extract followed Beer's law. It was found that the .color could also be 
compared visually with permanent color standards ^rerjared from cobalt 
chloride. The standards v/ere made by mixing in various proportions a 10- 
percent solution of the cobalt salt in 96-percent alcohol, a 10-percent 
solution of the cobalt salt in water, and 96-percent alcohol. Ifhen kept 
in I sealed tubes these color standards were stable for a long period. The 
color reaction required a strongly acid medium. Seventy percent trichloro- 
acetic acid instead of sulfuric also gave the color out with a more reddish 
shade. Acetic, oxalic, and tartaric acids gave no color. Hydrochloric 
acid gave only a faint pink color. Since the varif>ty of derris known in 
the Dutch East Indies as "Toeba woeloeng" had previously been shown to 
have a definite ratio of rotenone to total extract, it was suggested that 
this method would give approximate values for rotenone in this type of root. 
, joudswaard and Timraers (43) in 1937 stated that this reaction could 
be usrd in the inverse sense for the detection of nitrates and nitrites 
in sulfuric acid. Sulfuric acid that conformed to the Dutch pharmacopoeia 
contained sufficient nitrites to give a color with rotenone. In the usual 
form of the test the color developed was proportional to the rotenone 
present and was stable for 24 hours. The test was said to be unsuitable 
for the estimation of rotenone in derris root because the reaction was not 
specific for rotenone. 
Cahn, Phipers, and Boam (17) in 1938 found that the Meijer color 
test was given by many substances other than derris extract; consequently, 
the method was applicable only in the absence of interfering substances and 
v/hen the genuineness of the root was certain. The color was given v.rith 
equal intensity by rotf^none, deguelin, toxicarol, and sunatrol, as well as 
by many of their derivatives. All derris extracts tested w-re fo-und to 
give the color with about 90 percent of the intensity given by rotenone. 
A modification of the Meijer test was used in this work (private communication). 
In 1939 Jones (68) used the sulfuric acid-nitrite test in the form 
described by Meijer, and made color comaarisons with a rotenone standard in 
a Daboscq type of colorimeter without a filter. Values for the derris 
samples averaged about 90 percent of the extract, but those for the cube 
samples were lower. The test was said to give a rough estimate of the 
total mrterials of the rotenone type. 
The Rogers end. Calamari Test 
Rogers and Calajnari (l02) found in 1936 that in the presence of 
hydrochloric acid and certain phenols rotenone developed colors ranging 
from blue to violet-red depending upon the solvent and the phenol used. 
Such organic solvents as chloroform, ethylene dichloride, carbon 
tetrachloride, ether, alcohol, and acetone were used. Phenol, guaiacol, 
and thjanol reacted similarly in these solvents. Small amounts of hydrogen 
peroxide, and nitric acid and light exerted a marked influence in accelerating 
the reaction. The color was also given by certain derivatives of rotenone. 
Both qualitative and quantitative tests based on this color reaction were 
developed. Substances usually found in proprietary liquid insecticides, 
such as pyrethrum extract, aliphatic thiocyanates, and oil of sassafras, 
were said not to interfere with the tests. In the qualitative test a 
chlorofonp solution of the sample vras treated with a chloroform solution 
