65 
of hydrogen chloride and pointed o'jt t}iat Cshn and Eoam used an acid contain- 
ing only atout ?0 percent of hydrogen chloride. They found that when the 
stronger hydrochloric acid was used the nitrogen peroxide content of the 
nitric p.ci'i v/as unimportant. The intensity and speed of the color reaction 
depended on the concentration of the acid used. They "believed that the acid 
reag. nt depended on the formation of nitrosyl chloride for its action and 
that the reagent should stand at least 3 minutes "before use. 
Cahn and Boam (l5) in 1937 reported that when they used 3.-6.45 petcent 
hydrochloric acid (sp. gr. 1.18) their results were in su"bstantial agreement 
wit"n those of Rogers and CalaiTari. They found, hovrever, that even t'nen the 
rate of development of color nnd its final intensity increased greatly as 
the acid mixture was allowed to stand "before use. They emphasized that 
the sensitivity of the reaction depended .rreatly on the exact conditions 
used. 
According to DeOng (27) the Rogers and Calamari method proved un- 
satisfactory for the quantitative det ormination of rotenone in fly sprays. 
In 1339 Jcnes (68) modified the Rogerr, and Calamari test for the 
analysis of several s;amoles of derris and cu"be roots. The color produced 
in the acetone test was not proportional to the rotenone present. In 
chloroform solution the proportionality "between color and concentration 
held. Eeat as well as light accelerated the color formation, "but the 
latter v-as adopted. The solutions v/ere exposed in glass cylinders to 
daylight (not direct sunlig'nt) for PA hours. Perchloric acid ufas found 
to effect a more rapid development of the color than hydrogen peroxide. 
At a rotenone concentration of 0.12 mg. per cubic centimeter, 2 drops of 
60-percent perchloric acid gr've a moderately intense, pure-"blue color in 
24 "noiirs, Zven in this form results v/ere erratic and duplicate standards 
varied as much as 10 percent. Deguelin was found to give a color intensity 
a"bout 125 percent of that given "by rotenone, whereas toxicarol gave only 
a"bout one-balf the rotenone color. VJhen rotenone was used as a standard 
values for the derris roo Us ranged from 60 to 120 percent, and those for 
cube and tim"bo from 140 to 160 percent of the total extractives. 
The method of Rogers pnd Calamari v/as recently used as a qualitative 
test for rotenone in miscellaneous insecticides (127) • The characteristic 
"blue color did not develop vrhen too much rotenone was present; therefore, 
in case of failure to obtain the test a repeat should be made with a 
smaller sample. 
Other Color Reactions 
Geoffrey (29) in 1B95 was the first to study the color reactions of 
rotenone with several reagents. The most characteristic involved treatment 
with bromine, followed 'by application of concentrated sulfuric acid to the 
residue. A violet color was produced, 
Dennis (26), in a patent on cube issued in 1927, described a color 
reaction for testing the material using sulfuric and nitric acids followed 
by potasuum hydroxide. Jones (6S) in 1939 found that this te:.t gave 
identic?! color reactions with roots of derris, cube, and Tephrosia 
virgiriana. 
