where ∆H d is the fraction of enthalpy related to dispersion or non-polar forces, ∆H h is the fraction of enthalpy related to hydrogen bonding forces, and ∆H p is the fraction of enthalpy related to polar forces. The average values for the total and fractional enthalpies for a solution at T m equal the enthalpies of the T4 bacteriophage DNA. These averages are presented in Table . Based on these data, we calculated the fractions of the enthalpy for dispersion, polar, or hydrogen types of DNA bonding.