456 CLAYS AND CLAY INDUSTRY. 



It is a whitish, gritty clay, with tiny mica scales, and slakes 

 rather slowly. It is not highly plastic, and feels flaky and gritty 

 when mixed with water. The air shrinkage was 4.6 per cent., 

 and its tensile strength averaged 78 pounds per square inch. It 

 behaved as follows in burning : 



Burning tests of the top-sandy clay, Anness & Potter, Woodbridge. 



Cone 4. Cone 8. 



Fire shrinkage, 1.4% 3-4% 



Absorption, 1 1.98% 2.9% 



Color, light buff gray buff 



The bricklets became steel-hard at cone 4, but the clay is only 

 semirefractory, for it fused easily at cone 27. Its composition 

 was as follows : 



Chemical analysis of the top-sandy clay, Anness & Potter, Woodbridge. 



Silica (Si0 2 ), 68.67 



Alumina (AL0 3 ), 21.46 



Ferric oxide (Fe 2 3 ) , 0.78 



Titanium oxide (Ti0 2 ) , 1.34 



Loss on ignition (water) , 6.40 



Lime, magnesia, alkalies (By diff.) , 1.35 



100.00 

 Total fluxes, 3.13 



This analysis is an interesting one when compared with that 

 from Valentine's pit, locality 14, on p. 440. The difference in 

 refractoriness is so large that it seems doubtful whether it can be 

 due entirely to increased fluxes. It is probably caused in part by 

 the higher silica contents of the clay. 



Burt Creek. — A so-called No. 1 blue fire clay belonging to the 

 South Amboy fire-clay bed is dug in J. R. Crossman's bank, near 

 Burt Creek (Loc. 65). Its position in the bank can be seen from 

 the following section, made in September, 1901, near the western 

 end of the excavation : 



