i9o6] IN CHEMICAL GEOLOGY. 21 



In this computation the figures for C, Zr, CI, F, Ni, Cr and V 

 are only very rough approximations. They show, however, that 

 these elements exist in igneous rocks in determinable quantities. 

 The elements not included in the calculation represent minor cor- 

 rections, to be applied whenever the necessity for doing so may 

 arise. For estimates of their probable amounts, the papers by Vogt^ 

 and Kemp- can be consulted. It is probable that no one of them 

 would reach o.oi per cent. The elements not mentioned in the table 

 cannot amount to more than 0.5 per cent, altogether; and even that 

 small figure is likely to be an overestimate. 



Shale. Sandstone. Limestone. 



A. B. C. 



SiO^ 58.38 78.66 5.19 



AL03 15.47 4.78 .81 



FcoOs 4-03 1.08 ^ 



FeO 2.46 .30 I '^"^ 



MgO 2.45 1. 17 7.90 



CaO 3.12 5.52 42.61 



NaaO 1.31 .45 -05 



K2O 3-25 1-32 .33 



H2O at 110° 1.34 .31 .21 



HoO above 110° 3.68 1.333 .56^ 



TiO, .65 .25 .06 



CO2 2.64 5.04 41.58 



P.O5 17 .08 .04 



S ...... .09 



SO3 65 ^ .07 .05 



CI trace .02 



BaO .05 .05 none 



SrO none none none 



MnO trace trace .05 



LioO trace trace trace 



C, organic .81 



^ 100.46 100.41 100.09 



Before we can finally determine the composition of the litho- 

 sphere, the sedimentary rocks must be taken into account; and to 

 do this we must ascertain their relative quantity. First, however, 

 we may consider their composition^ which has been determined by 



^ Zeitsch. prakt. GeoL, 1898, pp. 225, 314, 377, 413, and 1899, pp. 10, 274. 

 ^Science, Jan. 5, 1906, and Economic Geology, vol. i, pp. 207. 

 3 Includes organic matter. 



