168 DETAILED REPORT ON ALABAMA CLAYS. 



had, when air dried, a tensile strength of 68 pounds per 

 square inch and a maximum tensile strength of 78 pounds 

 per square inch. 



Incipient fusion occurs at 2000 F., vitrification at 

 2200 F. and viscosity at 2400 F. 



The clay burns to a dense yellowish body ; the com- 

 position of it is as follows : 



Analysis of Pottery Clay, H. H. Cribbs, Tuscaloosa (No. 1, S.) 



Total silica 65.35 



Alumina 21.30 



Water 7.35 



Ferric oxide 2.72 



Lime 60 



Magnesia .86 



Alkalies tr. 



Moisture , 1.44 



99.62 



Free silica (sand) 39.25 



Total fluxes 4.18 



Specific gravity 2.34 



Another analysis of this white clay from the Cribbs bed 

 was made by Dr. Wm. B. Phillips and is as follows . 



Analysis of White Plastic Clay, Ortb&s Place, Tuscaloosa, Ala. 



Silica 62.25 



Alumina 27.90 



Lime 2.36 



Ferric oxide 0.10 



Lois at red heat 10.00 



102.61 

 Total fluxes 2.46 



If coarse grained this clay would probably work for a 

 low grade of fire brick, as its fusibility would probably be 

 less. It would probably work for potters clay, although 

 it would no doubt be desirable to add a clay possessing 

 greater plasticity and tensile strength to it. 



The comparative purposes there are given herewith the 



