288 Mr. W. J. Walker: J? elation ship between Viscosity, 



Summary. 



The amount of light given by the unstriated discharge 

 and by the arc indicates that the rate at which ions re- 

 combine in these forms of discharge varies as the first power 

 of the current, while the equations usually assumed for 

 discharge through gases would lead us to expect that this 

 rate varies as the square of the current. This is explained 

 by assuming that approximately all of the current is carried 

 by electrons and not by ions of molecular size, and that the 

 great majority of the electrons combine first with molecules 

 and afterwards with positive ions. 



The fact that the electric force in this form of discharge is 

 a linear function of the pressure of the gas is explained by 

 assuming that the ionization is caused by the impact of the 

 more rapidly moving electrons on the molecules, and that 

 but few of the collisions between electrons and molecules 

 result either in ionization or in recombination, the greater 

 number resulting in no permanent change in either electrons 

 or molecules. 



The fact that the electric force decreases slightly when the 

 current is increased, is explained by the added assumption 

 that the potential difference through which an electron must 

 go in order to ionize is smaller with larger currents than 

 with small ones. 



Colgate University, 

 October, 1913. 



XXXII. On the Relationship between the Viscosity, Density, 

 and Temperature of Salt Solutions, By W. J. Walker, 

 JB.Sc, Carnegie Research Scholar, University College, 

 Dundee *. 



[Plate IV.] 



npHE following notes are derived from the results of 

 J_ experiments carried out at the suggestion of Professor 

 A. H. Gibson in connexion with tests on the resistance to 

 flow of brine solutions through pipes of different diameters. 

 The solutions were of sodium chloride and calcium chloride. 

 The primary object of the experiments was the de'.ermination 

 of " the kinematic coefficient of viscosity,''' or the ratio 

 viscosity/density. Absolute values of the viscosity were 

 obtained by means of the apparatus shown in fig. 1. 



Reservoir A was used to maintain a constant head of about 



* Communicated by the Author. 



