478 Lieut. Gk 0. Squier on the Electrochemical 



circulation in the liquid, and that an acidulated gelatine, 

 which was allowed to harden around the poles, was best 

 suited for this purpose. The great irregularity observed in 

 any one experiment made it necessary to eliminate everything 

 possible which might mask the true phenomenon, if any ac- 

 curate comparisons were to be drawn between the effects 

 observed in the different cases ; accordingly a standard form 

 of experiment was adopted, which was carefully repeated 

 many times. The cell found best suited for this purpose was 

 composed as follows * — 



Disk electrode, diameter 14*4 millim. 



„ „ thickness 2*6 „ 



Point electrode, total length 15'2 , r 



„ „ diameter 4*4 „ 



„ length of point 5*2 fr 



Distance of point from centre of disk. . . 10 „ 



The same electrodes were used throughout any set of experi- 

 ments, being carefully cleaned and polished each time. 



With nitric acid the liquid was finally made up as 

 follows • — 



Distilled water 10 grammes. 



Hard gelatine 1 gramme. 



C. P. nitric acid (sp. gravity 1*415) 0*533 gramme. 



The gelatine and water were allowed to stand until the 

 former had dissolved without the application of heat, when 

 the acid was added and the whole thoroughly mixed. Too 

 strongly acidulated gelatine would not harden at all. 



In some cases, in order to protect the point from the 

 beginning, the electrodes, secured as usual at the ends of two 

 small glass tubes containing the connecting wires, were 

 firmly clamped in the proper position between the poles of 

 the magnet, and the magnetic field put on before the cell was 

 completed, by pushing the beaker containing the solution up 

 in position round the electrodes. 



With this cell a series of parallel experiments were con- 

 ducted to obtain the variation of the effects with time, the 

 amount of iron salts present, the fluidity of the solution, and 

 with constant and variable magnetic fields. 



A. Behaviour of the Cell with Time, in the Earth's Field. 



The cell was placed entirely outside the magnetic field, and 

 galvanometer-readings taken at intervals of one minute for 

 three hours. The curve fig. 1 (I.) shows these results. Posi- 

 tive ordinates indicate a current from the point to the disk, 



