CLAYS OF NEW YOKK S45 



MIl^OR USES OF CLAY 



In tlie foregoing pages of this report attention lias teen given 

 entirely to those uses of clay wliicli depend on the presence of plas- 

 ticity when wet and hardness when burned. There are, however, 

 several other directions in which clay or shale can be used, in either 

 the raw or the burned condition. At times the plasticity is of value 

 in promoting the usefulness of the clay in some of the directions 

 about to be discussed, at others it has no bearing on the matter, 

 being entirely a question of proper chemical composition. The 

 minor uses of clay may be classed under the following heads: 



Portland cement 



Mineral paint 



Clarifying oils and fulling cloth 



Filling paper 



Food adulterants 



Ultramarine manufacture 



Polishing and abrasive uses 



Road material 



In engineering work for making puddle 



Portland cement 



As there is a state museum bulletin in preparation, discussing 

 the lime and cement materials of the state, this question need not 

 be gone into in any great detail in the present report. 



Portland cement is made of a mixture of clay or shale, with lime- 

 stone, marl or chalk. The essential ingredients of this cement are 

 silica, alumina and lime, the first two being supplied by the argilla- 

 ceous constituent, and the third by the calcareous one, the lime 

 stone. As a rock containing these three ingredients mixed in 

 exactly the right proportions is seldom found in nature, it is conse- 

 quently necessary to mix them artificially. Both the materials are 

 ground very fine in order that they be intimately mixed, and this 



