初学化学的人,便已懂得把锌放在硫酸里,或是把金属钠放在水里来制取氢,因为这些金属有一种能力从酸里或水里把氢离子取代。而在各种金属之中,有些会作用得很烈,甚或可能会发生爆炸;有些没有那么剧烈。但也作用很迅速;但有些却是慢吞吞的,而有些却不能够从酸中放出氢,甚至没有作用。假如我们将一片锌放入硝酸铅或醋酸铅的溶液中,不久便可以见到锌片上生成结晶铅的所谓 Beginning chemists already know how to put zinc in sulfuric acid or metal sodium in water to make hydrogen because these metals have the ability to replace hydrogen ions from acid or water. And among all kinds of metals, some will work very hard, or may explode; some may not be as dramatic. But it also works very quickly; but some are slow, while others are not able to release hydrogen from the acid, even without effect. If we put a piece of zinc into a solution of lead nitrate or lead acetate, we can soon see the so-called crystalline lead