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| Emulsions |
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| Emulsions are colloidal solutions in which both the dispersed phase and dispersion medium are liquids. Emulsions are broadly classified into two types. |
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| i) Oil-in-water emulsion |
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| ii) Water-in-oil emulsion. |
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| i) Oil in water emulsion |
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| In this type of emulsion oil is the dispersed phase, while water is the dispersion medium. Examples are milk and vanishing cream. |
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| ii) Water in oil emulsion |
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| In this type of colloidal system water is the dispersed phase and oil acts as the dispersion medium. Examples of water in oil emulsions are butter, cold cream and cod liver oil. |
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| The two types of emulsions can be identified by the following methods. |
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| Dye test |
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| When some oil soluble dye is added to the emulsion, the background becomes colored, it implies that the emulsion is water-in-oil type. If the droplets become colored, the emulsion is oil-in-water type. |
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| Dilution test |
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| If the emulsion can be diluted with water, this indicates that water is the dispersion medium and the emulsion is of oil-in-water type. If water forms a separate layer, the emulsion is water-in-oil type. |
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