242 J. Olsen — Investigation into the Existence of 



disk of an electropliorus could be brought as close as I pleased 

 to either electrode. 10, 5, 1 and \ per cent solutions of sub 

 phuric acid were tested in this cell. The deflections just after 

 the electrodes were put in the solution were very large and the 

 cell could not be worked to any advantage until after a couple 

 of days. The deflections with the more dilute solutions were 

 not so large, and thus it did not take so long for them to get 

 into working condition. 



The electrophorus disk did not hold the charge over 8 or 

 10 minutes and had to be recharged. Every time a charged 

 body was brought near to the cell, although the galva- 

 nometer circuit was open there was a considerable deflection 

 due to ordinary electrostatic induction, and this would show 

 itself also on closing the circuit to take a deflection. It was 

 necessary then to avoid this as much as possible, and this 

 could be done if the charge could be retained for a con- 

 siderable time. The knobs of two Leyden jars were then 

 placed close to the opposite electrodes and charged, the one 

 positive and the other negative, by a friction machine. The 

 jars of course hold the charge much better, but the effect 

 did not seem to be very decided, which is perhaps due to the 

 small surface exposed by the knobs. 



In order to have a charge that would waste but slowly and 

 at the same time have a considerable surface exposed, I con- 

 nected the knobs of two Leydeji jars to the disk of an electro- 

 phorus. The disk was about 21*0*^°' in diameter and was gener- 

 ally brought to within about 2*0 or S'O'^'" of the cell and the knobs 

 of the jars charged with the friction machine. The intensity 

 of the electrostatic charge was judged, partly, by the induction 

 produced while charging, and as this arrangement gave by far 

 the greatest induction, it was believed to have the greatest 

 effect on directing the ions, as was found later to be true. 

 The friction machine gave a spark of from f to 1 inch in 

 length. The induction while charging is considerable, and 

 although it seems to be about the same in whatever position 

 the electrodes or disk are placed, so long as the charge is of 

 the same sign, and although the recharging, with the jars, 

 need be done only every 20 or 30 minutes, yet it was thought 

 best to charge the jars only wlien the electrodes and jars are 

 always in the same relative position. 



The following positions were used and will be designated as 

 follows :— Positions. (1), (2), (3) and (4), flgure 1. 



The T-shaped flgure represents the disk,which can be charged 

 by the jars and the electric machine. The cell is represented 

 as seen from above. The arcs of circles represent the plati- 

 num electrodes. 



