Oct. 13, 1923 
Chemical Examination of “ Chufa" 
73 
when, after drying, it amounted to 12 gm., or 12 per cent of the weight 
of the tubers. 5 This starch formed a perfectly white powder, and its 
very dilute aqueous solution gave a bright blue color with iodin. 
The clear, aqueous filtrate from the starch w r as mixed with twice its 
volume of alcohol, when a very slight flocculent precipitate was produced. 
After standing for several hours the precipitate was collected, washed 
with a little alcohol, and dried. The dark-colored product could then be 
triturated to a brownish powder, and amounted to 0.6 gm. Its aqueous 
solution gave the biuret reaction, a precipitate with potassium-mercuric 
iodid, and developed ammonia on heating with a caustic alkali, thus 
showing the characters of a protein. It also slowly hydrolyzed amyg- 
dalin, which indicated the presence of an enzym. 
Two kgm. of the chufa, consisting of material from which the fatty oil 
had previously been extracted with light petroleum, were mixed with 8 
liters of water, and the mixture allowed to stand for two days. It was 
then strained, the expressed marc mixed twice successively with two 
portions of water of 4 liters each, and each time strained as before. The 
deposited starch was collected, washed first by affusion and decantation 
with water, subsequently on a filter with alcohol, and finally dried. It 
was thus obtained as a nearly white powder and amounted to 360 gm. 
Inasmuch as the 2 kgm. of chufa deprived of oil represented 2813 gm. of 
the original tubers, the calculated yield of starch would be 12.8 per 
cent, or only a little more than was obtained in the previously described 
experiment. 
The clear aqueous filtrate from the starch was treated with a slight 
excess of a solution of basic lead acetate, which caused a voluminous 
grayish precipitate. 
BASIC LEAD ACETATE PRECIPITATE 
This material, after being washed with water, was suspended in water, 
decomposed by hydrogen sulphid, and the mixture filtered. The filtrate 
from the lead sulphid had a pale yellow color and was concentrated 
under diminished pressure to a small volume. On the addition of alcohol 
it gave a considerable precipitate of gum, which was removed by filtration, 
and after further purification was obtained as a nearly white powder. 
After the removal of the alcohol the dark colored aqueous liquid had a 
strongly acid reaction, gave no coloration with ferric chlorid, but 
abundantly reduced Fehling’s solution, which was evidently due to the 
occlusion of sugar by the original lead precipitate. The liquid was 
extracted several times with ether, which, however, removed only a very 
small amount of material containing nothing of interest. As nothing 
could be obtained directly from the liquid it was finally divided into two 
equal portions, one of which was heated with 5 per cent of its weight of 
sulphuric acid and the mixture extracted with ether, while the other 
portion was heated with an amount of potassium hydroxid correspond¬ 
ing to 10 per cent of its weight. This alkaline mixture, after being acidi¬ 
fied with sulphuric acid, was likewise extracted several times with ether. 
In both cases only a very small amount of dark colored, amorphous 
material was obtained. 
5 The amount of starch actually present in the tubers is somewhat greater than that obtained, but its 
exact quantitative determination was not attempted. Luna (6) has recorded the presence of 29 per cen t 
of starch in the European chufa, but his determination was made by polarimetric observations after hydrol¬ 
ysis of the starch and a calculation based on the amount of cane sugar present, which was also determined 
polarimetrically before inversion. As the optical rotations would also have been influenced by any reduc¬ 
ing sugar originally contained in the liquid, which was not directly determined, there would appear to be 
a possibility of error. 
