 Pauling estimated that the ice rule reduces this to formula_37, a number that would agree extremely well with the Giauque-Stout measurement of formula_30.It can be said that Pauling's calculation of formula_30 for ice is one of the simplest, yet most accurate applications of statistical mechanics to real substances ever made.The question that remained was whether, given the model, Pauling's calculation of formula_40, which was very approximate, would be sustained by a rigorous calculation.