As the immediate result of the ingestion of certain chemical compounds—chloral, camphor, benzol, phenol, &c.—substances make their appearance in the urine which have long been known to possess the power of reducing the oxides of some of the metals when in solution in the presence of an alkali, if that mixture be raised to the boiling point, but considerable confusion has resulted from the difficulty of finding a short process whereby many of these substances may be readily recognised as not belonging to that comprehensive group of conditions generally styled as glycosuria.