73 
It is suggested that in this case also the plants should be cropped 
when the fifth leaf is well developed. The oil from the roots contains 
82 per cent, of citral. The citral estimation is carried out by Dr. de 
Jong as follows • Thirty-five grams of crystallised sodium bisulphite 
is placed in a “cassia flask” and dissolved in 50 c.c. of water, and to 
it is added 12 grams of sodium bicarbonate in power and 10 c.c. of oil. 
The flask is shaken for an hour, then heated on the water-bath for 
thirty minutes, and water added to the mark, and the flask set aside 
for twelve hours. At the end of that time the quantity of unattacked 
oil is read off, the difference between this and 10 c.c. being the citral 
content of 10 c.c. of oil. The Java oil is derived from a variety of 
Andropogon citratus, and belongs to the group of “ insoluble lemon- 
grass oils,” since it does not form a clear solution with two parts of 
70-per-cent, alcohol. The author states that the present low price of 
lemongrass oil is due to the use of the oil of Backhonsia citriodora as a 
source of citral, but this is very improbable. 
Rusa grass is grown in much the same way as citronella grass, 
but in differs markedly from citronella and lemongrass in its smailer- 
leaf production as well-developed stem and flower system. The \ueld 
from fresh leaves and stems is generally about 0.6 per cent. The 
value of the oil (palmarosa oil) depends on its geraniol content, which 
is generally from 80 to 90 per cent. An unidentified Andropogon sp., 
which yields an oil rich in geraniol, is also known in Java. This 
variety is similar to citronella grass in habit and yields only 0.2 to 0.3 
per cent, of oil, which contains 40 to 60 per cent, of geraniol, and is 
said to possess a more pleasantly rose-like odour than ordinary 
palmarosa oil. 
Two varieties of Vetiver or C use us grass {Andropogon muricatus) 
are known in Java, one native and the other introduced from British 
India. The leaves are free from oil, which is obtained only from the 
roots, to the extent of from 0.4 to 0.9 per cent. — {The Chemist and 
Druggist.) 
GADUNG. DIOSCOREA OAEfViONA. 
This is a well known yam with large trefoil leaves, commonly to 
be met with in Malay villages. Its tubers are used as food sliced and 
left in running water for two days before cooking, unless so washed 
the yams are poisonous. Researches on the poison of this yam, under 
the name of Dioscorea hirsuta BL are published in the Bulletin du 
Department de L’ Agriculture aux Indes Neeriandaises XLIV. The 
principle is known as Dioscorine and Mr. Schutte finds that it pro- 
duces cramps like those induced by pierotoxine, but it is less poisonous 
than that drug. 
It is mentioned in the old series of this Bulletin as one of the 
occasional ingredients in the Sakai-dart poison. -Ed. 
