This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1922 edition. Excerpt: ...or cupellation. In general it may be said that the metals in a molten alloy, such as a lead button on a cupel, or the lead ...Read MoreThis historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1922 edition. Excerpt: ...or cupellation. In general it may be said that the metals in a molten alloy, such as a lead button on a cupel, or the lead alloy in a scorifier, are oxidized in succession, each partly protecting those which are less easily oxidized than itself. This separation is not quantitative however, owing to the effect of mass action, and in the case under discussion, where we have a large amount of lead and small amounts of other metals, a considerable amount of lead would be oxidized during the complete oxidation of the metals above it in the table. Those metals which lie below lead in the table will be but slowly slagged in scorification and only at the expense of a large amount of lead. Thus, during scorification or cupellation, bismuth, copper and tellurium are concentrated in the residual unoxidized lead and this explains why it is so difficult to separate these metals from silver by scorification and cupellation. This can only be done by repeated scorification with fresh lead and, as might be expected, this will result in a considerable loss of silver. From their positions in the table, it is evident that silver is not easily oxidized and that gold is protected by all other metals. To one who has a knowledge of the mineral character of the ore, a glance at the ignition temperature of the sulphides shown in Table XVI will afford an idea of the initial temperature required for scorification. From a comparison of the heats of oxidation of the metals present with that of lead, the relative ease or difficulty of their elimination in scorification may be determined; and a knowledge of the solubility of the metal oxides in litharge and in borax will indicate the relation between ore, lead and flux which will give the most satisfactory results. A...Read Less
New. 268 pages. Reprinted from 1922 edition. Smyth/Section Sewn, Hard-Cover. Exact/Strict reproduction of text, no changes has been made in respect to the original text. If the original book was printed in multiple volumes/bindings than this reprint is of only a single volume/binding. A lot of effort has been made to check and improve each page/scan manually for its quality of text and illustrations (if any, are in b/w). Folded illustrations, if any, are not included in the book. This is not a retyped or an ocr'd book. Index, contents, etc, if any in the original book, are included. This item is printed on demand using good quality natural shade paper.
Copyright in bibliographic data and cover images is held by Nielsen Book Services Limited, Baker & Taylor, Inc., or by their respective licensors, or by the publishers, or by their respective licensors. For personal use only. All rights reserved. All rights in images of books or other publications are reserved by the original copyright holders.