192 DETAILED REPORT ON ALABAMA CLAYS. 



appearance of vitrification , while the maximum shrinkage 

 amounted to 21 per cent. Viscosity was obtained in the 

 Deville furnace at cone 27. 



This clay therefore thows an appreciable and safe dis- 

 tance between vitrification and viscosity. The tensile 

 strength is however low, averaging 75 pounds per square 

 inch, with a maximum of 97 pounds per tquaie inch, 

 and a minimum of 68 pounds. Specific gravity, 2.41. 



(No. 26 A. Stevens.) 

 BRICK CLAY. 



WOOKSTOCK, BIBB CO. 



This is quite a plastic clay, which requires 29 per 

 cent, of water to produce its maximum plasticity. The 

 air shrinkage was 6 per cent., and the average tensile 

 strength was 101 pounds per square inch, with the max - 

 mum of 104 pounds. The fire test gave the following 

 results : 



At 2250 F., the shrinkage 10 per cent, clay incipiently 

 fused, color buff. 



At 2400 F., shrinkage 11 per cent., color a dark buff. 



At 2500 F., clay vitrified, color reddish. 



Viscosity occurs at cone 27 in the Deville furnace. 



The composition of the clay is : 



Analysis of BricTt Clay, Woodstock, J5i&6 Co. (No. 16 A. Steven*.) 



Silica 74.20 



Alumina 17.25 



Ferric oxide 1.22 



Lime 30 



Magnesia .40 



Alkalies tr. 



Ignition 7.35 



Total fluxes 



