38 BULLETIN 704, U. S. DEPARTMENT OF AGRICULTURE. 
from the bins themselves by means of proper sampl:ng tubes, provided samples. 
are taken from points well distributed over the face of the bins; or from the 
bins at the point of discharge, provided sufficient material is drawn from each 
discharge to obtain samples representative of the material in the bins. In no 
case should a single composite sample represent over 200 barrels. Samples 
should be shipped and stored in air-tight containers. Before testing, they 
should be passed through a 20-mesh sieve in order to thoroughly mix the 
sample, break up lumps, and remove foreign material. 
PAVING BRICK. 
Samples of vitrified paving brick may be taken at the point of manufacture 
or from cars at the point of delivery. Samples from the plant should preferably 
be taken from the kiln at the time of emptying. One or more sets of tests, de- 
pending upon the size of the kiln, each set consisting of three separate tests, 
should be made on each kiln. Each test in a set of three ‘should represent 
approximately a single degree of burning (based on the position of the brick 
in the kiln), and all 10 of the brick in a single test should be of the same 
approximate degree of burning. In general, samples selected from piles at the 
plant should be as nearly as possible representative of the entire run of the 
brick. Samples from piles should be taken from as many different points corre- 
sponding to the length, breadth, and depth of the pile as possible. In no case 
should they be confined to the upper or outer few layers. Where controversy 
arises regarding the admissibility of certain types or portions of the lot, en- 
tire test samples may be selected from such types or portions having a char- 
acteristic appearance in common. When sampled at the point of delivery, a 
representative sample should be taken from each carload received. Consid- 
erations covered under sampling from piles at the plant apply equally to sam- 
pling from cars. No bricks should be included in the test lot which would be 
rejected on the basis of cracks, chips, or other defects covered by the specifica- 
tion clauses for visual inspection. Samples should be shipped in stout boxes or 
crates in lots of 12, put up in 2 rows of 6 bricks each, separated by a wood 
partition. 
STONE BLOCK. 
Stone block may be sampled for quality and size either at the quarry or from 
ears. A preliminary sample for quality consisting of at least four standard 
blocks should be submitted from each proposed source of supply at least two 
weeks prior to the date of acceptance or rejection. Additional samples of 
blocks may be taken from time to time during the progress of the work, when- 
ever the quality or appearance of the blocks varies, and at such other times as 
may be directed. No sample should include blocks which would be rejected on 
visual inspection. Preliminary samples may be omitted in cases where material 
from the proposed source of supply has been tested within one year prior to the 
date of acceptance or rejection, in which cases the report of such tests may be 
used as the basis for acceptance or rejection. Samples of stone blocks should 
be shipped in stout boxes or crates. 
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