other methods, and vaoh with carbon tetrachloride saturated 
with rotenone soDvat^ at room teiipf^ratare . Leave the 
crucitle on th-^ vacuum for 15 to 20 minutes and then wei^h. 
Warm (not over 50° C.), a^ain apply vacuum, and reweigh. 
Repeat this procesr, luitil constant v/oi^ht is attained. 
Fine grinding of the samplG v/as said to "be ■ot.recesaary in this method; the 
root need "be ground only to 20 inesh. It was stated tnat the method gave 
complete extraction of roots of high rotencne content. 
In 1936 Hobiixson (lOl) prcpo^^ed a method for estimating rotenone 
in haiaris from ioritish G-uianr,, which involved extraction with carbon 
tetrachloride in a Soxhlat for 12 to 24 hours, crvstallizeticn of the 
concentrated and filtered extract for about 22 hoiirs in a freezing chamber, 
and filtraticsn of the extract after chilling to -10^ C. The crystals were 
washed with carbon tetrachloride at -10° C., dried in a desiccator over- 
night, and weighed. 
Georgi and Teik (35) in 193o urged t^e adcT)tion of a star.dard method 
for the estimation of rotenone and ,m'^''e details of the method tentatively 
adopted in the Department of Agriculture of ths Straits Settlements and 
federated llals-y States. The method v/ap based or one that they had described 
earlier (34), the chief difference b^ing that recrystaliization of the 
crude complex from boiling alcohol wag replaced b-/- tritiuation with cold 
alcohol. Other modif icatioii*- were as follovs: (l) -■ran 20 to 50 gm. of 
root was used, depending en th'^ rotenone content, ro that not more than 
4 gm. of solvate v/ould be obtained. (2) I'he extraction time was reduced 
to 16 hours by using two b-hour periods and removing the sample and lightly 
grinding and miring between these periods. The metiiod was said to be satis- 
factory with all species of Derr is in which th^ rotenone content exceeds 15 
percent of the extract. With '^. i^r-.l accer.s is, 'linta type, (Sumatra type of 
Cahn and Eoam), in which tne rotenone content is about 2 percent , it was 
necessary to add sufficient rot'?non3 to raise the proportion of that sub- 
stance to about 30 percent ci the total extract to induce crystallization. 
It was suggested that tne final figure uight be low because of rotenone 
remaining in tne mother liquor and son^e passing into soiution when the 
solvate was triturated with alcohol. Trie possibility of using the weight 
of the crude solvate and apolying an aporopriate co"^rection factor was 
sttidied, but the purity of the solvate ■''•aried too widely, both in roots 
of the same and different species. Consequently tn^? authors did not 
recommend the weignt of the solvate as n. standard on whicn to base the 
rotenone content . 
Buckley (ll) in 193S, in r. stud,;,' of the conc-tituents of derris root, 
mentioned that long heating of extracts to expel residual solvent v.-as to 
be avoided, as some change occurred which rendered subsequent crystalliza- 
tion of rotenone incomplete. 
In this year also V/orsley (130) msde a study of the deteniiination of 
rotenone in derris root and the barh of M-ju:idulea sube rcsa . He described 
ail apparatus for extracting the root by percolation v;itn hot ethyl scetate, 
wnich comprised a percolator vdth a v/ater .jacket for maintaining an elevated 
temperat-ure and a receiver immersed in cold v/ater. With this apparatus 
