ERNEST GUENTHER, THE SCIENTIST 289 the lime oil industry in Mexico, this honor would go unquestionably to the Medalist. Many of us can remember the time when odd lots of lime oil of inferior quality were produced in Mexico and were offered, generally with- out success, to dealers in New York. Dr. Guenther undertook a thorough investigation of Mexican lime oil because he believed that high-quality oil could be produced with adequate know-how. This entailed a field study with careful evaluation of the unsatisfactory methods then employed. Samples were obtained representing variations in distillation times, batch sizes, maturity of fruit, methods of processing, etc. These experimental samples were produced at Dr. Guenther's suggestion and under his personal supervision in Mexico. They were sent to the New York laboratories of Fritzsche Brothers, Inc., for complete examination of their physical and chemical properties. The resulting data were transmitted to Dr. Guenther in the field. Direction was thus given to the experimental work. Further samples representing the effects of other variables were prepared. As a re- sult of this intensive work, it was shown that lime oils of excellent quality could be produced competitively. Through his efforts, the lime oil in- dustry in Mexico was put on a firm scientific basis. At the present time the production in Mexico far exceeds that in the West Indies, formerly the only source of world supply. As a final step in this problem, upon Dr. Guenther's return to New York he initiated an investigation of the chemical constituents of distilled lime oil as produced in Mexico. I was fortunate to have been associated with Dr. Guenther during this investigation an investigation which required more than a year and which resulted in the publication in the •ournal of the Atmerican Chemical Society of an article elucidating the composition of this oil. The year 1948 represents another milestone in the life of the Medalist the first volume of his authoritative work, "The Essential Oils," was pub- lished. Four years later the sixth' volume was released, completing the series. This monumental work, twelve years in preparation, was immedi- ately acclaimed throughout the world. Dr. Guenther's lifework as a scientist has been devoted to the field of essential oils. His success has resulted from a remarkable combination of his training, his unusual ability, his enthusiasm, and his unique personality. I heartily endorse the selection of the Society of Cosmetic Chemists in choosing as Medalist for 1955 the foremost authority on essential oils in the world today, Dr. Ernest Guenther.

RECENT DEVELOPMENTS IN THE FIELD OF ESSENTIAL OILS By ERNEST GUENTHER, Ph.D. Vice-President and Technical Director, Fritzsche Brothera, Inc., New York 11, N.Y. LIKE EVERY field of human endeavor, the industry of essential oils is subject to the continuous change. Without change there would be no progress. The series "The Essential Oils" (64) covers the essential oil in- dustry up to the years 1948-1952, but since then many developments have taken place--in the laboratory and the producing regions--which, as part of a highly specialized field, have not come to the attention of all users of these complex products. The purpose of this paper is to review these re- cent developments. ANALYTICAL PROCEDURES* I. Improvements in Existing "PFet Methods" Little work has been reported along these lines but further standardi- zation of existing methods has been accomplished by various trade and scientific organizations, among them the Essential Oil Association (56) (the latter has so far published 100 Specifications and Standards covering essential oils, isolates and aromatic chemicals), the manufacturers in Grasse (168), the Essential Oil Sectional Committee of the Indian Standards Institute (80) and the British Standards Institute (26). The International Organization for Standardization (I.S.O.) has a Technical Committee working in this field (81). One important method now being evaluated in various laboratories is a modification of the existing Hydroxylamine Hydrochloride Method for the determination of aldehydes: the use of tertiary butyl alcohol has been suggested as a solvent to prevent acetal formation during the process (83). II. Instrumentation A major development in the field is the extended use of instrumentation, * For bibliographic reviews covering this subject see the reports by E. Guenther and E. Langenau, published in zlnal. Chem., 21,202 (1949) 22, 210 (1950) 23, 217 (1951) 25, 12 (1953) 27, 672 (1955). A further review is slated for publication in the same journal in 1957. 290