Certain metals projecting through a mercury surface are known to have the property of ``anchoring'' the cathode spot. A variety of metals have been examined for this ability and it has been found to exist for all of them tried, Fe, Pd, Zr, Pt, Cr, Cb, Ir, Mo, Ta, W. The property depends upon wetting of the metal by the mercury, and this in turn depends upon having a clean metallic surface. The spot lengthens into a fine bright cathode line (C.L.) at the meniscus edge. These metals differ in the ease of cleaning and of maintaining cleanliness. Electrolysis, hydrogen firing, vacuum firing and ion bombardment were used in different cases. The first five show attack by the cathode spot, the Mo shows slight disintegration. Besides the bright line spectrum, the C.L. has also a strong, continuous spectrum from red into ultraviolet which is quite different from hot body radiation. The C.L. consists of a multitude of small emitting areas which are in constant rapid and chaotic motion. The details as shown by moving film photographs differed with the anchor. Cb showed the most clear‐cut phenomena. Its individual spots passed 0.22 amp. each and they moved with a predominant velocity of 46 cm/sec. They oscillated in intensity with a period of the order of 10−4sec. Their current density was ∼9000 amp./cm2. The behavior of the C.L. under different kinds of varying current has been observed, and the change in C.L. length with current plotted. Increasing the arc current while maintaining the length of C.L. fixed resulted in a lowering of the C.L. even to below the pool level and to the formation of a trough in the liquid outside the C.L. This helps explain the mechanism of spot freeing at large current densities and gave the upper limit for a circular anchored spot at about 40 amp./cm.