Profs. Ayrton and Perry on Ice as an Electrolyte. 43 



the real facts. The opinion of M. Lorenz, that the great dif- 

 ference between the results found by MM. W. Weber, F. Kohl- 

 rausoh, and the physicists of the British Resistance Committee 

 was the consequence of our imperfect knowledge of the laws 

 of such induced currents, finds no confirmation at all in the 

 above experiments. 



(2) Absolute measurements of resistance can, with the 

 means of galvanic observations nowadays at our disposal, be 

 carried out with such exactness and certainty as can only be 

 attained in few departments of physics. The notion widely 

 accepted among physicists, that absolute measurements of resist- 

 ance belong to those physical measurements which are capable 

 of giving only roughly approximate values, and require pecu- 

 liarly equipped localities for carrying them out — an opinion 

 to which W. Siemens, among others, has given expression in 

 the sentence, " we may certainly pronounce positively that 

 even the most practised physicists, supplied with the most 

 perfect instruments and localities, will not be able to make 

 absolute resistance-measurements that would not differ by 

 some percentage "—is refuted by the above results of experi- 

 ment. According to my experience, these measurements can 

 be effected with tolerable accuracy with very small means and 

 in moderately equipped localities. 



[To be continued.] 



Y. Ice as an Electrolyte. — Second Communication. By W. 

 E. Ayrton and John Perry, Professors in the Imperial 

 College of Engineering, Tokio, Japan*. 

 [Plate II.] 



IN our former paper on Ice as an Electrolyte, read before 

 the Physical Society on May 26th of this year, we de- 

 scribed experiments which proved, among other things, that 

 as the temperature of ice is allowed to gradually rise the con- 

 ductivity increases regularly, and that there is no sudden 

 change in passing from the solid to the liquid state. We also 



determined roughly the specific inductive capacity of < +o . ( 



at -13°-5 C. and at +8°-7C., and found that at the latter 

 temperature it was about 2240 times as great as in the former. 

 Preliminary experiments also showed us that there w T as very 

 little change in the specific inductive capacity up to 0°C; and 

 it was anticipated that there would not be a very great change 

 after 0° ; we therefore concluded that a very great change must 



* Communicated by tbe Physical Society. 



