222 



CLAYS AND CLAY INDUSTRY. 



usually the fusing-point of cone I or 2, while for buff-burning 

 clays it is commonly necessary to go to cone 7 or 8 to make the 

 brick steel-hard. 



The following table gives the physical characters of several 

 clays used for pressed brick in New Jersey. 



Physical properties of some New Jersey clays used for front brick. 



Formation. 



Raritan, . 



Cohansey, 

 Cohansey, 



locality 

 num- 

 ber. 



45 



195 



Water 



required, 



per 



cent. 



32.00 



23-17 



37-50 



Air 

 shrink- 

 age, 

 per 

 cent. 



5-0 



7-5 

 5-5 



Aver, 

 tensile 

 strength, 

 lbs. per 

 sq. in. 



65 



282 



cone i 

 cone 5 

 cone 8 

 cone 1 

 cone 5 

 cone 8 

 cone 8 



Fire 

 shrinkas 



5-0% 



6.6% 

 2.8% 

 4-5% 

 6.5% 

 9.1% 



Absorp- 

 tion. 



Color. 



.68% [ Buff 



II 



11.34% 



8.09% 

 3.08% 

 0.84% 

 4.01% 



Buff 

 Buff 



In New Jersey the Raritan, Pleistocene and Cohansey forma- 

 tions supply materials for the manufacture of pressed brick. The 

 Raritan clays found around Perth Amboy were formerly much 

 used for making pressed brick, but at the present time compara- 

 tively few are manufactured in this district, although much Rari- 

 tan clay is shipped to> other States to be used for this purpose. 

 They are commonly molded in stiff-mud machines and re-pressed. 

 The Pleistocene (post-Glacial?) clay loams were much used in 

 former years for making red pressed brick, and are still employed 

 to some extent. They cover large areas around Trenton, in Mer- 

 cer county, but, owing to> their shallowness, much of the material 

 has been removed. Similar loams are found in western Burling- 

 ton and Camden counties. The Cohansey clay is often found to 

 make a good buff-burning brick, with either the stiff-mud re- 

 pressed, or dry-press process, but trouble is experienced now and 

 then in making the bricks flash well. These Cohansey clays are 

 available in Burlington, Camden? Atlantic, Cumberland, and 

 Ocean counties. They are not fire clays, and can barely be classed 

 as semirefractory, but burn to a good hard buff brick at cones 6 

 to 8. They are utilized for this purpose at present at Winslow 

 Junction, Mays Landing and Rosenhayn. 



Enameled brick. — The clays used for these are similar to those 

 employed in the manufacture of pressed brick. There are two 



