196 DETAILED REPORT ON ALABAMA CLAYS. 



paste, which to the feel was very slightly plastic and it 

 tasted gritty. In shrinkage in drying was 6 per cent, and 

 3 per cent, in burning, making a total shrinkage of 9 per 

 cent. 



Air dried briquettes of the mud had an average tensile 

 strength of 66 pounds per square inch, and a maximum 

 tensile strength of 68 pounds per square inch. 



Incipient fusion occurred at 2000° F.; vitrification at 

 2160° F. and viscosity at 2300° F.; at 2000° F. it burns 

 to a buff, but on retrifying it becomes red in color. 



The composition of the clay is as follows : 



Analysis of Clay, H. Palmer, Bexar, Marion Co. (No. 40 S.) 



Silica (total) 4 71.33 



Alumina 21.88 



Water 5.54 



Ferric oxide .32 



Lime 234 



Magnesia .305 



Moisture 1.05 



100.659 



Free silica (sand) 46.45 



Fluxes 859 



Specific gravity 2.305 



(No. 12.) 

 CLAY FROM H. PALMER, 



BBXAK, MARION CO. 



A fine grained clay, with sandy laminae and mica 

 scales between the layers. It slakes slowly to fine particles 

 and grains of sand. 



The clay required the addition of 31 per cent, of water 

 and gave a moderately plastic mass, that shrank 5 per 

 cent, in drying and 3 per cent, in burning, making a 

 total shrinkage of 8 per cent. The briquettes made from 

 this paste had, when air dried, an average tensile strength 



