Measurement of the "scaled dissipation ratio" *, is proposed as a method of discriminating between mixing processes because of the difference in the two model predicted values. Measurements in a thermohaline staircase are supportive of the predicted salt finger model * value. The method is used to examine the significance of salt fingers in an area of low density ratio and "intermittent steppiness" in T and S profiles. The observations there are not consistent with the turbulent mixing model, although they indicate that turbulent mixing is the dominant process. Assuming that the higher than turbulent values of * are due to salt fingers, a computed vertical salt flux enhancement factor [McDougall and Ruddick, 1991] suggests that salt fingers enhanced mixing by 50%.