Since the appearance in 1882 of t,he pioneer researches of Baumann on the urinary phenols, a large number of investigations has been made on this subject. The method used for the quantitative determinations of these bodies has been ahnost invariably the iodometric titration variously modified and improved by Kossler and Penny,l by Neuberg,2 Mooser,s and by Hensel.4 At best the iodometric method has many disadvantages, being extremely time consuming and requiring the use of a comparatively large amount (500 cc.) of urine. Further, as will be shown below, if the directions given by Ohe various investigators who have worked on the technique of this method be followed a considerable portion of the phenol contained in the urine may be lost. The first step in the determination of phenols according to the methods of Kossler and Penny, Neuberg, Mooser, etc., consists in evaporating the faintly alkaline urine on a water bath to about one-fifth of its original volume. We have found that during this evaporation a considerable proportion of the phenol is oxidized, thus producing results much below t,he truth.