natural soda saltpetre. Now to us in this country, so near the sources
of abundant supply of soda saltpetre, this substitution becomes a matter
of great interest. We possess and can produce the alkaline salt of
potash in almost unlimited quantity, and, excepting for some special
purposes, it is consumed for its alkaline energy alone. When soda
saltpetre in proper proportion is dissolved and thus mixed with potash
salt, an exchange of bases takes place, and no loss of alkaline energy
follows. The soda in a quite pure state is eliminated from the soda
saltpetre, and will serve for the manufactures of glass and soap; while
the potash, taking the oxygen compound of the soda saltpetre, produces,
as a final result, a pure and beautiful prismatic saltpetre, most
economically and abundantly.

Instead of working on a hundred pounds of earth to obtain at most eight
or nine pounds of saltpetre, a hundred pounds of soda saltpetre will
afford more than one hundred and nine pounds of potash saltpetre, when
skilfully treated. Here, then, we have, by simple chemical treatment
of an imported, but very cheap salt, a result constituting a source of
abundant supply of potash saltpetre, _without the loss of the agent_
concerned in the transformation.

We have traced slightly in outline the formation of saltpetre to the
action of ozonized oxygen on nitrogen compounds, in the atmosphere, or
in the earth,--the conditions being the same in both cases. If we pursue
the study of this action of ozonized oxygen farther, we shall not
restrict its combining disposition to these compounds, but prove that it
has the power of uniting directly with the nitrogen naturally forming
part of the pure air. While nitrogenized bodies are present, however,
in the atmosphere, or in the humid artificial heaps of saltpetre
plantations, the action of ozonized oxygen is on these, and the nitrous