VEGETABLE ALKALOIDS. 
255 
§ 3I4-] 
The extraction may be conducted at a gentle heat, and should be 
continued for several hours. The glycerin solution is filtered, a process 
which is facilitated by diluting the glycerin ; with this extract, as with 
the Stas-Otto process, it is advisable to extract the fat by petroleum 
ether before filtration. 
It is best in practice to combine the Stas-Otto process with Kippen- 
berger’s, that is to say, to apply Kippenberger’s process to the ultimate 
alcoholic extract derived from the Stas-Otto process, in order to get rid 
of impurities. 
In either case the final aqueous, slightly acid solution may be treated 
with either the general alkaloidal reagents or it may be very carefully 
alkalised by a solution of potash ; if no turbidity or precipitate occurs, 
then no ordinary alkaloid is present. Should a cloud or precipitate 
occur, the liquid can be made acid, so as to dissolve the precipitate, 
and be submitted to Dragendorff’s process. 
Most alkaloids can also be purified by Kippenberger’s 1 iodine method, 
which is as follows :—The supposed alkaloid is dissolved in a little acid 
water, which is then just made neutral by soda solution ; it is then pre¬ 
cipitated by a solution of iodine and potassic iodide (12-7 grins. I and 60 
grms. KI to the litre), the precipitate is filtered through an asbestos 
filter and washed with cold water. 
In the last edition of this work, a method of recovering the base by the 
use of acetone and thiosulphate was given. A better process, introduc¬ 
ing no inorganic matter, is to grind up the periodide in warm water 
in presence of finely divided copper. This is prepared by treating a 
saturated solution of copper sulphate by zinc dust ; the precipitated 
copper is washed by decantation, and freed from traces of zinc by the 
action of very dilute hydrochloric acid. The copper is kept under 
water ready for use. 
Many alkaloids can be readily purified by preparing the picrate or 
picrolonate, especially bases which form chlorides insoluble in ether. 
The picrate is dissolved in hot dilute hydrochloric acid, the liberated 
picric acid extracted with ether or toluene. Alkaloids may be recovered 
from Dragendorff’s reagent by grinding the precipitate with freshly 
prepared lead hydroxide. The filtrate from this reaction is treated with 
SH 2 , any lead sulphide filtered off, the filtrate concentrated to a syrup, 
and the alkaloid extracted with alcohol. 
§314. Selmi’s Process for Separating Alkaloids. — A method of 
separating alkaloids from an ethereal solution has been proposed by 
Selmi. 2 The alcoholic extract of the viscera, acidified and filtered, is 
evaporated at 65° ; the residue taken up with water, filtered, and 
decolorised by basic acetate of lead. The lead is thrown out by 
1 Zeit.f. anal. Chemie, 1896, p. 414. 
2 Selmi, dazett. Chim. Ilal., vi. 153-166; and Journ. Chern. Soc. i. 93, 1877. 
