- 7 - 
They concluded that itio.isture determinntioa siould 'b'' made by dryin.^ a 3- 2711, 
s.ample at 105° C. to consta.nt weight. The xylene or heptane method gave 
higher values, but the higher teir.perature to which the material v/as exposed 
was thought to leacV to decomposition, and the method was not recc-niiiended. 
Jones and Gr&haa (71) in 1938, in the ana.lysis of a large number of 
derris, cube, and timbo roots, determined moisture by drying 2-f^. sa-p.-'les 
at 106° C. for 2 hours. Two days' additional drying of some of the samples 
caused no signifibant additional loss in weiirht. 
Results for moisture content of oerris root by heating in tue oven 
and by toluene distillation v;ere compared in a repo:^'t of collaborative 
work by the Imperial Institute and the xtothamsted Experimental Station (5S) . 
Values bytne oven method were only slightly lov/er than those by the dis- 
tillation method. 
Meijer and Xoolhaas (89). in 1940 determined the- moisture content of 
powdered derris root by drying a 2- .to 3-gm. samtile to constant weight at 
105° C. 
Of some interest in connection with the determination of the moisture 
content of derris powder is the hygroscopicity of the material. Meijer (87) 
in 1938 studied this question by keeping samples at different relative 
humidities at approximately room teinpsrature and neasijuring the increase in 
weight. After standing at 75 percent relative humidity roots originally 
having 6 to 8 percent of moisture were fouxid to contain 11 to 12 percent of 
moisture, while at 95 percent relative humidity these roots had about 24 
percent of moisture. He concluded that pov/dsred derris root was "freely 
hygroscopic. " 
Discussion 
It may be concluded from the references given that the most suitable 
method for determining moisture is the drying of a 2- to 5-gm. sample at 
about 105° C. to constant v/eight. This should require only a few hours in 
maxLy ca,ses, but overnight d.rying before the first weighing should be a good 
practice. 
TOTAL HJXTHACT 
'The determination of the total-extract content of derris and cube 
roots, although a com.paratively simple procedure and one that has been made 
from the time of the earliest work on these materia,ls, is nevertheless 
sub.ject to consid.erable variation. 
Tattersfield and Ecach (l22) in 1923, in the course of an investi- 
gation of Derris elliptica, pointed out that the following factors are to ' 
be considered in the determination of total extract: 
(1) 'The extraction solvent must be selective. 
(2) The root must be ground to sn almost impalpable powder. 
(3) Extraction must take place at fairly low temperatures; 
otherwise sr)arin£rlv soluble cnmnounds are formed. 
