§ 3 x 5 -] dragendorff’s process. 257 
at the common temperature is necessary, with substitution of acetic 
for sulphuric acid. 1 
II. The extract is next evaporated until it begins to be of a syrupy 
consistence ; the residue mixed with three to four times its volume of 
alcohol, macerated for twenty-four hours at about 34°, allowed to become 
quite cool, and filtered from the foreign matters which have separated. 
The residue is washed with alcohol of 70 per cent. 
III. The filtrate is freed from alcohol by distillation, the watery residue 
poured into a capacious flask, diluted (if necessary) with water, and 
filtered. Acid as it is, it is extracted at the common temperature, with 
frequent shaking, by freshly rectified petroleum ether ; and, after the 
fluids have again separated, the petroleum ether is removed, carrying 
with it certain impurities (colouring-matter, etc.), which are in this way 
advantageously displaced. By this operation ethereal oils, carbolic acid, 
picric acid, etc., which have not been distilled, besides piperin, may also 
be separated. The shaking up with petroleum ether is repeated several 
times (as long as anything remains to be dissolved), and the products are 
evaporated on several watch-glasses. 
The fluid is next successively shaken up with benzene and chloroform, 
the solvents being removed and evaporated as before, the last traces of 
chloroform are removed by petroleum ether, and the liquid alkalised 
by ammonia is shaken up successively with petroleum ether, benzene, 
chloroform, and lastly amyl alcohol. 
The original process was based upon the supposed fact that volatile 
solvents, such as ether, petroleum ether, acetic acid, tetrachloride of 
carbon, extracted from acid solutions, fats, glucosides, and various non- 
alkaloidal substances, while the same solution alkalised gave up to an 
appropriate solvent alkaloidal substances—the said alkaloidal substances 
being, with a few exceptions, almost insoluble in the volatile solvent 
acting on acid solutions. This has now been shown to be only true to a 
certain extent. For example, Kippenberger has shown that 200 mgrms. 
of strychnine dissolved in 70 c.c. of water, acidified by 2 c.c. of HC1, and 
the whole shaken up with 50 c.c. of chloroform, is taken up by the 
solvent to the extent of 43 to 49 per cent. ; 200 mgrms. of papaverine 
dissolved with 1 c.c. of HC1 in 70 c.c. of water can, by repeated shaking 
with chloroform, be entirely extracted ; and, according to the dilution 
and the kind and strength of acid, a great number of the alkaloids may 
be to a considerable extent shaken out of acid solutions. The reason 
of this is that dissociation of the alkaloidal salt takes place under certain 
conditions of dilution and acidity ; then the alkaloidal base is soluble 
in the volatile solvent, the hydrochlorides being more easily dissociated 
1 When blood is to be examined, it is better to dry it, and then powder and 
extract with water acidified with dilute sulphuric acid. However, if the so-called 
volatile alkaloids are suspected, this modification is to bo omitted. 
17 
