790 NEW YORK STATE MUSEUM 



The mecliaiiical analysis is: 



Clay substance 92 . 50 



Silt 2.30 



Yery fine sand .80 



Fine sand 4.60 



100.20 



A sample of tlie better grade fire clay from tbe present large 

 opening was likewise tested, as it represents a common type of clay 

 found on Staten Island. 



This was far more plastic than the other two; it had a tensile 

 strength of 45 pounds a square inch. 80^ of water gave a workable 

 mass, whose air shrinkage was 8.25^. When burned to cone 12 

 the color was yellowish white and the total shrinkage 17^. 



The clay did not fuse at cone 30 in the Deville furnace; so that 

 it can be properly classed as a fire clay. 



The mechanical analysis gave : 



Clay substance YO 



Silt 7 



Yery fine sand ; 7 



Fine sand 14 



98 



