Shortly after the appearance of Die atherischen Ole by E. Gildemeister and Fr. Hoffmann, a similar work in French was published by Charabot, Dupont and Pillet,11) another in English by E. ). Parry.12)

1) Dr. Julius Maier, Die atherischen Ole, ihre Gewinnung, chemischen und physikalischen Eigenschaften, Zusammensetzung u. Anwendung. Stuttgart 1867.

2) Dr. Stanislaus Mierzinski, Die Fabrikation der atherischen Ole und Riechstoffe. Berlin 1872.

3) Dr. George William Askinson, Die Fabrikation der atherischen Ole. Wien 1876.

4) Dr. Heinrich Hirzel, Die Toiletten-Chemie. Leipzig 1864 and subsequent editions.

5) S. Piesse, The Art of Perfumery. London 1862 and subsequent editions.

6) Dr. Georg Bornemann, Die fluchtigen Ole des Pflanzenreichs, ihr Vor-kommen, ihre Gewinnung und Eigenschaften, ihre Untersuchung und Ver-wendung. Weimar 1891.

7) J. Ch. Sawer, Odorographia. London 1892-1894.

8) Dr. Fr. Heusler, Die Terpene. Braunschweig 1896.

9) The Chemistry of the Terpenes by F. Heusler. Authorized Translation by Francis J. Pond. Carefully revised, enlarged and corrected. Philadelphia 1902.

10) O. Schreiner, The Sesquiterpenes. A Monograph. Milwaukee 1904.

11) E. Charabot, J. Dupont et L. Pillet, Les huiles essentielles et leurs principaux constituants. Paris 1899.

12) Ernest J. Parry, The Chemistry of Essential Oils and Perfumes. London 1899 and 1910.

Dealing primarily with artificial perfume materials, but also with natural products, the smaller works by J. M. Klimont,1) E. Charabot,2) P. Jeancard and C. Satie,3) G. Conn4) and R. Knoll5) should be mentioned. O. Simon's6) book deals exclusively with analysis.

Also indispensable to the terpene chemist working along scientific lines are the excellent treatises on related subjects by C. Harries7) and O. Aschan.8)

Die atherischen Ole is the title of a large four volume work by Semmler9) published between 1905 and 1907. It is replete with references to original literature and treats of all substances found in volatile oils and might well have been labled "Chemistry of the constituents of the volatile oils." Finally, there should be mentioned the recent French book on volatile oils by Durvelle.10)

This extraordinary growth of our knowledge of the volatile oils during the past twenty-five years has had a very stimulating effect on the practical development. Hence, parallel with the scientific development, the industry of volatile oils and artificial perfumes has to record a vigorous growth. Older factories, having outgrown their former quarters, had to be enlarged, and a number of new factories, both foreign and domestic were established.

The progress made in the investigation of the composition and properties of the volatile oils has resulted in a similar development of the analysis of these oils. Hence the pharma-copoeial requirements concerning the volatile oils have become more specific and exacting. Not only are pure oils demanded, but such that are rich in active constituents. However, the great variation existing in the requirements of the several pharmacopoeias, merely reveals the fact that the composition of these natural products as well as the variation to which they are subject, has not yet been sufficiently investigated. Hence the methods of testing still leave much to be desired. If this is true of the oils used medicinally, which as a rule are among the better known oils, this lack of knowledge is felt even more among the non official and lesser used oils. The recent rapid scientific and technical development of this field, however, justifies the hope that the present defects will be removed in the not distant future, and that problems still to arise will also be solved in a satisfactory manner.

1) J. M. rvlimont, Die synthetischen und isolierten Aromatica. Leipzig 1899.

2) E. Charabot, Les Parfums artificiels. Paris 1900.

3) P. Jeancard et C. Satie, Abre'ge' de la Chimie des Parfums. Paris 1904. 4) G. Cohn, Die Riechstoffe. Braunschweig 1904.

5) R. Knoll, Synthetische und isolierte Riechstoffe und deren Dar-stellung. Halle 1908.

6) O. Simon, Laboratoriumsbuch fur die Industrie der Riechstoffe. Halle 1908.

7) C. Harries, Einkernige hydroaromatische Verbindungen einschlieBlich der Terpene und Campherarten. Erschienen im Lehrbuch der organischen Chemie of Victor Meyer and Paul Jacobson. Leipzig 1902.

8) O. Aschan, Chemie deralicyclischen Verbindungen. Braunschweig 1905. 9l) F. W. Semmler, Die atherischen Ole nach ihren chemischen Bestand- teilen unter Berucksichtigung der geschichtlichen Entwicklung. Leipzig 1906 - 1907.

10) J. P. Durvelle, Fabrication des Essences et des Parfums. Paris 1908.