RECENT DEVELOPMENTS IN ESSENTIAL OILS 321 upon the care given by each individual grower to his fields. (Complete .eradication of all weeds, etc., is a must for every "clean" peppermint igrower in any producing region.) In years of cool and moist weather mint Irust, a fungus disease (Puccinia menthae), may do much damage and iseriously affect the yield. In 1955 the yield of oil per acre was 50 pounds i(which is normal), and Oregon produced 650,000 pounds of the oil. (3) Far Western States east of the Cascade Mountains (eastern Washing- •ton and lately to a small extent also eastern Oregon). Growing conditions [in these recently opened territories are excellent, the land is still relatively •1ow priced, irrigation feasible and usually effected by means of ditches. IYield of oil per acre is higher than in any other peppermint region. In 11955 the average yield per acre was 65 pounds, but yields as high as 100 pounds have been reported in some individual cases. It is not surprising then that production in eastern Washington has increased during the past Ifew years, attaining 637,000 pounds in 1955. Production continues to rise despite the fact that (unfortunately) some of the so-called Yakima or i Kennewick oils possess an inferior odor and flavor. Moreover, these low .grade oils frequently fail to conform with the requirements of the United ,States Pharmacopoeia. Even rectification or careful fractionation does inot eliminate certain constituents which impart an objectionable odor and •fiavor to them. The Yakima oils, because of their inferior flavor, usually I find their way into the market in the form of blends with midwestern oils. The off-flavor of the Yakima oils is perhaps associated with the presence iof excessive quantities of mentholutah. Several possible factors h•ve been •adduced to explain the high percentage of menthofuran in these oils, for example, the high luminosity in eastern Washington (i.e., the influence of ultraviolet light upon the plants), or perhaps faulty irrigation. It has been proved that the essential oil contained in the blossoms of the peppermint plant is particularly rich in mentholutah and perhaps related compounds. For this reason many farmers in the Yakima Valley now harvest the mint after most of the bloom is gone, which practice improves the quality of the •oil. Moreover, it has been observed that peppermint raised under sprinkler i irrigation in the Yakima Valley does not appear to develop the same heavy I bloom that the plant produces when raised under corrugate (ditch) irriga- tion, whfch is still the usual practice in the Yakima region. The fact remains that, encouraged by the high yield of oil per acre, pep- permint oil production in eastern Washington continues to increase. If this section should ever succeed in supplying oils of a quality equal to that of western Oregon or the Midwest, these latter regions might find them- selves in a difficult position. C. Spearmint Oil. The story of the American spearmint industry (including methods of cultivation and distillation) resembles that of pepper- mint. After having flourished for many years in the Midwest (Indiana

322 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS and Michigan) production has now expanded to the eastern part of Wash- ington State. In 1939 the Midwest produced about 375,000 pounds of spearmint oil which was used chiefly in chewing gums. In 1947 chloro- phyll toothpastes appeared on the market and the demand for spearmint oil (with which they were flavored) increased sharply. Since the Midwest was unable to satisfy this demand, progressive large-scale producers began to look toward the Far West for expansion in spearmint acreage. This movement to the Pacific Northwest was encouraged by the fact that yield of oil per acre proved to be much higher in that area than in the Midwest. (In 1955 the average yield of oil per acre was 33 pounds in Indiana, 26 pounds in Michigan and 95 pounds in eastern Washington.) As a result of new plantings, production of spearmint oil in eastern Washington increased to 218,000 pounds in 1955, against 211,000 pounds for Indiana and 156,000 pounds for Michigan. Total U.S. production of spearmint oil in 1955 was therefore 585,000 pounds. Like the peppermint plant, spearmint is exposed to wilt and rust. lfilt has done much damage to the spearmint fields in the Midwest, this being one of the reasons for the low yield of oil per acre. Spearmint rust, on the other hand, flourishes only in areas exposed to cool and humid weather, for which reason cultivation of spearmint would be a risky business in the Wil- lamette Valley for example. Since rust does not thrive in hot and dry areas, cultivation in the Yakima Valley has proved most successful. In general, it is easier and more economical to grow spearmint than peppermint, substantially higher yields of oil per acre being obtained. For this reason cultivation of spearmint in eastern Washington (Yakima Valley) is still increasing. BIBLIOGRAPHY (1) Abe, Y., Harukawa, T., Ishikawa, H., Miki, T., and Sumi, M., "Nomenclature of Santonin and Related Compounds," Chemistry & Industry, 91 (1955). (2) Abe, Y., Harukawa, T., Ishikawa, H., Miki, T., Sumi, M., and Toga, T., "A New Racemic Stereoisomeride of Santonin," Proc. )rapan ,qcad., 29, 113 (1953). (3) Abe, Y., Harukawa, T., Ishikawa, H., Miki, T., Sumi, M., and Toga, T., "The Syn- thesis of Two Optically Inactive Stereoisomerides of Santonin," 5 t. •lm. Chem. $oc., 75, 2567 (1953). (4) Abe, Y., and Sumi, M., "Configuration of the Santonins," Chemistry & Industry, 253 (1955). (5) Aebi, A., Barton, D. H. R., Burgstahler, A. W., and l.indsey, A. S., "The Stereochem- istry of the Tricyclic Derivatives of Caryophyllene," )t. Chem. Soc., 4659 (1954). (6) Aebi, A., Barton, D. H. R., and Lindsey, A. S., "The Nature of v-Caryophyllene," Chemistry & Industry, 487 (1953). (7) Aebi, A., Barton, D. H. R., and Lindsey, A. S., "The Relationship Between Clovene and •-Caryophyllene Alcohol," Ibid., 748 (1953). (8) Aebi, A., Barton, D. H. R., and Lindsey, A. S., "The Stereochemistry of Caryophyl- lene," )t. Chem. Soc., 3124 (1953). (9) Arigoni, D., and Jeger, O., "Ueber die absolute Konfiguration des Zingiberens," Helv. Chim. dcta, 37, 881 (1954). (10) Atwater, N. W., and Reid, E. B., "On the Nature of •-Caryophyllene," Chemistry & Industry, 688 (1953). (11) Barton, D. H. R., "Conformational Analysis of Substituted cycloHexanes," Ibid., 664 (1953).