Response of cottonseed oil products to the kreis test for rancidity : In the Kreis test a fat or oil is shaken with equal volumes of hydrochloric acid and a solution of phloroglucinol in ether. The development of a red color indicates that the fat or oil is rancid; its formation is probably due to the presence of aldehydes or ketones in the material tested. Chromogenetic substances, which give a positive Kreis reaction, occur in crude cottonseed oil. The researches of W. B. Smith (Journal of Industrial and Engineering Chemistry, 1920, xii, 764–766)