454 CLAYS AND CLAY INDUSTRY. 



The stoneware bed, which is layer 7 of the above section, 

 increases to 3 feet in Mr. Cutter's eastern bank. It is a sandy, 

 yellowish clay with many small mica scales, and differs from the 

 top-sandy only in the amount of sand which it contains. When 

 thrown into water it slaked moderately fast, and an air-dried 

 sample required 28 per cent, of water for mixing. The air shrink- 

 age was 7 per cent, and the average tensile strength 60 pounds 

 per square inch. Its behavior in burning was as follows : 



Burning test of stoneware clay, W. H. Cutter, Woodbridge. 



Cone 3 5 8 



Fire shrinkage, 2% 3% 3.3% 



Absorption, 12.33% 10.02%, 8.37% 



Color, light yellow yellowish deep yellow 



The bricklets burned steel-hard at cone 5, and became viscous 

 at cone 33. It, therefore, equals a good No. 2 fire clay in its re- 

 fractoriness, but burns denser at all the cones at which both were 

 tested. 



South Amboy. — The stoneware clays dug in the vicinity of 

 South Amboy differ from the other clays of equal refractoriness 

 of the same district in being more plastic, of higher tensile 

 strength and burning denser at cone 8 or 10. As shown in 

 Chapter VIII they belong to an entirely different bed geologically. 



The No'. 1 stoneware clay from H. C. Perrine & Son's bank did 

 not vitrify until cone 30, and probably would not have fused lower 

 than cone 32. 



The two grades of stoneware clay sometimes occur alone or 

 may be found together in the same bank and have to be sorted by 

 hand picking, as at locality 81, or they may be interbedded with 

 other clays, as at locality yy, where the following section was 

 observed in September, 1901 : 



Section at H. C. Perrine & Son's bank, South Amboy. 



1. Yellow sand, thin laminae of clay, 6-15 feet 



2. Black sandy clay, similar to fireproofing clay, but more sandy,. . 12 feet 



3. Gray- white clay with decomposed pyrite specks (No. 1 stone- 



ware clay) , 3-6 feet 



4. Red-spotted clay. For foundry work, 5 feet 



