- 20 - 
A quantity of root euTficient to ^ive 5 to 10 gm. of 
extract is extracted with trichloroethylene for 8 hours in a 
Soxhlet apparatus, 'ilie solvent is ch3.nged anc' the extraction 
continued for 4 hours longer. If the second solution is more 
than pale yellow, the extraction is repeated with fresh solvent 
for an additional 4 ho^Jirs!. The combined extract is evaporated 
until the extract b'^coires thick. A gentla current of air is tnen 
"blown into the flask v/hile the flask is rotated over a naked 
flame vintil the odor of solvent is replaced "by the odor of derris 
resin. The flask is weifihed to determine the approximate weight 
of resin, and 2 cc. of worn; carbon tetrachloride, satiirated with 
rotcnone , is added for each ff'ram of resin and the resin dissolved 
rapidly. The solution is cooled, seeded if necessary, snd kept 
c\'ernight . It is filtered b?- suction through a tared G-coch 
crucible containing a disk of filter paper, and the solvate is 
washed with carbon tetrachloride saturated with rotenone until 
the filtrate is nearly colorless. The crystalline material is 
dried to constant weight in air below 50° C. The purity of the 
solvate is tested by the alcohol-recovery method already described. 
A iiiethod for deterzr.inin.e hidden rotenone in resins poor in rotenone in- 
volved th-3 procedure alreadj^ described for thir purpose. The authors con- 
cluded that the usual carbon tetrachloride method f:ave low results if the 
rotenone content of tn.e resin was belov/ about 17 percent, was seriously 
in error if it v.'as below 10 percent, and failad completely for resins of 
verj' low rotenone content. 
The determination of rotenone by extraction with carbon tetrachloride 
was described by Pozzi-3scot (93) in 1935. If the deter:'iination was made 
at rooru temperature, the sa-nple was extracted for IS to 22 hours. Hot 
extraction, v;hich was recommended by the author, required only 6 to 8 hours. 
The rotenone was crystallized as the carbon tetrachloride solvate, separa- 
ted, and weighed. With certain products it was found preferable to extract 
with acetone or ether. After the solvent had been evaporated, the residue 
was extracted v;ith hot carbon tetrachloride and the crystallization con- 
ducted as before. 
Later in this year the same investij^ator (94) suggested that extrac- 
tion with acetone, alconol, ether, or eth,vl acetate considerably saortened 
th--! time required for tiis operation. The use of a "Shumagawa"^ instead of 
a Soxhlet extractor v;as qlso said to permit more rapid extraction. The 
extract, freed of solvent, was treated with hot carbon tetrachloride, and 
the rotenone crj'stallized from this solvent. 
r-ow:. an (104) in 1935 described the rethod for determining rotenone 
in derris and cube roots used at the Colonial Institute of Amsterdam. In 
condensed forn? it was as follows: 
Evidently the apparatus of Kumagawa and Suto (81), which is also men- 
tioned by Guillaume and nerve (53). 
