THE FIXING POWER OF ALKALOIDS ON VOLATILE ACIDS AND ITS 
APPLICATION TO THE ESTIMATION OF ALKALOIDS WITH THE 
AH) OF PHENOLPHTHALEIN OR BY THE VOLHARD METHOD/ 
By Elias Elvove. 
Technical Assistant, Division of Chemistry, Hygienic Laboratory, U. S. Public Health 
and Marine- Hospital Service. 
The Yolumetric estimation of the vegetable alkaloids has been a 
subject of much study, and numerous methods have been proposed 
which, with more or less success, have been practiced by various 
authors. The desirability of perfecting a suitable volumetric method 
for the quantitative determmation of this class of substances grows 
out not only of the general advantages of rapidity and ease of manipu- 
lation which volumetric methods in general possess over gravimetric 
processes, but also because in this case the most commonly practiced 
gravimetric processes are open to serious errors which render them 
quite unreliable. Thus Kebler^ expresses this fact in connection 
with the estimation of the vegetable alkaloids in the following words : 
From the hundreds of assays made by the author, he feels justified in stating that all 
of the gravimetric processes yield products containing considerable non-alkaloidal 
matter, and hopes that the day is not far distant when all gravimetric results will at 
least be supplemented by volumetric methods, if not displaced by them. 
Most of the volumetric methods given in the literature for the 
estimation of this class of substances naturally fall into two classes : 
(1) Those which are based upon the precipitation of the alkaloid 
from solution and measuring the amount of reagent required to effect 
complete precipitation. 
(2) Those which are based upon the alkaline nature of most 
alkaloids toward certain indicators and measuring the amount of 
acid required for complete neutralization. 
As the most important of the methods belonging to class (1) we may 
mention the various modifications of the old and well known method 
of estimating alkaloids by means of potassium mercuric iodide 
a Manuscript submitted for publication July 9, 1909. 
& Jour. Amer. Chem. Soc., 17 , 822-831 (1895 ). 
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