This International Standard specifies a titrimetric method for the determination of the nitrogen content and of the "hide substance” of leather. The method is applicable to all types of leather in all types of tannage. NOTE— Other nitrogenous substances (e.g. certain fixatives, synthetic tannins, cationic fats and dyestuffs) falsify the value for the "hide substance". If these materials are present, it is not possible to obtain an accurate result for the "hide substance".