19 
more drop of the phenolphthalein indicator is added, and if the solu- 
tion at once assumes a very deep pink color, standard acid is added 
until the color remaining is only light pink, the alkali equivalent of 
the acid thus added being deducted from the total alkali added first. 
Knowing that in the case of quinine, quinidine, cinchonine, or cin- 
chonidine two molecules of the sodium hydroxide are equivalent to 
one molecule of these alkaloids, we can of course calculate the actual 
amount of alkaloid in the specimen under examination. Similarly^ 
in the case of strychnine the calculation is made on the basis of one 
molecule of the sodium hydroxide being equivalent to one molecule 
of the strychnine. The result thus obtained may also be confirmed 
by determining the chlorine in the solution by means of the Volhard 
thiocyanate method. In the case of other alkaloids, no complete 
s}'Stematic investigation has yet been made, but it is highly probable 
that with perhaps some slight modification such procedure will be 
found applicable to most, if not all, the alkaloids usually met with 
in practice. In fact, some preliminary work with a number of other , 
alkaloids would seem to indicate that such is really the case. 
It is interesting to note in this connection that the results which 
might be obtained from a study of the fixing power of the alkaloids 
on volatile acids under exactly equal conditions and using the same 
indicator (instead of a large number of different indicators) in the 
titrations of all the alkaloids compared, as is here done for several 
of them, should furnish conclusive evidence as to the exact relation 
of the various alkaloids to acids, i. e., their combining power with 
acids, a subject which appears to still remain, at feast as far as 
some of the alkaloids are concerned, surrounded by uncertainty. 
Thus Schimpf ® expresses himself in this respect with reference to the 
cinchona alkaloids as follows : 
In the titration of cinchona alkaloids such anomalous results are obtained that there 
is some doubt as to whether the relation of these alkaloids to acids is thoroughly under- 
stood . 
Further, as examples of monacid alkaloids, Schimpf^ enumerates 
quinine, morphine, and strychnine. Similarly, the U. S. Pharma- 
copoeia, as may be seen from the tables of equivalents in which the 
alkaloids are enumerated, apparently regards such alkaloids as qui- 
nine and strychnine, for example, as being equal in their combining 
power with acids, assigning to both strychnine and quinine a monacid 
value. This same view is also manifested in the U. S. Pharmacopoeia 
by the nomenclature which it adopts for the salts of such alkaloids 
as quinine. Thus the combination of one molecule of quinine and one 
« Schimpf: Manual of Volumetric Analysis, 5th ed., p. 502 (1909). 
^>Ibid., p. 498. 
cU. S. Pharmacopoeia (1905), pp. 555, 567, 568. 
