CLAYS OF CUMBERLAND COUNTY. 411 



Burning test of clay at Millville, Perth Amboy Terra Cotta Co. 



Cone 5 8 10 12 



Fire shrinkage, 7-4 % 7-7% 8.4 % 9.0% 



Absorption, 3.26% 1.80% 0.09% 



Color, buff buff deep buff gray buff 



A dry-pressed bricklet at cone 8 showed 8 per cent, shrinkage, 

 and another one at cone 12, the same, with gray color and im- 

 pervious body. 



Rosenhayn. — Another important bed of Cohansey clay has been 

 opened at Rosenhayn (Loc. 185), along the N. J. Southern R. 

 R. (PI. XVII, Fig." 2). 



Section of clay pit at Rosenhayn. 



Gravel and sand, with some iron crusts, 4-6 ft. 



Clay, upper two feet more or less weathered and laminated, yellowish 



color, red-burning ; lower part said to burn buff, 5-6 ft. 



Alternating layers of clay and sand, 6 in.-i ft. 



Yellow sand, 8 ft. 



Two clays are distinguished in working, viz., a lower or buff- 

 burning clay, and a red-burning top clay. The former is under- 

 lain by a bed of sand, termed fire sand. A mixture of the two is 

 used for making a buff brick, and the under clay with fire sand 

 is employed for fire brick. The main use of the deposit is for 

 making buff brick, the raw material working up well on a stiff- 

 mud machine with few laminations and smooth surface and edges. 

 The stripping is of little value. 



The general physical characters of these two 1 clays are as fol- 

 lows : The red top clay (Lab. No. 682) is a fairly plastic ma- 

 terial with some coarse grit, and in mixing required 32.4 per 

 cent, water. Its air shrinkage was 8 per cent., and average 

 tensile strength 158 pounds per square inch. It behaved as 

 follows in burning: 



Burning test of the top clay, Rosenhayn. 



Cone 158 



Fire shrinkage, 5.3 % 8 % 7-3 % 



Absorption, 10.82% 4.68% 0.01% 



Color, red red gray 



Condition, steel-hard steel-hard 



