hygrometric state, to the influence of bodies attracting a portion of
it, such as decomposing substances, or when it forms the medium of
electrical discharges, it suddenly assumes new powers, acquires a
greatly increased activity, affects our organs of smell, dissolves
in fluids, and has been mistaken for a new substance, and even named
"ozone." Among the new characters thus conferred on it is the power of
uniting with or burning many substances. This ozonized oxygen, when
brought into mixture with many nitrogenized bodies, forms with them
nitrous acids, completely destroying their former condition and
composition; hence, in the atmosphere, this part of the oxygen becomes
a purifier of the whole mass, from which it removes putrescent
exhalations, miasmatic vapors, and the effluvia from every source of sea
or land. Very curious are the effects of this active oxygen, which is
ever present in some portion of the atmosphere. Moved by the wind, mixed
with the impure upward currents rising from cities, it seizes on
and changes rapidly all foulness, and if the currents are not too
voluminous, the impure air becomes changed to pure. As ozonized oxygen
can be easily detected, we may pass from the city, where (overpowered
by the exhalations) it does not exist, and find it in the air of the
vicinity; and moving away several miles, ascertain that a normal amount
there prevails, and that step by step, on our return to abodes of a
dense population, the quantity diminishes and finally all disappears.

We are now prepared to answer the second part of the question which was
suggested, and to find that nitrous acids formed in the atmosphere
by direct oxidation of nitrogenous matter may unite with the ammonia
present to produce one kind of saltpetre; and when the rains or the dews
carry this to the earth, the salts of lime, potash, and soda there found
will decompose this ammoniacal saltpetre, and set the ammonia free, to
act over again its part. So in regard to decomposing organic matters in