348 



Mr. W. Crookes on 



[Feb. 20 y 



ebonite bad a muck greater effect on the gold leaves tkan at a lower 

 exhaustion ; for a long time however I was not able to charge the 

 leaves permanently, in consequence of their falling together as soon 

 as the source of electricity was removed. 



Fig. 1. 



When a hot substance was brought near the bulb facing a gold leaf y 

 so as to warm the glass, molecular repulsion took place, and the leaves 

 retreated from the warm spot, standing out at an angle of about 45°. 

 As the glass cooled the leaves resumed their former vertical position. 



While the leaves were repelled from the hot glass, the excited 

 ebonite had a very powerful action on them, and if it were brought 

 near hastily, the leaves flew off to the side of the glass, destroying the 

 apparatus. By careful management and repeated trials, however, the 

 ebonite could be brought near the warm spot of glass, the leaves 

 suddenly extending at an angle to each other. The appearance was as 

 if a spark had been able to pass across the bridge formed by the line 

 of advancing and retreating molecules connecting the hot glass with 

 the gold leaves. On the ebonite being removed and the glass allowed 

 to cool, it was found that the repulsion of the leaves was permanent. 

 The rubbed ebonite would attract and repel them as it was moved to 

 and fro, but the angle formed by the leaves with one another re- 

 mained unchanged. A warm body brought near the glass opposite 

 one leaf would repel the pair as a whole ; on then warming the opposite 

 side of the glass repulsion on that side took place, the angle of the 

 leaves being somewhat diminished, but on cooling the leaves opened 

 again to their former extent. 



When the glass bulb was strongly heated by a spirit flame the 

 leaves suddenly discharged and fell together. 



Another bulb (fig. 2) was prepared, containing a plate of mica, a, 

 which could be suddenly placed between the gold leaves, lb. The 



