- 8 - 
(4) The extract undergoes chemical change on drying. 
(5) The type of extraction flask may modify results. 
(6) The extract is freed from the last traces of solvent with 
great difficulty. 
They proposed the extraction of the root in a Soxhlet apparatus, using a 
flat-tottomed flask, with ether (dried over anhydrous calcium chloride and 
sociium) , and drying the extract as rapidly as "008311)16 to constant weight 
of 100° C. 
A similar method was used ty Georgi ard Curtler (32) in 1929. They 
also pointed out that slight decomposition took place on drying the extract, 
and the results were slightly low. 
In the 1929 report of the Colonial Institute of Amsterdsun (77) it 
was stated that when a large sar.ple of root had been ground once to a 
coarse condition, a portion of this sample ground ac^rain to a finer stats, 
and some of the latter ground a tnird time to a very fine powder, the 
amount of ether extract was found to "be higher as the root was more finely 
ground. 
Dodwell and Company (private communication) in 1930 outlined the 
method in use in the trade for determining total extract of derris root. 
Ten grajDs of powdered root was dried in a vacuum over sulfuric acid and 
extracted exhaustively in a Scxhlst apparatus with dry ether, free from 
alcohol. The powder was then reground in a mortar and extracted. for an 
additional 4 hours. The extract was dried for about l/2 hoxir in a water 
oven. Later Dodwell and Company, (private communication) quoted a revised 
method for total extract in which the root was dried at 100° G. to constant 
weight and then extracted with dry, alcohol-free ether until exhausted. 
No second treatment v;as used. The extract was dried to constant weight at 
100° C. 
Total ether extract was determined by Spoon (115) in 1931 by extract- 
ing 5 gm. in a Soxhlet with absolute ether for 15 hours and drying the 
extractives at 100'-0-102° G. 
K^oolhaas's (76) ether extraction method for rotenone included the 
determination of total extract. The filtrate and washings from the rotenone 
separation were evaporated, seated at 80° C. in a vacuiom for 1/2 hour, dried 
in a desiccator, and weighed. Their weight was added to that of the crude 
rotenone. 
The method for rotenone proposed by Jones (62) in 1933 and involving 
extraction of the root with carbon tetrachloride included a procedure for 
total extract, by which the filtrate from the rotenone separation, upon 
evaporation, was dried 1 hour at 105° C. and its weight added to that of 
the separated rotenone. 
