化学实验室里的学生经常鼓吹:在整天的使用硝酸银或多仑(Tollen)试剂实验后,清净的双手是良好实验技术的标志,缺乏这方面技术的学生以黑色污迹无情地产生在他们的皮肤或衣服上而著名。这就是他们操作失误的明显暴露,而给人以杀神或灶神之感。如果告知他们这些污迹跟皮肤一样不会永久存在,一两周内就会逐渐褪去,那 Students in chemistry labs often preach that clean hands are a sign of good experimental technique after a full day of experiments using silver nitrate or Tollen reagents. Students lacking this technique are relentlessly produced with black smears. They are famous for their skin or clothes. This is the obvious exposure of their mistakes in operation, and gives people the sense of killing God or stover. If you tell them that these stains are not permanent like the skin, they will gradually fade in a week or two.