CLAYS OF NEW YOKK 



821 



The following are analyses of Long Island stoneware clays made 

 by C. H. Joiiet. {School of mines quart. Jan. 1895) 



Silica 68.34 



Alumina 19.89 



Ferrous oxid 



Lime 



Magnesia 



Carbonic acid 



Sulfuric acid 



Potash 



Soda .' 



Combined water 



White clay 



from 

 Northi; ort 



Black clay 



from 

 Northport 



White clay 

 fiom 

 Seaciiff 



68.34 



58.84 



62.35 



19.89 



23.40 



23.14 



.90 



1.18 



1.12 



.35 







tr. 









1.03 



1.09 



3.55 



5.04 



3. 17 



.84 



.34 



1.76 



6.03 



9.20 



6.77 



99.90 



99.03 



99.40 



A physical test of the yellow clay from the pits of the ISTorthport 

 clay and fire sand co. gave the following results. It took 25^ of 

 water to mix the clay up to a workable mass, that was very gritty, 

 but possessed good plasticity. The tensile strength of the clay does 

 not stand in direct relation to the plasticity, as the average is only 

 25 pounds a square inch with a maximum of 30 pounds. The 

 air shrinkage of the bricklet was 5-|^, and at 2300° F. the total 

 shrinkage was 12;^. At this temperature the clay had burned buff, 

 and was nearly vitrified. Viscosity occurred in the Deville fur- 

 nace at cone 27. 



The mechanical analysis of the clay shows the high percentage of 

 sand contained, which is evidently responsible for its low refractory 

 quality. 



Clay substance 



30 



Silt 



Very fine sand 60 



Line sand 9 



99 



