为实现教学内容现代化,在新的中学化学教学大纲里,选入了一些内容比较先进的实验。例如,初中化学课本里的“纸上层析”就是明显的一例。纸上层析是过去中学没有讲过的,是一种简便易行的分离和鉴别物质的新方法。通过这个实验,不仅可以使学生在开始学习化学不久就能接触比较先进的实验内容,了解把含有微量物质的混合物进行分离和鉴别的方法,开阔眼界,还可以帮助学生更广泛地思考问题。由于纸上层析的原理比较复杂,在初中阶段不宜给学生讲述。但作为教师在研究教材时,还是有必要对纸上层析的简史、操作、原理和应用做进一步了解的。下面仅就我 In order to modernize teaching contents, some new experiments have been selected in the new chemistry syllabus of middle school. For example, “paper chromatography” in junior high school chemistry textbooks is a clear example. Paper chromatography was not mentioned in secondary schools in the past, is a simple and easy way to separate and identify substances. This experiment not only allows students to gain access to more advanced experiments soon after they begin learning chemistry, understanding how to separate and identify mixtures containing trace substances, broaden their horizons, and helping students think more broadly. As the principle of paper chromatography is more complicated, junior high school should not be about to students. However, as a teacher in the study of textbooks, it is still necessary to further understand the brief history, operation, principles and applications of paper chromatography. Just below me