335 
Most of the rubber obtained from vines is valued at a much lower 
figure than the best known tree- rubbers, but this may well be due 
to the adulteration (referred to above) by the native collectors, 
who put together the rubber of any vine producing it however bad, 
and is doubtless also due to their carelessness in collecting: still 
rubber vines have not as yet shewn themselves very tempting to 
planters. 
VOLATILE OILS. 
The distillation of volatile oils from plants is in these days a 
very important branch of chemical industry and the number of 
plants from which volatile-oils are obtained "is very large, of these 
products some are used for scents, others in medicine or for various 
purposes in the arts. There are a considerable number of plants 
growing, cultivated or wild, in the Malay Peninsula which produce 
these oils and probably there remain very many more to be exam- 
ined and experimented with. At present the oils actually distilled 
in the Straits are but few in number, and considering the expense 
of the machinery required to distil on a large scale, perhaps this is 
not to be wondered at; on the other hand as the Citronella and 
Lemon grass oils, of Singapore, have been so well known for many 
years, it is possible that the distillation of these and other useful 
oils might be profitably increased and even done on a larger scale 
than at present. It may therefore be of interest to enumerate the 
local plants which produce oils of economic value and to give some 
account of them, and in doing so I extract much of these remarks 
from the work by GlLDERMElSTER & Hoffman, “The Volatile 
Oils’' written for the well known firm of SCHIMMEL & Co. of 
Leipzig, and translated into English by E. KREMERS, a work which 
gives a most complete account of distillation and the products 
derived. 1 he distillation of oils dates back from very early times, 
and the methods employed were very simple but gradually im- 
proved till within the last few decades there was a very rapid 
development of the whole industry due at first to the use of steam 
under pressure, and later to the great development of chemical 
technology. 
The essential oils of plants are secretion products in the cells, 
or intercellular spaces, or in spiral ducts in various parts of the 
plants. In some cases the roots, in others, the stems, leaves, seeds 
or flowers are used. I hese parts if hard, require to be ground up 
or crushed before being subjected to the distillation process. The 
prepared material is put into the distilling apparatus and heated 
by steam, the vapours saturated with oil-particles are condensed 
in the cooler and the distillate consisting of water and oil is sepa- 
rated and the oil eventually purified. To this account of distilled 
oils, I have added some description of the method of extracting 
the perfumes of flowers with the processes of maceration and 
enfleurage, as it may be of interest to some readers as showing a 
possible industry to which attention here has never been paid, and 
