590 KEPOBT — 1887. 



(B) ' The object of this research was to try to learn the parts played by the 

 various portions of the evolved gases — (1 ) that occluded by the electrodes ; (2) that 

 deposited on them ; (3) that contained in the liquid, in influencing the time-rate of de- 

 polarisation. The method employed was to vary the conditions under control — e.ff., 

 time of charging, density of current, &c. — and to observe the time-rate of the fall of 

 the polarisation thus produced in closed circuit. It was found to be very difficult to 

 apply this method ; because, though the conditions under control were kept as con- 

 stant as possible, yet the time-rates of fall in two successive observations were often 

 difl'erent. This was thought to be due to the insufficient cleaning of the electrodes 

 between each experiment, and A-arious methods were tried to remedy it, with the 

 general result that the more perfect the cleaning became the more regular did the 

 ciirves giving the time-rate of the fall of the polarisation become, but still the in- 

 consistencies were not wholly removed. Heating of the electrodes by the electrical 

 current seemed to be preferable to the other methods of heating. 



(C) Whilst electrolysing strong sulpluiric acid between platinum electrodes it 

 was noticed that when the current density at the anode had exceeded a certain 

 value decomposition apparently ceased. The value of the anode current density 

 necessary to produce this phenomenon is increased by diminishing the concentration 

 or increasing the temperature of the acid, and is diminished by cleaning the elec- 

 trodes. It was found that the great diminution of the current was not caused by 

 the formation of an opposing E.M.F., but by a sudden increase of from 500 to 50,000 

 ohms in the resistance of the voltameter. That the insulating condition occurs at 

 the anode is shown by successively replacing the kathode and the anode by a clean 

 plate ; in the first case, the stoppage of the current persists ; in the second case, the 

 current is readily conducted. The cause turn/ be a sheath of oxygen bubbles, which 

 firmly adhere to the anode when the insulating condition is formed. The film is re- 

 moved by breaking the current momentarily, or short-circuiting the voltameter, or 

 reversing the current. 



(D) During the electrolysis of various liquids with palladium electrodes it has 

 been observed that a dense-looking liquid streams from one of the electrodes fthe 

 anode in dilute sulphuric acid, the kathode in caustic soda) after a reversal of the 

 current. The liquid seems to be a compound of oxygen and hydrogen, presumably 

 hydroxyl. 



10. On the IjlerAro- deposition of Alloys. 

 By Professor Silvands P. Thompson, B.Sc. 



11. On the Actio7i of the Solvent in Electrolytic Conduction. 

 ByT. 0. FiTZPATRiCK, B.A. 



12. On the Industrial Electro-deposition of Platinum. 

 By Professor Silvanus P. Thompson, B.Sc. 



MONDAY, SEPTEMBER 5. 



The following Papers and Reports were read : — 



1. On the Princeton Eclipse Expedition. 

 By Professor C. A. Young, Ph.B., LL.B. 



Origin of Expedition. — The expedition had its origin in the desire of the author 

 to verify and re-examine the question of the existence of the so-called ' reversmg 

 layer ' at the surface of the sun — a question of special interest to himself, as the 



' Tills is a continuation of experiments described by Messrs. Lees and K. W. 

 -Stewart in the Proc. Manchester Lit. and Phil. Soc. Feb, 22, 1887. 



