DANGERS OF MUD AND SCALE.
Mud within the boiler, and scales adhering to the heating surface, are dangerous enemies to the preservation of boilers; and engineers should strive to prevent their evil effects by rooting them out so far as practicable. Much can be banished by washing out frequently; and scales can, to some extent, be prevented by selecting the softest water on the road. If water in a tank is so hard that it makes soap curdle instead of lather when a man attempts to wash with it, that tank should be avoided as far as possible.