trouble. If you blow out your boiler hot, or if the mud and slush bakes
on the tubes, there is soon a scale formed on the tubes, which decreases
the boiler's evaporating capacity. You, therefore, in order to make
sufficient amount of steam, must increase the amount of fuel, which of
itself is a source of expense, to say nothing of extra labor and the
danger of causing the tubes to leak from the increased heat you must
produce in the firebox in order to make steam sufficient to do the work.

You must not expect economy of fuel, and keep a dirty boiler, and don't
condemn a boiler because of hard firing until you know it is clean, and
don't say it is clean when it can be shown to be half full of mud.

SCALE

Advertisements say that certain compounds will prevent scale on boilers,
and I think they tell the truth, as far as they go; but they don't say
what the result may be on iron. I will not advise the use of any of
these preparations, for several reasons. In the first place, certain
chemicals will successfully remove the scale formed by water charged
with bicarbonate of lime, and have no effect on water charged with
sulphate of lime. Some kinds of bark-summac, logwood, etc.,-are
sufficient to remove the scale from water charged with magnesia or
carbonate of lime, but they are injurious to the iron owing to the
tannic acid with which they are charged. Vinegar, rotten apples, slop,
etc., owing to their containing acetic acid, will remove scale, but this
is even more injurious to the iron than the barks. Alkalies of any
kind, such as soda, will be found good in water containing sulphate of
lime, by converting it into a carbonate and thereby forming a soft
scale, which is easily washed out; but these have their objections, for,
when used to excess, they cause foaming.