- 45 - 
to flask for extraction with fresh solvent, i'^inally combine 
extracts, evaporate almost to riryness, anct proceed as directed 
alDove, be^;:innin£; at point where aliquot has "been evaporated 
almost to dryness." 
The same commercial sources that supplied information on the deter- 
mination of total extract also discussed the methods used "by them for the 
determination of rotenone (private comm\ini cat ions ) . Two of them, IlcCormick 
and Company and John Powell and Company, employed the official A. 0. A. C. 
method. The laboratory of S. B. Penick and Company, regularly used the 
official m?^bod but also occasionally employed a modif " - ation for compara- 
tive purpos'^'Cs. Thn s method, which depended on measuri^.£: the carbon tetra- 
chloride of crystallisation and assumed that rotenone is the only solvated 
material present, was as follows: 
Place ths crucible containing the crude solvate (dried to 
constnr;t weiffht) in a lOO-cc. beaker and weigh. Add 5 cc. of 
alcohol (or acetone) to the material in the -nrur-".ble and keep in 
a modcrav.ely warm place, where evaporatr'.on /'■j.ll prcT-sed iJowly, 
until all the solvent has evaporated. Repeat this step ,' /;ice 
and then dry the beaker and contents at 100*^ C. 'co con!;i;r.nt weight. 
This procedure removes the carbon tetrachloride of crystallization, 
which was combined in equimolecular ratio with the rotenone in the 
solvate. The difference in weight divided by 0.281 and multiplied 
by 0.719 gives the weight of rotenone. . 
Another firm, Derris, Incorporated, preferred to use acetone as 
the extraction solvent, claiming that this solvent extracted the resins 
and rotenone in less time than any other solvent tried. The method was 
briefly as follows: 
?rom 40 to 50 gm. of the coarsely vround or 25 to 50 gm. of 
finely powdered root is extracted in a Soxhlet with acetone. 
(If powdered root is -jsed, it is mixed with an equal voliune of 
fine sand or sodiiyn chloride.) At the end of TA hours the extraction 
flask is replaced by another containing fresh acetone and the extrac- 
tion continued for about 20 minutes, or until a negative color test 
(I>arham) shows that the marc is depleted of rotenone. The combined 
acetone extracts are then concentrated to about 10 cc, when two or 
three a.'iditions and evaporations of 25 cc. each of carbon tetra- 
chloride are made to remove the acetone. 
One hundred cubic centir^-eters of carbon tetrachloride and about 
3 gm. of Celite are added to the residue and the whole is heated 
to boiling and filtered by suction. The residue is washed with two 
or three lots of about 25 cc. each of hot carbon tetrachloride. 
The carbon tetrachloride solution is concentrated to about 25 cc. 
and transferred to a 50-cc. graduated cylinder with ground-glass 
stopper. The volume is adjusted to 40 cc. with carbon tetrachloride 
and the cylinder placed in the refrigerator to remain overnight. 
The filtration, washing, and determination of purity are carried out 
approximately as in the official A. 0, A. C. method. 
