This International Standard specifies a method of determination of water-soluble matter, water-soluble inorganic matter and water-soluble organic matter. It is applicable to all leather types. The result obtained by this analysis depends on factors such as: — the degree to which the leather is ground; — the extraction temperature; — the extraction period; — the ratio of leather to water. To obtain comparable results, it is consequently imperative that test conditions should be accurately reproduced. In all cases, any ammonium salts in the filtrate are included as part of the water-soluble matter and are then decomposed on ignition. Thus they contribute towards the result for water-soluble organic substances. The concentration of the ammonium salts can be determined in the filtrate separately if required.