E-text prepared by Peter Yearsley, Josephine Paolucci,
and the Project Gutenberg Online Distributed Proofreading Team
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Transcriber's Note:
Parentheses have been added to clarify fractions.Letters in brackets with a = sign before it meansthat the letters have a macron over them, e.g. H[=A=c] signifies thatthe Ac has a macron over it.
Minor typographical errors have been corrected. Footnotes have beenmoved to the end of the chapter, and all advertisements have been movedto the end of the book.
ASSOC. OF THE ROYAL SCHOOL OF MINES; FELLOW OF THE CHEMICAL SOCIETY ANDOF THE INST. OF CHEMISTRY; PRINCIPAL OF THE CAMBORNE MINING SCHOOL; ANDLATE PUBLIC ANALYST FOR THE COUNTY OF CORNWALL.
LONDON:
CHARLES GRIFFIN AND COMPANY, Limited,
EXETER STREET, STRAND.
1904.
The continued popularity of the present work, the last edition of whichwas published only a little over a year ago, continues to be a source ofgratification to the publishers, who have much pleasure in issuing thepresent edition.
January 1904.
The principal changes in this edition are additions to the articles onGold, Cyanides, and Nickel, and a much enlarged Index. The additionalmatter covers more than forty pages.
J. J. BERINGER.
Camborne,
January 1900.
The Text-book now offered to the public has been prepared to meet theexisting want of a practical "handy book" for the Assayer.
To mining men the word "assaying" conveys a sufficiently clear meaning,but it is difficult to define. Some writers limit it to thedetermination of silver and gold, and others imagine that it has only todo with "furnace-work." These limitations are not recognised inpractice. In fact, assaying is becoming wider in its scope, and thedistinction between "assayers" and "analysts" will in time be difficultto detect. We have endeavoured rather to give what will be of use to theassayer than to cover the ground within the limits of a faultydefinition.
At first our intention was to supply a description of those substancesonly which have a commercial value, but on consideration we have addedshort accounts of the rarer elements, since they are frequently metwith, and occasionally affect the accuracy of an assay.
Under the more important methods we have given the results of a seriesof experiments showing the effect of varying conditions[Pg vii] on the accuracyof the process. Such experiments are often made by assayers, but seldomrecorded. Statements like those generally made—that "this or thatsubstance interferes"—are insufficient. It is necessary to know underwhat conditions and to what extent.
Students learning any particular process cannot do better than repeatsuch a series of experiments. By this means they will, at the same time,acquire the skill necessary for performing an assay and a confidence intheir results based upon work under different conditions.
The electrolytic method of copper assaying