444 



Mr. S. Ratner on tlie 



ebonite column L fixed in an earthed guard-ring K. The 

 plate is cut out in the middle in the way shown in figs. 1 

 and 3, and in this gap a strip of thin platinum foil mn is 

 stretched in the plane of the plate. One of the extremities 

 of the strip is insulated from the plate by the ebonite plugp, 



Fig. 1. 



while the other extremity is brought into contact with the 

 plate and is fixed on a sliding metal support n pulled by a 

 weak spring s. The strip can be heated to any desired 

 temperature by passing a current through it from an insu- 

 lated battery of accumulators kept at the same potential as 

 the plate A. The plate B, 8 cm. wide and 14 cm. high, has 



