Rare metals in electron tubes

The paper discusses some of the problems arising in the manufacture of electron tubes, and shows how the use of rare metals assists in overcoming some of the difficulties, or is necessitated by the nature of the problems. Typical cases referred to are: electrodes for operation at high temperatures; improvement of vacuum by the use of getters; production of high thermionic, secondary, and photo-emission; reduction of electron emission from grids; and the use of rare metals in brazing and soldering. The properties of the rare metals, which make them useful in dealing with these problems, are described, and in one or two cases reference is made to the preparation of the metals concerned.