688 NEW YORK STATE MUSEUM 



These clays are sticky when mixed with water, but they are by 

 no means to be called highly plastic; indeed, when worked up with 

 water the mass shows a certain resistance to mobility that is hard 

 to describe, but is not unlike a mass of powdered feldspar in its 

 behavior. 



When thrown into water the clay slakes quite readily to a 

 flocculent mass. 



Two samples were tested physically, the one from Rose's yard 

 at Roseton above JSTewburgh, and the other from the Brockway 

 brick cO'.'s yard above Fishkill. 



The sample from the bank of the Brockway brick co. (109) 

 worked up to a sticky, but not highly plastic mass with 29^ of water. 

 The bricklets showed an air shrinkage of 5^-6^. 



The tensile strength of air-dried briquettes was Y5 to 90 pounds 

 a square inch, but so^me reached 120 pounds a square inch. 



The clay also gave .2^ of soluble salts. 



In burning, the clay burned red with increasing depth of color 

 as the temperature was raised and at viscosity passed to a brownish 

 glass. Incipient fusion occurred at cone .05 with a total shrinkage 

 of 8^. Vitrification at cone .04: with a shrinkage of 15^. Viscosity 

 took place at cone .01. 



The clay from Roseton was very similar in its behavior to the 

 previous one. 



The air shrinkage was 6fo. Incipient fusion occurred at cone .05, 

 vitrification at cone .04 with a total shrinkage of 14^. At .01 the 

 clay became viscous. The tensile strength ranged from 75 to 93 

 pounds a square inch. 



The soluble salts amounted to .3^. 



A mechanical analysis of the clay from the bank of the Brock- 

 way brick CO. yielded 



Clay substance 49 . 83^ 



Silt and very fine sand . , 28 . 30^ 



Fine sand 21 . Y5^ 



