Acetone, petrol and perfume are volatile liquids (which can change into vapours easily). When we put some acetone, petrol or perfume on our plam, the acetone, petrol or perfume evaporate rapidly and our palm feels cold. This is due to the fact that to change from the liquid to the vapour state, acetone, petrol or perfume require latent heat of vaporisation. The acetone, petrol or perfume take this latent heat of vaporisation from our palm. The palm loses heat and feels cold.