BBICK CLAYS. 191 



While this clay is not to be looked upon as a refractory 

 one, it would seem that owing to the beautiful color, to 

 which it burns, it would be highly desirable for the manu- 

 facture of pressed brick. 



The composition of the clay is : 



Analysis of Pressed Brick Clay, Shirley's Mill, Fayette Co. (No. 110.) 



Silica 71.32 



Alumina 20.10 



Ferric oxide 1.05 ' 



Lime tr. 



Magnesia .316 



Alkalies tr. 



Ignition 7.505 



100.291 



Total fluxes 1.366 



Specific gravity 1.90 



(No. 1-22.) 

 BRICK CLAY. 



CHALK BLUFF, ELMORE CO. 



The upper half of tlie clay bed at this locality is com- 

 posed of a dark, dense, grayish brown clay which contains 

 a large amount of organic matter, either in a finely divided 

 condition or izi the form of leaves. Although not sandy, 

 at the same time it is rather lean when mixed up with 

 water, and owing to the presence of so much organic ma- 

 terial absorbed 40 per cent, of water when it was being 

 worked up to a plastic mass. The air shriukage was 

 however only 6 per cent. At 1900° F. it had reached a 

 total of 14 per cent., but the bricklet was still very ab- 

 sorbent ; at 2100° F. incipient fusion had been reached 

 and the total shrinkage was 18.7 per cent., while the 

 color was brownish red ; and at about 2200° F. the total 

 shrinkage was 20 per cent, and the color brown, and this 

 color had deepened considerably at 2250° F. with the ap- 



