PBEFACE 99 



Few of the clays are found to be of sufficiently refractory char- 

 acter to be used for maliing fire brick, gas retorts, or other pro- 

 ducts which in"" use are subjected to a high degree of heat; but 

 for the manufacture of coarse pottery, terra -cotta, paving brick, 

 etc., many of the clays are eminently suited. 



"Within the last four or five years the manufacturers in 'New 

 York have turned their attention toward the extensive beds of 

 argillaceous shale which the state contains, and which on trial 

 have given very satisfactory results. Several large firms are 

 using them for the manufacture of sewer pipe, terra cotta and 

 roofing tile. The shale formations at present used are the Salina, 

 Hamilton and Chemung. The Hudson River shales are no doubt 

 sufficiently argillaceous over many areas to be used for the manu- 

 facture of clay products, and the same may be said of the JS'iagara 

 shale, which weathers to a red clay. A sample of this latter 

 shale from Niagara Falls was first ground and then molded in a 

 stiff mud machine and found to burn to a white brick, which was 

 unaffected by a temperature of 2,500 degrees. 



That the clays and shales of ISTew York are comparatively 

 undeveloped is, no doubt, largely due to the lack of knowledge 

 of their extent and character. There seems, however, to be no 

 reasonable doubt that they will in future become a valuable 

 source of revenue. 



HEINRICH RIES. 



New York city, April, 1893 



