214 THE MINERAL RESOURCES OF CECIL COUNTY 



following results: Air-shrinkage, 1^$. "When burned to cone 5 the 

 total shrinkage was 9$, but the bricklet was still easily scratched, and 

 had a very white color. At cone 10 the clay was barely scratched with 

 a knife, and showed the total shrinkage 14$. The color was whitish. 

 At cone 27, in the Deville furnace, the material had preserved its 

 form perfectly, and showed signs of incipient vitrification. In refrac- 

 toriness it is fully equal to many of the best kaolins put on the market. 

 Its composition is: 



Analysis of Washed Kaolin, Northeast, Cecil County. 



Silica 55.65 



Alumina 30.53 



Ferric oxide .97 



Lime .75 



Magnesia .60 



Alkalies 20 



Moisture 35 



Water 12.30 



Total 100.35 



Total fluxes '. 2.52 



A sample of the second grade of crude kaolin from the Maryland 

 Clay Company, at Northeast, was also tested. This differs from 

 the first grade chiefly in having a larger percentage of iron oxide, 

 and consequently the washed clay from it does not burn to as white 

 a color. It is very sandy and when thrown into water falls apart 

 very rapidly. 



A sample of the crude material was washed through screens with 

 the following results: Residue on 80-mesh, 5.6$; on 100-mesh, 1.5$; 

 on 150-mesh, 4.5$. 



The material therefore contains 88.4$ of grains sufficiently fine to 

 pass a 150-mesh sinve. In actual practice, however, this is a much 

 larger proportion than could be floated off to settle in the tanks em- 

 ployed for that purpose. 



When burned to cone 4 the material shows a total shrinkage of 5$ 

 and is white in color, but above this it begins to develop a yellowish 

 tint, so that it could not be used in the manufacture of good grades 

 of white ware. 



It is unaffected at cone 27 in the Deville furnace. 



