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Fic. 1.—Abrasion machine—Deval type (front view). 
BULLETIN 704,,.U. S. DEPARTMENT OF AGRICULTURE. 
to the axis of the cylinder as it is pos- 
sible to make it. After drying and cool-. 
ing, a specimen to be tested is placed on 
the anvil (W) of a Page impact ma- 
chine, shown in figure 2, taking extreme 
care that when in position the specimen 
rests with a perfect bearing on the anvil 
and that the spherical end of the plunger 
is tangent to the specimen exactly in the 
center of its upper surface. The small 
thumbscrew used for separating the 
clips which hold the specimen in place 
should be so adjusted that the clips hold 
the test piece firmly without any undue 
pressure on the spring. Attention to 
these details is very important if accu- 
rate results are to be obtained. When 
the specimen is in position the current 
is turned on the magnet and the upper 
cross-head is lowered until the rod pro- 
jecting from it just comes in contact 
with the rod projecting from the lower 
cross-head (M). This occurs at the in- 
stant the pilot lamp, in series with the 
magnet circuit, flashes out. The dial 
(Q) is then adjusted to O, the upper 
cross-head raised 1° centimeter, and the 
motor started. After each blow the fall 
of the hammer is increased 1 centi- 
meter until failure of the test piece 
occurs. 
The height in centimeters of the blow 
at failure is recorded as the toughness of 
the material, using for the final value 
the average of three determinations. In 
the case of foliated rock the average of 
three determinations in each direction is 
taken as the toughness of the sample. 
Weight per Cubic Foot of Broken 
Slag.—The weight per cubic foot should 
be determined by shaking the dried slag 
to refusal in a cubic foot cylindrical 
measure. About % of the total amount 
of slag necessary to fill the measure is 
first introduced in such a manner as to 
avoid any separation of sizes. This ma- 
terial is then shaken down by rocking 
the measure from side to side until no 
further settlement takes place. - This 
process is repeated until the measure 
has been filled to overflowing, after 
which it is struck off level with the top 
with a straight edge and weighed. 
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