Excerpt from Wave-Length Measurements in the Arc and Spark Spectra of Zirconium The majority of the wave lengths of Table 1 represent the means of from 3 to 11 determinations. The majority of those of Table 2 are based on 2 to 4 determinations. Lines of impurities in the zirconium have been omitted in all cases where their chemical origins have been established with certainty. Although the samples of metallic zir conium represented chemical purity approximating or surpassing 99 per cent, yet all contained as impurities the elements Fe, Ti, and Cr, and in two of them were detected traces of Al, Mn, and Si. Of course, the prominent lines of the recently discovered hafnium were also present, and with a few exceptions these, too, so far as their identity has been established, have been omitted from the following wave-length lists. The comparison of the Zr wave lengths with the infra-red Hf spectrum is based on recent unpublished observations by Meggers at the Bureau of Standards. 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.