编辑同志: 用硝酸溶样时产生的氧化氮使指示剂破坏而影响终点的观察,是该法应用时常遇到的问题。为此,本文作了改进。用铬酸铅沉淀—亚铁滴定法间接测定黄铜中的铅(见机械工厂实用化学分析下册p 29)虽然操作简单、快速,但经多次实验,终点很不理想,有时 Editor comrades: nitric acid generated when the sample dissolved nitrogen oxide indicator to affect the destruction of the end point of observation is the application of the law often encountered problems. To this end, this article made improvements. Indirect Determination of Lead in Brass with Lead Chromate Precipitation - Ferrous Titration Although the operation is simple and fast, the end point is not ideal after many experiments, sometimes