he various chapters have been chosen with a
view not only of fixing the principles developed in the text in the mind
of the student, but also of enabling him to answer such questions as
arise in his laboratory work. They are, therefore, more or less
practical in character. It is not necessary that all of them should be
solved, though with few exceptions the lists are not long. The answers
to the questions are not directly given in the text as a rule, but can
be inferred from the statements made. They therefore require independent
thought on the part of the student.

With very few exceptions only such experiments are included in the text
as cannot be easily carried out by the student. It is expected that
these will be performed by the teacher at the lecture table. Directions
for laboratory work by the student are published in a separate volume.

While the authors believe that the most important function of the
elementary text is to develop the principles of the science, they
recognize the importance of some discussion of the practical application
of these principles to our everyday life. Considerable space is
therefore devoted to this phase of chemistry. The teacher should
supplement this discussion whenever possible by having the class visit
different factories where chemical processes are employed.

Although this text is now for the first time offered to teachers of
elementary chemistry, it has nevertheless been used by a number of
teachers during the past three years. The present edition has been
largely rewritten in the light of the criticisms offered, and we desire
to express our thanks to the many teachers who have helped us in this
respect, especially to Dr. William Lloyd Evans of this laboratory, a
teacher of wide experience, for his continued interest and helpfulness.
We also very cordially solicit correspondence with teachers who may find
difficulties or inaccuracies in the text.

The authors wish to make acknowledgments for the photographs and
engravings of eminent chemists from which the cuts included in the text
were taken; to Messrs. Elliott and Fry, London, England, for that of
Ramsay; to The Macmillan Company for those of Davy and Dalton, taken
from the Century Science Series; to the L. E. Knott Apparatus Company,
Boston, for that of Bunsen.

THE AUTHORS

OHIO STATE UNIVERSITY

COLUMBUS, OHIO

CONTENTS

CHAPTER PAGE
I. INTR