Studie jednoduchého kohereru. 57 



4. The iudiictive effect of electric spark appears as two kinds 

 0Í" changes of the initial resistauce. The permanent change is the 

 diminution of résistance at a low pressure, and the enlargement of 

 résistance at high pressures. The permanent résistance of the same 

 contact has same différent values, which seem to be simple multi- 

 2)les of the same number. 



The moment ary change could be studied only by observing 

 the ballistic déviations of the galvanometer by means of télescope 

 and Scale. The momentary change was zéro at high pressures. 



The ballistic déviations showed generally the enlargement 

 of the résistance, the exceptional diminution ended with absolute in- 

 sensibility to the spark. 



The ballistic déviations are in table 3 in the last coluran; the 

 numbers ariangcd in two lines are déviations and time (in minutes) 

 refering to the moment of observation. The table contains beside that 

 the number of the measurement (first column), the pressure (the se- 

 cond column), the intensity (the third column), and the résistance (the 

 forth column), The spark affected the coherer in shorter or longer in- 

 tervais according to the time in which the résistance of the contact 

 became be steady. The ballistic deflections were not constant, but 

 showed a periodical character; this is in consent with the 

 Step— values of the changed résistance and with the p'eriodic nature 

 of the spark. 



The measurements of the résistance of layers of chlorid are 

 put together in table 4. which is of the same arrangement as table 2. 



1. The dependence of the résistance of a contact on the pressure 

 shows a rather complicated character in compare with the results 

 obtained with the jodid-layer. The initial-resistance is always high, 

 but it sinks in few seconds to a low value. 



2. The „age" of the layer diminishes the résistance, the ligte- 

 ned layer have greater résistances than the layers prepaired and me- 

 asured in darkness; these results being quiet reversed to those got 

 with the jodide-layers. 



3. The résistance diminishes when the cunent (going through the 

 contact) gets strenger. It affirms the hypothesis about the thermal 

 effect of the current mentioned above. 



4. The inductive effect of the spark appears both as a perma- 

 nent and a momentary change of the résistance of the contact. The 

 permanently changed résistances show graduai values — steps — of the 

 résistance as simple multiples of the smallest value of the résistance. 



