Vol. 6, 1920 
CHEMISTRY: W. D. HARKINS 
601 
outline may have been sufficient to indicate the very fundamental charac^ 
ter of those problems. 
Geophysical Laboratory, 
Carnbgib Institution of Washington. 
June, 1920. 
1 U. S. Geol. Survey, Prof. Paper 85C, 1913 (35). 
2 See Lambert, Journ. Wash. Acad. Sci., 10, 1920 (122-143). 
3 In this connection it is important that the study of the composition and probable 
sources of the matter now being received by the earth, in the form of stony and metallic 
meteorites, be continued and extended. 
THE TONIZATTON OF STRONG ELECTROLYTES 
By William D. Harkins 
Kent Chemical Laboratory, University of Chicago 
Communicated by J. Stieglitz, April 14, 1920 
It is well known that in all branches of knowledge it is sometimes diffi- 
cult to express certain thoughts with accuracy on account of the fact 
that the meaning of words changes. So in science there are periods when 
either the same words have a dissimilar meaning, or unlike words have the 
same meaning, to different workers. This sometimes becomes so marked 
that old hypotheses may seem to disappear, or new ones to appear, when 
only the significance of the technical terms has undergone a change. In 
other cases old terms may be used in new ways to suggest valuable new 
points of view. 
The recent paper by A. A. Noyes and D. A. Maclnnes in these Pro- 
ceedings^ which supports the idea of Sutherland,^ Milner,^ Ghosh, ^ and 
Bjerrum,^ that strong electrolytes are completely ionized in solution, 
may be considered as belonging to the last category. They use the term 
ion in the sense of a charged particle, and not as a charged particle which 
is free to move in the electric field, which is the older meaning of the 
term as applied to solutions, though it must be admitted that their use 
of the word is in harmony with the meaning attached to it in recent 
papers in physics. However, it is not the terminology, but the idea it is 
apt to convey to workers in various fields, which is to be the subject of 
attention in this short note. The idea developed by Bragg, that a solid 
salt consists not of a collection of molecules, but of atoms, has led to the 
