The recently reported accurate data of Herzberg and Howe have been used to calculate the potential energy curves for the X 1Σg+ and B 1Σu+ states of hydrogen by the Rydberg-Klein-Rees (RKR) method. The results are compared with the results of the quantum calculations of Kolos and Roothaan and Dalgarno and Lynn. The agreement is good; in fact, the interaction energy obtained by Dalgarno and Lynn for the ground state agrees with the RKR values to within 2% in the region where the two curves overlap. The rotational predissociation observed in the ν″=14 level of the X 1Σg+ state is discussed. It appears as if there may exist here an unusual case of a sharp spectral line associated with a state which is very close in energy to the maximum of a potential barrier.