FIRE GLAY8. 153 



The tensile strength is moderate, and varied from 100 

 to 110 pounds per square inch. 

 The ultimate composition is : 



Analysis of Fire Clay, Woodstock, BiWt Co. (No. 111). 



Silica 65.82 



Alumina 24.58 



Ferric ozide 1.25 



Lime 



Magnesia ; tr. 



Alkalies .60 



Ignition 8.165 



100.415 



Total fluxes 1.85 



Specific gravity 2.40 



The rational analysis fiave : 



Clay substance 82.90 



Feldspar "1 



Quart. I 3700 



99.90 



(No. B). 



FIRE CLAY, 



AUXFORDS, NEAR HULL'S STATION, TUSCALOOSA CO. 



This is a sandy micaceous gray clay, with a slightly 

 reddish tinge, which crumbles to pieces very qu^'ckly 

 when immersed in water. When worked up it gives 

 quite a plastic mass, and requires 33 per cent, of 

 water to accomplish it. 



The air shrinkage is from 9 to 10 per cent., and at 

 2000° F. the total shrinkage was only 12 per cent. At 

 this latter temperature the bricklet was hard, grayish 

 red in color, but still somewhat absorbent, while at 

 about 2200° F. vitrification occurred, with a total 

 shrinkage of 14 per cent. The viscosity occurred at 



