1.1 本试验方法包括测定铬鞣液的可滴定酸度。通过 可滴定酸度 这意味着不仅游离酸度很少存在，而且阴离子与弱碱性阳离子结合，例如铬（III），可以在酚酞终点用碱滴定。 1.2 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.4 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 4.1 根据本试验方法测定的铬鞣液的酸度很少采用这种方法。该结果通常与铬分析结果相结合（见试验方法 D3898 )测定酒的碱度。该性质等于所分析溶液中正常铬盐中阴离子被羟基取代的百分比，与溶液的鞣制行为密切相关。

1.1 This test method covers the determination of the titratable acidity of chromium tanning liquors. By titratable acidity is meant not only free acidity, which is rarely present, but also anions combined with weakly basic cations such as Chromium (III), which can be titrated with base at the phenolphthalein end point. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 4.1 The acidity of a chrome tanning liquor, as determined by this test method, is rarely employed as such. This result is normally combined with the results of a chromium analysis (see Test Method D3898 ) to determine a property of the liquor called basicity. This property, equal to the percentage by which anions in a normal chromic salt have been replaced by hydroxyl in the solution being analyzed, is closely related to the tanning behavior of the solution.