210 Messrs. Mendenhall Sf Ingersoll on Phenomena 
the observations which form Table I. the effect was considered 
to exist when a particle showed a definite tendency to tip 
over one way or the other, the direction reversing with 
reversal of current. 
(3) The size and shape of the particles is not important, 
most irregular shaped particles rolling as readily as nearly 
round ones ; in general small particles have a more rapid 
angular motion, though they may not cover as much ground. 
Long flat pieces usually move very readily even when touching 
the glower only at the tip. The forces involved are not at 
all proportional to the size of the particle, but are sufficient 
to move small particles up a vertical glower against gravity. 
The fact that particles will also move along the under side of 
the glower, and that they are found to be more or less firmly 
stuck to the glower when it is allowed to cool, indicates that 
there is incipient fluxing or sticking of the metal to the 
glower even at temperatures below the melting-point. 
(4) The rapiditv of the motion increases both with the 
temperature of the glower and the current density in it. By 
superposing a direct on an alternating current through the 
glower (the latter doing most of the heating, and the former 
serving to direct the motion), we have inia measure separated 
current and temperature influence, and, find that the 
current is the more important of the two. If the current 
density in the glower is sufficient, the motion will take'place 
at a temperature a good deal below the melting-point of the 
metal : for example, cobalt, which melts at say 1500° C, has 
been observed to move at 1150° C. In general the higher the 
melting-point of the metal, the higher the temperature 
necessary to produce noticeable motion. 
(5) We have attempted to influence the motion by pro- 
ducing electrostatic and electromagnetic fields near the 
particle on the glower, but without success. Nor could the 
motion be produced on a hot piece of glower material not 
carrying a current, but having electrostatic and magnetic 
fields along and at right angles to it in such a way as to 
simulate the effects of a current. Negative results were also 
obtained when particles supported on mica were brought up 
underneath a running glower to within microscopic distances 
of its surface. 
(6) We have not been able to produce the effect on any 
metallic conductor, nor have we succeeded in observing it 
on any electrolytic conductor which differed much in com- 
position from the ordinary Nernst glower, the trouble being 
either that these became molten and sticky at too low a 
temperature and with too small a current density (for 
