determinations of one sample of sumach gave results ranging from 18 to 28 per cent., and similar variations occurred when the experiment was repeated with valonia. Wagner's method by precipitation with a standard solution of cinchonine and magenta has proved wholly unreliable. Gerland's method with a volumetric solution of tartar emetic, used in presence of ammonic chloride, gives constant results with sumachs, 2/3 of those given by permanganate and Neubauer's equivalent. Tartar emetic does not precipitate the tannins of cutch and gambier. Fleck's, by precipitation with copper acetate, and subsequent washing with ammonic carbonate and gravimetric estimation, either of the tannate dried at 212° F. (100° C.), or of the copper oxide left on ignition; and Carpene's, by precipitation with ammoniacal zinc acetate, and subsequent estimation with permanganate and indigo, though giving fairly accurate results on some tannins, are only of limited application. They may therefore be passed over, as well as Jean's method with a volumetric solution of iodine in presence of sodic carbonate, and Allen's method with lead acetate, which are tedious and difficult, and present no advantage over Löwenthal's improved process. This last is easy of execution, constant in results, and universally applicable. Before proceeding to describe it in detail, it may be well to give some hints as to the best modes of sampling and preparing tanning materials for analysis, since this is often more difficult and tedious than the actual analysis.