- 9 - 
Georgi and Teik (34) in 19.33 compared other solvents with ether 
for the determination of total extract of derris root. FetroleTom ether 
was unsatisfactory, since its solvent action was so low. Acetone gave at 
higher value than ether. Slightly higher figures were obtained with 
chloroform, and slightly lower results v/ith carbon tetrachloride than with 
ether. Preliminary drying of the root did not change the amount of ether 
extractives' obtained. 
In a comparison of chemical composition and toxicity to insects of 
rotencne-bearing plants Jones, Campbell, and Sullivan (§9) in 1935 deter- 
mined total carbon tetrachloride extractives of several samples of derris 
and cube by the method cf Jones (62). Acetone and benzene e::tractives 
were prepared by Soxhlet extraction of 10- to 20-fTn. S3.vjples for 7 to 
8 ho^lrs. In general the amount of materia-l extrsctec' v/ith acetone was 
higher than that with carbon tetrachloride, while that v;ith benzene was 
slightly lov;er. 
Tatter sfield and I'artin (l^0_) in 1935 gave results of the determina- 
tion of total ether extract on several samples of .derris. In the extrac- 
tion of 5-gm. samples v/ith ordinary ether slightlj'- higher results were ob- 
tained in Malaya than in Snfland. The results that voce obtained with 
sodiura-dried ether in England were slightly lover . than those obtained by 
the use of ordinary ether. 
In proposing their trichloroethylene extraction method for rotenone, 
Cahn and Boam (13) in 1935 stated that total extract could be determined 
by evaporation of the trichloroethylene solution to dryness and heating to 
constant weight in an oven at 100° C. 
In 1936 Georgi and Teik (35) gave directions, for the determination 
of ether extract of derris root. Five grams of the finely pov.'dered root 
was extract-od with ether in a Soxhlet for 16 hours. No appreciable addi- 
tional extract was recovered when the marc was regrotmd with sand and. again 
extracted v/ith ether. The ethereal solution was filtered if necessary to 
remove tiaces cf suspended matter, the solvent distilled off, and the 
residue dried to constant v/eight in a steam oven. Constant weight was 
usually reached in 6 hours. 
Mei.jer (85_) in 1936 proposed a colorimetric method for the approxi- 
mate determination of the total extra,ct of derris root. Tliis method is 
described in the section on Miscellaneous Colorimetric Determinations. 
V-'orsley (132) in 1937 determined total ether extract by extraction 
of a 10-na. sample in a Soxhlet for 24 honors and subsequent drying of the 
extract to constant weight at lOO" C. 
C-uillaume and Proeschel (54) in 1937 determined total ether and ace- 
tone extract of derris and other plants by treatment of 5-gm. samples in 
a specially designed continuous oercolatcr. Only 150 cc. of solvent was 
required, and the extraction v/as said to be complete in 12 hours. Ex- 
tractions with chloroform and carbon tetrachloride were made in a contin- 
uous percolator of different design. All extracts were filtered, con- 
centrated to about 20 cc, placed in the refrigerator until the solvent 
