71 



have done little harm on pure plantations of Hevea, but where Cacao 

 is grown with it, the disease is more serious. Close planting adds 

 to the risk, and it chiefly occurs in wet weather. It attacks the Rubber 

 capsules as well as the bark. 



Cacao is so scantily grown in the Malay Peninsula that it is not 

 probable that here we shall be troubled with this disease, but occa- 

 sionally old Cacao trees occur near estates, and in this case the 

 planters should keep a watch for the attacks of the Phytopthora.— Ed. 



JAVA GRASS OILS. 



In the C. & D. for December I/, 1910, attention was directed to 

 the results of the examination of a number of carefully authenticated 

 ^rass oils from Ceylon, and it is of interest to mention a similar 

 investigation of Java grass oils recently carried out by Dr. de Jong. 

 The author statts that the source of Java citronella oil is the grass 

 known in Ceylon as " Mahapengiri," while the bulk of the Ceylon oil 

 is derived from " Lenabatu " grass, consequently he proposes to call 

 them A. Nardus, Java, and A. Nardus, Ceylon, respectively: these 

 names therefore correspond to Cymhopogon Winterianus and C. Nardus, 

 Lena Batu, assigned respectively by Stapf to these two species in Cey- 

 lon (loc. cit.). The former gives a larger yield of better oil than the 

 latter, but requires a richer soil and more careful cultivation. In 

 Java the grass is generally propagated by splitting old roots and 

 planting the separated parts, so that each has a space about 3 ft 

 square to itself. It does fairly well in shade, but better in sunny 

 situations. 



De Jong states that the number of crops, which can be taken 

 each year, depends on the soil and climate, and no general rule can 

 be given. When the first leaf is fully unfolded the following yields 

 of oil in c.c. per 100 grams of leaf are obtained : First leaf 7.7, second 

 leaf 3.7, third leaf 3.6, fourth leaf 2 6, fifth leaf 2.4, sixth leaf 2.1. The 

 leaf sheaths contain much less — viz., 3. 1 c.c. per ICQ grams in the 

 first, 0.2 in the third, and traces in the fifth. If, however, regard is 

 had to the relative bulk of the different leaves, the yields of oil"* are 

 found, for the same number of each of the first four leaves, to be as 

 follows : No. 2.9 ; No. 2, 5, 2 ; No. 3, 5.8 ; No. 4, 4.7 ; and consequently 

 the author recommends cutting when the fifth leaf is well developed. 



The oil is always obtained by steam distillation, and in Java often 

 with superheated st^am under a pressure of three or four atmospheres, 

 the latter method giving a better yield and being much more rapid. 

 It is advantageous to cut the grass into fairly fine shreds before dis- 

 tilling. The yield of oil obtained in practice varies from 0.5 to 0.9 per 

 ■cent, of the weight of fresh leaves taken. 



