Purpose
To demonstrate the formation of stalagmites
and stalactites.
| Procedure |
| 1. |
Fill
each jar with Epsom salt. Add just enough
water to cover the Epsom salt and stir. |
| 2. |
Tie
a washer to each end of the string. |
| 3. |
Place
one washer in each of the jars and place
the sheet of paper between the jars. |
| 4. |
Position
the jars so that the string hangs between
them with the lowest part of the loop about
1 inch (2.5 cm) above the paper. |
| 5. |
Allow
the jars to stand undisturbed and out of
any draft for 1 week or longer. |
Results
Water drips from the center of the loop onto the paper.
A hard, white crust forms on the string and grows down
as time passes. A mound of white crystals builds up on
the paper beneath the string.
Why?
Water containing Epsom salts moves through the string.
As the water evaporates, crystals of Epsom salts are
deposited. The Epsom salts formations are models of how
crystals deposits form in caves. Stalactites are icicle-shaped
crystals that hang from a cave's roof. Stalagmites are crystals
that build up from the floor of the cave.
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