44 DEPABTMEXT BULLETIN 1216, U. S. DEPT. OF AGBICTTLTUEE 
Per cent 
Combined carbon, not under 2. 50 
Graphitic carbon, not over o' 25 
Silicon, not over i* qo 
Manganese, not over o! 50 
Phosphorus, not over '_ 0.25 
Sulphur, not over • q[ 08 
For each new batch of sphere? used the chemical analysis shall he furnished 
by the maker or be obtained by the user before introducing the spheres into the 
charge, and unless the analysis conforms to the requirements specified the batch 
of spheres shall be rejected. 
21. The scales used shall be placed on a solid level foundation and shall be 
sufficiently sensitive to determine the initial weight of 10 bricks to the nearest 
0.1 pound. The scale shall be tested by a standard-test weight at intervals of not 
more than every 10 tests. 
TEST SPECIMEN 
22. The number of brick per test shall be 10 whole bricks for all weights of 
brick, and the brick shall be weighed to the nearest 0.1 pound. No brick should 
be selected as part of a regular test that would be rejected by any other require- 
ments of the specifications under which the purchase is made. 
PROCEDURE 
23. (a) The -ample, together with the abrasive charge, shall be placed in the 
rattler and the rattler closed. The rattler shall be rotated at a uniform rate 
of not less than 2!'.. 5 nor more than 30.5 revolutions per minute, and 1,800 revo- 
lutions shall constitute the test. A counting machine shall be attached to the 
rattler for counting the revolutions. A margin not to exceed 10 revolutions will 
be allowed for starting and stopping. Only one start and stop per test is in 
general acceptable. If, from accidental causes, the rattler is stopped and 
started more than once during a test, and the percentage loss exceeds the 
maximum permissible under the specifications, the test shall be disqualified 
and another made. 
(&) Any test. ;it the expiration of which a stave liner is found detached from 
tlie stave or seriously out of position, shall be rejected. 
24. The loss shall be calculated as a percentage of the initial weight of the 
brick composing the charge, by weighing the brick remaining in the rattler at 
the end of the test, deducting this weight from the initial weight of the brick, 
dividing this difference by the original weight of the brick and multiplving bv 
100. 14 
Pe^tage of loss ^^ TSgBtSff* """ xiM 
In weighing the rattled brick, any piece weighing less than 1 pound shall be 
rejected. 
25. The percentages of loss, as calculated in accordance with section 24, shall 
be corrected by subtracting from it the differential obtained from the following 
tabulation, winch corresponds to the initial weight of the 10 bricks composing 
the test charge.® The corrected result shall be reported as the corrected per- 
centage of 
Weight of 10 brick Correction differential, 
before test, pounds per cent 
9H or over 
90 to 94, inclusive 1.0 
85 to 89, inclusive 1. 5 
80 to 84. inclusive 2.5 
75 To 79. inclusive 3.0 
70 to 74. inclusive 3.5 
65 to 69, inclusive 4.0 
60 to 64. inclusive 5.0 
59 or under 6.0 
In all cases where the initial weight of 10 brick in pounds and tenths of a 
pound lies between the upper limit of one grade and the lower limit of the 
34 The percentage of loss to be taken as the standard remains -within the province of 
the contracting parties. For their information, the average percentage of loss after cor- 
rection as provided in section 25 should not exceed 22 per cent for heavy traffic and 24 
per cent for light traffic. 
25 At the option of the purchaser, the results of the rattler test may be reported direct 
without concction for size of brick. 
