ELISHA MITCHELL SCIENTIFIC SOCIETY. 75 



THE PROPER STANDARD FOR THE ATOMIC 



WEIGHTS. 



BY F. P. VENABLE. 



Among tlie iuiportant questions attracting the attention of 

 chemists to-day is that of the proper standard to be adopted for 

 the atomic weights. It is a question whose settlement cannot be 

 much longer postponed without injury. It must be settled by 

 careful consideration on the part of associations and individuals, 

 and then by general usage — a sort of majority vote. I therefore 

 venture to bring the question in its present status to the atten- 

 tion of chemists, asking a careful, thoughtful discussion and 

 consideration of it. 



Two elements lay claim to the position of standard for all 

 other atomic weights, hydrogen and oxygen. Hydrogen is called 

 by Meyer and Seubert the Dalton-Gmelin unit and oxygen the 

 Wollaston-Berzelius unit. The contention is an old one then, 

 and first one then the other has been forced to give way in the 

 struggle. For a long time oxygen was the accepted standard of 

 the only approximately accurate atomic weights — those of Ber- 

 zelius. It was then displaced by hydrogen, and this element has 

 so fixed itself in the literature that it cannot well be in turn dis- 

 placed as the unit. But I would make a careful distinction 

 between unit and standard. To make a radical chansce now would 

 be inconvenient and difficult, and should be done only under stress 

 of absolute need. When one considers the difficultv and tedi- 

 ousness of becoming accustomed to new numbers and the decrease 

 in value and intelligibility of all the literature in the old nota- 

 tion that would follow a change of unit, one can properly realize 

 the cost of such a change. 



We are closing a century\s labor, however, and a century's 

 history, and it is important that we should come to some agree- 

 ment on this point, and so be in a position to confer some degree 

 of constancy upon our so-called constants. As it stands now 



