A study of the line shape of the transitions of various concentrations of Cr+++ ion in potassium cobalticyanide and potassium aluminum alum single crystals has been made at 9300 Mc/s. The line shape is found to change gradually from Lorentzian to Gaussian with chromium concentration. Lorentzian shape of gadolinium ion in lanthanum ethyl sulphate and exchange narrowing in case of free radical and copper sulphate are reported. The line width and relative intensity of the transitions in a highly dilute cyanide salt at 4.2° K are plotted and it is found that the intensity followed the maximum of the matrix element squared for various transitions. The value of g is found to be 1.992. The actual concentration of Cr+++ in dilute salts is less than the concentration of the solution from which they are grown by more than a factor of 10 as the dilution is increased.