16 
BULLETIN 1460, U. &. DEPARTMENT OF AGRICULTURE 
the manner illustrated in Figure 3. The contents of probes 1 to 5 
and 6 to 10, inclusive, were composited separately, thoroughly 
cleaned, mixed, and reduced to 75 grams in size to be ground for 
making protein tests. The mixing and reducing process were ac- 
complished by the means of a Boerner sampler. The results of 
these tests are shown in Table 10. Moisture determinations were 
made at the time the protein determinations were made so that the 
results reported are on a uniform moisture basis. 
Table 10. — Variation in protein results obtained from analysis of duplicate 
samplings of 2^1 car lots of spring icheat 
[Basis 13.5 per cent moisture] 
Number of cars sampled 
Percentage variation in duplicate tests 
Percentage of total car samplings 
85 
to 0.04 
35.2 
56 
0.05 to 0.09 
23.2 
53 
0.10 to 0.14 
22.0 
27 
0.15 to 0.19 
11.2 
Number of cars sampled I 10 
Percentage variation in duplicate tests I 0.20 to 0.24 
Percentage of total car samplings j 4. 2 
2 4 
0.25 to 0.29 0.30 to 0.34 
.8 1. 7 
2 
0.40 
Data from these tests show that over 9G per cent of the test varied 
by less than 0.25 per cent. This value, moreover, is the variation 
Fig. 3. — Showing method used in sampling of wheat for the duplicate sampling test de- 
scribed in the text. Arrows show the sequence of sampling 
permitted by the American Association of Cereal Chemists 10 in the 
matter of making protein tests. It is evident then that car lots of 
wheat can be sampled a number of times with a reasonable degree 
of accuracy, providing, of course, that other conditions effecting the 
protein tests be controlled. 
CLEANING SAMPLES BEFORE ANALYSIS 
The methods used in preparing the samples for protein analysis, 
especially the removal from the sample of foreign material, show 
need for improvement, as they are far from uniform. Sieves, dock- 
age machines, and forceps are regularly used to remove foreign mate- 
rial. As the result of using oversized sieves, cases are known in 
which small-sized kernels, high in protein, are regularly sieved out, 
making concordant tests difficult. 
10 Mangels, C. 
Chem., vol. 2, No. 
E., and others. 
4, p. 235. 
report of committee ox methods. Jour. Cereal 
