shall be included in an elementary text on
chemistry is perhaps the most perplexing one which an author must
answer. While an enthusiastic chemist with a broad understanding of the
science is very apt to go beyond the capacity of the elementary student,
the authors of this text, after an experience of many years, cannot help
believing that the tendency has been rather in the other direction. In
many texts no mention at all is made of fundamental laws of chemical
action because their complete presentation is quite beyond the
comprehension of the student, whereas in many cases it is possible to
present the essential features of these laws in a way that will be of
real assistance in the understanding of the science. For example, it is
a difficult matter to deduce the law of mass action in any very simple
way; yet the elementary student can readily comprehend that reactions
are reversible, and that the point of equilibrium depends upon, rather
simple conditions. The authors believe that it is worth while to
present such principles in even an elementary and partial manner because
they are of great assistance to the general student, and because they
make a foundation upon which the student who continues his studies to
more advanced courses can securely build.

The authors have no apologies to make for the extent to which they have
made use of the theory of electrolytic dissociation. It is inevitable
that in any rapidly developing science there will be differences of
opinion in regard to the value of certain theories. There can be no
question, however, that the outline of the theory of dissociation here
presented is in accord with the views of the very great majority of the
chemists of the present time. Moreover, its introduction to the extent
to which the authors have presented it simplifies rather than increases
the difficulties with which the development of the principles of the
science is attended.

The oxygen standard for atomic weights has been adopted throughout the
text. The International Committee, to which is assigned the duty of
yearly reporting a revised list of the atomic weights of the elements,
has adopted this standard for their report, and there is no longer any
authority for the older hydrogen standard. The authors do not believe
that the adoption of the oxygen standard introduces any real
difficulties in making perfectly clear the methods by which atomic
weights are calculated.

The problems appended to t