AMERICAN JOURNAL 



OF 



AGRICULTURE AND SCIENCE. 



No. XI. MARCH, 1847. 



THE LIMESTONES, AND LIME. 



Continued from page 82. 



The limestones of the New-York system belong mostly to its 

 inferior part. If we take our depaiture in the series from the 

 Potsdam sandstone, and extend our exainination to the top of the 

 Catskill mountains, the limestones of the most important varieties 

 and kinds will fall in the lower division of the series; the upper 

 being almost destitute in New-York and Pennsylvania, not only 

 of deposits of limestone, but of calcareous matter. The first ap- 

 pearance of this rock is the calciferous sandstone, a rock which 

 was denominated by the late Prof. Eaton, Calciferous Sandrock. 

 The predominant color of the rock is gray; but it appears of va- 

 rious shades of light and dark gray, and light and dark drabs. In 

 the main, it is an impure limestone, and is rarely sufficiently free 

 from silex to admit of its manufacture into good lime. In addition 

 however to silex, it contains magnesia in a large proportion: 

 alumina and iron are also constantly present. It therefore usually 

 makes very good hydraulic lime, and has been so employed with 

 success. It contains encrinal beds, which appear to be nearly a 

 pure limestone; at any rate, they are quite free from silex. The 

 same remark may be made of the oolitic beds. Some parts of 

 the rock contain chert, which is arranged in parallel bands. 

 These beds are the poorest part of the rock for economical pur- 

 poses. 



Geologically the calciferous sandstone succeeds the Potsdam 

 sandstone, from which it departs first by a small sprinkling of 

 calcareous matter, which, on increasing, soon becomes apparently 

 a tolerably pure limestone. Its sandy character, however, is often 

 disclosed by the presence of fine particles of sand, which invest 

 the weathered surface. The nature of these particles may be 

 proved by rubbing them between two plates of glass, which will 

 be found to be scratched by the operation. 



Vol. V. No. n. 8 



