I 3 

 2.5 % 2.5 % 



5 

 2-5 % 



8 

 5-i% 



12.04% 12.01% 

 yellow buff 



buff 



nearly impervious- 

 deep buff 



steel-hard 





370 CLAYS AND CLAY INDUSTRY. 



This material shows a good color and low fire shrinkage, which 

 accounts for its high absorption. The grit holds back the shrink- 

 age, but still there is not enough sandy matter to lower its tensile 

 strength. 



The whitish clay is similarly a somewhat plastic material, but 

 has less grit. It took a little less water to mix, viz., 29.1 per cent. r 

 but its air shrinkage, 7.5 per cent., is slightly greater. Its tensile 

 strength is also good, averaging 192 pounds per square inch. Its- 

 burning qualities are as follows : 



Burning tests of a clay from David Doerr's pit, Da Costa. 



Cone 05 



Fire shrinkage, 0.5 % 



Absorption, . . . 17.20% 



Color, pale yellow 



Condition, .... not steel-hard 



Comparing the two, it will be seen that the latter has a lower 

 fire shrinkage at cone 5 than the former or red-burning clay, but 

 shrinks about the same at the temperature of common-brick kilns. 

 The lighter burning one is not a fire clay, and it is doubtful 

 whether it could be used for buff brick. If any of the buff-burn- 

 ing clay gets into the brick mixture it shows as whitish spots in 

 the brick. The clay is now employed for common, soft-mud,, 

 building brick. 



Elwood. — In the summer of 1902 a new pit was started by 

 Messrs. Rupp & Sawyer (Loc. 198) at a point' 2 miles north- 

 east of Elwood, exposing a bed of yellowish, sandy clay from 4. 

 to 5 feet thick and with 2 to 11 feet overburden. The bottom is- 

 sand, which at times is gravelly, and is mixed in with the bricks. 

 This clay is red-burning like the run of the bank at Da Costa, and 

 burns equally porous. At the time the pit was visited it had not: 

 been opened up enough to give a very definite idea of the extent or 

 thickness of the clay. If many pebbles get into the clay it tends 

 to split in burning. 



Mays Landing. — Clay for making pressed brick has been dug 

 to a considerable extent (Loc. 195) at Mays Landing, several 

 strata of clay being found in one pit. In part they resemble those 



