﻿346 Prof. W. M. Hicks on certain Assumptions in the 



(1914), Z. Elektrochem. xix. pp. 329, 473 (1913) ; Loeb, 

 J. Gen. Phys. xx. p. 173 (1919), ii. pp. 273, 255, 387, 577, 

 563, 673, 659). The part played by the adsorption of ions 

 in these phenomena is twofold. The origin of the potential 

 is in many instances due to the adsorption of ions (cp. Baur, 

 Z. Elektrochem. xix. p. 590 (1913) ; Z. Phys. Chem. xcii. 

 1916, p. 81). 



Secondly, the electrostatic forces of the surface probably 

 determine the relative permeabilities of the two ions. To 

 this the semi- permeability of an ion can be referred. 



Regarding negative osmosis, attention may be drawn 

 to the suggestion of Freundlich [Koll. Zeitsch. xviii. p. 1 

 (1916)) that the thin walls of the membrane substance 

 conduct electricity, and electro-osmotic flow of the liquid 

 occurs. A necessary condition is that one ion is permeable 

 and the other relatively impermeable. This explanation 

 meets thermoclynamical requirements, and is the only satis- 

 factory one hitherto put forward. 



In all these cases the same influences of polyvalent ions 

 and ions of opposite charge are noticeable. 



The change in the collodial properties of the membrane is 

 an important additional factor which has to be remembered. 

 The influence of the electrostatic forces is unmistakable. 



Physical Chemistry Department, 



University College, London. 



XXX. On certain Assumptions in the Quantum-Orbit Theory 

 ' of Spectra. By W. M. Hicks, F.R.S* 



THE practically complete success of the quantum-orbit 

 theory in describing all the known facts of spectra, 

 in cases where we know experimentally that the source 

 consists of a single nucleus and a single electron, must 

 give assurance that the same procedure must also be capable 

 of application to more complicated atoms than those of the 

 hydrogen and enhanced helium types. Unfortunately, 

 however, mathematical difficulties have so far prevented 

 any rigorous application of the theory to definite cases, 

 even of the next simplest atomic configuration of a single 

 nucleus and two electrons. The attempt of Sommerfeld 

 at an approximate solution shows, on the one hand, how 

 hopeful we may be of a description of spectra on this basis, 

 and at the same time how far we are at present from its 

 * Communicated by the Author. 



