Chemistry and Physics. 71 



8. Polarization Capacity. — C. M. Gordon enters into a histor- 

 ical discussion of this subject, cites the various investigators 

 who have worked upon it and gives his own results, carried out 

 by Nernst's method under the direction of the latter. This 

 method consists in comparing the polarization capacity with a 

 known capacity in the Wheatstone bridge. It was found that 

 for small strength of current the polarization is a reversible pro- 

 cess and the contrary electromotive force is accurately given by 



Kohlrausch's equation e=— -=r— in which c is capacity, f a con- 

 ey j at 



stant, J equals current strength and t equals time. The capacity 

 of quicksilver electrodes depends mainly upon the quantity of dis- 

 solved mercury ions. The capacity of platinum electrodes depends 

 not only upon the occluded hydrogen or oxygen but also upon the 

 concentration of these electrolytes. The results of Gordon do not 

 agree with those of Wien, who found a close dependence of polar- 

 ization capacity upon the period of the alternating current em- 

 ployed to excite the Wheatstone-bridge combination. Gordon, 

 on the contrary, finds that Kohlrausch's law holds very exactly. 

 The capacity of plates of polished platinum, at a distance of 2 mm , 

 and having a surface 0*65 cm2 , was about 50 microfarads. — Wied. 

 Ann., No. 5, 1897, pp. 1-29. J. t. 



9. Oscillatory Currents arising in Charging a Condenser. — 

 Seiler gives a short analytical discussion of the conditions 

 which arise in charging a condenser, and shows that the same 

 equation holds for the charging oscillations as for the discharg- 

 ing oscillations, namely, T = 27rVXC, in which T represents time, 

 L self-induction and C capacity. The author uses this law for 

 the determination of the self-induction of suitable circuits. He 

 employed a Helmholtz pendulum and used two contacts which 

 broke the charging circuit at definite intervals. It was found 

 that only pure sine oscillations resulted when the circuit contained 

 no small spark gaps. — Wied. Ann., No. 5, 1897, pp. 30-54. 



j. t. 



10. Cathode Rays. — In a late discourse delivered at the Royal 

 Institution, Prof. J. J. Thomson described experiments which lead 

 him to believe that the cathode ray phenomena are due to pro- 

 jected electrified particles. Atoms are aggregations of small par- 

 ticles which he terms corpuscles. At the cathode some of the 

 molecules of the gas are split up into these corpuscles, wheh are 

 then charged negatively and moving with a high velocity are able 

 to pass between the interstices of molecules. The corpuscles are 

 smaller than the atoms of hydrogen. (Lond. Electr., May 21.) 

 Somewhat in line with Thomson's hypothesis is an observation on 

 Dr. Zeeman's discovery of the broadening of spectral lines in a 

 magnetic field, by Dr. Kalischer. (Elektrotecknische Zeitschrift, 

 April 15, 1897.) This author points out that there is a recent 

 ten dency to return to a " material theory," in which electrical 

 and magnetic phenomena depend not only upon the movement 

 of the ether but also on the material atoms which are sup- 



