14. (6 points) A 100-liter container is filled with pure alcohol. After pouring out a portion, it is filled with water; after mixing thoroughly, a volume equal to the first pour is removed, and then it is filled with water again. At this point, the volume of water in the container is three times the volume of pure alcohol. The volume of pure alcohol poured out the first time is $\qquad$ liters.
【Solution】Solution: Let the pure alcohol poured out for the first time be $x$ liters,
then $100-x-\frac{100-\mathrm{x}}{100} \cdot \mathrm{x}=\frac{1}{4} \times 100$
Simplifying, we get $x^{2}-200 x+7500=0$
Solving, we get $x_{1}=150>100$, discard, $x_{2}=50$,
so $x=50$
Answer: The pure alcohol poured out for the first time is 50 liters.
Therefore, the answer is: 50.