FIRE CLAYS. 143 



EEFACTOEY BAUXITES. 



EOCK RUN^ CHEROKEE COU^fTY. 



In addition to these bauxitic clays, six samples of 

 bauxite were also tested chiefly to determine their 

 refractoriness and their shrinkage in burning, the 

 method adopted with most of them being to grind up 

 the specimen, so that it would pass through either a 

 20 or a 30 mesh sieve, the particles which did not pass 

 through being also retainedl Several mixtures of the 

 coarse and fine niaterial yt^ere made. The mass pro- 

 duced in every instance by mixing it with water was 

 extremely low in its plasticity, and lacked greatly in 

 tensile strength, the latter in every instance being 

 not more than 2 or 3 pounds per square inch. 



In many cases, the bauxite showed so little tenacity 

 and was so little affected by the heat that bricks 

 which had been burned at a temperature of 2600° F. 

 were easily rubbed apart with the fingers. Another 

 point to be noticed is the enormous shrinkage which 

 all of the specimens exhibited, the air shrinkage, how- 

 ever, being very low. 



No. 1. This was powdered and passed through a 

 30-mesh sieve, and on working up gave a very lean 

 mass, which required 24 per cent, of water. The air 

 shrinkage was 3 per cent, and at 2400° F. the total 

 shrinkage was 11 per cent, while the bricklet was very 

 porous and white. At 2500° F. the bricklet had not 

 shrunk any more but the color had become reddish. 



In the Deville furnace at cone 30,. the bauxite was 

 totally unaffected although it had become somewhat 

 dense, and stowed a shrinkage of 23 per cent. The 

 composition was: 



