AS IS the case in all the major fields of the science, the litera-_ \_ ture pertaining to analytical chemistry is rapidly approaching a state of practical unwieldiness. One might say-and not too facetiously-that a detailed search of published information for an analytical project in applied analysis could conceivably involve a large proportion of the time devoted to the project itself. The number of annual published contributions to analytical studies of pharmaceutical and natural drugs alone is estimated to be nearly a thousand.The preparation of a review covering such a number and diversity of publications necessarily poses several problems. Foremost among these is the matter of selection of material, since it is obvious that an abstract of the contents of each article could not be included. The authors wish to repeat and to re-emphasize the fact that omissions from the review do not imply that the papers so omitted do not contain useful information. A conscious effort has been made, however, to include those studies and procedures which offer the greatest possibilities for use in pharmaceutical analysis.The classification of methods is the same as that published in the previous annual reviews of pharmaceuticals and natural drugs.