Excerpt from Cobalt, Nickel, and the Elements of the Platinum Group Again, the platinum metals are so closely similar in many of their properties that it was decided to treat of their detection and estimation all together in Chapter X, rather than to deal with each separately at the end of the chapters dealing with their compounds, as has been done with cobalt and nickel, and, indeed, with the elements in the remaining volumes. The state of our knowledge of the chemistry of the platinum metals, although greatly improved during the last twenty years, is still far from satisfactory. This, no doubt, is due to a variety of reasons, such as the rarity of the metals, their consequently high cost, apd their similarity to one another, which renders their preparation in a state of purity an extremely arduous task. This latter feature is well exemplified by the efforts of Matthey to prepare pure iridium. His work is described in fair detail on pp. 235 - 236 of the text. Even after a most elaborate treatment the metal still contained traces of ruthenium and rhodium. In consequence of this difficulty, there can be no doubt that the early investigators frequently worked with a very impure metal, and this may in some measure account for discrepancies and apparent contradictions in their results. 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.