We know as yet so little of natural forces, that imagination need set no bounds to its flights in considering the possibilities of the future.

Within but a few years we have made such discoveries as two centuries ago would have sent the discoverer's to the flames.

The liquefaction of oxygen; the existence of radium, of helium, of polonium, of argon; the different powers of Roentgen and Cathode and Bequerel rays.

And as we may finally prove that there are different kinds and qualities of light, so we may find that combustion may have its own powers of differentiation; that there are qualities in some flames non-existent in others.

It may be that some of the essential conditions of substance are continuous, even in the destruction of their bases.