Evidence is found to show that C=O bond frequency dv=1710 of monochloacetic acid, the total S5rmmetric line dv=910 of sulphuric acid and the total symmetric lino 1060 of the nitrate ion in solution are found to decrease on depolymerisation due to heating, contrary to expectation. This goes against the assumptions usually made that the bond in question is unaffected by the presence of the other atoms in the molecules and the other molecules in the liquid. It is surmised that the molecules change their shape during the formation of a complex. The structure of the nitrate ion is pyramidal in solution at low temperature and it becomes plane on heating. This is taken to be a direct evidence for crystalline nature of hydration of ion in solution postulated by Lengyel
