6o 4 SCIENCE PROGRESS 



enriched chemical literature with a valuable table of the es- 

 timated distribution of the chemical elements upon the known 

 crust of the earth that is, the lithosphere, or solid crust extend- 

 ing to a depth of ten miles ; the hydrosphere, which includes 

 the oceans and lakes ; and the atmosphere, which embraces the 

 gaseous envelope. Clarke's table is given in percentage of weight, 

 the figures therefore simply state, e.g., that oxygen forms about 

 50 per cent., and hydrogen 0-9 per cent., of the weight of the 

 known terrestrial matter, and they therefore contain just as 

 much information as the statement that water contains 88-89 

 per cent, of oxygen and 1 1 - 1 1 per cent, of hydrogen. To arrive 

 at the chemical meaning of these numbers— that is, the propor- 

 tions of the atoms concerned- these values must be divided by 

 the atomic weight. Thus if m is the percentage or mass, and 

 A the atomic weight, then m/A = x, where x is the relative 

 proportion of the atoms. Taking the most abundant twenty- 

 five elements, it was found that the value x for Bromine was the 

 lowest, namely, -000125 '> an d using this arbitrarily as unity, the 

 values for the relative abundance a of the atoms were calculated 

 by the simple equation x/ -000125 = a. These new values give 

 a further insight into the distribution of the chemical elements. 

 They are, arranged as to their magnitude, as follows : 



These values of the relative abundance of the atoms indicate, 

 e.g., that for each bromine atom there are about 250,000 oxygen 

 atoms and 75,000 hydrogen atoms, while, e.g., for each carbon 

 atom there are about 250 oxygen atoms and 75 hydrogen atoms. 

 A comparison with Clarke's table of percentages reveals the 

 most striking fact that hydrogen advances from the ninth to 

 the second place, making the proportion of 0:H as 10:3. This 

 interpretation of the distribution seems to give a better view 

 of the importance of the elements. 



It is significant that all the important elements have a low 

 atomic weight, for they all fall between the atomic numbers 

 1 to 28, or atomic weight 1 to 58,6. Furthermore, the same 

 elements all enter into life, with the exception of titanium 

 (which so far has not been reported as being present in the living 

 organism). For the elements of the biosphere quantitative 

 data are meagre ; it is possible, however, to select two types for 

 which the ultimate composition has been calculated — namely, 

 man as representative of the mammals, 1 and the long-leaf pine * 



1 Hackh, Journ. Gen. Physiology, 1919, vol. i, p. 429. 

 3 Little, Journ. Ind. Eng. Chem., 1916, vol, viii, p. 102, 



