Book excerpt: Excerpt from Metallographic Etching Reagents, Vol. 2: For Copper Alloys, Nickel, and the Alpha Alloys of Nickel The work herein described forms part of the general investiga tion of nietallographic etching reagents in progress at the Bureau of Standards, In a previous article 1 the authors summarized the results obtained with typical etching regents when copper was used as the metal which Was etched. The results reported below were obtained in the extension of this investigation to the important industrial alloys of copper, the brasses and bronzes, to nickel, and to the common lnickel-rich alloys. Since the pres ent work was a direct continuation of_ the former study, the general method of investigation was similar to that previously employed. In addition to the reagents'of the previous investi gation certain others which were found to be' particularly suited to some of the new materials were also used. The results ob tained With copper suggested strongly the importance of oxida tion in the successful etching of metallographic specimens. _it was shown that most oi. The metaiiographic etching reagents. Used for etching. Copper and its alloys are oxidizing in their nature, the efi'iciency of the reagent depending largely upon this charf acteristic feature of the solution. Reagents Which have at best only a very slight efl'ect upon copper can be made to etch fairly readily either by passing oxygen through the liquid while the specimen is immersed or by adding an oxidizing agent. The character of the etched surface produced - that is, whether of 'the plain or of the contrast type - depends almost entirely upon the results of the oxidation which aids and accompanies the solution of the metal. In general, the results obtained in the present investigation with the typical copper-rich alloys chosen serve to confirm and to substantiate the conclusions reached in the former study. The alloys containing nickel are usually con siderably more resistant to etching reagents than are the alloys of copper.. This is particularly true for nickel itself, Which is often satisfactorily etched only With extreme difficulty. 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.