Ries — Physical Tests of Devonian Shales. 



687 



er case hardened. There shall be a space of one-fourth of an inch between 

 the staves for the escape of dust and small pieces of w aste. Other machines 

 may be used having twelve to sixteen staves, w ith openings from one-eighth to 

 three-eighths of an inch between the staves; !>nt if this is done, a record of it 

 must be attached to the official report of the test. 



III. Composition of the charge. All tests must be made on charges 

 composed of one kind of material at a time. No test shall be considered 

 official where two or more different bricks or materials have been used to 

 compose a charge. 



IV. Quantity of the charge. The quantity ot the charge shall l>e 

 estimated by its bulk and not by its weight. The bulk of the standard 

 charge shall be equal to fifteen per cent, of the cubic contents of the rattling 

 chamber, and the number of whole brick w hose united volume comes nearest 

 to this amount shall constitute a charge. 



V. Revolutions of the charge. The number of revolutions of a standard 

 test shall be 1,800, and the speed of rotation shall be thirty per minute. The 

 belt power shall be sufficient to rotate the rattler at the same speed whether 

 charged or empty. Other speeds of rotation between twenty-four and thirty- 

 six revolutions per minute may be used, but in this case a record of the speed 

 must be attached to the official report. 



VI. Condition of the charge. The bricks composing the charge shall be 

 dry and clean, and, as nearly as may be possible, in the condition in which 

 they were drawn from the kiln. 



VII. Calculation of the results. The loss shall be calculated in per- 

 centage of the weight of the dry brick composing the charge, and no result 

 shall be considered official unless it is the average of two distinct and complete 

 tests, made on separate charges of brick. 



Specifications for Absorption Test. 



1. The number of bricks for a standard test shall be five. 



2. The tests must be conducted on rattled bricks. If none such are 

 available, the whole bricks must be broken into halves before treatment. 



3. The bricks should be dried for forty-eight hours at a temperature 

 ranging from 230° to 250 c F. before weighing for the initial dry weight. 



4. The bricks should be soaked for forty-eight hours, completely 

 immersed in pure water. 



5. After soaking and before weighing, the bricks must be wiped dry 

 from surplus water. 



