﻿32 BULLETIN 23, U. S. DEPARTMENT OP AGRICULTURE. 



For each new batch of spheres used, the chemical analysis must be furnished by the 

 maker or be obtained by the user, before introducing into the charge, and unless the 

 analysis meets the above specifications, the batch of spheres shall be rejected. 



THE OPERATION OF THE TEST. 



Item 10. The brick charge. — The number of brick per test shall be ten for all bricks 

 of so-called "block size," whose dimensions fall between from 8 to 9 inches in length 

 and 3| inches to A\ inches in thickness. 1 No brick should be selected as part of a 

 regular test that would be rejected by any other requirements of the specifications 

 under which the purchase is made. 



Item 11. Speed and duration of revolution. — The rattler shall be rotated at a uniform 

 rate of not less than 29J nor more than 30£ revolutions per minute, and 1,800 revolutions 

 shall constitute the test. A counting machine shall be attached to the rattler for 

 counting the revolutions. A margin of not to exceed ten revolutions will be allowed 

 for stopping. Only one start and stop per test is generally acceptable. If from acci- 

 dental causes, the rattler is stopped and started more than once during a test, and the 

 loss exceeds the maximum permissible under the specifications, the test shall be dis- 

 qualified and another made. 



Item 12. The scales. — The scales must have a capacity of not less than 300 pounds, 

 and must be sensitive to one-half of an ounce, and must be tested by a standard test 

 weight at intervals of not less than every ten tests. 



Item 13. The results. — The loss shall be calculated in percentage of the ir.itial 

 weight of the brick composing the charge. In weighing the rattled brick, any piece 

 weighing less than one pound shall be rejected. 



Item 14. The records. — A complete and continuous record shall be kept of the opera- 

 tion of all rattlers working under these specifications. This record shall contain the 

 following data concerning each test made. 



1. The name of the person, firm or corporation furnishing each sample tested. 



2. The name of the maker of the brick represented in each sample tested . 



3. The name of the street, or contract which the sample represented. 



4. The brands or marks upon the bricks, by which they were identified . 



5. The number of bricks furnished. 



6. The date on which they were received for test. 



7. The date on which they were tested. 



8. The drying treatment given before testing, if any. 



9. The length, breadth and thickness of the bricks. 



10. The collective weight of the 10 large spherical shot used in making the test at the 

 time of their last standardization. 



11. The number and collective weight of the small spherical shot used in making 

 the test, at the time of their last standardization. 



12. The total weight of the shot charge, after its last standardization. 



13. Certificate of the operator that he examined the condition of the machine as to 

 staves, liners, and any other parts affecting the barrel, and found them right at the 

 beginning of the test. 



14. Certificate of the operator of the number of charges tested since the last standard- 

 ization of shot charge. 



15. Certificate of the operator of the number of charges tested since the stave liners 

 were renewed . 



16. Certificate of the operator that the requisite number of revolutions were made, 

 under the prescribed conditions, upon the staves after the last relining, before a brick 

 test was made. 



1 Where brick of larger or smaller sizes than the dimensions given above for blocks are to be tested, the 

 same number of bricks per charge should be used, but allowance for the difference in size should be made 

 In setting the limits for average and maximum rattler loss. 



