Detection of Specific Adulterants. In Bulgaria guaiac wood oil from Bulnesia Sarmienti with its agreeable tea-rose-like odor is also used as adulterant2). Its presence can be recognized microscopically by the guaiol crystals which separate from the oil upon cooling. Under the microscope guaiol appears as long needles with a canal-like groove in the middle. The crystals of rose oil stearoptene are smaller and thinner and reveal sharply articulated shapes3). The presence of guaiac wood oil in rose oil can be definitely established by the isolation of the guaiol which melts at 91°.
Guaiac wood oil increases the specific gravity, the optical rotation and the congealing point of the rose oil to which it has been added. It decreases the ester value but very little. Upon evaporation such an oil leaves a resinous residue1).
1) E. Gildemeister and K. Stephan, Arch, der Pharm. 234 (1896), 326.
2) Report of Schimmel & Co. October 189S, 38.
3) F. Dietze, Suddeutsche Apoth. Ztg. 38 (1898), 672 and 680.
According to communications received by Schimmel & Co.2), a mixture of salol and antipyrine is sometimes added to increase the congealing point of oil of rose. Presumably their presence has not been definitely established.
According to E. J. Parry8) nonylic and decylic aldehydes have recently been used as adulterants of rose oil. They are added in the form of a 5 p. c. alcoholic solution. Parry has examined such a solution that had been sent to him from Bulgaria. He describes it as colorless, permeated with crystals of paraffin, the odor reminding of oranges. Specific gravity 0,813 at 30°; index of refraction 1,3655 at 20°. The isolated aldehyde had the specific gravity of 0,835 and an index of refraction of 1,4226 at 20°. After recrystallization the oxime melted at 68,5°. Since nonylic and decylic aldehydes occur as natural constituents of the oil, their addition could not be detected in the small amounts of oil subjected to examination. However, the alcohol added at the same time can readily be detected. The test for alcohol4) is all the more desirable since it is occasionally added to counteract the increase in specific gravity produced by the addition of geraniol, palmarosa oil or gurjun balsam oil. Hence the specific gravity should always be determined both before and after the oil has been shaken with water (and subsequently dried). If the density of the oil has been increased by this operation, the alcohol should be isolated from the water after this has been filtered through a moist filter. The alcohol can be identified by the well known methods recorded on pages 349 and 612 of vol. I.
Recently Schimmel & Co.5) found that gurjun balsam oil had been used as adulterant. Its detection can be caused in the following manner. The stearoptene is separated by means of dilute alcohol, which also precipitates the gurjun balsam oil, and its optical rotation ascertained. Whereas the normal stearoptene is inactive and solid at room temperature, the stearoptene which includes the gurjun balsam oil is optically dextrogyrate and is liquid at ordinary temperature.
1) F. Dietze, Suddeutsche Apoth. Ztg. 38 (1898), 672 and 680.
2) Report of Schimmel & Co. October 1902, 75.
3) Chemist and Druggist 77 (1910), 531.
4) Report of Schimmel & Co. October 1908, 108; April 1910, 92; April 1911, 99.
5) Ibidem April 1912, 109; October 1912, 96.
In order to prove chemically the presence of gurjun balsam oil, the paraffin is separated as completely as possible by freezing. The residue is then oxidized in acetone solution with permanganate according to the method of E. Deussen and H. Philipp1). Those components which have not been attacked by the permanganate are removed by fractional distillation at 104 to 105° (5 mm.) and the distillation residue is treated with semicarbazide. If gurjun balsam oil be present the semicarbazone of the gurjunene ketone results which, after re-crystallization from hot alcohol, melts at 234°.
Production and Commerce. So far as the world's commerce in rose oil is concerned only that from Bulgaria comes into consideration. The oils produced in southern France, Saxony, Asia Minor and Russian Transcaucasia, whether by distillation or other methods, are quantitatively of minor importance. With the exception of a few years, the Bulgarian statistics of the commerce in oil of rose reveal the peculiar phenomenon that the amount of oil exported considerably exceeds the amount produced. Moreover, this difference is of such a nature that it cannot be explained away by assuming that these excess amounts represent the overproduction of previous years. In the Report of Schimmel & Co. for October 1908 the accompanying curve was published. It represents the amounts of oil produced, also the amounts of oil exported by the individual countries and totals. As a result of the publication of this discrepancy, the Bulgarian statistician has become cautious in the publication of his export figures. In the statistics for recent years we find the following data concerning production and exportation: -
The excess of oil exported over that produced is probably accounted for by the assumption that the natural oil is extensi1) Liebig's Annalen 367 (1909), 56; 374 (1910), 105.
Production of rose oil in Bulgaria, compared with the total exports in the years 1896 to 1907, and countries of destination.
Vely mixed with the adulterants enumerated in the previous paragraphs (palmarosa oil, gurjun balsam oil, alcohol &c). In spite of regulations against their importation and other well-meant rules that are difficult to enforce, it must be assumed, judging from current literature, that the profitable business of adulteration continues undiminished. In this respect the sealing of the oil by the Bulgarian Export Revenue Office, has caused but little change. Originally it was, no doubt, conceived as guaranty for the purity of the oil. At present the sealed flasks are merely an indication that the oil is of Bulgarian origin.