836 . KEW YORK STATE MUSEUM 



Ferric oxid 9.07 



Lime 82 



Magnesia 2.32 ' 



Alkalis 3.78 



Total impurities 16.97 



The principal ontpnt of these works is fireporoofing. On ac- 

 count of its softness the shale is easily mined and transported in 

 cars to the dry pans, where it is first ground and then tempered in 

 a wet pan. The tempered material is then conveyed to the upper 

 floors and discharged into the usual form of sewer pipe press. 

 The glazing of the sewer pipe is done by means of salt. 



Cheiming. The most southern shale formations of 'New York 

 state are included under this head. As a whole, the group con- 

 sists of interbedded shales and sandstones, the former prominent 

 toward the west, the latter becoming predominant to the east. 

 The shales vary in color, and are black, olive or green. The shales 

 sometimes pass into shaly sandstones ; these are often highly mica- 

 ceous. The members of the group recognized by Prof. Hall, be- 

 ginning at the top, are : 



6 Sandstone and conglomerate 



5 Old red sandstone 



2 Black, slaty shale 



3 Green shale with gray sandstones 



4 Gray and olive shales and shaly sandstone 

 1 Olive, shaly sandstone 



Portage sandstone 



Of these members 2, 3 and 4 are the most important to clay 

 workers ; the beds of shale exposed are often 20 or 30 feet in thick- 

 ness and free from sandstone. 



" On the Genesee river the shale is often in thick beds of a 

 bright green color and scarcely interrupted by sandy layers ". 



" Westward from the Genesee river there appears to be a con- 

 Btant augmentation in the quantity of the green shale, which is 



