Abstract
Two types of purification devices for gases are described. The purification effect is based on the cataphoretic segregation in the positive column of a low‐pressure discharge. This segregation as a function of time is given in terms of the tube current, gas pressure, and the tube dimensions. From them optimum conditions can be chosen for a high final purity and a high purification velocity. Experimental results of the segregation in a discharge in neon with an impurity of argon are given.