Yes; and this is the case with the perfect metals, which, on that account, preserve their metallic lustre so well.
EMILY.
Are all metals capable of decomposing water, provided their temperature be sufficiently raised?
MRS. B.
No; a certain degree of attraction is requisite, besides the assistance of heat. Water, you recollect, is composed of oxygen and hydrogen; and, unless the affinity of the metal for oxygen be stronger than that of hydrogen, it is in vain that we raise its temperature, for it cannot take the oxygen from the hydrogen. Iron, zinc, tin, and antimony, have a stronger affinity for oxygen than hydrogen has, therefore these four metals are capable of decomposing water. But hydrogen having an advantage over all the other metals with respect to its affinity for oxygen, it not only withholds its oxygen from them, but is even capable, under certain circumstances, of taking the oxygen from the oxyds of these metals.
EMILY.
I confess that I do not quite understand why hydrogen can take oxygen from those metals that do not decompose water.
CAROLINE.
Now I think I do perfectly. Lead, for instance, will not decompose water, because it has not so strong an attraction for oxygen as hydrogen has. Well, then, suppose the lead to be in a state of oxyd; hydrogen will take the oxygen from the lead, and unite with it to form water, because hydrogen has a stronger attraction for oxygen, than oxygen has for lead; and it is the same with all the other metals which do not decompose water.
EMILY.