Set-up A – Take a small, well-watered plant, preferably one with broad leaves. Place the pot completely in the polythene bag and wrap the mouth of the bag tightly around the stem. This will prevent evaporation from the pot. Now cover the whole plant under a metal pot as in (A).

Set-up B – Arrange another similar plant and cover it with a metal pot exactly the same as the first one, except here again you keep a piece of dry cobalt chloride paper next to the plant inside the metal pot (B). This paper can be pinned to a wooden stick or to a piece of cork sheet.

Set-up C – Take a third pot of iron out of the plant, but it contains the same piece of cobalt chloride (C) paper. Now, keep all three metal pots aligned in the sun.

After half an hour,

1. The first metal pot (A) will show water vapor closing its inner walls.

2. The second metal pot (B) will also show the same consistency and at the same time, the first blue cobalt chloride paper on it would turn pink.

3. The blue color of the cobalt chloride paper in the third metal pot (C) does not change at all and there are no water droplets on the inner walls of the jar as well.

The third metal pot in this test is a control that proves that there was no moisture in the air due to the rotation as there was no plant in it.