Hold a cold plate over boiling water. Observe how the water-dust gathers
into drops that roll down the plate.

You have seen the inside of windows in cold weather covered with
moisture. Where does it come from? Why did it form there? Why does it
sometimes run down on the cold pane?

The vapor in our breath turns into water on frosty mornings. Explain
this.

Carry a pitcher of ice-water into a room, and notice what takes place. A
thin mist at once gathers on the outside of the pitcher. What takes
place among the little drops of mist? What becomes of these larger
drops?

Where does the water which collects on the outside of the pitcher come
from? Does it come through the pitcher from the inside? Would the same
thing have taken place if some other cold object had been used instead
of a cold pitcher?

_Write_ out what you have learned about vapor.




LESSON XVI.

DEW, CLOUDS, AND RAIN.

The sun is all the time heating the water on the land and in the sea,