Q. Are liquids good conductors of heat?
A. No; liquids are bad conductors; and are, therefore, made hot by convection.
Q. Why are liquids bad conductors of heat?
A. Because heat converts a liquid into steam, and flies off with the vapour, instead of being conducted through the liquid.
Q. Explain how water is made hot?
A. The water nearest the fire is first heated, and (being heated) rises to the top; other cold water succeeds, is also heated, and rises in turn; and this interchange keeps going on, till all the water boils.
Q. Why is water in such continual ferment, when it is boiling?
A. This commotion is mainly produced by the ascending and descending currents of hot and cold water.
The escape of air from the water contributes also to increase this agitation.