11 
The theoretical amount of the pure alkaloid required to make a 
fiftieth-molar solution (one-fiftieth of the molecular weight in grams 
per liter) was carefullr weighed out and dissolved m X/2 hydro- 
chloric acid (m a few instances X/2 acetic acid was used instead), 
usmg sufficient of the latter to yield the required volume of solu- 
tion. Equal volumes (10 or 20 cc.l of such solution were then trans- 
ferred to porcelain dishes and the latter with their contents placed 
on the water-bath (90-95 C.), where they were kept until the liquid 
had completely evaporated, when the time was noted and there- 
after, at intervals of half an hour, one of the dishes was removed 
and allowed to cool to room temperature. The residues in the 
dishes were then taken up with distilled water (usually 10 cc.), three 
drops of phenolphthalein uidicatorT added, and the acidity of the 
solution determined by means of X/10 sodium hydroxide. It was 
found that in the case of some of the alkaloids studied (e. g., quinine) 
when a drop, of the phenolphthalein solution is added to the alka- 
loidal salt solution which had been titrated as just described until 
a light-pink color developed, that such additional drop of the phe- 
nolphthalein, especially when comparatively larger amounts of the 
alkaloid are present, causes the light-pink color to at once turn very 
deep pink. Hence at the end of each titration an additional drop 
of the phenolphthalem indicator was added in all cases, and when 
this caused the color to deepen very much, standard acid was added 
until only a light-pink color remained, an amount of alkali ecpiiva- 
lent to the amount of acid thus used up being deducted from the 
total amount of alkali added in the first place, and the difference 
taken as the amount^of standard alkali required to neutralize the 
acidity of the solution; it having been found that such procedure 
yielded results quite close to that theoretically required, whereas if 
the numbers representing the first titrations with the alkali were 
taken, the results were somewhat too high. After the acidity of 
the alkaloidal salt solution had been neutralized and the amount of 
alkali thus determined, the chlorine in the solution was determined 
by means of Yolhard’s thiocyanate method. And when it was found 
that a product of constant acidity is obtained under conditions of 
time varying, temperature and amount of alkaloid remaining con- 
stant, the experiments were then repeated with these conditions 
reversed, namely, amount of alkaloid varying while both time and 
temperature remained constant. The amount of hydrochloric acid 
becoming fixed being, likewise here, determined both alkalimetric- 
ally and by the Volhard method. The results obtained with the 
alkaloids cinchonine, quinidine, cinchonidine, quinine, and strych- 
nine are given in the following tables : 
Prepared according to the U. S. Pharmacopoeia, 1905, page 544. 
