This test is based on the fact that oils and fats are soluble in organic solvents such as chloroform, ethanol, etc., but are insoluble in water. Shake a small amount of the given sample with 5 cm3 each of water, ethanol and chloroform in three test tubes. Observe the solubility and draw inferences.
TRANSLUSCENT SPOT TEST
Press a little of the substance in the folds of the filter paper. On unfolding the filter paper, the appearance of transluscent or greasy spot on filter paper indicates the presence of fat or oil. The spot grows larger on heating and drying the filter paper.
Heat a little of the sample with some crystals of KHSO4 in a test-tube. A pungent irritating odour of acrolein confirms the presence of fat or oil.