ELISHA MITCHELL .SCIENTIFIC SOCIETY. 105 



The differences between the elements are too small for speedy 

 recognition or for easy memorizing. 0=1 is manifestly too small. 



Considering next the fourth suggestion, 0=100, we see that 

 just the opposite objection holds good. Over one-fifth of the 

 elements would be represented by numbers exceeding 1000. Few 

 of these could be accurately given as far as the fourth place. 

 For instance, shall gold be represented by the number 1229.4, or 

 1225.1, or 1234., or 1249., all of which are actual determina- 

 tions? From long custom we have come to regard a whole num- 

 ber as being correct and the decimals as indicating approxima- 

 tions. It would seem to be best still to hide our imperfections 

 under the decimals. 



The only claim that can be adduced in favor of O=10 is that 



we will then have ihe atomic weights on the decimal system. 



This is not true, however, unless the other atomic weights are 



multiples of ten. A glance at a few of the elements will show 



that the numbers would be complicated, rather than simplified, 



by such an unit. 



H = o.2<;:> c = 7.502 



Li = 4.39 N = 8. 77'. I 



Be = 5.89 F =11.94 



B =6.83 Na =14.408 



C = 7.502 Fe =35.01 



N = 8.779 Co =36.70 



F =11.94 Mn=34.30 



Na= 14.408 Cu =39.50 



That is, the eight first elements which in our present tables are 

 approximately whole numbers and in ordinary calculations com- 

 monly taken as such (especially in technical analyses, and we 

 must not let theoretical considerations take us out of sight of 

 the practical side of chemistry) are when compared with 0=10 

 burdened with cumbrous fractions and brought inconveniently 

 near to one another. 'This last consideration is of especial weight 

 when the clearness of the Periodic Law is considered. 



There remains, then, only 0=16 to be considered. The 

 advantage of this unit may be summed up as follow-: 



1st. Every atomic weight is above unity and yet not inconven- 

 ientlv large. 



