MRS. B.
Yes; but the term is not confined to metals, though chiefly applied to them. Any body whatever, that has combined with a certain quantity of oxygen, either by means of oxydation or combustion, is called an oxyd, and is said to be oxydated or oxygenated.
EMILY.
Metals, when converted into oxyds, become, I suppose, negative?
MRS. B.
Not in general; because in most oxyds the positive energy of the metal more than counterbalances the native energy of the oxygen with which it combines.
This black powder is an oxyd of manganese, a metal which has so strong an affinity for oxygen, that it attracts that substance from the atmosphere at any known temperature: it is therefore never found in its metallic form, but always in that of an oxyd, in which state, you see, it has very little of the appearance of a metal. It is now heavier than it was before oxydation, in consequence of the additional weight of the oxygen with which it has combined.
CAROLINE.
I am very glad to hear that; for I confess I could not help having some doubts whether oxygen was really a substance, as it is not to be obtained in a simple and palpable state; but its weight is, I think, a decisive proof of its being a real body.
MRS. B.