MISCELLANEOUS CLAYS. 197 



of 85 pounds p.r square inch, with a maximum of 89 

 pounds per square inch. 



Incipient fusion occurs at 1950 F., complete vitrifica- 

 tion at 2150 F., and viscosity at 2350 F. The clay 

 burns to a yellowish red body. 



Its composition is as follows : 



Analysis of Clay, H. Palmer, Bexar, Marion Co. (No. 12) 



Total silica 09.93 



Alumina 20.15 



Water 5.90 



Ferric oxide 1.38 



Lime 42 



Magnesia tr. 



Alkalies tr. 



Moisture 1.20 



Total fluxes 1.80 



Specific gravity 2.28 



(No 41 S.) 

 MOTTLED CLAY. 



BEXAR, MARION CO. 



A very open grained, sandy clay, with scattered scales 

 of mica and occasional iron stains. It slakes very 

 quickly to its component mineral grains. 



It required 39 per cent, of water to work it up. It is 

 slightly plastic, and shrunk 6 per cent, in drying with 

 an additional 11 per cent, in burning, making a total 

 shrinkage of 17 per cent. 



Air dried briquettes of the mud had an average ten- 

 sile strength of 15 Ibs. per square inch, and a maximum 

 of 80 Ibs. per square inch. 



Incipient fusion occurs of 2000 F., vitrification at 2150 

 F., aud viscosity at 2300. The clay burns to a red, but 

 not very smooth body. 



The clay analyzed as follows: 



