354 CLAYS AND CLAY INDUSTRY. 



ferent character, overlying each other. Thus west of Asbury 

 Park the clay bank at Drummond's brick works shows the fol- 

 lowing section beginning at the top: 



Section at Drummond's clay pit, Asbury Park. 



Top loamy clay, 6 feet. 



Yellow loam, sand and clay, 6 



Black laminated sandy clay, _ 8 



The black clay contains considerable organic matter and sand. 



The Asbury clays are exposed in many of the gullies and along 

 the roadway west of Asbury Park, but are worked at only a 

 few localities. 



Slaking. — The Asbury clays are mostly rather porous and 

 hence slake fast. 



Air shrinkage. — The air shrinkage is usually low, and ranges 

 from 3.3 per cent, to 6.3 per cent, in the samples tested, as 

 might be expected from the gritty character of the material. 



Water required. — The amount of water necessary to> work up 

 the clay into a plastic mass is high, as compared with its low 

 plasticity, and ranges from 20.9 per cent, to 37.3 per cent. 

 Where several distinct beds are found in the same bank these 

 may differ in their behavior towards water, a point which is 

 discussed in more detail below. 



Tensile strength. — Although very sandy, there is still consider- 

 able clay substance in the raw material to bind the sand grains 

 together, 'and produce a briquette of very fair tensile strength, 

 so that, when the clay alone was tested, averages of 107, 124, 

 137 and 182 pounds per square inch were obtained. A mixture 

 sometimes produced better results, but at other times it decreased 

 the strength, as shown below. 



Behavior in firing. — Not one of the Asbury clays, so far as 

 tested, burns steel-hard at cone 05, nor do any of them burn a 

 good brick red at this temperature, unless heated longer than is 

 required in the case of the Clay Maris. One from locality 217 

 (Lab. No. 658), does not burn better than a very light pink 

 at this cone. Their fire shrinkage is also low, being under 1 

 per cent, in most cases, and they are therefore very porous. 



