es to use the culm,
low-grade slack, and lignites, the lowest form of coal, in short, all
the waste of the mines. Still another plan is the manufacturing of
electricity by water-power, as we have seen in a previous chapter.

The manufacturing industries of the country waste a large amount of fuel
annually, but here the waste is mostly due to expensive methods of
producing power, and to careless stoking, and is largely preventable. As
we have shown, gas-engines are a far more economical form of producing
power than are steam-engines. Steam uses from five to ten per cent. of
the heat-units of coal, gas-producer engines use fifty per cent. and
burn a lower grade of coal.

One of the great problems of cities is the heavy volume of bituminous or
soft coal smoke that hangs over the entire surrounding region, levying a
heavy tax in cleaning and laundry work, making the air difficult to
breathe, and shutting out the daylight itself. Every residence adds its
mite, but the factories and public buildings are the worst offenders.
There are several good smoke-consuming devices on the market that have
been thoroughly tested by the government, which will furnish their names
on application.

If factory owners who use steam power could realize that the gases, the
highest heat-producing part of the coal, escape with the smoke, and
that by using smoke consumers they not only prevent all the evils of
the smoke nuisance but save fully half of the value of their coal, they
would gladly put in this equipment. What manufacturer would not eagerly
welcome any device that would cut his fuel bills in half?

The other cause of waste of coal in the manufacturing industries is
recklessness in the use of fuel, filling the furnaces with the drafts so
disposed that much of the heat is wasted. Every factory owner should
learn (from the government reports if he has no other means of learning)
the best methods of firing furnaces, and should employ them in his
factory.

The last great waste of coal is in households. In stoves and furnaces,
and to a certain extent in kitchen ranges, this waste is through
carelessness in firing, as it is in factories. There still remains a
large amount of wasted energy in cooking that is unavoidable. The amount
of coal consumed before certain articles can be cooked, the heat
remaining after the meal is prepared, are wastes that it seems
impossible to prevent, though wise management will prevent undue waste
even here. Fi