1.   Cook, stirring, until mixture boils and thickens slightly.

2.   When mixture boils, it will throw sugar on to sides of pan.

3.   On no account should the mixture boil.

4.   Mixture E boils at one atmosphere at the temperature of the system.

5.   Since the total vapour pressure is higher than that of either component, the temperature at which the mixture boils is lower than that of either component.

6.   As a consequence the mixture boils at a lower temperature.

7.   As the mixture boils, notice little pools of fat on the surface.

8.   Be sure that the mixture does not boil.

9.   Add vanilla bean and heat until mixture almost boils, about five to eight minutes.

10.   Continue cooking over medium heat until sugar is dissolved and mixture boils.