POTTERY OR STONEWARE CLAYS. 175 



This clay would probably work very well for stone- 

 ware. 



(No. 71S.) 



POTTERY CLAY. 



W. DOTY, PAYETTE CO. 



A fine grained, red clay, with little coarse grit, and 

 very few mica scales. Slakes quickly to fine grains. It 

 required 34.3 per cent of water to work it into a mass of 

 good plasticily, the bricklets made from it shrinking 7 

 per cent, in drying and an additional 6 per cent in burn- 

 ing, giving a total shrinkage of 13 per cent. 



The tensile strength of the air dried briquettes, was 

 on the average; 116 pounds per square inch, with a max- 

 imum of 155 pounds. 



Incipient fusion occurs at 2000° F., vitrication at 

 2200° F., and viscosity at 2400°. 



It burns to a dense hard body of a nice deep red color, 

 which darkens as vitrification is approached. 



The composition of the clay is as follows: 



A nalyais of Pottery Clay, W. Doty, Fayette Co. ( No. 71, S. ) 



Silica (total) 65.58 



Alumina 19.23 



Water 5.50 



Ferric oxide 4-48 



Lime *-^* 



Magnesia ^'^■ 



Moisture ^-^^ 



96.19 



Free silica (sand) - J45.85 



Total fluxes *-48 



Specific gravity 2.42 



