(1) Of individual objects made from metals or other substances capable of being wrought into various shapes.  We know a number of objects made of iron.  The material iron embraces the metal contained in them all; but we may say, “The cook made the irons hot,” referring to flat-irons; or, “The sailor was put in irons” meaning chains of iron.  So also we may speak of a glass to drink from or to look into; a steel to whet a knife on; a rubber for erasing marks; and so on.

(2) Of classes or kinds of the same substance.  These are the same in material, but differ in strength, purity, etc.  Hence it shortens speech to make the nouns plural, and say teas, tobaccos, paints, oils, candies, clays, coals.

(3) By poetical use, of certain words necessarily singular in idea, which are made plural, or used as class nouns, as in the following:—­

The lone and level sands stretch far away.—­SHELLEY.

From all around—­
Earth and her waters, and the depths of air—­
Comes a still voice.—­BRYANT.

Their airy ears
The winds have stationed on the mountain peaks. 
—­PERCIVAL.

(4) Of detached portions of matter used as class names; as stones, slates, papers, tins, clouds, mists, etc.

[Sidenote:  Personification of abstract ideas.]

16.  Abstract nouns are frequently used as proper names by being personified; that is, the ideas are spoken of as residing in living beings.  This is a poetic usage, though not confined to verse.

     Next Anger rushed; his eyes, on fire,
      In lightnings owned his secret stings.—­COLLINS.

     Freedom’s fame finds wings on every wind.—­BYRON.

     Death, his mask melting like a nightmare dream, smiled.—­HAYNE.

     Traffic has lain down to rest; and only Vice and Misery, to
     prowl or to moan like night birds, are abroad.—­CARLYLE.

[Sidenote:  A halfway class of words.  Class nouns in use, abstract in meaning.]

17.  Abstract nouns are made half abstract by being spoken of in the plural.

They are not then pure abstract nouns, nor are they common class nouns.  For example, examine this:—­

     The arts differ from the sciences in this, that their power
     is founded not merely on facts which can be communicated, but
     on dispositions which require to be created.—­RUSKIN.

When it is said that art differs from science, that the power of art is founded on fact, that disposition is the thing to be created, the words italicized are pure abstract nouns; but in case an art or a science, or the arts and sciences, be spoken of, the abstract idea is partly lost.  The words preceded by the article a, or made plural, are still names of abstract ideas, not material things; but they widen the application to separate kinds of art or different branches of science.  They are neither class nouns nor pure abstract nouns:  they are more properly called half abstract.