27 
bath and the residue extracted with absolute alcohol. The alcoholic 
extract was then evaporated to dryness on the water bath or until the 
alcohol was removed. A brownish sirup was thus obtained, which, 
on cooling, solidified to a mass of cr} 7 stalline scales or plates. Some 
of these were dissolved in water and a portion of the solution made 
alkaline with sodium hydroxide. Only a very slight change of color 
was observable. Two portions of the solution of 1 cc. each were 
treated with dilute hydrochloric acid. One of these was boiled for 
five minutes, the other just brought to the boiling point and then 
cooled. Both were then made alkaline with sodium hydroxide. The 
former became deep purplish red, the latter light red. This obser- 
vation goes to show that the phenolphthalein compound in the urine 
is soluble in absolute alcohol and also that its decomposition by 
hydrochloric acid is of the nature of an hydrolysis, inasmuch as it is 
not an instantaneous but a gradual process. Unfortunately, however, 
absolute alcohol dissolves other substances from the residue of the 
urine besides the compound in question, and the same thing has been 
found to be true of acetone and certain other organic solvents. 
Hydrolysis Iny acids. — Secondly, it has been found that the extent to 
which the compound of phenolphthalein in the urine is decomposed or 
hydrolyzed by acids depends on the affinity or strength of the acid. 
That such is a fact ma} 7 be seen from the following: Three tubes 
were prepared, each containing 1 cc. of a fresh specimen of urine con- 
taining the phenolphthalein compound. To (1) was added 2 cc. of 2N 
hydrochloric acid, to (2), 2 cc. of 2N sulphuric, and to (3), 2 cc. of 2N 
acetic acid. These tubes were then heated for ten minutes on the 
water bath at 100° C., at the end of which time an excess of 2N sodium 
hydroxide was added to each tube, when the following changes of color 
were observed: 
(1) Dark red. 
(2) Light red. 
(3) Colorless. 
Thirdty, the phenolphthalein compound is not readily decomposed 
or hydrolyzed even by powerful acids in the cold. That such is the 
case is evident from the following: 
(1) Contained 1 cc. of urine, containing the phenolphthalein com- 
pound and 2 cc. of water. 
(2) Contained 1 cc. of urine, same specimen as employed in (1), 1 cc. 
of water, and 1 cc. of 2N Irydrochloric acid. 
(3) Contained 1 cc. of urine, same as employed in (1) and (2), and 2 cc. 
of 2N hydrochloric acid. 
These tubes were kept at room temperature for one hour, at the end 
of which time a slight excess of sodium hydroxide was added to each. 
Tubes (1) and (2) were found to remain colorless after the addition of 
the sodium hydroxide. Tube (3) showed a faint trace of pink color. 
