Chemical distillation apparatus is used as a method of separating chemicals out from a liquid mixture by heating them. The liquid in the left-hand bulb is heated over a Bunsen burner and a reagent is added from the flask above it. The products of the ensuing chemical reaction can then be separated by distillation. The most volatile compound will boil off at the lowest temperature. Its vapor passes into the condenser, a tube which is surrounded by a cooling water jacket (long tube across the center). The hot vapor cools and condenses on the walls of the tube and is then collected in the "receiver" flask (on the right).