p the stack.

22. Q. Is smokeless firing practicable?

A. Yes, but it is necessary in order to obtain good results that boiler
and fire-box be in good condition, coal broken to the proper firing
size; then, with the hearty and intelligent co-operation of both
engineer and fireman, smokeless firing is both economical and
practicable.

23. Q. In what condition should the fire be in order that the best
results may be obtained from the combustion of the coal?

A. The fire should be as light as the work being done by the engine will
permit, evenly distributed over the grates and free from clinkers.

24. Q. How should the blower be used?

A. A blower should be used very lightly, being careful not to draw too
much air into the fire-box and through the flues, especially when fire
is being cleaned or thin on grates.

25. Q. What is the result of opening the fire-door when the engine is
working steam?

A. It will cause a cooling effect in the fire-box and is liable to start
the flues leaking.

26. Q. What is the effect of putting too many scoops of coal on a bright
fire? Is this a waste of fuel?

A. It has the effect of temporarily deadening and cooling the fire,
causes emission of quantities of black smoke, as only a limited amount
of gas can be burned in a fire-box at a time; all in excess of that
amount escapes from the stack and is a waste of fuel.

27. Q. What effect has the fire upon a scoopful of coal when it is
placed in the fire-box?

A. The heat from the fire drives the gases from the coal and they are
ignited by the hot flame as they pass over the bright fire; the coke
which is left burns where it is.

28. Q. In what condition should the fire be to consume these gases?

A. A bright white coke fire, almost incandescent.

29. Q. What is the temperature of the fire when in this condition?

A. It must not be less than 1,800 degrees Fahrenheit to consume the
gases liberated from the coal, and it only requires from 750 to 900
degrees Fahrenheit to burn the coke that remains on the grate; as coke
burns from the outside, less heat is required to consume it.

30. Q. How can the fire be maintained in this condition?

A. By adding coal to the fire in small quantities, spreading it over the
grate surface and no faster than it is burned.

31. Q. What is black smoke? Is it combustible?

A. Black smoke consists of small particles of carbon suspended in the
gases of combustion and indicates incomplete combusti