- 22 - 
with a S-j2natra-t;rpe root from which no rotenone separated "by the norm-al 
procedure, after most of the toxicarol had "been reir.oved "by alkali treat- 
ment of the ether extract the rotenone separated readily when the residual 
resin v/as taken up in .carbon tetrachloride. Tv/o Suaatra-type roots frctn 
waich no rotenone could he ohtainad "by the usual nethod (^/ithout removal 
of toxicarcl) , ga\'« ahout 2 percent of crude rotencne "by Cahn and Boan^ s 
(15) procediire for "hidden" rotenone (adding excess rotenone). Purifi- 
cation of the crude solvate resulted in the p:reatly reduced values of 
0.54 percent and 0.67 percent. Aliquots of resin fro^i the same two roots 
v/ere dissolved in ether, extracted with 5-percent potassium hydroxide, 
and the ether was recovered from the alkali-insoluhle portion. The 
residual resin was dissolved in carhon tetrachloride and the solvate 
crystallised in the usual way. Values of 0.47 and 0.89 percent, respec- 
tively, of crude rotencne v;ere obtained ty this method, and these results 
were reduced to 0.40 and 0.66 percent, respectively, hy purification. 
It thus appeared that in Simatra-type roots the presence of large amounts 
of resinous material rich in toxicarol prevented the separa-tion of the 
rotenone present, or treatment with potash removed some other inhihitor 
of crystallisation, furthermore, the solvate, v>rhich separated readily 
after treatment with alkali, wa.s obtained in an s.mc^ant agreeing closely 
with the figure obtained for the purified rotenone by the ncrnal method. 
With I'er ris malaccer^ sis root, although rotenone separated without the 
use of t'le lidden-rotenone technique, the procuct was very impiure. Here 
again t'^^e alkali treatment gave a value for crude rotercne agreeing 
closely ;\'it'-' that obtained for purified rotenone by the ui'-^al me thod . 
The authors adciitted the possibility that the alkali carced sorre loss by 
inducir-A" ozioa'cion of the. rotenone , but they suggested thi.t- an slkali 
pretreatn:ant such as they described, if suitably controlled, might form 
the basis of a standard method of rotenone cietern-ination. In purifying 
the crude solvate by trituration v;ith alcohol these in-'-estigators preferred 
to filter at 0° C, usin^ alcohol saturated with rotenone at this tempera- 
ture . 
Peach (3) in 1936 proposed a serviceable cnethod for determining 
rotsnon'=i b')Ged on extraction v/ith chloroform, evaporation of an aliquot 
of the zi\-:^red. extract., and crystallization of the rotenone from ca.rbon 
tetracb-loride. The method was essentially-- as follov;s: 
Shake 30 gm. of root with 300 cc. of chloroform in 
a stop-nered 600-cc. fl^sk at rooir temperature for 2 or 3 
hourt. Let stand overnight and then shake 1 hour more. 
Chill flask and filter contents rapidly into a suitable flask, 
observing precautions to prevent loss from evaporation. Ad- 
just the temperature of the filtrate to that of .the original 
chloroform and transfer a 200-cc. aliquot to a 500-cc. flask. 
Remove the chloroform by vacuiJir". distillation, and treat with 
two successive portions of carbon tetrachloride, evaporating 
under vacuum eacn time to remove traces of -chloroform. 
Dissolve the extract in 15 to 20 cc. of carbon tetrachloride 
saturated with rotenon^^ solvate R.t refrigerator temperat\n'e. 
Induce crystallieatio!: of the extract in an ice bath and 
allow to crystallize overnight in the refrigerator. Cool the 
extract in an ice bath, filter through a G-cocn cr^icible as in 
