CHAPTEES ON THE CEMEI^T INDUSTRY 875 



3 Limestone and shale. Tlie use of this combination of materials- 

 is confined^ at present^ to a single plant. If this plant be success- 

 ful, it is probable that its example will be extensively followed^ 

 for exactly similar materials outcrop on the shores of Canan- 

 daigiia, Seneca, Caynga and other lakes of central E'ew York. 

 Certain technologic difficulties in the use of these materials are 

 noted in an earlier part of this paper, and the progress of the 

 enterprise will be followed with much interest. 



4 Argillaceous limestone and pure limestone. This type of mix- 

 ture, used so extensively in Pennsylvania and I^ew Jersey, has not 

 been utilized, as yet, in this state. It is practically certain that 

 deposits of this type of material exist in at least one county of the 

 state, but no attempt has been made to map or develop them. 

 Prof. Spencer B. i^ew^berry has pointed out that^ an argillaceous 

 limestone used with a comparatively small quantity of a purer 

 limestone, as in the Pennsylvania and l\ew Jersey plants, possesses 

 one decided advantage over a limestone and clay mixture, inas- 

 much as less thorough mixing and fine gTinding is required, for 

 even the coarser particles of the argillaceous limestone will vary 

 so little, in chemical composition, from the proper mixture, as to 

 affect the result but little, should either mixing or grinding be 

 incompletely accomplished. This argument bears against a marl 

 and clay mixture as well as against a limestone and clay mixture^ 

 though to a less extent. 



Mr P. 11. LcT^ds has also discussed the adva.ntages possessed by 

 this type of material, and comes to the same decision regarding its 

 superiority over the limestone and clay mixtures. The l^ew York 

 plants, however, show that it is possible to produce good Portland 

 cement from limestone and clay; and the fact that several Penn- 

 sylvania companies are contemplating the establishment of plants 

 in the Hudson river valley would seem to be proof that cheap 

 cement can be made there. 



1 Mineral resources of United States, {see 20th an. rep't U. S. geol. sur.. 

 1898, pt 2, p. 545; 22d an. rep't U. S. geol. sur. l&OO, pt 2. ) 



