1023 
in methyl alcohol; a small part again remaining undissolved. The solution is 
again filtered, concentrated to a small volume, precipitated fractionally with ether, 
and the ether-alcohol mixture allowed to stand over the saponin for twenty-four 
hours, which is sufficient time to allow any resinous substances borne down by 
the precipitated saponin to redissolve. The product is now filtered, and dried in 
vacuo. A repetition of the alcohol-ether precipitation will further purify the 
saponin. I consider this method to be the best one for isolating seponin from 
gogo. The yield is 5 to 6 per cent of the weight of macerated fiber employed. ‘The 
fiber, as it is obtained in the markets, contains from 7 to 10 per cent of saponin, 
as is shown by the physiological tests on the crude extracts. 
Saponin, as thus obtained, is a white, amorphous powder. In some 
cases crystalline needles, which gave al] the tests for saponin, were isolated 
from water, but, as the ash content was very high and as the exact 
conditions for isolating these crystals have not yet been worked out, it 
is impossible as yet to state whether or not they consist of saponin or of 
a saponin addition product to an inorganic substance. 
Saponin is rather easily soluble in water, giving a solution which is 
slightly acid toward litmus and congo red. It dissolves more readily 
in slightly alkaline than in pure water. When all dialyzable impurities 
such as sugars, etc., have been removed, saponin is not hygroscopic, and 
it is possible that the hygroscopic character of these substances mentioned 
in the literature may be due to impurities. 
Basic lead acetate precipitates saponin in while flocks; lead acetate gives no 
precipitate. Barium hydrate gives a very abundant precipitate in an 8 per cent 
but only a very slight one in a 1 per cent solution. Saponin is readily soluble in 
methyl alcohol, difficultly so in cold ethyl alcohol; it is insoluble in ether, petro- 
leum ether, chloroform, benzene, carbon tetrachloride, carbon bisulphide, acetic 
ester, or organic solvents in general. Saponin gives a red color with concentrated 
sulphuric acid; concentrated nitric acid gives no color, neither does ferric chloride. 
An intense, red color, which later turns to a blue, is produced with an alcoholic 
solution of sulphuric acid to which a little ferric chloride has been added. 
Selenious acid, dissolved in concentrated sulphurie acid gives a red color, much 
like that produced by sulphuric acid alone. Mercurie acetate, to which a drop of 
potassium nitrite has been added, developes an intense, purple red. 
Saponin can be heated to 180° before it begins to turn brown or to 
show a perceptible change. It does not melt, but at a high temperature 
it chars, giving a burnt-sugar odor. Its solutions in water and in methyl 
alcohol foam very markedly, an addition of ethyl alcohol decreases this 
tendency. It leaves a lasting taste somewhat resembling that of an 
alkaline soap. It is not precipitated by saturating its solution with 
ammonium sulphate, as is the case with the majority of acid saponins. 
It shows the characteristic usual of this class of bodies of being able to 
hold powders in suspension; charcoal, lead sulphide, barium sulphate, 
barium carbonate, etc., are held so tenaciously as to render it impossible 
to separate them by filtration. Mercury is readily “killed” by an aqueous 
solution of saponin and oils are easily emulsified. It is very difficult to 
obtain crystals from boric or salicylic acid solutions to which a little 
49083——2 
