THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



NOVEMBER 1900. 



XLV. On the Action of the Coherer. By T. Mizuno *. 



SINCE the discovery that when a metallic powder is ex- 

 posed to the influence of electric radiation its electric 

 resistance undergoes alteration, many investigators have 

 attacked the problem by various methods. It is, however, 

 not necessary to mention one by one all the names of the 

 investigators and the results at which they have arrived. It 

 may suffice to notice that the results tend to show that the 

 action of the coherer is correlated in some way to microscopic 

 sparks induced in an assemblage of fine metallic particles in 

 virtue of the action of electric waves ; that is to say, these 

 sparks might give rise to "welding" action, whereby con- 

 ducting chains of particles are formed, and consequently the 

 resistance of the coherer greatly reduced. 



Now the author thought that in order to make the so-called 

 welding-theory more definite, a thorough systematic study of 

 the subject was necessary, and also that such study might add 

 some interesting facts to our knowledge of the action of the 

 coherer. Accordingly a series of experiments was undertaken 

 on a number of metals, some alloys, and also their mixtures. 

 The experiments were conducted in the following manner : — 



The source of electric waves was a Hertzian parabolic 

 vibrator, emitting electric waves of about 60 cms. wave- 

 length. The coherer consisted of a glass tube about 5 cms. 

 in length, 5 mms. in diameter, having two movable and 

 finely-adjustable small pistons, between which the metallic 

 powder under question could be introduced. To the ex- 

 tremities of the pistons were respectively attached wires 

 * Communicated by the Author. 



Phil. Mag. S. 5. Vol. 50. No. 306. Nov. 1900. 2 I 



