16 



RELATIVE ABUNDANCE OF THE ELEMENTS 



many analyses of rocks, but our acquaintance with the distribution 

 and relative abundance of these rocks must obviously be incomplete. 



The above table, however, giving as it does the proportions by 

 weight of the elements, does not really represent their relative abund- 

 ance reckoned in atoms. This latter certainly appears to the author 

 to be the more correct way of grading their importance. In 

 order to find the relative number of atoms it is only necessary to 

 divide the numbers in the above table by the respective atomic weights. 

 In this way the following table has been calculated, giving the number 

 of atoms of each element present in a total of 100,000 atoms. 



Table showing the relative numbers of atoms of the elements pre- 

 sent in the earth's crust to a depth of 10 miles, including the ocean 

 and the atmosphere : 



100,000 



The great changes in the order of hydrogen (from 9th to 2nd 

 place), iron (4th to 7th), and calcium (5th to 8th) will be noted. The 

 low position of nitrogen, which is usually regarded as so abundant, in 

 both tables is also worthy of attention. It is hardly necessary to say 

 that the other elements are very much less abundant and have been 

 ignored in the compiling of the above tables. 



