An oil distilled by ). H. Burkill (Calcutta) in North Bengali had the properties of West Indian lemongrass oil, hence the plant was supposed to be Cymbopogon citratus, Stapf3). Later, however, the grass was identified as Cymbopogon pendu/us, Stapf4).
1) Only very fresh oils are soluble (see composition). The solubility is reduced after several days and after some time very turbid solutions only are obtained from which a part of the oil again separates. According to De Jong (Teysmannia 1907, No. 8; Report of Schimmel & Co. October 1908, 81) this change can not be attributed to oxidation for it has been observed in connection with oils that have been kept excluded from air. Several attempts made to prevent the change were unsuccessful. It was further observed that the change occurs rapidly when the oil is heated to 100°.
2) Jaarb. dep. Landb. in Ned.-Indie, Batavia, 1909, 64.
3) Report of Schimmel & Co. October 1909, 76.
4) Ibidem October 1911, 59.
The grass in question was obtained in the Jalpaiguri district (Northern Bengal). In part it was distilled on the spot (Sample I), in part in Calcutta (Sample II)1).
I. d15o 0,8954; aD - 0°28'; aldehyde content 90 p.c. (bisulphite method) and 84 p.c. (sulphite method).
II. d16o0,8924; aD - 0°49'; aldehyde content 87 p.c. (bisulphite method) and 82 p. c. (sulphite method).
Neither of the oils was soluble in 70 p. c. alcohol, but dissolved in 0,9 vol. of 80 p.c. alcohol. The addition of more alcohol caused turbidity. Similar was their behavior toward 90 p. c. alcohol and even absolute alcohol. The solution which was clear at first became strongly opalescent upon dilution.
Burkill has also investigated the influence of the stage of development and of the time of harvest of the grass on the properties of the Northern Bengal oil1).
The oils were obtained from grass collected in the same region (Jalpaiguri district) at different periods. In July grass that was not yet in blossom was distilled immediately on the spot (la) and later in Calcutta (lb). Two months later, in September, grass that had not yet reached the flowering stage was distilled (II). During the flowering period the flowers only were distilled (III), likewise the leaves only (IV). The data thus obtained, it was thought, would make it possible to draw conclusions as to the effect of different stages of vegetation on the properties of the oil. However, no remarkable differences were observable either between leaf and flower oil, or between the several leaf oils among themselves. The leaf oil is somewhat more dense and contains slightly more aldehyde than the flower oil, but the few observations at hand do not justify any final conclusion. The results are tabulated in the following table. (Page 209).
All of the above oils yielded a clear solution only in the beginning with even 90 p.c. alcohol. Upon dilution the solution became strongly opalescent.
1) Report of Schimmel & Co. April 1910, 73.
Origin, condition and time of harvest of the grass
Aldehydi with NaHs03
content with Na,.SO,
A. Non-flowering Jalpaiguri plants
a) Distilled in Jalpaiguri . . .
b) Distilled in Calcutta . . .
Distilled in Jalpaiguri ....
B. Flowering Jalpaiguri plants
B. T. Brooks1) described an oil closely related to lemongrass oil that was distilled in the Philippines from an unknown Andro-pogon species. It had the following constants: d30/30o 0,8777; a + 0°; nD80o1,4868; and contained about 72 p.c. citral (m. p. of semicarbazone 155 to 160°) and 12 p. c. of geraniol that had been isolated with the aid of the calcium chloride compound.