Excerpt from A Study of the Deterioration of Nickel Spark-Plug Electrodes in Service The nickel electrodes in which the deterioration was studied were taken from spark plugs in which the electrodes are arranged as a central one with the ground or Side electrode attached firmly at both ends to the Shell of the plug. In some of the plugs two side electrodes were used, one on each side of the central one. Although both electrodes were found to have deteriorated to some extent, the attack of the central one was quite negligible as com pared to that of the side ones. These latter wires had developed in service transverse cracks which in many cases were as Sharp and definite as a knife cut. After a separation occurred, the breach widened by loss of material from the ends of the fractured wires until a gap of as much as 1 cm often resulted. Fig. 2 Shows the appearance of some of the Side electrodes in different stages of deterioration. In Fig. 3 is shown the appearance of the surface of the side electrodes after removal of the carbonaceous deposit which usually covers them. The surface is roughened by a Series of parallel transverse cracks; none of these, however, has pene trated deeply enough to cause a break of the wire. In general, these transverse cracks occur more frequently on the Side of the electrode on which most of the Sparking occurs - that is, the one facing the central electrode - than on the farther side. The central electrode shows no appreciable change other than a Slight roughening of the tip. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.