can be obtained if any question arises in using these directions.
And finally, in describing the experiments, special attention has
been given to the explanation of why it is necessary to follow
the directions carefully, and what will happen if these directions
are not followed.

Although the main object in this series is to give the most convenient
laboratory methods for preparing various substances in one-half
to five pound lots, an attempt has also been made to have these
processes as far as possible adaptable to large scale development.
For example, extractions have been avoided wherever possible,
cheap solvents have been sub-stituted for expensive ones,
and mechanical agitation, a procedure extremely important in the
success of many commercial processes, has usually been specified.
The apparatus used is always carefully described and wherever necessary
an illustration is given. Accompanying each preparation there will
be found a bibliography containing references to all the methods
for the production of the substance described in the literature.
This is given in order to aid any future investigator who
may wish to study or improve the methods of preparation.
It is not claimed that the methods are, in every case,
completely perfect, but only that the yields are very satisfactory
and allow the production of the substances at a reasonable cost.
It is hoped therefore that the pamphlets will benefit not only
the scientific research man of the university, but also the
technical chemist who desires to develop the preparation of one
of these substances to a large scale process of manufacture.
The editors trust also that this work may be used to advantage
as a preparation manual in intermediate or advanced courses in
organic chemistry in university laboratories, and that it will aid