M.V, YORK M A I E Ml'H I'M 



■a] X« w Fork, in the Lehigh valley of Pennsylvania, in the 

 James, Potomac, and Ohio river valleys, the result being that 

 natural rock cemenl at all these Localities at a com- 



paratively early da1 



Tn L899 the total production of natural rock cement was 

 9,868,179 barrels. This was unequaled by any other country, 

 pproach to ii being France, with six million to seven 

 million barrels a year of both hydraulic lime and hydraulic 

 cements. The [Jnited States La probably in the lead, owing to 

 excellence and abundance of raw materials. The . 3t pro- 



duction was in 1892; since then both product and price have de- 

 creased, one reason for this being the in* in the Portland 



cement industry. 



The American natural cements are made from argillac< 

 lim< of varying geologic age. In western New York state 



they are mostly derived from the waterlime hods at the top of 

 the Salina. Those of the Rbsendale region are from the base 



the lower Held< rberg. In Wisconsin, natural rock cement is 

 made from rocks of Devonian age near Milwaukee; and in Ken- 

 tucky there is an important cement-producing area near Louis- 

 vi! \n Pennsylvania thick cement beds are found in the 



i renton limestone of the Lehigh valley, but magnesian hydraulic 

 limi also known in the Carboniferous. In Wisconsin 



cement rocks are quarried near Milwaukee, belonging to the 

 Hamilton period. Jn Illinois near Utica and La Salle cement 

 is obtained from the Calciferous limestone. The rocka of Mary- 

 land are also Silurian. 



The deposits at Rosendale (N", Y.) are perhaps the most im- 

 portant; but those of the Lehigh valley in Pennsylvania are re- 

 markable for their purity and extent. 



[Tie hydraulic limestones, or natural rock cement-, can be 



divided into two classes based on the different amounts of car- 



I onate of magnesia which they contain. In one class it- does not 



. while in another L5# to 35* Is found. Most of 



the hydraulic limestone of the [Jnited States Is magnesian, but 



