58 XXXVI. V. Novák a B. Macků: Studie jednoduchého kohereru. 



Table 5. contains the expérimental data and the calculated values 

 of the smallest résistance and the mean value. These values dépend 

 not on the pressure and thickness of the layer and. are due to the 

 complicated nature of the spark, which can be considered as an 

 aniount of harmonie electric waves. 



The minimal value of the diiîerent résistances observed on the 

 same contact is less on ligtened layer than on freshly prepaired. 



The temporary changes are seen in table 6. The sensitivness of 

 the layer for these changes is greater if the layer is changed by means 

 of sun shine, the „âge" of the layer has a contrary influence. 



The layers of the freshly prepaired chloride were flesh-coloured 

 but they became quiet dark (blue dark) if ligtened for some hours 

 with sun beams. It is very curions, that the black colour gets in the 

 darkness in to the previous coloration. Table 7 showes the résulta, 

 which we obtained for two layers 10 weeks old. There was a certain 

 change in the galvanic arrangement of the observing method for the 

 two last measLirements, such one, that the intensity of the current 

 passing through the coherer was about 33 times smaller than before, not- 

 withstanding both the measurements show that the ligtened layer, 

 which was at first not very sensitiv to the inductiv power of sparks, 

 found its sensitiveness in darkness, as also the layer which has been, 

 lightened and put in darkness got not only the previous flesh-colour, 

 but also the electric qualities of the fresh prepaired layer. This cyclic 

 change of the colour (which was proved twice on the same layer) is 

 perhaps due to the great araount of absorbed halogen in the layer, 

 the gas getting rid of the layer in darkness and changing the dar- 

 kned surface into the previous state. 



