Question

Why should we always use a water bath while boiling the leaf in an alcohol solution ?

Answer 1

Alcohol is highly flammable, volatile, and the vapors are explosive, so limiting the heat applied is essential. The boiling water bath provides a constant temperature only just a few degrees over the boiling point of the isopropyl alcohol , so to limit boiling of the alcohol to a safe rate.

If the heat is applied by open flame, the slow boil-off of alcohol vapor can burn off without exploding or igniting the leaf bath