In the work of Doctors Gildemeister and Hoffmann we find a happy blending of history with chemical science and technology that is quite unique in modern chemical literature. Moreover it covers a chapter of organic chemistry of which Professor Emil Fischer of Berlin recently remarked that it had undergone more rapid development within the past fifteen years than any other.

The translation of such a work should indeed prove of value. To make such a translation and to take cognizance of the numerous contributions on volatile oils and related subjects that have appeared since the original German edition was issued a year ago, has proved a severe task for one whose time was already divided between instructional duties and editorial labors. In judging the English edition, it is hoped that the limitations as to time and the difficulties encountered will be taken into consideration.

Owing to the impossibility of satisfactorily translating many of the numerous quotations in the historical introduction, chapters two and three have been condensed. Inasmuch as but very few if any readers are in a position to consult the numerous historical works quoted by Dr. Hoffmann, all bibliographic information has been placed in an appendix.

To the special part a few oils were added, and changes rendered necessary by recent investigations were made as far as time permitted.

The writer desires to acknowledge with thanks his indebtedness to Mr. Carl Fritzsche and to Dr. Hoffmann for suggestions, as to the scope of the translation and as to minor details. Mr. O. Schreiner has assisted in the translation and proof reading and Dr. C. Kleber of Garfield, N. )., has kindly read one proof. His long experience as chemical expert on the subject of volatile oils rendered his co-operation especially valuable.

Madison, Wis., July 1900.

Edward Kremers.

Errata.