M\v YORK STATE MUSEUM 



beyond the range of weathering. Richardson gives the follow- 

 ing density for tin' Roaendale rock, 



\ i arest Biirfi 



Lighl rock 2.83 



k ruck 2.^49 



Medium 



Light rock 2.815 



Dark rock -■^ 1 



Light rock 2.827 



Di rk rock -- >1: ' 



The Fort Scott (Kan.) rook which is nearer the Burface has 

 a density according to Mr Richardson of only 2.7:5. the Round 

 ■ rock, Maryland, is 2.731, the hydraulic limestone of Illinois 

 >nly 2.667 and does not produce as dense a cement. It is 

 also desirable that the various ingredients of the rock should he 

 as thoroughly mixed in as possible. If the sand is coarse or 

 the clay in lumps or the carbonate in pickets by itself, the rock 

 is not adapted for making cement. Generally mere inspection 

 will supply information on this point, and the >ize of the partic 

 can be determined by dissolving a weighed fragment in acid and 

 determining the size and quantity of the insoluble particles of 

 .-and remaining. The residue of the Rosendale rock found at 

 various depths is noted by Richardson as follows. 



Per cent erf residue on Bieve 200 mesh, 100 mesh, and 50 mesh 



Nearest surfs 



Light rock 2.9 ... 



Dark rock 



Medium 



Light rock. 

 I ».: rk rock 



... ... •« 



. • • • • ■ 



. . ... 



I deepest 



Light rock 6 • r » .4 



Hark rock 1.2 .5 .5 



