- 12 - 
Eraak (9) . in 1939 rspQi*ted on the analysis of a sam'Bl^' oif dsrris 
root anal^/zed by the Laboratory for Chemical Research in Java; by Seil, 
Putt, and Rusby in New York; and by Salamon and Seaber in Loiidon. The 
three laboratories obtained almost identical values for the' ether- • .' 's 
extract, content , .. , . 
In collaborative work carried out between the Imperial Institute' 
and Rothajasted 3zperimentai Station (^) the ether-extract contents of 
three samples of der^-is root were determined. Values obtained at the 
former laboratory, where a 16-hour extraction was made, were about- 1 per- 
cent higher than those obtained at the latter station, where ' two 6-hour ' '' 
periods were used. By the latter scheme little additional extract was 
obtained in the second &-hour period except in the case of a high-rotenone 
root, which gave 1.4 percent additional material. All values ranged from 
25 to. 30 percent, of total extract. 
i'eijer and Koolhaas (89) in 1940 described th^ method used in •"-- 
tneir laboratory for determining rotenone by extraction of a 50-gm. 
sample . for '65 hours with ether. The determination of total-ether extract 
was made in conjunction v;ith this as follows: 
"The ether is distilled off (from the mbther liquor 
from rotienone separation) on a water bath and the last 
trapes are removed in, a vacutim in a water bath not exceeding 
40° C. The contents of tie flask are blown up to a voluminous 
mass, and placed in a desiccator over lime for 2 days, after 
_ which time constant weight has been reached. 
"The difference in weight between the fl'ask with resin 
and the empty, flask gives the amount of resin. To this the 
amount of crude rotenone is added, giving the ether extract 
in 50 g. of the sample..." 
These authors stated that the total-extract content was about the same 
when benzene, chloroform, or. ether was use."; hence the extra determination 
of ether extract was unnecessary when chloxciorm or benzene had been used 
as extraction solvent. 
A scheme of automatic hot percolation was described by I^.artin (83) 
in 1940. The apparatus consisted of a glass liner fitted into a wider 
glass oube connected with a 250-ml. flask and a condenser. The powdered 
root was supported in the liner on a pad of cotton wool, and rapid extrac- 
tion at the boiling point of the solvent was said to be effected. The 
percentages of resin extracted oy this method with several solvents from 
25-gm. portions of a sample of D erris elliptica were determined. <vith most 
solvents extraction was reasonably complete in 2 hours. Solvent efficien- 
cies of a 'similar order to those given by Jones and Sullivan (75) were 
found. 5thyl. acetate , et'i^'-lene dichloride, and chloroform were equally 
effective in extracting; the toxic principles with a minimum of extraneous 
matter. The method described was said to have the advantages over the 
percolation method of ^vorsley (130) of being automatic and requiring 
little more than 150 ml. of solvent. 
