VI

PREFACE

instruments and methods there discussed are too seldom under-
stood by the chemists who use them in industrial work. In our
own classes we have found lectures upon the theoretical principles
underlying the construction and use of these forms of apparatus
to be of very great value.
In Part III is included a treatment of the six classes of materials
most often considered in courses in agricultural analysis, and
probably of interest to the greatest number of agricultural
chemists. The significance of the results of the analyses, in
connection with agricultural problems, has been given as much
attention as was thought possible, without going outside the
proper scope of a book of this.character. This, it is believed,
will add an interest to the laboratory work and supply a certain
motivation, otherwise largely lacking.
In certain parts of the book we have drawn rather freely upon
portions of another text by one of us.1 This is particularly true
in the discussion of materials and general operations, of the
analysis of oils, fertilizers and dairy products and of the deter-
mination of nitrogen. Certain cuts have been borrowed from
the same source, while others are from original drawings, made
by G. B. Wilson.
Problems in analytical calculations have not been included.
Several good problem texts are now available and the authors
believe that a systematic course with one of these, as an
accompaniment to the laboratory work and lectures, is the best
method of impressing this phase of the subject upon the mincl
of the student.
E. G. MAHIN,
R. H. CARR.
PURDUE UNIVERSITY,
September, 1922.
IMAHIN, "Quantitative Analysis."