This equation was obtained in 1955 by Yu. I. Shimansky, at first empirically, and later derived theoretically. The Shimansky equation does not contain any arbitrary constants, since the value of T C can be determined experimentally and L 0 can be calculated if L has been measured experimentally for at least one given value of temperature T. The Shimansky equation describes quite well the heat of vaporization for a wide variety of liquids. For chemical compounds that belong to the same class (e.g. alcohols) the value of ⁠ L 0 T C ⁠ ratio remains constant. For each such class of liquids, the Shimansky equation can be re-written in a form of