Good air has no smell at all.
And now I have something to say to you about the use of noses.
I dare say you can not see much use in the sense of smell. Seeing,
hearing, touching, are very needful to us, we all know; but as to
smelling, that does not seem to have any particular value.
It is pleasant to smell a sweet rose or violet; and, I believe, smelling
really forms a good part of what we call tasting.
Of all our senses, smell is the one that soonest gets out of practice.
If people would always accustom themselves to use their noses, they
never would consent to live in the horrid air they do.
If you go from the fresh air into a close room, you will notice the
smell at once. Then, if you remain there, you will soon get accustomed
to the smell and not notice it; but it will still be there, and will be
doing you a great deal of harm.
In good air there are, mainly, two sorts of gas.
The first is a very lively sort of gas, called oxygen; it is very fond
of joining itself with other things, and burning them, and things burn
very fast indeed in oxygen.
The second is a very slow, dull gas, called nitrogen; and nothing will
burn in it at all.
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