Ries — Physical Tests of Devonian Shales. 



695 



When ground to thirty mesh it required 21.4 per cent, of water to make 

 • a workable paste, which was moderately plastic. This paste shrunk four per 

 cent, in drying and an additional ten per cent, in burning. The air-dried 

 briquettes had an average tensile strength of ninety-two pounds per square 

 inch, and a maximum of ninety-five pounds per square inch. Incipient fusion 

 occurs at 1,900° F., vitrification at 2,050° F., and viscosity at 2,200° F. 



The analysis of the clay is as follows : * 



' Silica . . . « 65.15 



Alumina 15.29 



Ferric oxide 6.16 



Lime 3.50 



Magnesia 1.57 



Alkalies ■ 5.71 



97.38 - 



Total fluxing impurities 16.94 



In general composition it resembles a Carboniferous shale used for paving 

 brick at Kansas City, Mo.f This shows the following analysis : 



Silica 64.37 



•• Alumina 19.73 



Ferric oxide 9.07 



Lime 82 



Magnesia 2.32 



Alkalies 3.78 



Total impurities 16.97 



The principal output of these works is sewer pipe and fire-proofing. On 

 account 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. 



Ckemimg. The most southern shale formations of New York state are 

 included under this head. As a whole, the group consists of interbedded 

 shales and sandstones, the former prominent towards the west, the latter 

 becoming predominant to the east. The shales vary in color, and are black, 



* Bulletin New York State Museum, III, No. 12, p. 228. 

 t Clay Worker, December, 1893. 



