- 33 - 
In 1939 the Imperial Institute (59) reported the results of work 
carried out in collnooration v/ioh tae Hctnamstad ^jxp-srimental Station. 
Ihroughout the irveTti.jfi.tf-on three Rsimples of dsrric v;ere used, one each 
of D. inalacc e:-gi_s_ (115 nba (Sixa-^tra) trype), L. n.aXacc.en'^is var. s arawa.kensis , 
and D. ellipVa ca, Cn?n^5 (bi^^h rcterone). 'r.is netliud usod "by the Imperial 
Institute (i) invclved psrcoU-ticn of :he root with cold ethvl acetate, 
crystallization fro^ carbon tetrach'.orice , and pnrificrtion of the sol- 
vate by trituration 5 if n-^cestr^r'y twice, with alcoriol. In the Hcthsjnsted 
metnod (II) the root was extrscted in an automatic percolator vath boiling 
ethyl acetate, chDoioform, or ethylene dichloride. The dried extract was 
dissolved in ether and thin- solution e^'trrcted v/ith dilute alkali to 
remove to:cicarol and other alkali -soluole n;aterialb. The alkali-insoluble 
portion was subject-^^d to crystallisation from carljor tetrachloride, and 
the rotenone v-as calculated from the v/cisht of solvate. In method I it 
was fo'umd necessary to e/iZ rotsricne to ootain separation from the Kinta 
type root. The general concordance hy method II was good. 
As a result of thir. work metho-^. I was r.odified to that extraction 
was made by hot percolation, pu~"e rct3ncne was added if necessary, and 
a second crystallia-tion of- the solvate frcrn carbon tetracnloride was 
introduced. J'ethod II was modified hy the are of ^n ether-'benp:en9 irixture 
(25 percent benzene) instead of ether ns sol"^'ent during alkali extraction 
of the resin. In method I othyl acetate, str^'lene c-ichloride, and chloro- 
form were tried; in method II only chloroforru '-/as used. Pm'ity of the 
complex was determined in both cases by cry s tall i -nation from ahsoluta 
alcohol. The results by method I Indicated that the three sol-"'Gnts tried 
were of about equal value as extr^^ctants, even for the h'gh-rotenone root. 
It was also fo-ond that addition of rooeione to aid crystrJli?ation in the 
case of the bigh-rctenon? root effected no inproveir.ent in yield. When 
method II, involvir.fc removal of alkali- c-tlucl 5 material, vas used, it 
was unnecessary to add rotenone to produce cc-rolete cryst-eliization even 
in the case of the Kinta type root. In {jenoral, results by both methods 
at both laboratories were in fair agrcer.ent , although values for the 
Kinta-type root showed considerable 'variation. 
Because the xju:'ity tost was unsaiiisfr.ctnry , f-'orther work vas done 
on schemes for deter'niniiif: purity. In method I the first crystallization 
was made at two concentrations, namely, from a volume of carbon tetra- 
chlori.(3G (a) numorically 10 times the v/ti^ht of resin, and a volume (b) 
10 times the woi^ht of rosin plus added rotenone. In each case the com- 
plex was recrysialli^od fron c.':rfc;..n tetrachloride, and the puritv of the 
second coEpT.ex v.as deteririncd both by recryptalli-ation from alcohol and 
by optical rotation. In m-^thod li the first ccmTDlex was crystallized in 
the usual way pxi6 recrystallized from carbon tetrachloride, and the purity 
of this complex was determined by optical rotation. Values by method XI 
were in /;,ooa aforeeir-ent. In method I there was no appreciable difference 
in tha purity of second solvates obtained froia solvates originally crys- 
tallized at dilutions (a) and (b) . In freneral , th^ purity of the second 
complex as determined "by rotation agreed with the value obtained by 
alcohol recrystallization when the determinations w?re mad-j in either 
lahoratory. In m.^thod I, hcwover, when dilution (a) was used, there 
were serious d-isci-epancies between the values obtained by the two la.hor- 
atories. For this reason additional v/ork was done at the Imperial 
