241 



Mr. Alger read a paper on the comparative value of 

 various kinds of American Sandstone as building material. 

 He exhibited specimens of the New Brunswick, New 

 Jersey, and Connecticut Sandstones, and gave a detailed 

 chemical and mineralogical description of each. From a 

 comparison of their various qualities he concluded that the 

 first two are of about equal value for building purposes, 

 and both of them superior to the third. He spoke of Dr. 

 Ure's test of the durability of Sandstone by immersing it 

 in a saturated solution of sulphate of soda, the crystalliza- 

 tion of which it was thought would imitate the action of 

 the freezing of water in its pores. He had understood 

 that in Great Britain it was much relied on in selecting 

 building stone, but he thought it doubtful whether it would 

 be of much value in this country, from the greater severity 

 of the climate. 



Prof. Rogers said he distrusted the value of the test, as 

 the process of crystallization was not strictly analogous to 

 freezing. In the formation of ice there is no loss of water, 

 like that which occurs in the process of crystallization. A 

 specimen of Sandstone, which had stood Dr. Ure's test, 

 having been used for the construction of a public building 

 in Philadelphia, was found to exfoliate after two years' 

 exposure to the action of the elements. 



Dr. C. T. Jackson confirmed Mr. Alger's and Prof. 

 Rogers's statements as to the value of Dr. Ure's test. He 

 thought the surest way of ascertaining the power of a Sand- 

 stone to resist the action of water and temperature, was to 

 examine the rock in the quarry, where it was always easy 

 to obtain, on the exposed surfaces, the most satisfactory 

 evidence. 



Prof. Wyman exhibited some fossil bones of Seals found in 

 the Miocene deposit beneath the city of Richmond, Va., where 

 they occur in company with the teeth of Sharks and Zeuglodonts. 

 The only other locality in the United States where similar 

 remains have been found is at South Berwick, Me., as men- 



FROCEEDINGS B. S. N. H. 16 JUNE, 1850. 



