The Pharmaceutics and Compounding Laboratory
Emulsions:
Preparation and Stabilization

Bottle (Forbes) Method

This method may be used to prepare emulsions of volatile oils, or oleaginous substances of very low viscosities. It is not suitable for very viscous oils since they cannot be sufficiently agitated in a bottle. This method is a variation of the dry gum method. One part powdered acacia (or other gum) is placed in a dry bottle and four parts oil are added. The bottle is capped and thoroughly shaken. To this, the required volume of water is added all at once, and the mixture is shaken thoroughly until the primary emulsion forms. It is important to minimize the initial amount of time the gum and oil are mixed. The gum will tend to imbibe the oil, and will become more waterproof.

It is also effective in preparing an olive oil and lime water emulsion, which is self-emulsifying. In the case of lime water and olive oil, equal parts of lime water and olive oil are added to the bottle and shaken. No emulsifying agent is used, but one is formed "in situ" following a chemical interaction between the components. What emulsifying agent is formed?