60 BULLETIN 691, U. S. DEPARTMENT OF AGRICULTURE. 
through the discharge pipe for a short time before the sample is taken and the 
drip valve should be so regulated that the operation of collecting the sample 
continues through the entire period of loading the containers. 
SAMPLING FROM STORAGE TANKS AND TANK CARS. 
(1) When the material is in a fluid condition three samples should be taken 
from each tank or tank car, one from the top, one from the bottom, and one from 
the center of the tank. The bottom sample may be taken from the discharge 
pipe through which a sufficient amount of the material is first allowed to flow 
so as to clean it properly. If there is no outlet at the middle of the tank a 
thief sample may be taken by lowering a closed bottle or can to the center of 
the tank and then removing the stopper or cover by means of a stout cord or 
wire to which it is attached. (2) Tank cars containing cold semisolid or solid 
bituminous material may be sampled through the dome by the use of a 
clean hot shovel. 
SAMPLING FROM BARRELS AND DRUMS. 
(1) Separate samples should be taken from not less than 3 per cent of the 
containers. (2) When the material is semisolid or solid samples should be 
taken at least 3 inches below the surface. A hatchet may be used if the 
material is hard and a broad stiff putty knife if the material is soft. 
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