( 469 ) 



about way lo th<' iiiidoiildrdlv shorici- one llir(iii<:;li llic scivoii. 

 This was <l(»ie in (lie following- way : A.^aiji the anode was Ihiiiü: 

 in a platinnni cnp. ovoi- the brim oC which luing a bcnl ^hass-lubc, 

 filled with the coj^per-sidphate solution, thus foi-niinp; the eoniieetion 

 between the electrolyte at the inner- and onter side of the cup. 

 Even if a capillary tnbc was used, a deviation was ol)served in \hr 

 coppei'-deposit, namely: a part of the cup near the lower end of 

 the tube was not coppered, this, however, only when the tube was 

 hung over that place on the brim of the cup between the electrodes. 

 A 3 mm. tube, however, caused a deviation of the deposit, even, if 

 the tube was hung over the brim of the cup on the prolongation 

 of the centre-line of the electrodes. 



Of course, there must be some relation between the coppering of 

 the iimer surface of the cup in these cases and the circular deposit 

 on the screen. It must be possible, therefore, to pass gradually from 

 one deposit into the other. Instead of the cup a cylinder of platinum, 

 having a diameter of 4 cm., was used, which at the bottom was 

 melted in a basin with paraffine and projected from the fluid. The 

 anode was hung in it again. The circuit being closed, the inside of 

 the cylinder was of course coppei-ed again as far as it was immersed 

 in the electrolyte (50 mm.). Then a vertical cleft of 1 mm. wide 

 and 1 mm. high was made in the cylinder on the extension-line of 

 the centres of electrodes. A part of the innei" wall round the cleft 

 remained again uncovered. When gradually givijig the cleft a height 

 of 20 mm., the uncovered part took the form of an ellipse, till at a 

 height of 25 mm, a strip of 8 mm. wideness was not covered with 

 copper, along the whole height, i. e. 50 mm., of the electi'olyte. 

 When still enlarging the cleft, the deposit gi-adually receded more 

 from the margins and after unfolding the cylinder into a jdane it 

 finally took the already known circular foi-ni again. 



To make the explanation, given of the deviation of the stream-lines 

 on account of the polarisation of the platinum, more acceptiblc, the 

 experiments were made with different electromotive forces by inserting 

 resistance. By means of a resistance box, connected parallel with 

 the voltameter, the terminal voltage of the latter coidd be increased. 

 The current-intensity could be read on a milli-amperemeter, joined 

 in circuit with the voltameter. As long as the potential difference 

 was less than the electro-motive force of the j>olarisation, nothing 

 was precipitated. After moi'e resistance had been inserted in the 

 resistance box, a current began to pass through the voltameter, but 

 without forming a deposit on the sheet of |)latiniim, althctugh tiie 

 experiment was cari-icd (ni some hours. V\\v that reason this current 



