An Eggs-periment in Egg Anatomy

 

by Jennifer Burcke

In my last post, I shared the horror of finding two frozen and cracked eggs waiting for me in our coop on a frigid January morning. I removed their shells and placed them in a bowl in the hopes that they would defrost and be usable in a baking recipe. After they had spent several hours in the refrigerator sans shells, they did in fact thaw and by the end of the day we had chocolate chip cookie bars to eat for a bedtime snack.

In the days that followed, countless chicken keepers shared their methods for combating the bitterly cold weather and frozen water in their coops. I was amazed at the creativity and thankful for all of the great suggestions. I can’t wait to give a few of them a try and share the outcome with you.

As the comments and suggestions came in, I continued to think about the frozen eggs. My curiosity was piqued. My inquisitive nature has a long history of getting the best of me. In fact, my curiosity was responsible for me getting the slightly crazy idea that we should add a flock of heritage breed hens to 1840 Farm. Here we sit less than two years later with a herd of dairy goats living in our circa 1840 barn and a French Angora rabbit happily munching on alfalfa hay.

Now that I consider us a full-fledged farming family, I was ready to put my curiosity to practical use. I wanted to learn more about the anatomy of the egg. As a homeschooling parent, I took it as an opportunity to teach my children a science lesson while also learning something valuable myself.

Enter the website for The Exploratorium Museum in San Francisco. I had visited their site in the past and my children and I had already completed several of the experiments detailed there. In moments, I discovered that their section regarding eggs contained just the type of experiment I was looking for.

If my goal was to learn more about the shell and membrane of an egg, than I had found just the way to do so. It seemed simple enough, didn’t require any materials that weren’t easily at hand in my kitchen, and was bound to make for an interesting educational experience. It was time to gather our supplies and make a few naked eggs.

It didn’t take long to assemble the few tools necessary for this experiment. While the instructions call for putting two or more eggs into one container and then making sure that they are not touching, we opted to put each egg in its own container. Pint-sized Mason jars proved to be just large enough to hold each egg and easy to close in order to mitigate the smell caused by the vinegar.

Soon it was time to select a few eggs. Let me be clear: No farm-fresh eggs were harmed during the course of this experiment. We actually purchased a half dozen eggs at the store. While buying eggs at the grocery store is something I try to avoid at all costs, it seemed like a better option than ruining two perfectly fresh eggs from our coop. I just couldn’t bring myself to put one of our farm-fresh eggs in harm’s way.

We weighed each egg and recorded their weights at 58 grams each. Then it was time to lower them gently into their jars using a tablespoon. We covered them with white vinegar and sealed the jars. Initially, nothing seemed to be happening. We set the jars in the refrigerator and wondered how long it would take for them to begin their transformation.

When we checked on the eggs a few hours later, the shells were still intact. However, bubbles were forming on the shells and rising to the surface of the vinegar. The vinegar contained in the jars resembled a carbonated beverage more than it did plain vinegar. We were hopeful that by morning we would have two shell-less eggs to investigate.

By morning, the shells were not gone, but we were making progress. The shell had begun to break down and small portions were completely dissolved. Bubbles were still forming and rising to the surface taking small particles of the disappearing shell with them.

The acetic acid in the vinegar was clearly breaking the egg’s calcium carbonate shell into calcium, which was rising to the surface. At the same time, the acid was reacting with the shell to create carbon dioxide in the form of bubbles. We also noticed that the eggs began to float in the vinegar solution. Each time we opened the refrigerator door, they seemed to be closer to floating to the surface of the vinegar.

Once we hit the 24-hour mark, we checked and found that the eggs were far from being shell-less. So, as the instructions recommended, we removed the eggs from the jars to observe them and then returned them to clean jars and covered them with fresh vinegar. According to the experiment’s instructions, we would find completely naked eggs in another 24 hours.

We did not find shell-less eggs the next day. We made the decision to repeat the process of draining the jars and replacing the day-old solution with fresh vinegar. Apparently, the third time was the charm. The next morning, we discovered that our eggs were finally free of their shells and it was time to remove them so that we could take a closer look.

The first observation we made was how much the naked egg had increased in size. In fact, it was nearly double the size of an egg that we had reserved from the half dozen purchased at the store. The eggs had weighed 58 grams at the beginning of our experiment. We now had two shell-less eggs that weighed 90 grams and 98 grams, respectively. It was clear that not only was the vinegar working to dissolve the shell, it was also being transferred through the membrane into the egg.

Using a paper towel, we carefully removed the remnants of the dissolved eggshell. The membrane was intact and resembled a water balloon. Pressing on the membrane with my finger allowed me to make a depression, but its elasticity prevented it from breaking. I found myself marveling at the strength and flexibility of the membrane. Even though the egg’s membrane was now holding over an ounce of vinegar along with the egg, it was still doing the job that nature intended.

In minutes, my children were talking to each other about the eggs, the shells, and the miraculous membrane that had survived an environment that the shell could not. Out came the microscope. Soon there was a slide made with a fragment of the dissolving eggshell. Under the microscope, it became clear that what was left of the shell was incredibly porous.

After we had all given the naked eggs a full inspection, it was time to move on to the second part of the experiment. We had already seen firsthand that the eggshell could not stand up to the acetic acid in the vinegar while the membrane had emerged unscathed. Now it was time to see what the membrane could do on its own.

We placed one egg in a clean jar filled with tap water. The second egg was destined for a jar filled with corn syrup. While the first egg was happy to sink in the water, the second refused to be submerged in the thick corn syrup. Instead, it floated on top like an egg-shaped ship lost at sea. I tried to push it down into the syrup, but it was no use. Now it was time to place them both back in the refrigerator for 24 hours.

The next morning, the corn syrup egg had already been transformed. The membrane had given us a lesson in osmosis that was so easy to understand that my 6-year-old grasped it immediately. Because the corn syrup does not contain much moisture, the selectively permeable membrane of the egg had allowed liquid from inside the membrane to exit into the container in order to equalize the pressure. When that happened, the egg was suddenly flabby and deflated, weighing a mere 50 grams. In fact, there was a considerable amount of vinegar now floating on top of the corn syrup in the Mason jar.

We could actually pinch the membrane between our fingers and even pick the egg up by the membrane. In contrast, the egg that had spent the evening in water had ballooned up to 91 grams. Its membrane was stretched so tightly that we could no longer press our fingers into it. It felt as if it might burst at any moment.

We held the egg that had been in water up in front of a light to see how translucent it was. We could see the contents of the egg clearly. It was as if we had a three-dimensional cross section of an egg. It was easy to see the yolk, albumen and chalaza. By rotating the egg, we could watch as the contents moved freely.

After we finished inspecting the egg in the bright light, we moved on to complete the experiment. We returned the full egg to its water bath. The egg that had spent 24 hours in corn syrup was placed in a clean jar and covered with water. Within a few hours, it had absorbed enough water to be fully formed. When we weighed both eggs the next morning, they each weighed 94 grams.

This experiment reminded me of the marvel of nature that an egg represents. Magic happens out in our chicken coops every day. Now, thanks to our hens and a few store-bought eggs, magic had happened in my farmhouse kitchen. My children learned not just about the egg, but about chemical reactions, osmosis, and permeability while having fun. Here's another amazing fact: I had as much fun as they did and learned a lot about the anatomy of the egg in the process.

Tomorrow morning, when I’m out in the coop delivering morning oatmeal to our hens, I may have to make one change to our morning routine. Instead of addressing them by their names: Hedwig, Amelia, Bertha, Marigold, Abigail, Fawkes and Sally, I may have to call them by a more descriptive moniker. Until I can figure out the appropriate greeting, I’ll guess that, “Good morning, professors” will have to do.

This spring, we'll be making a few additions to our flock and sharing the experience with you. The chicks are ordered and will be arriving in April. I will be chronicling the life of our new chickens from day-old chicks into laying hens through a recurring series of posts about life in the coop at 1840 Farm. Stay tuned!

You're always welcome at 1840 Farm. Visit our blog at www.1840farm.wordpress.com.

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