Abstract :
About fifty years ago, much scientific work was done on the passage of electricity in air between two electrodes, one of which was red hot. A little later, as an outgrowth from these experiments, electron emission in a high vacuum proved to be of such interest and promise in the new but expanding science of electronics that the phenomenon in air has been all but forgotten. However, a new, interesting, and useful leak detector has been developed from this neglected effect, and there is reason to believe that positive-ion emission may well be of importance for other applications.
