164 DETAILED REPORT ON ALABAMA CLAYS. 



cent, of water to the air dried clay gives a fairly elastic 

 mass, and bricklets made from this have an air shrinkage 

 of 6 per cent. At 2100 F. the total shrinkage is 11 \ er 

 cent., and the color of the burned clay is s Dine what red- 

 dish. Incipient fusion occurs at this temperature, while 

 vitrification takes place at 2200 F. with a total shrink- 

 age of 13 per cent., the color of the clay when burned to 

 this point being a dull red. Viscosity took place at 

 2600, so that the clay is not to be classed as a fire clay, 

 it would probably work however for vitrified ware. The 

 tensile strength is exceedingly high, and runs from 300 

 to 384 pounds per square inch, and while there is con- 

 siderable variation, at the same time even the lower figure 

 is very great. 



The chemical composition is : 



Analysis of Stoneware Clay, Chalk Bluff, Elmore Co. (No. 101). 



Silica 60.38 



Alumina 20.21 



Ferric oxide 6.16 



Lime 09 



Magnesia 720 



Alkalies 1-80 



Ignition 10.21 



99.570 

 Total fluxes 8.77 



(Nos. 88 and 89.) 



POTTERY CLAY. 



MCLEAN'S, EDGEWOOD, ELMORE CO. 



Considerable clay is dug for pottery on the land of Mr. 

 McLean, 4 miles from Prattville, along the line of the C. 

 M. R. R. This clay occurs in large pockets surrounded 

 by sand, it is chiefly of two kinds, i. e., a smooth plastic 

 clay and a sandy one. 



The former (No. 88) is very tough, and quite plastic. 



