21 
alkaloid, as the normal salts, while those in which only one of the acid 
affinities of the alkaloid is satisfied, as basic salts. 
SUMMARY. 
1. The literature is briefly reviewed and it is shown that although 
it is known that the salts of most of the alkaloids can be estimated 
by means of phenolphthalein as indicator, no application of this fact 
to the estimation of the purity of the uncombined alkaloids as found 
in commerce or as obtained in the course of the various pharma- 
copoeia! assays, has been made where the phenolphthalein is used as 
the only indicator and hence as the controlling factor of the accuracy 
of the titration. 
2. It is therefore pointed out that in the course of the various 
pharmacopoeial assays, if instead of dissolving the alkaloid in an 
excess of sulphuric acid, as is usually done, an excess of a volatile 
acid be employed, such as hydrochloric acid, a definite amount of the 
acid proportional to the amount of alkaloid present would become 
fixed by combining with the alkaloid and which combination of 
alkaloid and acid might be found stable at the temperature employed 
for volatilizing the excess of acid remaining free. In the present 
communication the alkaloids quinine, quinidine, cinchonine, cincho- 
nidine, and strychnine are taken up, and it is shown that fairly close 
results may be obtained by such procedure, whether we use the 
alkalimetric method with the aid of phenolphthalein or determine 
the chlorine in the solution by means of Yolhard’s thiocyanate 
method. 
3. It is further pointed out 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) 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 least as far as some of the alkaloids are concerned, 
surrounded by uncertainty. Thus the results obtained with strych- 
nine and quinine, for example, show that the view that both quinine 
and strychnine are monacid alkaloids is not in entire harmony with 
these facts, and that it is perhaps more rational to look upon the 
salts of quinine, for example, in which the latter acts as a diacid 
alkaloid as the normal salts (instead of acid salts), while those in 
which only one of the acid affinities of the alkaloid is satisfied (at 
present generally regarded as the normal salts), as basic salts. 
