Experiments on the paramagnetic resonances of two nickel Tutton salts were performed at 47000 MC and at room temperature. The crystalline field constants were determined and compared with the results obtained by Griffiths and Owen on the same salts but at lower frequencies ; for nickel ammonium salt, the result was in satisfactory agreement. but some differences between both the values were found in the case of nickel potassium salt. The crystalline field constants of the nickel potassium salt were found respectively to be D= -3.50±0.01 and E= -5.55±0.01
