combustion as this, though valuable, are plainly of limited application;
but for the great bulk of fuel consumption some gas-making process must be
looked to. No crude combustion of solid fuel can give ultimate perfection.

Coal tar products, though not so expensive as they were some time back, are
still too valuable entirely to waste, and the importance of exceedingly
cheap and fertilizing manure in the reclamation of waste lands and the
improvement of soil is a question likely to become of most supreme
importance in this overcrowded island. Indeed, if we are to believe the
social philosophers, the naturally fertile lands of the earth may before
long become insufficient for the needs of the human race; and posterity may
then be largely dependent for their daily bread upon the fertilizing
essences of the stored-up plants of the carboniferous epoch, just as we are
largely dependent on the stored-up sunlight of that period for our light,
our warmth, and our power. They will not then burn crude coal, therefore.
They will carefully distill it--extract its valuable juices--and will
supply for combustion only its carbureted hydrogen and its carbon in some
gaseous or finely divided form.

Gaseous fuel is more manageable in every way than solid fuel, and is far
more easily and reliably conveyed from place to place. Dr. Siemens, you
remember, expected that coal would not even be raised, but turned into gas
in the pits, to rise by its own buoyancy to be burnt on the surface
wherever wanted. And not only will the useful products be first removed and
saved, its sulphur will be removed too; not because it is valuable, but
because its product of combustion is a poisonous nuisance. Depend upon it,
the cities of the future will not allow people to turn sulphurous acid
wholesale into the air, there to oxidize and become oil of vitriol. Even if
it entails a slight strain upon the purse they will, I hope, be wise enough
to prefer it to the more serious strain upon their lungs. We forbid sulphur