398 CLAYS AND CLAY INDUSTRY. 



high, the upper 5 to 6 feet being weathered and containing some 

 sandstone crusts. The clay in the lower two-thirds of the bank 

 is very similar to that at Crosswicks. It burns to- a good, red, 

 hard body. Practically no loam is added to the clay, so that the 

 brick mixture represents the run of the Clay Marl. The prop- 

 erties of a sample (Lab. No. 650) were as follows: Water re- 

 quired for tempering, 34.9 per cent. ; air shrinkage, 10 per cent. ; 

 average tensile strength, 286 pounds per square inch. Its be- 

 havior in burning was as follows : 



Burning test of Dobb's brick mixture, Collingswood. 



Cone 05 1 



Fire shrinkage, 3-3 % 3-3 % 



Absorption, 11.12% 9-92% 



Color, red red 



The clay burned steel-hard at cone 05, and became viscous at 

 cone 10. 



The body of the bricks made from this clay are dense and show 

 high transverse strength. 



Haddoufield. — A bed of Clay Marl II outcrops in the Penn- 

 sylvania R. R. cut, i}'2 miles north of Haddonfield (Loc. 145). 

 The clay (Lab. No. 715) is rather sandy, although quite plastic, 

 and is covered by 8 feet of Columbus sand (Clay Marl III). 

 "When tested for its physical properties it was found to work up 

 with 30.7 per cent, water, but its air shrinkage was only 6.6 per 

 cent. Its average tensile strength was 168 pounds per square 

 inch. At cone 05 the lire shrinkage was 0.4 per cent. ; absorp- 

 tion, 19.98 per cent. ; color, buff, and at cone 5, fire shrinkage was 

 4.9 per cent. ; absorption, 7.70 per cent. ; color, reddish buff, and 

 bricklet steel-hard. 



This clay burns to a somewhat lighter color than most of the 

 Clay Marls, but not to a very dense body. 



Westniount station. — A weathered plastic outcrop of Clay Marl 

 II is seen 1 mile due north of Westmount station (Loc. 146). 

 The sample (Lab. No. 638) was taken from a bank in the woods 

 about 300 feet east of the Pennsylvania R. R., and the bed of 

 weathered clay is probably not less than 8 feet thick. . The total 



