( 470 ) 



could not have chosen its Avav tliroii;j:]» the screen and must liave 

 gone Iherefore round it. If some more resistance was inserted, then 

 a deposit came gradually on tiie screen, smaller and more uneven 

 than in the ordinary case, hut also taking the normal size and 

 thickness as formerl}-, when going on inserting more resistance. 



Different salts were used as electrolyte, in none however, a deposit 

 was so easily formefd as in cupricsulphate. The phenomenon, when 

 using this salt, was so clear, that once a deviation in the shape of 

 the deposit was ob.served, because the wire which was connected to 

 the anode, was not sufficiently insulated. In saturated solutions of 

 zinc-, aluminium-, nickel-, cot)alt-, ferrous- and ferricsulphate deposits 

 were formed, one clearer than the other even if in all these cases 

 the constant current-intensity was secured by inserting resistance. 



Chlorides were also used as electrolytes. In chlorides of zinc and 

 cadmium exactly the same circular deposit was formed, but in those 

 metals, which can form more than one chloride (e.g. iron), a secondary 

 phenomenon always appeared. When a solution of cupric-chloride 

 was electrolysed, coj)per precipitated on the kathode; when, however, 

 a platinum screen was |)ut l)etween the electrodes, again a circular 

 deposit of a white substance was formed on the screen, q^uickly getting 

 green in the air and being hygroscopic then ; probably it might have been 

 cuprous chloride, afterwards becoming cupric chloride again. When using 

 a solution of Hg CI, as electrolyte a white deposit of Hg CI came on 

 the platinum. A solution of Au (-1, gave conformable results; a brown 

 red deposit was formed. Using H, Ft CI, and a screen of gold-leaf, 

 a yellow brown one was formed on the latter. When a solution of 

 ferric chloride was used no deposit Avas ever formed. The explanation 

 may be found perhaps in the solubility of ferrons chloride which 

 is precipitated on the platinum as copper before. 



Though in many of the former cases an explanation could be found 

 in the polarisation, yet, however, there is one thing, that cannot be 

 explained, i. e. the curious sharp margins of the deposit. It seems 

 as if the stream-lines keep their original direction within a certain 

 tubular surface also in the presence of the platinum screen, while this 

 screen has a strong influence on the lines outside of it. which change 

 their direction and go round the screen. Perhaps the explanation 

 may be found by calculating the course of the circuit, but I am 

 not able to do it. 



In the making of all these experiments I have become indebted 



