500 CLAYS AND CLAY INDUSTRY. 



road. When the clay dries out on the surface it breaks into 

 blocks. When tempered with 46.5 per cent, of water, its air 

 shrinkage was 10.6 per cent., and it had an average tensile 

 strength of 337 pounds. At cone 03 the fire shrinkage was 3.4 

 per cent., the absorption 9.89 per cent. ; at cone 1 they were 3.4 per 

 cent., and 7.96 per cent, respectively. 



Woodstown. — Two* miles east of Woodstown (Loc. 177) there 

 is an exposure of the usual tough, dry, mottled clay so character- 

 istic of the Alloway formation. The material (Lab. N0 1 . 673) 

 was sampled by boring to a depth of 4 feet, and when worked up 

 was found to^ be quite plastic. It tempered with 35.8 per cent, 

 water to> a mass having 8.3 per cent, shrinkage. Its burning qual- 

 ities were as follows : 



Burning tests of a clay near Woodstown {Loc. 177). 



Cone 05 03 1 5 



Fire shrinkage, 4.7% 5.7% 7.7% 9.3% 



Absorption, 11.76% 9-45% 3-59% .36% 



Color, pale red streaky red red deep dirty red 



Hardness, steel-hard steel-hard steel-hard steel-hard 



Viscous at cone 12. 



The following are two analyses of clays of the Alloway forma- 

 tion: 



Chemical analyses of two Alloway clays. 



1 2 



Silica (Si0 2 ), 52.30 67.40 



Alumina ( AI2O3) , 32.01 19.62 



Iron oxide (Pe 2 3 ) , 1.59 2.45 



Lime (CaO), 0.25 



Magnesia (MgO), 0.34 



Water (H 2 0), 12.02 8.08 



1. Source unknown. 



2. Sample collected by the Survey from railroad cut north of 

 Alloway, and analyzed for this report. 



