174 DETAILED REPORT ON ALABAMA CLAYS. 



In burning it has to be heated very slowly to prevent 

 cracking, and the same holds true of the drying. Its 

 excessive plasticily is in part due to the contained organic 

 matter. 



(No. 27 S.) 

 STONEWARE CLAY. 



J. B. GREEN, FERNBANK, LAMAR CO, 



A dense, fine grained, compact, tough clay, that falls 

 to pieces extremely slowly in water. No pyrite notice- 

 able. Taste somewhat gntty. 



It required 32.6 percent, of water to make it work up, 

 giving a plastic mass. The shrinkage in drying was 10 

 per cent., and an additional 7 per cent, in burning, mak- 

 ing a total shrinkage of 17 per cent. The tensile strength 

 as determined by pulling apart air dried briquettes of the 

 clay was on the average 152 pounds per square int.h with 

 a maximum of 185 pounds per square inch. 



Incipient fusion occurs at 1900° F., vitrification at 

 2100° F., viscosity at 2300° F. 



The clay burns to a hard, impervious body, of a deep 

 red color. There is considerable organic matter present 

 in the clay, which adds somewhat to the plasticity. 



Tire analysis of the clay is as follows : 



Analysis of Stoneware Glay, Fernbanle, Lamar Co. (No. 27 S.) 



Silica (total) 69.50 



Alumina 13.00 



Water and organic matter 6.70 



Ferric oxide 6.40 



Lime .25 



Magnesia tr. 



Allialies .■ tr. 



Moisture 3.40 



99. 2 S 



Free Bilica (sand) 43.90 



Total impurities 6.65 



Specific gravity 2.305 



