ACCORDING to Nernst's theory of electrode potentials, a very small concentration of a reactive metal should be deposited on a noble metal when the ions of the former are brought in contact with the latter. The effect is usually regarded as being too small for demonstration. Dr. G. von Hevesy showed the effect by radioactive methods some years ago. He deposited radioactive isotopes of lead and bismuth, presumably as metal, on such noble metals as platinum, gold, mercury, and copper, in some cases quantitatively; he showed, indeed, that the ions of any radio-element could to some extent be deposited on noble metals when the latter were merely immersed in a solution. The effect, I find, can be shown by some metals which are not radioactive. I have obtained it with reactive metals like uranium, titanium, tungsten, and molybdenum on such noble metals as mercury, copper, and tin.