CLAYS OF NEW YORK 721 



The clay (PI. 22) is dug by means of a plow and loaded on cars, 

 which are drawn to the yard by horses, where it is discharged 

 either into the rolls for the soft mud machine or is carried 

 to a conveyer that discharges it into a series of rolls and png mills 

 (PI. 27), which temper it for the stiff nmd machine. The latter is 

 used only for drain tile and hollow bricks. 



All the drying is done on pallet racks, some of which are pro- 

 vided with a movable roof to allow the sunlight to enter (PI. 37). 

 The kilns are mostly of the Wingard type, but there are also four 

 round down-draft kilns for burning the hollow ware, and a con- 

 tinuous kiln (PI. 47) which is used for burning common brick. 



The product finds a ready market in Rochester. 



The lower clay alone is used for making tile,- while a mixture of 

 tlie top and bottom clays works best in making the bricks. 



The lower or tile clay, as it is called, is very plastic, but requires 

 only 20 fo of water to temper it. The air shrinkage is 9-|^, and 

 the tensile strength of the air-dried briquettes ranges from 100 to 

 130 pounds a square inch with an average of 120 pounds. 



Incipient fusion occurs at cone .05, vitrification at .01, and vis- 

 cosity at cone 2-3. At incipient fusion the total shrinkage was 12/^^ 

 and the color red; at vitrification, IQfc The soluble salts were .5fo. 

 The brick mixture is more sandy, but is also very plastic, and yet 

 not so tenacious. It takes 18^ of water to work it up, and the 

 bricklets have an air shrinkage of 7^^. The tensile strength ranges 

 from 110 to 120 pounds a square inch. Incipient fusion occurs at 

 cone .05 with a shrinkage of 10/^. The clay vitrifies at cone .01 

 with a total shrinkage of 16^, and a deep red color. It becomes 

 viscous at cone 2-3. 



A mechanical analysis of the clay gave : 



Clay and silt 72 . 90 



Fine sand 27 . 85 



100.75 

 The soluble salts were .35^. 



