Effects due to Magnetization. kll 



H' = 1299*48 d'K, and as d' varied from ^V to 16, the range 

 of field employed was from 65 to 20,800 EL 



A curve was constructed so that from accurate ammeter 

 readings in the field circuit the strength in absolute measure 

 could he read off at once. 



Experimental Results. 



Preliminary. — The first experiments were made with very 

 dilute nitric acid and iron electrodes — one a circular disk of 

 5 millim. radius, and the other a small wire 1 centim. long 

 and 1 millim. in diameter, turned to a sharp point at one end. 

 The point was placed opposite the centre of the disk, at a dis- 

 tance of 1 centim. from it, and the whole placed so that the 

 cylindrical electrode coincided with the direction of the lines 

 of force. When the minute point and the centre of the disk 

 were exposed to the liquid, and the magnet excited, a momen- 

 tary " throw " of the galvanometer was observed in the 

 direction indicating the point as being protected or acting as 

 the copper of the cell. 



When the pointed pole was slightly flattened at the end, 

 and the insulation so cut away that the surfaces of exposure 

 on the two electrodes were exactly the same, the throw of the 

 galvanometer on making the field was very much diminished, 

 although still perceptible, since the disposition of lines of 

 force would still be very different over the two plane surfaces 

 of exposure. 



With ball-and-point electrodes precisely similar pheno- 

 mena were observed as with a disk and point, except to a less 

 degree. 



The gradual reversal of the current shortly after exciting 

 the field, the independence of the throw of the direction of 

 the current through the magnet, the disappearance of the 

 throw when the nature of the magnetic field at the exposed 

 parts became the same, and the effects of artificially stirring 

 the liquid, were observed exactly as described by Messrs. 

 Rowland and Bell. 



In the course of a large number of preliminary experi- 

 ments with nitric acid, it was soon observed that under 

 certain conditions the effect of suddenly putting on the 

 magnetic field was to produce a less rapid deflexion of the 

 galvanometer in the opposite direction, or indicating the 

 point as acting as a zinc. Plainly this irregular behaviour, 

 due to the magnet, required a more systematic study than it 

 had yet received. It had been found that the reversal of the 

 current, which regularly followed the " protective throw/' 

 was decreased or destroyed by anything which prevented free 



