' 52 
of the color. On the other hp.nd, the aethod was said "by Schonberg (iiO) to 
present several advantages over the crystallization method. Among these were 
the fact that it would determine very small quantities and that it was rapid 
and practical. Furthermore, the oxidation of rotenone to dehydrorotenone could 
be followed by this colorimetric method but not by crystallization methods. 
Cahij, Phipers, and Boam (jLZ) in 1938, in an extensitre study of the com- 
position of derris root, used this colorimetric method, making color comparisons 
in a Duboscq colorineter. They proposed to call the result obtained the "G-ood- 
hue value"; this was the percentage of rotenone that the material would contain 
if roti^none virr? the only ingredient siving a color in the test. They found 
these values to bear a definite relation to the rotenone content of derris 
extract. For ordinary extracts the relation was as follows: Goodhue value = 
percent rotenone -^ 22-3, This relation did not hold for Sumatra-type extracts, 
vhich usually had C-oodhue values of 10 to 15. As mentioned in the section on 
Rotenone, this relation was used by Cahn^Phipers , and Boam to determine approxi- 
mate rotenone contents by the color method. According to these wri,ters,,8x>t.enone 
and deguelln ^ . .were the only substances (kmown at that time) in derris 
extract vrhich gave this color test. They found that the color given by deguelin 
was only four-fifths the intensity of that given by rotenone. Consequently, they 
stated •tiiat the "excess" . value a^ove the actual rotenone content mast be multi- 
plied by .1.S5 to indicate the degij.elin content of an extract. Using this value, 
they concluded the deguelin content of derris extracts to be 27 ^ 4 percent, 
except Sumatra- type extracts, which -contained 9 to 15 uercent of degaelin. 
Again in 1939 Cahn and Soam {^S) discussed the determination of approxi- 
mate rotenone content by means of the Goodhue value. This scheme has been 
m.entioned in the section on Rotenone. 
In a study of colorimetric procedures in 1939. J ones (68) used this method 
and made color comp^^ri sons in a neutr&l wedge photometer using a filter with 
its optical center at 0.56 micron. This neans of measuring the color had been 
in use for Bome time by Goodhue and '-oy Cassil in the laboratories of this 
Bureau. 
Begue (_5) in 1939 recommended this method for the analysis of products 
containing; less than 1 percent of active principles. 
Guilla-ume and Herve ( 53) in 1939 described and discussed Goodhue's 
modification of this method. They suggested that for this test a 1-gm. sample 
be extracted with ICO cc. of acetone in a Soxhlet or a Kumagava"(8l) apparatus 
for 5 to 8 hours. They also found that complete exhaustion of 1 sjn. of powder 
was obtained oy agitating with 100 cc of acetone in a "flask .for 2 hours. They 
found it unnecessary to prepare a standard solution of rotenone each time the 
test v/as made. Instead, they made a 0.05-percent solution in acetone and kept 
it in the dark in ice (or at laboratory temperature) for use in a large number 
of deter:riir.ations. The procedure used for the development of the color was 
essentiall,," t'le same as that already described. Although this method gave 
results on freshly prepared powders agreeing with those of the blue color test 
and the methoxyl method, it gave lower results on old powders than the other 
two methods. 
