Chemistry and Phystes. 391 
mained unproved. r. Rowland has now carried out a series of 
the middle to admit the axis of the ebonite disk. The glass disks 
of these parts, iron was avoided. Re : 
Close above the upper glass disk an extremely sensitive astatic 
15 centim, long, but at a considerable distance (17°98 centims.) 
from each other, Their deflections were read off with a mirror an 
4 telescope, The opening in front of the mirror was protected 
< 
se action of rotation-magnetism was shown, mostly arising fro 
e brass axis of the rotating disk, and considerably diminished by 
> ucing it to 0-9 centim. thickness. The action of the electrifica- 
Hon of the disk could be separated from that of the an eseieptra 
oi the rotation was maintained unaltered. The displacement of the 
em pa the position of equilibrium amounted to from 5 to 74, 
fis ; of oscillation on changing the electrification, therefore, to 
™m 10 to 15 scale-divisions, This result ensued in hundreds of 
