152 DETAILED REPORT ON ALABAMA CLAYS. 



was not attained until the clay was heated to cone 27 

 in the Devilie furnace, and evec at this temperature 

 the clay cone remained still perfectly sharp. 



The tensile strength is moderate, ranging from 75 

 to 110 pounds per square inch, with an average of 102 

 pounds per square inch. 



The analysis of this fire clay is : 



Analysis of Fire Clay, Bibtville, BiW Go. (Wo. 112). , 



Silica '^4.25 



Alumina 17.25 



Ferric oxide ^-^^ 



Lime *0 



Magnesia tr. 



Alkalies 52 



Ignition 6.30 



99.89 



Total fluxes 2.11 



Speciflc gravity 2.44 



(No. 111). 



FIEE CLAY, 



ELGIN PROPERTY, NEAR WOODSTOCK, BIBB COUNTY. 



A sandy, micaceous clay, of yellowish color, which 

 breaks up slowly, but completely, when immersed in 

 water. This needed 23 per cent, of water to work it 

 up, and gave a moderately plastic mass. The air 

 shrinkage amounted' to 7 per cent. In burning the 

 bricklets incipient fusion occurred at 2150° P., with a 

 total shrinkage of 14 per cent, and the color of the 

 clay light buflf. At about 2300° F. the shrinkage was 

 16 per cent., and the color yeUow. Vitrification took 

 place at 2350° F., and at this point the shrinkage had 

 incresaed to 18 per cent., while the color had 

 changed to grayish. Fusion took place at 2900° F. 



