called and explained it. Only the readily accessible volatile oil can volatilize 
days, subsequent distillation yielding three mes the quantity of a of 
distillation. This is a sure sign of. diffusional distillation, as von Rech« 
carried away by the steam, whereas the oil enclosed in the untouched cells _ > 
penetrate through the walls of the cells by slow diffusion. This process requires 
more time, the coarser the pieces of the raw material. The consequence is incom 
and uneven distillation results. The term used by the author as to ‘sufficient cc 
minution is not, therefore, applicable, for comminution must have been insufficie 
For this reason the question raised by the author, as to whether wood gathered 
autumn or in spring contains more oil, cannot be answered definitely. On the othe 
hand, he established beyond doubt that the content of volatile oil decreases very | con- | & 
siderably with storing the wood, for juniper wood which had been kept ina bag for. 
about a year only yielded 0.275 per cent. of volatile oil. . 
Finally the-author examined as to whether rectification of the oil had best be carried 3 
out by water distillation, or distillation with superheated steam under atmospheric — 
pressure, or under reduced pressure. He found that with the last-named method — 
ratio of oil to water in the distillate was most favourable. Me es a 
His findings are correct, as they are based on scientifically recognized facts. é 
Evidently the author has remained ignorant of the research work done by von Rechen- 
berg”) who not only explained the processes observed in the distillanion by superheated 
steam but also determined them quantitatively. oy 
Oil of Lemongrass. Some years ago E. J. Parry’) observed that West Indian as 
well as Cochin lemongrass oils showed a gradual decrease in citral content when # 
stored. This decrease was up to 5 per cent. with West Indian oil after several years — 
of storage, with Cochin oils it was observable even after two-months. At the same. 
time solubility decreased likewise. 3 
When reporting on Parry’s publication‘) we expressed our surprise at the Sack that — 
in no case had the drop in citral value been more than 5 per cent., and had ventured — 
the opinion that the products formed in the process of alteration rindetet possibly ‘Havel : 
a preserving effect on the remaining citral. We ourselves had observed no change © 
either in citral content nor in solubility in a lemongrass oil from pee even after” 
two years’ storing. Se 
That the drop in citral value may, however, be far more considerable than 5 per cent, 
is now shown by observations*®) made on this subject. At the same time the alteration | 
were determined which the specific gravity of lemongrass oil underwent during storage. : 
In a Bourbon oil which had a specific gravity of 0.889 and a citral content of 78 per cent. 
in July 1913 the specific gravity was found to have risen to 0,895 and the: citral val 
oe: 
3 
in citral value was, therefore, 18 per cent. 
a 
1) C. v. Rechenberg, Theorie der Gewinnung und Trennung der dtherischen Ole durch Decistbatie 
near Leipzig 1910. p. 418. — 2) von Rechenberg and Weifwange, Journ. f. prakt. Chem. ll. 72 (1905), 
von Rechenberg, Theorie etc. 1. c., page 403. — Report October 1905, 78. — #) Perfum. Record 4 
*) Report April 1918, 70. — *) Perfum. Record 7 (1916), 95. 
