Have you ever wondered why every time you eat salty foods, you get thirsty? Or why fresh vegetables tend to shrivel up when you sprinkle salt on them? The answer is simple. Salt is a desiccant - it helps remove water from things, including human bodies. In this activity, you will experiment with different salt compounds and discover which makes the best mummified apple.

Materials

• 2 fresh apples
  
• large box of table salt
  
• large box of Epsom salts
  
• large box of baking soda
  
• knife
  
• eight 12-oz disposable plastic cups
  
• measuring cup
  
• large mixing bowl
  
• permanent marking pen
  
• roll of masking tape
  
• sensitive balance or food scale
  
• piece of graph paper and pencil

Method

1. Slice the two apples into quarters so that you have eight slices similar in size. Place a piece of tape on each cup and write the words "starting weight." Select one slice, weigh it, and record the weight on the outside of cup 1. Follow the same procedure with the other seven apple slices until each cup has been labeled with the appropriate starting weight.
   
2. Add exactly 1/2 cup of baking soda to
   cup 1, making sure to completely cover the apple. Write the words "baking soda only" on the outside label. Fill cup 2 with 1/2 cup Epsom salts. Fill cup 3 with 1/2 cup table salt. Make sure you label each cup.
   
3. Repeat the same procedure for cups 4-6 using a 50:50 mix of Epsom and table salts in cup 4, 50:50 mix of table salt and baking soda in cup 5, and a 50:50 mix of baking soda and Epsom salts in cup 6. Again, make sure each cup has the correct label.
   
4. In cup 7 make a mixture of 1/3 baking soda, 1/3 Epsom salts, and 1/3 table salt. Leave cup 8 alone as a control. Place the cups on a shelf out of direct sunlight and let them sit for seven days. After a week has gone by, take out each apple slice, brush off as much salt as possible, and reweigh. (Do not rinse the apple off because that will rehydrate it.) Compare the starting and ending weights of each slice and calculate the percentage of weight which is moisture lost for each by dividing the difference in weight by the starting weight.

    

Salts and special drying solutions played important roles in preserving mummies, but they also served another purpose. Before refrigerators and freezers, people had to preserve food by pickling, drying, salting, and smoking. Visit a local food store and see how many foods you can find that have been preserved the same way as mummies. Try your hand at drying different fruits. How do the textures and tastes compare?

Find out how hard it is to reconstruct pottery at an archaeological site. Assemble five or six old clay flower pots and decorate them on the outside with either magic marker or paint. Try to make each design distinctive. Now, place all the pots into a large paper bag and close the top. With a hammer, gently bang on the pots inside the bag until they are all broken into pieces. Next, shake the bag several times and dump out half the pieces. Using white glue, try to reassemble as many of the original pots as you can.

How do you look inside something without opening it up? This is a problem that archaeologists face every time they find a new mummy. To get an idea of how tough this really is, try the following activity. Take an old shoe box with a lid and have a friend place a "mystery object" inside. Tape the lid closed and try to figure out what's inside by sliding it back and forth, shining a light in it, tapping on it with a pencil, etc. The only thing you can't do is open it up and look inside!