CLAYS OF NEW YORK 



747 



six months' immersion, thoiigli the great bulk of the water was 

 taken in the first week. 



Broken bricks absorb more water than whole ones, and small 

 pieces from the interior of the brick absorb more proportionately 

 than large ones. 



The following conclusions were reached. 



1 That to obtain accurate absorption figures, a hard brick will 

 require not less than four days' drying and eight weeks' soaking. 



2 That only roughly approximate figures are obtained within time 

 limits which woiTld be short enough to make the figures useful for 

 ordinary competitive tests of material for immediate use. 



3 That only rattled bricks should be used for the absorption test. 

 as the absorptive power of brick in use is increased by its chipping 

 and grinding under trafiic. 



4 'No relation seems to exist between loss by rattling and per- 

 centage of absorption. 



As a result of the committee's experiments the following speci- 

 fications were adopted. 



Specifications for abrasion test 



1 Dimensions of the machine. The standard machine shall be 

 28 inches in diameter and 20 inches in length, measured inside 

 the rattling chamber. Other machines may be used, varying in 

 diameter between 26 and 30 inches, and in length from 18 to 24 

 inches, but if this is done, a record of it must be attached to the 

 official report. Long rattlers may be cut up into sections of suit- 

 able length by the insertion of iron diaphragms at proper points. 



2 Construction of the machine. The barrel shall be supported 

 on trunnions at either end; in no case shall a shaft pass through 

 the rattling chamber. The cross section of the barrel shall be a 

 regular polygon, having 14 sides. The heads and staves shall be 

 composed of gray cast iron, not chilled or casehardened. There 

 shall be a space of one fourth of an inch between the staves for 

 the escape of dust and small pieces of waste. Other machines may 



