396 CLAYS AND CLAY INDUSTRY. 



Chemical composition of the brick mixture, Budd Brothers, Camden. 



Silica (SiO«), 66.66 



Alumina ( AL0 3 ) , 14-15 



Ferric Oxide (Fe 2 3 ), 3.43 



Lime (CaO), 2.15 



Magnesia (MgO), 0.38 



Potash (K.O), 2.32 



Soda (Na 2 0) , 1.38 



Ignition (water and organic matter), 8.40 



98.87 

 Total fluxes, 9.6 



The composition indicates a rather easily fusible clay, and the 

 burning tests — viscous at cone 8 — confirm this conclusion. 



Merchantville. — Another outcrop of Clay Marl I is seen in the 

 railroad cut on the bridge branch of the Pennsylvania R. R. (Loc. 

 140), three- fourths of a mile east of Merchantville. The section 

 there shows : 



Section along railroad near Merchantville. 



Pensauken, 8 ft. 



Greenish-yellow sand and clay sand, 6 " 



Light chocolate clay, 2 " 



Black clay, 4 " 



Green sand, little clay, 6 " 



The upper two feet of the last layer of the section are more or 

 less cemented by iron oxide. The clay (Lab. No. 605) shows 

 good plasticity when wet, and considerable fine grit. It takes 23 

 per cent, of water to temper it and has an air shrinkage of 8.3 per 

 cent. Its tensile strength is quite high, being 257 pounds per 

 square inch. The fire shrinkage is low. 



Burning tests of clay from railroad cut near Merchantville. 



Cone 05 01 1 3 



Fire shrinkage, 1.7 % 1.7 % 2% 2.3% 



Absorption, 14-95% 9-95% 5-57% 5-8% 



Color, light red red red red 



Condition, not steel-hard not steel-hard steel-hard 



