are run through. This 
can be done by running through not less than 15 to 20 grams of the 
new sample before taking any of it for the test. Proof of this is 
given in Table 13. A sample of high protein wheat was ground 
until no further meal was obtained and the residue was left in the 
