A new type of rectifier

Preliminary announcements have been made of a new type of rectifier which is extremely simple in principle and operation and which will be described in detail in a forthcoming paper before the Institute. The discoverer of the principle is Dr. L. 0. Grondahl, who described it in a recent number of Science. The rectifier consists of a disk of copper having a coating of oxide formed on its surface and another metallic disk forming the opposite electrode. Under suitable conditions current flows more readily from the oxide to the copper than in the reverse direction.