FIRE CLAY8. 135 



in Marion county and No. 57 S. from Pegram in Col- 

 bert county. (4) The lower Tertiary formation, No. 

 S from Cnoctaw county. Of these only the clays 

 from Bibbville and Woodstock have been regularly 

 mined. 



(No. 191.) 

 FIEE CLAY. 



FROM PEACEBURG, NEAR ANNISTON. 



A grayish white clay of very fine grain, and contain- 

 ing a noticeable amount of very fine mica scales. In 

 water it slakes moderately fast. 



Twenty-five per cent, of water was required to 

 work it up r and the resulting mass was rather lean, 

 and had a somewhat flaky structure, which interfer- 

 red with the development of the plasticity. 



Bricklets made from the mixture had air shrinkage 

 of 5 per cent. 



When burned to about 2100 F. the total shrinkage 

 amounted to 10 per cent, the clay was white with a 

 faint tinge of yellow and the brick was still very por- 

 ous. At about 2250 F. incipient fusion has barely 

 been reached, w'th a total shrinkage of 13 per cent., 

 the color being white tinged to a noticeable extent 

 with yellow. At about 2300 F. the bricklet burned 

 cream color, was incipiently fused, and the' total 

 shrinkage amounted to 15 per cent. 



In the Deville furnace the clay vitrified at cone 30, 

 but did not lose its shape. 



Owing to the leanness the tensile strength was very 

 low, and ranged from 20 to 25 pounds per square inch. 



The chemical analysis of the clay gave: 



