CHINA CLAYS. 127 



(N0.38S.) , 

 CHINA CLAY. 

 J. J. MITCHELLS^ CHALK BLUFF^ MAEION CO. 



Pure whitej fine' grained clay, brittle when dry, 

 and with conchoidal fracture. It slakes easily in 

 water, all of it passing through a 60 mesh sieve and 

 most of it through a 100 mesh one. 



The clay ground to pass through a 30 mesh sieve, 

 and mixed with 24 per cent, of water, gave a lean 

 mass whose air shrinkage was 4 per cent, and an addi- 

 tional shrinkage of 3 per cent, took place in burning, 

 giving a total of 7 per cent. 



Air dried briquettes of the clay gave the usual low 

 tensile strength of kaolin, the average being 15 pounds 

 per square inch, with a maximum of 17 pounds per 

 square inch. 



Incipient fusion occurs at 2300° P., vitrification 

 at 2600° P., annd viscosity at 2700° P. 



The clay burns to a clear white body. Its composi- 

 tion is as follows: (No. 1 being by H. Eies and No. 2 

 by W. B. Phillips. No. 3 is the composition of- pure 

 kaolin given for comparison.) 



Analyses of China Clay, OhalTc Bluff, Marion Co. 



12 3 



Silica 47.25 47.20 46.30 



Alumina 36.50 37.76 39.80 



Water 13.35 14.24 13.90 



Ferric oxide 2.56 tr 



Lime tr tr 



Magnesia tr tr 



Moisture -50 tr 



100.16 99.20 100.00 



Totai fluxes (!) 2.56 



Specific gravity 2.44 



