Key concepts

Human biology

Water

Mummification

Desiccation

Decomposition

Introduction

Mummies are frequently featured in movies and television shows—often playing the part of a scary, undead monster. But in ancient Egypt and in other cultures, mummification was a serious religious burial ritual. In this activity you will learn about the science behind the process of mummification by mummifying a hot dog.

Background

A mummy is a corpse—human or other animal—whose tissue has been preserved, whether intentionally by a process developed by humans or in nature by an accident of chemistry or weather. Ancient Egyptians believed that preserving the body was an important preparation for one’s afterlife. The oldest evidence of Egyptians performing mummification dates to about 3500 B.C. (although older purposefully mummified remains have been found elsewhere, such as ones dating to about 5050 B.C. in Chile). We have also learned a lot about early animals and humans from individuals that were naturally preserved, thanks to a fluke burial in sediment or ice.

There were several steps to the Egyptian ritual of mummification that were important for preserving a body: After thoroughly washing it in the waters of the nearby Nile River, specialists would remove several internal organs from the body. This was important because internal organs are some of the first bodily parts to decompose. The body would then be stuffed and covered with natron to desiccate it (or dry it out). Natron is a naturally occurring salt mixture that includes baking soda (sodium bicarbonate). Once desiccated (dried out), the body was rubbed with perfumed oils and then carefully wrapped with linen bandages. The remains were then placed inside of a sarcophagus, which was in turn placed inside a tomb. In this activity you'll get to play embalmer and mummify a hot dog using baking soda.

Materials

• Disposable gloves (optional)

• Meat hot dog

• Paper towels

• Ruler

• Piece of string or yarn

• Scrap piece of paper and pen or pencil

• Airtight plastic storage box with lid that is longer, wider and much deeper than the hot dog.

• Approximately six pounds of fresh baking soda. You will need enough to thoroughly surround and cover the hot dog in the box twice.

Preparation

• Place the hot dog on top of a paper towel on a counter or other hard surface. If you want to, you can wear disposable gloves while handling the hot dog.

• Observe the hot dog. How does it look and smell?

• Measure the length of the hot dog and its circumference. (Measure its circumference by wrapping the string around the hot dog and then laying that length of the string up next to the ruler.) Write these measurements down.

• If you do not wear gloves while handling the hot dog, be sure to thoroughly wash your hands after handling it.

Procedure

• Put at least one inch of baking soda (from a new, unopened box) in the bottom of the storage box. Lay the hot dog flat on top of the baking soda. Cover the hot dog with at least one more inch of baking soda, making sure the hot dog has baking soda along its sides and is completely covered on top.

• Seal the box with its lid and put it in an indoor shady location away from heating and cooling vents where it will not be disturbed. It should remain undisturbed for one week.

• After one week check on the hot dog. You may use gloves to handle it or wash your hands afterward. Gently tap and dust all of the baking soda off of the hot dog and into a trash can. How does the hot dog look and smell now?

• Place the hot dog on a paper towel and measure its length and circumference. Write these measurements down. Has the length or circumference changed?

• Discard the old baking soda and clean out the box. Make sure you dry it thoroughly. Again, from a fresh box, put at least one inch of baking soda in the bottom of the storage box. Lay the hot dog flat on top of the baking soda and then cover it with at least one more inch, making sure there's baking soda along its sides and completely covering it on top.

• Seal the box again and put it back in the location where it was before. It should remain undisturbed for one more week.

• After the week has passed check on the hot dog. Gently tap and dust all the baking soda off of the hot dog and into a trash can. How does the hot dog look and smell now? How is its condition different from that of the first day, and after being mummified for just one week?

• Place the hot dog on a paper towel and measure its length and circumference. How have the measurements changed compared with the first day and after just one week of mummification? What do you think this tells you about the mummification process?

• Extra: Try this activity with different varieties of hot dogs. Do chicken hot dogs mummify faster than beef hot dogs? What about hot dogs made with a variety of meats?

• Extra: If you saw a big difference in the hot dog at two weeks compared with one week, then the hot dog may still only be partially mummified. You could continue to mummify it, adding fresh baking soda and recording measurements and observations once a week for a few weeks until you do not see any more changes. How long do you need to repeat this mummification process until the hot dog is completely mummified?

• Extra: Investigate the different ways that ancient people mummified human remains and/or how living things have been naturally preserved (such as with the bog bodies found in northern Europe or even a mummified dinosaur that was discovered in North Dakota). How could you apply any of these techniques to mummifying a hot dog?



Observations and results

After one week of mummification did the hot dog look darker in color, smell bad and shrink slightly? After two weeks did the hot dog look about the same and shrink only a tiny bit more, if at all?

Baking soda is a desiccant, which is a substance that dries out things close to it. It does this by absorbing moisture from its surrounding environment. The baking soda should have absorbed the moisture from the hot dog, desiccating (drying) it. (Fresh baking soda is needed because older baking soda will probably not be as effective, having already absorbed moisture from its surrounding environment.) As the hot dog lost moisture, it changed color, smelled bad and shrank, with the most significant changes (and moisture loss) being observed after one week and only smaller (if any) changes after two weeks total. For example, you may have seen that the hot dog became about 4 percent shorter and 25 percent smaller in circumference after one week, and about 6 percent shorter and only 27 percent smaller in circumference after two weeks total compared with its original condition. It may not have noticeably changed in color or smell after two weeks compared with its condition after the first week.

Cleanup

Do not eat the mummified hot dog! It can be disposed of in the trash.

More to explore

Secrets of the Pharaohs, from PBS

Mummification, from The British Museum

Mummy Maker, from Discovery Kids

Minding Your Mummies: The Science of Mummification, from Science Buddies



This activity brought to you in partnership with Science Buddies

