With the great increase in the use of palm kernel cake, which has taken place in this country in the last few years, attention has been drawn to the rancidity which the cake is liable to develop under certain conditions. R. B. Calder (see this Journal, April, 1916, VII, 470) has shown that the cake develops rancidity under sterile conditions and concludes that the action is due to the presence of a lipase. Calder has taken as his criteria of rancidity a sour smell in some cases and an acid reaction with litmus in others. There is some confusion in the use of the terms “rancidity” and “ acidity.” Although rancidity stands in close relationship to acidity and invariably accompanies a high acidity in oils and oil cakes, the terms are not synonymous.