NEW SOURCES OF RADIATIONS 19 



produces any. A piece of sheet-iron or 

 silver, heated to dull redness by a Bunsen 

 burner, placed behind them, gives off rays 

 at about the same rate as an Auer burner. 



A plate of polished silver was arranged so 

 that its plane made an angle of 45 with the 

 horizontal plane. This plate having been 

 heated to cherry-red by a Bunsen burner, its 

 upper face emitted rays analogous to those of 

 an Auer burner. A horizontal pencil of these 

 rays, after traversing two sheets of aluminium 

 of 0*3 mm. total thickness, sheets of black 

 paper, etc., was concentrated by a quartz lens ; 

 with the aid of the small spark, the existence of 

 four focal regions was ascertained. I further 

 found that the action on the spark was 

 much more pronounced when the spark was 

 arranged vertically that is, in the plane of 

 emission than when it was normal to this 

 plane. The new radiations emitted by the 

 polished plate are therefore polarized, as 

 are the light and heat emitted at the same 

 time. The silver plate having been covered 

 with lampblack, the intensity of emission in- 

 creased, but the polarization disappeared. 



