Natron and mummies: an old use of alkalis
In Egypt, at salt lakes in the desert of Wadi El Natrun, a natural white powder collects as the water dries. It is called natron. Natron is a mix of salts, and it is alkaline. It has a special power: it takes up water, a bit like a dry sponge. The ancient Egyptians used this power to dry things. They also used natron for cleaning. Natron was one of the materials they used to keep a body from decaying when they made mummies, because a dry body does not spoil as quickly. This is an old use of an alkaline material. You do not need to know how the mummies were made in detail; the main idea is that a natural salt that absorbs water was very useful. Today we know natron is alkaline, because we can test such materials with litmus paper.
| Fact card | Natron |
|---|---|
| colour | white |
| found at | desert salt lakes |
| special power | takes up water |
| kind of solution | alkaline |
Water-takers. With a grown-up, put three drops of water on a dry sponge and three drops on a plastic lid. Which one takes the water in? Natron is a powder, not a sponge, but it takes up water in a similar way. Do not taste anything.