35o CLAYS AND CLAY INDUSTRY. 



much organic matter, and that from locality 213 shows tiny 

 specks of iron oxide after it is burned. 



One curious feature of some of the Cohansey clays is that 

 their color, when freshly dug, is sometimes so brilliant as to de- 

 ceive one regarding their buff-burning character. 



In several pits where red-burning clays are dug for brickmak- 

 ing, patches of lighter clay are also found in the same bank, and 

 are often referred to as buff-burning clays. While these may 

 burn buff in a common-brick kiln, where the temperature does 

 not usually exceed the fusing point of cone 05, they will not 

 retain this color if burned to cone 7 or 8, these being the cones at 

 which the manufacturers of buff ware, such as terra cotta or 

 pressed brick, commonly burn their product. 



Uses. — So far as the writer is aware, no attempts have been 

 made to wash out the grit from the Cohansey clays and use them 

 for floor tile, but this might be found profitable. Their most 

 important use at the present time is for the manufacture of 

 pressed brick. These are made at Rosenhayn and also at Mays 

 Landing by the stiff-mud process, and by the hydraulic dry-press 

 method at Winslow Junction. Conduits have been made at Clay- 

 ville, and common brick from more impure beds at Bridgeton and 

 Toms River. Considerable sandy clay has been shipped from 

 near Woodmansie for making terra cotta, and clay for the same 

 purpose has been dug at Blue Anchor and east of Millville. The 

 ochre dug at Toms River is said to have been used by linoleum 

 manufacturers. Next to the Raritan clays, those of the Cohansey 

 formation seem to have the most extensive use of any found in 

 the State. Some of the Cohansey clays have been incorrectly 

 termed fire clays, and have even been used to make bricks for 

 lining brick kilns, or even boiler settings, but in neither of these 

 cases would they be subjected to a high heat. So far as the 

 writer's experiments have gone, only one of the series examined 

 is to be classed as a fire clay, and it seems doubtful whether any, 

 with the exception of this one, should be used in anything which 

 requires burning at a higher heat than cone 10. 



Further details regarding their occurrence are given under the 

 description of clay in Ocean, Burlington, Camden, Atlantic and 

 Cumberland counties. 



