Page 3 - APPLIED INORGANIC ANALYSIS

vi PREFACE

occur. Again, there is very often more or less contamination through
inclusion or mechanical adherence with distinetly foreign material that
could not be removed. Hence the analysis resolves itself into one of
mineral mixtures, analogous to that of rocks, and what might have
been a relatively simple task may become one of extraordinary com-
plexity, difficult not only in execution but in interpretation as well.
A fair eritieism of much of the work that has been published on
methods for the determination of the elements is that a great deal is
claimed on the basis of experiments that have been carried out in pure
solutions, and very little, if anything, is said as to how the methods
are to be applied or what results can be expected in analyses of the
more or less complex materials in which the elements are found. There
is no lack of methods that are satisfactory when applied to the analysis
of pure compounds. On the other hand, there is great need for the
development of quantitative procedures that can be applied to the
separation or determination of substances in complex mixtures. An.
accurate determination of columbium, which is a simple matter in its
pure compounds, is absolutely impossible if it is accompanied by tanta-
lum, as is probably always the case. The aim throughout the book
therefore has been to stress the preparation of the solution for the
determination that is to be made, rather than to describe processes that
can be used with certainty only in the speeife applications for which
they were devised. Obviously, a method of analysis that would meet
any possible contingeney would be very cumbersome if it could boa
developed at all.
For the most part, the procedures that are given are based on data
obtained by the senior author in the course of analyses of thousands
of rocks and minerals, and by the junior author in researches and
analyses dealing with miscellaneous inorganic materials, and partieu-
larly in directing the analyses of the U. S. Bureau of Standards' stand-
ard analyzed samples of ores, ceramie products, ferrous and non-
ferrous materials such as irons, steels, alloy steels, ferro-alloys, brasses,
bronzes, bearing metals, light aluminum alloys and pure chemicals, and
in formulating standard methods for the analysis of such materials in
cooperation with committees of the American Society for Testing Ma-
terials and the American Ceramic Society. Nevertheless, if a book that
deals with applied inorganic analysis is to be even approximately eom-
prehensive it is necessary to draw on the work of others, for the
subject is so vast that no chemist can have had the opportunity of
critically testing all of the methods. Wherever our experience has been
meager, we have endeavored to present the methods that appear to have
the most merit, and to give proper reference as to their soure. No
doubt the authors have failed to include desirable methods for the