We are aware of the controversial nature of this result. We also expected a linear relationship similar to the one observed by Dudek. However, we have in this work extended the range of compounds to include species of types J, K, and L, apparently resulting in the observed non-linear relationship. The correlation in Fig. 2 involves only experimental values, most of them from the literature, and we have no reason to doubt their reliability. The exponential regression yields R2 = 0.975, SD = 34.3 cm–1, while the corresponding linear regression gives R2 = 0.837, SD = 93.3 cm–1. Hence, the indication of a non-linear correlation is evident. We have added the sentence "Probably the extension of the range of compounds to include species of the types J, K, and L has led to the non-linear correlation” to the first paragraph on page 13.
The authors should give the reason for the nonlinear v(NH) vs delta correlation as it was (according to Dudek) linear for OH-O.