LVI. The disappearance of gas in the electric discharge (V.)

Summary The purpose of these experiments is to discover a relation between the rate of absorption of a gas in the electric discharge and the rate of ionization of its molecules. It is pointed out that the true electrical absorption, dependent simply on ionization or allied processes, is entangled with other causes of absorption and evolution of gas; the main difficulty is to disentangle it. The experiments show that, in nitrogen and carbon monoxide, the rate of absorption is proportional to the rate of ionization and, approximately at least, independent of the pressure, the speed of the ionizing electrons, and the arrangement of the electrodes. It depends very greatly on the condition, but not very greatly on the material, of the wails of the vessel. The number of molecules disappearing is often greater than the number ionized. In argon there is no evidence of an absorption simply related to ionization. In hydrogen the facts are obscure; but it is probable that there is au electrical absorption more rapid than in N2 or CO. An attempt is made to explain the facts. In spite of the simple relation between absorption and ionization, it does not seem possible to hold that the ions are absorbed. Alternative theories are discussed: (1) that monatomic molecules liberated by ionization, (2) that partially ionized or excited molecules are absorbed; but both are open to grave objection. The molecules almost certainly are absorbed by reaction with the walls of the vessel, but no suggestion can be made as to the nature of the reaction. Some observations, to be completed in a later paper, are described on the evolution of gas from glass vessels when heated, after they have been submitted to the usual processes of baking during exhaustion. It appears that there is no definite amount of gas that can be evolved by such heating, but rather that an equilibrium pressure is established. The paper consists of the following parts:—1. § 1–2. Statement of the Problem.2. § 3–4. Experimental Methods.3. § 5. General Nature of the Results.4. § 6–11. Detailed Results. Effects of anode voltage (6); Arrangement of electrodes (7); Nature of gas (8); Pressure of gas (9); Nature of walls (10); Thermal evolution of gas (11).5. § 12. Comparison with Previous Work.6. § 13–17. Discussion of Results. Absorption and ionization (13, 14); Absorption and monatomic molecules (15); Absorption and excited molecules (16); Nature of absorption (17).