4 i2 CLAYS AND CLAY INDUSTRY. 



As shown by the above figures this clay burns to a dense body 

 at cone 5, and a very dense one at cone 8. It is said to have 

 been tried for the manufacture of stoneware. 



The mixture for buff brick (Lab. No. 683) is sticky, gritty 

 and plastic, and required 28.9 per cent, of water. Its air shrink- 

 age was 8.6 per cent., and its average tensile strength 127 pounds 

 per square inch. In burning it gave the following results : 



Burning tests of buff-brick mixture. Rosenhayn. 



Cone 



05 



1 3 



5 



Fire shrinkage, 



1-4% 



5-4% 6% 



6% 



Color, 



pale red 



buff red deep buff 





Absorption, . . . 





slightly absorbent 





Condition, .... 



not quite steel- 

 hard 



steel-hard 





6.7% 



A dry-pressed tile burned at cone 10 was gray brown, with 

 an absorption of 2.36 per cent., and a fire shrinkage of 9 per cent. 



Carmel. — The Cohansey clays are also, found at Carmel on 

 Mr. Miller's property (Loc. 186), but the thickness exposed in 

 the pit is not great. When wet the clay is tough, sandy and. 

 rather lean, so that its tensile strength is probably not very high. 

 It also pulls somewhat in molding, so that it could probably be 

 improved by the addition of a more plastic material. The ma- 

 terial (Lab. 704), when mixed with 28.1 per cent, of water, had 

 an air shrinkage of 6 per cent., and at cone 5 its fire shrinkage 

 was 4 per cent., the bricklet being buff-colored and its absorption 

 7.68 per cent., so that in its burning qualities it is similar to the 

 buff clay found at Rosenhayn. Some draintile have been made 

 from it experimentally. The bed has not been worked nor is its 

 exact extent known. Rosenhayn, about 3 miles distant, is the 

 nearest shipping point. 



Bridgeton. — Another exposure of the Cohansey clays is worked 

 at Bridgeton (Loc. 191), where the clay is seen in Erickson's 

 pits on the southern edge of the town. The clay is bluish-white, 

 mottled and often very siliceous and, so far as seen, without 

 pebbles. The thickness of the deposit, as exposed, ranges from 

 6 to 9 feet, and it is underlain by a layer of sand cemented by 

 limonite. The upper limit of the clay is fairly uniform, so that 



