174 Scientific Proceedings, Royal Dublin Society. 
evaporated more rapidly than an unelectrified one. Mascart 
came to the conclusion that an electrified surface, whether the 
electrification was positive or negative, evaporated more rapidly 
than an unelectrified one; while Wirtz found that electrification 
diminished the rate of evaporation of dust-free water, and that 
positive electrification had more effect than negative.”! Crookes’s 
experiments, however, hardly seem to bear directly upon the 
question. ‘The following are some extracts from his memoir, 
the first theoretical, the rest experimental :—“ Hlectrical vola- 
tilisation or evaporation is very similar to ordinary evaporation 
by the agency of heat. ... If we consider a liquid at atmo- . 
spheric pressure—say, for instance, a basin of water in an open 
room—at molecular distances, the boundary-surface between the 
liquid and the superincumbent gas will not be a plane, but 
turbulent like a stormy ocean.... The intrinsic velocity of 
the molecules is intensified by heat and diminished by cold. 
If, therefore, we raise the temperature of the water without 
materially increasing that of the surrounding air, the excursions 
of the molecules of the liquid are rendercd longer and the force 
of impact greater, and thus the escape of molecules into the 
upper region of gas is increased, and we say that evaporation is 
augmented. If the initial velocities of the liquid can be increased 
by any other means than by raising the temperature, so that their 
escape into the gas is rendered more rapid, the result may be 
called ‘evaporation’ just as well as if heat had been applied . . . 
“¢ Evaporation of water.—A. delicate balance was taken and two 
very shallow porcelain dishes were filled with acidulated water 
and balanced on the pans. Dipping into each dish—touching the 
liquid, but not the dish—was a platinum wire, one connected 
with the induction coil and the other insulated. The balance was 
left free to move, but was not swinging, the pointer resting at the 
centre of the scale. ‘The water in connexion with the coil was 
first made positive. After one and three-quarter hours there was 
scarcely any difference between the weight of the insulated 
water and that which had been exposed to the positive current. 
Kquilibrium being restored, the current was reversed, the negative 
current being kept on the dish for two hours. At the end of this 
l Discharge of Electricity through Gases, 1898, p. 16. 
