ON ELECTROLYSIS IN ITS PHYSICAL AND CHEMICAL BEARINGS. 413 



18. M. BOUTY, On Polarisation and Conductivity (abstract by the Editor) . . 348 

 ] 9. M. BouTY, On the Conductivity of very dilute Salt Solutions (abstract by 



the Editor) 350 



20. MM. BouTY and Foussereau, On the use of Alternating Currents in 



Measuring Conductivity .......... 356 



21. M. BouTY, On Mechanical and Thermal Effects accompanying Electrolysis 



(abstract by the Editor) 357 



22. Dr. Arrhenids (first part), On the Conductivity of Electrolytes (analysis 



by the Editor) 357 



23. Dr. Arrhenius (second part), A Chemical Theory of Electrolytes (abstract 



and translation by the Editor) 362 



24. Dr. Arrhenius, Letter respecting the above criticism. Communicated by 



the Editor, with a foot-note . , 384 



25. Dr. Arrhenius, Letter on the Eelations between Conductivity and Vis- 



cosity. Communicated by the Editor 387 



26. Professor WiLLARD Gibbs, Letter on Electro-chemical Thermo-dynamics. 



Communicated by the Editor, vsdth a note 388 



27. Dr. Oliver Lodge, On the Migration of Ions and an Absolute Measure of 



Ionic Velocity 389 



Sixth Report of the Comonittee, consisting of Mr. R. Etheridge, Mr. 



Thomas Gteay, and Professor John Milne (Secretary), appointed 



for the puipose of investigating the Volcanic Phenomena of 



Japan. {Drawn up by the Secretary.) 



[Plate VIIL] 

 I. The Gray-Milne Seismograph. 

 In 1883, partially at the expense of the British Association, Mr. James 

 White, of Glasgow, constructed a seismograph to be used in Japan. I am 

 pleased to say that for some time past this instrument has been in good 

 working order, and examples of the records which it has furnished are 

 given in the following table. The time records are expressed as Tokio 

 mean time. The particular wave at which time was noted can only be 

 seen by reference to the original diagrams. It is usually very near the 

 commencement of a disturbance. The period which is expressed in seconds 

 is the time taken to describe one of the principal vibrations (or shocks} in 

 a disturbance. The longest period, it will be observed, is three seconds. 

 The amplitude, which is expressed in millimeters, is half a semi-oscillation, 

 the vibration which is measured being the one from which the period was 

 recorded. 



It will be observed that the larger the amplitude the longer is the 

 period. I am writing more fully on the relationship of amplitude to period 

 in a special paper. With period and amplitude before us, on the assump- 

 tion of simple harmonic motion we may easily calculate the maximum 

 velocity of motion which represents the projecting power of an earth- 

 quake, and the maximum acceleration which measures the overturning and 

 shattering power of an earthquake. The direction which is given is that 

 of the most prominent vibration in the disturbance. One disturbance, it 

 will be noticed, had a duration of ten minutes. Without the aid of an 

 instrument this disturbance might have been felt for a period of perhaps 

 three minutes. It will be noticed that vertical motion has only been 

 recorded twice. The records given in the following table are in the 

 same form as the records published in the Japanese daily papers imme- 

 diately after the occurrence of an earthquake. The original publications 

 followed Palmiere's method, where a set of arbitrary degrees took the 

 place of the present absolute measures. 



