# The density of the water

The density of the water varies depending on the temperature change. Do a simple experiment to prove it.

Take the empty eggshells from which very carefully through a small hole produced all the contents. Close up the hole with a wax. Attach to the wax on the wire or thread a small sinker. Lower this "device" in the high bottle with the water at room temperature. The sinker should be adjusted so that it is kept almost at the bottom of the banks, barely touching it. If you will make the bottle in the cold, you will see that after some time, when the water cools down, "device" will pop up on the water.

When the eggshells is lowered to its original position, bring the bottle in the room. The eggshells will do again the same way. The eggshells will rise up, and then go down.

What's the matter? The mystery is easily explained.

The water density greatest at +4 degrees Celsius. In the cold water the temperature is reduced and its density increases up until the temperature reaches 4 0C. The density of water increases and the eggshells pops up.

With a further decrease in temperature (below 4 degrees Celsius) the water density becomes smaller and the eggshells is lowered again. As soon as you bring a bottle in a warm room, raising the temperature to 4 degrees Celsius increase the density of water, and the eggshells pops up.

A further increase in temperature of more than 4 degrees Celsius again reduce the density of water, and the eggshells sink again.

The experiments were conducted by measuring water temperature with the help a thermometer at different positions of the eggshells.

The density of water also varies depending on its composition, for example, by its saturation with a salt.

Take a glass bottle and drop to the bottom of a cleaned raw potato. Pour half a tin of water. Your potato will lie on the bottom.

Now pour in the bottle a salt and stir it. When saline water density will be increased to potatoes density, the potato separates from the bottom of the bottle and will float between the bottom and the surface of the solution.

Add the fresh water. The density of solution decreases, and the potato begins to descend.