544 Passage of Electric Wave-trains through Electrolyte. 



approximate value can be found by trial and error ; 



7=0-4 



was found to be suitable. 7 furnishes us with a and /3 from 

 equations (2) and (3). The conductivity of the solution was 

 measured with the Kohlrausch bridge {vide p. 537), and hence 

 jp was known. We have, then, all the necessary data. 



The two curves, calculated and experimental, disagree 

 considerably ; the experimental curve stands all along much 

 higher than the other. Now this shift could not be caused 

 by any variation in the conductivity : that only causes a 

 quicker or slower downward trend of the curve. It could 

 be approximately brought about by an alteration in the re- 

 flected fraction, but by a decrease of it ; i. e. if we took the 

 conductivity into account in calculating the amplitude of the 

 reflected ray, it would only make matters worse. 



The fact of the matter is that we have all along neglected 

 the multiple reflexions that occur in all parts of the circuit. 

 The fraction reflected from the first surface of the electrolyte 

 is not lost for good, but is turned back again when it reaches 

 the secondary plates B B' (fig. 1), and is given another chance 

 of getting through the liquid layer. {Similar multiple re- 

 flexions occur not only between B and x x (fig. 1), but between 

 x 2 and D, and B and D. The matter becomes too complex 

 for calculation as we have a fresh unknown — the secondary 

 damping — introduced. The fact that the experimental curve 

 trends downwards towards the theoretical agrees with the 

 above explanation : as the thickness of the absorbent layer is 

 increased the weaves are so weakened by their passage through 

 it that multiple reflexions are of less account. 



Though, as I have said, calculation is impossible, a com- 

 parison of the two curves in fig. 6 shows at least that no great 

 alteration of conductivity has taken place. 



Conclusion, 



This investigation was carried out during the winter and 

 summer semesters (1892-93) in the Physical Institute of the 

 University at Bonn. It is with great pleasure that I take 

 this opportunity of expressing my thanks to Prof. Hertz for 

 his most useful advice and suggestions, and for the interest 

 he showed in the work throughout. 



