296 CLAYS AND CLAY INDUSTRY. 



for stoneware manufacture. That from Loc. 207 (Toms River), 

 might do for stoneware if mixed with a tighter burning clay. 



Clays for white ware, porcelain and sanitary ware. — Two kinds 

 of clay are used in the manufacture of these grades of ware, viz., 

 kaolin and ball clay. No kaolin of suitable quality has ever been 

 found in New Jersey, nor is there much chance of finding any — ■ 

 indeed, it is extremely doubtful whether any exists, the so-called 

 "kaolin" of the Woodbridge district not being a kaolin at all but 

 a micaceous sand. 



Ball clay is found only in the Raritan formation especially 

 near South River, and there is no> likelihood of its being found in 

 other formations in the State. Since the New Jersey ball clays 

 show a tendency to crack in burning they cannot be used in large 

 quantities in a pottery body. A ball clay should be plastic, burn 

 white, and not warp or crack in drying or burning, and should 

 burn steel-hard at cone 8 or lower. 



The other raw materials used in white-ware bodies are ground 

 flint and spar, but neither of these is found in commercial quantity 

 in New Jersey, although veins of them may possibly occur in the 

 Highland region. The crude materials are brought to Trenton 

 in large quantities from other states and milled there. 



The following table gives the composition of several American 

 ball clays and kaolins, as well as of foreign clays, these latter 

 being added for the purpose of comparison : 



Analyses of ball clays. 



1. 



Silica (SiO-), 46.11 



Alumina (A1 2 3 ), 39-55 



Ferrous oxide (FeO), 



Ferric oxide (Fe 2 3 ) , O.35 



Lime, (CaO), 



Magnesia (MgO), 0.13 



Soda (Na 2 0), 



Potash (K2O), ' 



Water (H 2 0), 13.78 



Sulphur trioxide (SOs), 0.07 



Titanium oxide (TiO?), 1.20 



Moisture, 



1, Edgar, Fla.; 2, Burt Creek, N. J.; 3, 

 Ky. ; 5 and 6, "Poole" clay from Wareham, England 



2. 



3- 



4- 



5- 



6. 



44.40 



44.89 



56.40 



48.99 



59.6i 



38.34 



37.269 



30.00 



32.11 

 2-34 



26.81 

 2.03 



0.86 



0.97 











0.41 



0.40 



0-43 



0.82 





0.19 



Tr. 



0.22 



0.44 



0.18 



1. 124 



2.01 





.... 



0.26 



0.317 



3.26 



3-31 



3-57 



1350 



14.47 



7-93 



9-63 



7.46 



1. 10 









2-33 



outh . 



A.mboy, 



N. J.; 



4, Ma 



yfield, 



