Experiments with Vacuum Tubes

Abstract

IN my letter published in the last number of NATURE I omitted to say that we have compared vacuum tubes without electrodes with a tube containing water. A tube was filled about nine-tenths full of water and then sealed hermetically. It was then applied to the prime conductor of the electric machine and electrified in the same way as the vacuum-tubes without electrodes, and it was found to behave precisely as they did. The water tube became charged as a double Leyden jar, positive outside and negative inside at the end next the prime conductor, and negative outside and positive inside at the other end. A great tendency to rupture of the glass was also observed. So far as we have been able to see the most perfect vacuum that I have been able to obtain with the Sprengel pump has behaved as to frictional electricity precisely as a perfect conductor such as water.