Titanium, and Vanadium by Thermelectronk Currents. 249 



obtained with the magnetic field on are specially marked — 

 a completely shaded circle, when the magnetic force was 



H*. 2. 



34-co 



3200 



2-0 



3-0 4-0 5-0 6-0 7-0 



Potent/3/ aradfent alonq p/ate in uo/ts oer centimeter. 



Temperature curve of graphite plate. 



acting upwards, and a half -shaded circle, when the force 

 acted downwards. There seems to be no definite effect due 

 to the presence of the magnetic field, for although Nos. 19 

 and 22 lie rather much above the line and seem, if anything, 

 to indicate a rise in temperature, when the magnetic force is 

 acting upwards, they are yet too near the limits of possible 

 •errors to allow of any positive conclusion being derived. 

 But the result, as it stands, is of the utmost importance for the 

 interpretation of certain phenomena to be discussed in § 9. 



A few additional temperature determinations were made 

 with plates which were not protected by a layer of car- 

 borundum powder, so that their upper surfaces were left 

 exposed and free to radiate heat. Under these conditions 

 the temperature of the undersurface, with a potential 



gradient along the plate of 5*93 , was found to be only 



2450° C. — namely, about 250° C. less than when the plate 



8-0 



