442 CLAYS AND CLAY INDUSTRY. 



It is not known just what pit the last one of the list came from, 

 for in the work done for this report no clays were found around 

 Sayreville as refractory as the one quoted above. 



Beds of No. i fire clay also occur in the pits of J. E. Berry 

 (Loc. n), J. H. Leisen (Loc. 16). W. H. Cutter (Loc. 29 and 

 30), J. P. Prall (Loc. 2j) , etc. They are mentioned here be- 

 cause they are probably as highly refractory as those described 

 above, although their fusibility was not tested. 



Ball or ware day. — W. H. Cutter. 1 Ball clay of the same re- 

 fractoriness as a high-grade No. 1 fire clay is dug in the immediate 

 vicinity of Woodbridgeby W. H. Cutter (Loc. 29, PI. XXXVII). 

 It is found at the extreme base of the pit and runs about 6 to 7 

 feet thick. 



The clay is shipped as mined, and, therefore, the crude ma- 

 terial was tested. Its physical properties are those of a very fine- 

 grained clay containing little or no- grit, and when dry breaking 

 easily with a conchoidal fracture. It slaked rapidly in water, 

 and when mixed with 33 per cent, gave a tough, plastic- feeling 

 mass, the air shrinkage of which averaged 3.4 per cent., but the 

 bricklets showed a tendency to warp somewhat in drying, and 

 showed the same yellowish coating seen on the clay in the sheds. 

 The tensile strength averaged 33 pounds per square inch, which is 

 low, and not as high as one would expect from the plastic feel of 

 the wet clay. The behavior of the bricklets in burning was as- 

 follows : 



Burning test of a ball clay. W . H. Cutter, Woodbridge. 



Cone. 4 8 10 



Fire shrinkage, 6.2% 14.6% 16.6% 



Absorption, very absorbent 7. 14% .22% 



Color, white, tinge of yellowish white yellowish white- 

 yellow 



The bricklet was nearly steel-hard at cone 4, and showed many- 

 small reticulating cracks. It is highly refractory, being nearly- 

 viscous at cone 34. The chemical composition is as follows : 



1 No. 14 of section on page 453. 



