interesting studies in the chemistry and physiology of the leaves of the Betel- Vine. According to them —
The younger leaves on the plant contain much more essential oil, much more diastase, and much more sugars than those which are older. On the other hand, the tannin does not vary in this direction. The leaves both on the middle branches and on the middle part of the main vine contain slightly the largest quantity of ' tannin.' * * * *
Nearly all the work done (except that of Eykman) has been done in Europe on dried leaves— and all, except the original preparation of Kemp, on Java or Siam oils. Our results differ considerably from those published hitherto, and we will simply indicate those which we have obtained.
As to the conclusions regarding the essential oil of betel- leaf, they say —
The essential oil of betel leaf consists essentially of two portions, consisting respectively of phenols and of terpene-like bodies. The relative proportion of these varies, and the higher the quality of the leaf, the higher the "proportion of phenols in the essential oil. The proportion of phenols in our samples varied from 42 per cent. (Poona) to 70 per cent. (Ramtek kapuri) in green leaves of the light green variety, and from 39 per cent, to 45 per cent, in green leaves of the dark green variety. The bleaching of the leaves not only increases very much the total quantity of the essential oil, but also the proportion of the phenols in it. In two cases where bleaching was carried out, the increase in the percentage of phenols was from 17 to 33 per cent.
The phenols consist essentially of eugenol in all our cases, mixed with a small percentage of betel phenol. The latter can be largely separated by washing the phenols with water in which it is very much more soluble than eugenol. No sign of any substance having the properties attributed to chavicol has been found in any of our samples.
The nonphenolic portion of the essential oil is a mixture of a number of substances as yet univestigated. Over 60 per cent, boils between 240° and 255°C. This has a light green colour, and a somewhat objectionable smell. It is not cadinene or caryophyllene.
They conclude their interesting studies as follows : —
We have shown the character of the leaf which is required for chewing, and have found more clearly than ever that it is the quantity, and also the character, of the essential oil which seems most largely to determine the value of any sample of betel vine leaf for this purpose.
The essential oil itself, however, is not always the same. It consists of a mixture of certain phenols and of certain terpene-like constituents. As far as the phenols are concerned, eugenol is always the chief constituent in Indian oils, mixed with a small quantity of betel phenol. We have never found chavicol in Indian oils. The best essential oil, from a point of view of public taste, is that which contains as large a proportion of phenols as possible. Those varieties of leaf which give an essential oil containing much terpene, are very pungent, but are looked upon as very coarse. Bleaching not only
