BRICK CLAYS. 189 



Vitrification took place at cone 27 in the Deville fur- 

 nace and fusion above cone 30. 



The tensile strength of the air dried briquettes varied 

 from 126 to 144 pounds per square inch with an average 

 of 140 pounds. The clay burns to a buff color, and is 

 to be classed as a refractory one although it is not highly 

 so. Its location is excellent for cheap working, and easy 

 shipment of the product, and while it has been put under 

 the head of paving brick clays there is no reason why it 

 should not find uses in other directions as well. 



The chemical composition of this clay is as follows : 



Analysis of Paving Brick Clay, Tuscaloosa Co. (No. A.) 



Silica 72.70 



Alumina 19.61 



Ferric oxide 934 



Alkalies 80 



Ignition 6.50 



100.544 

 Total fluxes 1.734 



PRESSED BRICK (LAY, 



DIXIE POTTERY CO., OXFORD, CALHOUN CO. 



This is the clay used by the Dixie Tile and Pottery Co. 

 For the manufacturer of buff brick, the clay is quite plas- 

 tic, and considering this fact it does not seem to require 

 an extraordinary amount of water to work it up. The 

 amount used being only 25.75 per cent. The average 

 tensile strength is 130 pounds per square inch, with a 

 maximum of 144 pounds. In air drying the clay shrunk 

 about 10 per cent ; at about 2200 F. incipient fusion be- 

 gan, and up to this point the clay had burned a buff color 

 but then began to burn to a grayish tint; vitrification took 

 place at 2400, and the total shrinkage to this point was 



