Wen we place a cold alcohol in glass in a hot tub of water then the glass will be warmed first so it will expand a little due to which the level of alcohal decreases. After some time when thermal equilibrium is achevied then the alcohol will expand more then glass as the alcohol has the greater coeficient of expansion then glass so there will be an incerease in the level of alcohol which will indicate how much high the temperature is.
