21 



[23] 



ceedingly protracted unless the crystallization of the salt were promoted by 

 moderate warmth, as by this time the detritus from some specimens was 

 hardly visible. 



After the change, the process went on with greater rapidity; and at the 

 end of four weeks the dipping was stopped, and the sediment or deposite in 

 each bowl was carefully weighed, and furnished the results as given in 

 the table. In some cases the comminution of the stone was exceedingly 

 fine; and in the washing and decanting process, ample time was allowei 

 for the deposite to settle after each washing, and the utmost care used ni 

 the subsequent operations of decanting, drying, and weighing. Tlie time 

 of one week for the operation of dipping the stones in the solution was not 

 deemed sufficient, as the deposite from the marbles and some othe^ varie- 

 ties was hardly apparent; and it was therefore continued, as above stated, 

 four weeks, and thus the slight errors of manipulation, if any occurred, are 

 proportionally diminished. 



Disintegrating effects of frost uj)on stones used for huilding-tnaterials. 



Not tested; the specimen being too small. 



Symington's close-grained marble (similar to 

 Worthington's) . - - - 



Connecticut sandstone, coarsest grained qual- 

 ity 



Dark red Seneca sandstone (similar to Peter's) 



Symington's large crystal marble 



Symington's blue limestone 



Coarse, large crystal marble, Mt. Pleasant, 

 New York . . . - 



Port Deposite granite . . . 



Too small to examine. 



Trinity sandstone, fine grained and light- 

 colored - - - - - 



Connecticut sandstone, finer grained quality 



Nova Scotia sandstone, coarse grained 



Light Seneca sandstone, dove-colored 



Pennsylvania marble, close-grained - 



Pennsylvania blue limestone 



Trinity church light colored, close-grained 

 sandstone, New Jersey 



Patent Ofiice light sandstone 



Soft brick - - - - - 



Hard brick - - - - - 



Granite from Potomac Great falls 



Dark coarse sandstone, of Seneca aqueduct, 

 Peter's quarry - - - " 



Sandstone four miles above No. 2 D, Pe- 

 ter's, next west of Beaver dam quarry 



2.S34 



I 



Loss by 

 frost, in 

 grains. 



0.10 



