门捷列夫在化学的定义里,特别强调,将与化学变化进程同时发生的现象的研究,应该列入化学课程之内。在我们这一世纪的开始,化学家们在很多化学变化的过程中碰到了各种各样的反常。例如,研究光化学反应(即是在光的作用下的化学反应)的工作者发现:一个被吸收的光量子(光能的基本单位)在某些条件下能够引起大量反应产物的生成。这个观察结果无论如何也不能和叫做爱因斯坦光化学等当量的定律结合起来。按照这个定律,一个光量子应该只引起化学变化的一个单元动作。在几次企图 Mendeleev in the definition of chemistry, with special emphasis on the phenomena that coincide with the process of chemical change should be included in the chemistry course. At the beginning of our century, chemists met with a variety of abnormalities during many chemical changes. For example, workers who study photochemical reactions (ie, chemical reactions under the action of light) find that an absorbed photon (a basic unit of light energy) can under certain conditions induce the production of a large number of reaction products. This observation can not in any case be combined with the law called the equivalent of Einstein’s photochemistry. According to this law, a light quantum should only cause a unit action of chemical change. In several attempts