The first application of electrolysis to chemical analysis was made by Gaultier de Claubry, in 1850, who employed the electric current for the detection of metals when in solution. Other early workers followed in this direction, and in 1861 Bloxam published two papers (J. Chem. Soc., 13, 12 and 338) on "The application of electrolysis to the detection of poisonous metals in mixtures containing organic matters." In these papers a description is given of means for detecting small quantities of arsenic and of antimony by subjecting their acidulated solutions to electrolysis. The arsenic was evolved as hydride and recognized by the usual reactions, while the antimony was mainly deposited as metal upon the cathode. The electrolytic method for the detection of arsenic, in which all fear of contamination from impure zinc is overcome, has since been elaborated by Wolff, who has succeeded in detecting as little as 0.00001 grm. arsenious oxide by this means (this Journal, 1887, 147). In a somewhat different manner the voltaic current is made use of in ordinary qualitative analysis for the detection of tin, antimony, silver, lead, arsenic, etc., by employing a more electro-positive metal to precipitate a less electro-positive one from its solution. The quantitative electrolytic methods of analysis, some of which I had the honor of bringing before the notice of the Society some time back (this Journal, 1889, 256), have placed a number of methods of determination and separation of metals in the hands of chemists, which can be employed with advantage in qualitative analysis, especially in case of medical and medico-legal inquiry. These methods are not supposed to supersede in any way the ordinary methods of qualitative analysis, but to serve as a final and crucial means of identification, and thus to render it possible to detect very small quantities of the substances in question with very great certainty. As such they fulfill the required conditions admirably, being readily carried out, comparatively free from contamination with impure reagents, and capable of being rendered quantitative whenever desired. In conjunction with Mr. E.V. Ellis, B.Sc., I have examined the applicability of the electrolytic methods for the detection of the chief mineral poisons (with the exception of arsenic, an electrolytic process for the detection of which has already been devised, as described), viz., antimony, mercury, lead, and copper. _Antimony_.--The method employed in the case of antimony is that adopted in its quantitative estimation by means of electrolysis, a method which insures a complete separation from those metals with which it is precipitated in the ordinary course of analysis--arsenic and tin. This fact is of considerable importance in reference to the special objects for which these methods have been worked out.