138 DETAILED REPORT ON ALABAMA CLAYS. 



The following tests mere made upon these samples: 



No. 1. This is a fine grained white clay, with a 

 splintery fracture, showing iron stains along the joint 

 cracks and other planes or fracture, but none in the 

 interior of the mass. It slakes quickly but not com- 

 pletely into angular fragments. In mixing it up, 32 

 per cent, of water was required and the resulting 

 mass was lean and granular. It had been previously 

 passed through a 30 mesh sieve, and it ground to a 

 finer mesh would, no doubt, be more plastic. The 

 lean granular character gives it a very low tensile 

 strength amounting to not over 6 pounds. 



The air shrinkage of the clay was 4 per cent, at 

 about 2200^ P., the total shrinkage was 9 per cent; 

 and at about 2300, 18 pr cent, at about 2500, the 

 total shrinkage was 21.50 per cent, and the color of 

 the burned bricklet was still white. 



When tested in the Deville furnace at cone 30 the 

 form of the clay still remained sharp, and it was 

 white in color, but showed signs of incipient fusion. 



The composition of the clay is as follows : 



Analysis of Fire Clay, Rock Run, Cherokee Co. (No. 1.) 



Silica 47.60 



Alumina 36.70 



Ferric oxide 1.10 



Lime 1.30 



Magnesia , trace 



Alkalies trace 



Ignition 14.20 



100.90 

 Total fluxes i.4( 



These tests indicate that the clay is quite refrac- 

 tory, and its burning to a white color would permit its 

 being used for products having a white body. The 

 high shrinkage is somewhat against it, but this could 



