158 DETAILED REPORT ON ALABAMA CLAYS. 



occurs at cone 27; vitrification at cone 32 and viscos- 

 ity at cone 34. 



The tensile strength is very low, ranging from 5 

 to 10 pounds. 



The very refractory character of this clay is evi- 

 dent, but its leanness would no doubt necessitate its 

 being mixed with a more plastic clay before it could 

 be used. 



(No. 57 S.) 

 FIKE CLAY, 



J. W. WILLIAMS, PEGRAM, COLBERT COUNTY. 



A black gritty clay, which slakes easily, considera- 

 ble organic matter present, but no pyrite or mica no- 

 ticeable. 



It required 28.6 per cent, of water to make a 

 workable mass, which, to the feel, was lean and 

 gritty. Bricklets made of this shrank 10 per cent, in 

 drying and 3 per cent, in burning, giving a total 

 shrinkage of 13 per cent. 



The average tensile strength of the air-dried 

 briquettes was 46 pounds per square inch. 



Incipient fusion occurs at 2150 F., vitrification at 

 2350 F., and viscosity at 2500 F. 



The clay burns to a white body, slightly tinged 

 with yellow. 



The following is its chemical composition : 



Analysis of Fire Clay, J. W. Williams, Pegram, Colbert Co. (No. 57, S.) 



Moisture 1.70 



Silica (total) 80. 55,. free sand 70.10 



Alumina 10.50 



Ferric oxide 1.53 



Lime 34 



Magnesia traces 



Water and organic matter 5.85 



100.47 

 Total fluxes.. 1.87 



