36 XLV. Bedřich Macků: Jednoduchý koherer s vrstvou bromidu měd. 



Résumé. 



Ä simple Coherer with a layer of Gu^Bv^. 



By B. Macků assistant on Physical Institution. Brunn. 



In „Study of a simple Coherer" published as No. XXXVI. of 

 ,, Věstník královské společnosti nauk, 1903" by Dr, Vladimír Novák 

 and myself, are observations made on a simple coherer consisting of 

 two copper-electrodes, the plate-electrode being covered with a thin 

 layer of Cugigs or CugClj- 



I continued the work using bromid-layers and raeasuring the ré- 

 sistances by the samé method, improved in respect of the ability to 

 change the potenciál différence on the poles of the coherer. 



The résistance of the contact, at a small pressure and with a 

 small potenciál différence is high and insensitiv to the influence of 

 an electric spark. It dépends as on the intensity as on the direction 

 of the current, the first thing being explaned by Joule's-effect, the 

 other by Peltier's phenomenon. 



Increasing the pressure and the potenciál différence I found 

 small values for the résistance of the coherer, the potenciál différences 

 of which were n-multiples of a constant value. 



The constant does not dépend on the intensity, on electromotive 

 force and the pressure of the coherer. The résistance of the coherer 

 changes very often by itself and these changes correspond with the 

 rapid changes of the potenciál différence from one multiple to another. 

 The spark makes the résistance temporary greater. The sensitiveness 

 of the coherer deminishes with increasing intensity and pressure. 



The „decohesion" and the diminishing of the sensitiveness is due 

 to the heat generated by the current. 



Ail the observations show the fact, that the constitution of the 

 bromid is changed by the current-heat ; the influence of the spark 

 appears as a return to the previous constitution which is characterized 

 with a high value of the résistance of the coherer. 



