- 19 - 
at 18° C. Sxcessivs w^shinp- with carbon tetrachloride saturated with 
rotenone led to marked decrease in yield, with no increase in purity. 
In the determination of rotonon$ in derris roots 6 to 17 hours' extrac- 
tion with carbon tetrachloride was not sufficient to remove all the 
resin or the rotenone. The authors preferred to use trichloroethylene, 
which usually gave complete extraction of rotenone in 8 to 12 hour?. 
The rotenone was determined by evaporating the extraction solvent and 
crystallizing from carbon tetrachloride saturated with rotenone. 
When pure rotenone-carhon tetrachloride solvate v;as stirred v/ith 
5 parts of alcohol saturated v;ith rotenone, a quantitative yield of pure 
rotenone vra.s obtained. Tests with fixtures of rotenone and "de-rotenon- 
ized" resin showed that a quantitative yield of the added rotenone was 
obtained from such a mixture when kept for 3 hours. It was later found 
advisable to keep such a mixtiire overnight. The alcohol recovery of the 
separated solvate from derris-root SJSiUples was said to range usually 
from S3. 5 to 69 percent and rarely from 80 to 90 percent. Tests of purity 
by methoxyl content, chlorine content., and optical rotation gave values 
ranging from 89 to 95 percent on samples on which the alcohol-recovery 
values ranged from 84.5 to 89 percent. The qijestion as to vmether the 
purity of the solvate should be taken into consideration wnen a rotenone 
content was stated was considered by these investigators. The yield of 
rotenone was said to be lower fnan tho amount actually present, and the 
amount of rotenone left in tno mother liquor might be greater or less than 
the 10 to 15 percent impurity in the solvate. The value given was there- 
fore only a minimum fi^ui'e obtained by determining the yield and the 
purity of the solvate. 
wTien an appreciable air.punt of pv.re rotenone v;as added to resins 
containing no rotenone by ths usual prcced;are, an excess of rotenone over 
that added was obtained. The excess ranged from 7 to 15 percent of the 
resin in the samples tested. Eesins of this kind were called "Sumatra- 
type" b" the authors, and the rotenone obtained from them was terT^ed 
"hidden" rotenone. The highest yields of hidden rotenone were obtained 
when 4 gm. of resin and 1 gm. of rotenone were dissolved in 10 cc . of 
carbon tetrachloride saturated with rotenone and the mixture was kept 
overnight and then filtered as in the usual procedure. Six samples of 
"normal" resins, containing appreciable proportions of rotenone, gave no 
significant amount of excess rotenone when treated in this way. However, 
a sample of root that had given a rotenone content of only 6.2 percent 
of the resin (1.5 percent of the root) as determined by the ordinary 
method gave 17 percent of rotenone in tae resin when treated for hidden 
rotenone. 
These authors stated that derris rcot should be dried, prior to 
extraction, in a vacuum desiccator to not more than 5 percent of moisture. 
The presence of much moisture was said to retard the rate of extraction 
and also to cause the development of acidity in chlorinated solvents. 
Drying at 100° C. caused decomposition and low results for rotenone. The 
procedure proposed by these authors was as follows: 
