60 
It was found that absolute or 96-percent alcohol could "be used. Pure ferric 
chloride offered no advantage over the commercial grade. Ferrous sulfate 
gave no color, while ferric alum gave only a slight color. The size of the 
drop was determined by the dropping pipette arbitrarily chosen; a similar 
drop of 3.5-percent ferric chloride solution gave a slightly weaker color, 
but 1 and 2 drops of the 5-percent solution gave identical colors, '.v'ithin 
limits, therefore, the ano-'ont of ferric chloride appeai*ed to be immaterial 
provided sufficient was used. The alcoholic solution could contain at 
least 3 percent of acetone, benzene, or ehlo reform without interfering v/ith 
the results. Extracts of Sumatra- tyoe roots gave a deep green ferric chloride 
color and were easily matched against pure toxic?rol. Hox^ever, as the 
rotenone content of an extract increased the ferric chloride color became 
more and more brown, and vith rotenone- rich extracts matching in the Duboscq 
colorirr.eter was v-'^ry unci?rtain. This difficulty was overcome by employing 
secondary standards. Thus it was found that extracts containing less than 
20 percent of rotenone could be matched against Sumatra-type extracts. One 
particular Sumatra- type extract was accordingly taken as a subsidiary stand- 
ard. For extracts containing more than 20 percent of rotenone even this 
was not satisfactory. Ethereal solutions of such extracts were shaken '"ith 
5-percent . aqueous potassium hydroxide and the phenols recovered from the 
alkaline layer and separated solid salts (if any) by acidification and 
extraction with ether. The ferric chloride value was then determined on 
this alkali-soluble part only. 
The authors proposed the term "ferric chloride value" to denote the 
percentage of toxicarol that the sample would contain if the intensity of 
color developed was due entirely to toxicarol. Although sumatrol gave a 
brown color with ferric chloride, this color was believed to contain a 
green component v;hich contributed to the total ferric chloride color. 
Consequently, the ferric chloride values of derris extracts were inter- 
preted as giving the sum of the percentage of toxicarol and sumatrol. How- 
ever, the yield of sumatrol isolated from derris was said to be always 
much less than the yield of toxicarol- Other substances giving a green 
color might also be present in derris, but they had not been isolated up 
to this time. 
Rowaan and Van Duuren ( lOS ) in 1936 described a quantitative method 
for the determination of toxicarol based on the earlier qualitative 
separation of this substance by Clark ( 2l) . It was as follows: 
The carbon tetrachloride filtrate from the rot^^none 
determination is freed of solvent and the residue dissolved, 
by warming, in 100 cc. of 95-percent ethyl alcohol. After 
the addition of 10 cc. of IN. sodium hydroxide the solution 
is boiled. On cooling, the separated sodium salt of toxicarol 
is filtered, washed with alcohol, dried at 100°- 105° C. , and 
weighed. The weight multiplied by 0.95 gives the weight 
of toxicarol. 
The ferric chloride color test of Cahn and his coworkers (r?) was used 
by Jones (68) in 1939 in the examination of a series of derris and cube 
roots. Determinations were made by the method already described including 
