become appreciably hotter over the very hot
fire than it does over the low fire, if it is boiling in both
cases? But in which case is more steam given off? Will a very
hot fire make the water boil away more rapidly than a low
fire?

When you are cooking potatoes, are you trying to keep them very hot or
are you trying to boil the water away from them? Which are you trying
to do in making candy, to keep the sugar very hot or to boil the water
away from it?

All the extra heat you put into boiling water goes toward changing the
water into steam; it cannot raise the water's temperature, because
at the moment when water gets above the boiling point it ceases to be
water and becomes steam. This steam takes up much more room than
the water did, so it passes off into the air. You can tell when a
teakettle boils by watching the spout to see when the steam[3] pours
forth from it in a strong, steady stream. If the steam took no more
room than the water, it could stay in the kettle as easily as the
water.

[Footnote 3: What you see is really not the steam, but the vapor
formed as the steam condenses in the cool room. The steam itself is
invisible, as you can tell by looking at the mouth of the spout of a
kettle of boiling water. You will see a clear space before the white
vapor begins. The clear space is steam.]

DISTILLING. When liquids are mixed together and dissolved in each
other, it looks as if it would be impossible to take them apart. But
it isn't. They can usually be separated almost perfectly by simply
boiling them and collecting their vapor. For different substances boil
at different temperatures just as they melt at different temperatures.
Liquid air will boil on a cake of ice; it takes the intense heat of
the electric furnace to boil melted iron. Alcohol boils at a lower
temperature than water; gasoline boils at a lower temperature than
kerosene. And people make a great deal of practical use of these facts
when they wish to separate substances which have different boiling
temperatures. They call this distilling. You can do some distilling
yourself and separate a mixture of alcohol and water in the following
manner:

EXPERIMENT 39. First, pour a little alcohol into a cup--a
few drops is enough--and touch a lighted match to it. Will it
burn? Now mix two teaspoonfuls of alcohol with about half a
cup of water and enough blueing to color the mixture. Pour a
few drops of this mixtu