Place the egg in a jar. Cover with vinegar. The second day, change the vinegar. Put the egg away. Don't look at it for about a week (sometimes it takes longer). Just let it soak away in the vinegar. After a week, the egg should be translucent but still pretty much egg-shaped. The vinegar eats away the shell (which is mostly calcium), leaving the membrane intact. Some of the vinegar permeates the membrane, and since this vinegar takes up more space, the membrane will stretch to accommodate it. This is why the egg looks a little bigger. If you shake the egg, you can see the yolk sloshing around in the white. If the membrane tears, the contents will spill out just the same as with any raw egg, only now they have been "pickled" in the vinegar.
If you do this with a hard boiled egg, the shell will dissolve in the same way, and you will be left with a rubbery egg that should actually bounce (if not dropped from too great a height).
If you are in a very silly mood, try soaking a bone in vinegar for several days to a week. If the bone was fresh enough, you should be able to bend it; even tie a knot in it. This is because most of the calcium has been dissolved, leaving behind other less rigid parts of the bone.
Spin the egg in question. If it spins pretty well on end, it is a hard-boiled egg. If it doesn't spin too well and wobbles, it is a raw egg. Try spinning a raw egg and very briefly touching it, just long enough to stop it. When you take your finger away, the egg will start to spin slightly more. This is due to the inertia of the liquid egg inside.
There are plenty of other dumb things to do with eggs, one being the egg in the bottle trick. Use a shelled, hard-boiled egg. The egg needs to be free from cracks in the white and smooth. Find a bottle with a neck just small enough that the egg won't fall in (a carafe, milk bottle, or some baby bottles). Wad up a little piece of paper and drop it in the bottle (you can also use 2 or 3 wooden matches). Light the paper or matches, allow to burn out, and immediately put the egg in the bottleneck, where it should be sucked in (making a very interesting sound in the process). Actually, the egg isn't sucked in, it's pushed. The fire heats the air, causing it to become less dense and to rise out of the bottle. This causes a decrease in air pressure inside the bottle. The higher pressure outside the bottle pushes the egg in.
A reader recently reminded me that you can easily get the egg out again by turning the bottle upside down and blowing into it very hard. When you take your mouth away, the egg should pop out due to the increased air pressure in the bottle.
A raw egg can also be made to float in very salty water. If you can half fill a glass with salt water, and top it off with fresh water without letting the two mix (pouring the water over the back of a spoon helps), you should be able to gently lower an egg into the glass and suspend it between the layers. It looks pretty cool especially if you don't know how it was done. It is also possible to mix a solution of salt water, through trial and error, that matches the specific gravity of the egg. The egg will float at whatever level it is placed in the jar. When a little salt is added, it will float to the top. If a little fresh water is added, it will sink.
If you are very careful and very steady of hand, a hard boiled egg can be made to balance on end. Any egg can be made to balance on its wide end much easier if you use the secret ingredient: table salt. Form a small heap of salt on a table, and balance the egg in the heap. Then, gently blow away the salt. The few grains which are actually holding the egg in place remain. The egg is covering these grains, so it appears to be balanced without any support.
Update: I have gotten more mail about this one project than anything else on this entire site! There is an ongoing debate about whether or not it is easier to balance an egg on the equinoxes. According to quite a few folks who responded, the "equinox" thing is bunk, and you can get an egg to balance on any day, if you are very careful. While it is true that with a little patience you can get an egg to balance any time, the court is still out on whether or not one will balance any easier or stay balanced any longer on the equinox. Someone with spare research funding should find this out once and for all so we can all sleep peacefully at night! - ed.
Sept. 29, 1999 Update: I ran a questionnaire from the spring equinox until the fall equinox of 1999 about the egg-balancing question. People are pretty evenly and passionately divided on the issue. Out of 245 votes, 30% felt it is at least probably true (half of these were absolutely certain); 12% were not sure either way; 25% were at least fairly certain that it was not true (about half of these felt it was absolute rubbish); and a whopping 33% were fortunate enough to have never even heard of the debate!
Many folks wrote to me describing their egg balancing adventures. The results and theories varied widely. Several people pointed out that an egg could be made to balance on any old day; others claimed that it was much simpler to balance one during the equinox. More than one person had great success, only to realize later that they had done their balancing on the wrong day! One fellow believes that it doesn't matter when the egg is balanced as long as it was laid on the equinox, which supposedly gives the egg a lower center of gravity. And so the debate continues, and the mystery of the balancing eggs still haunts us.
Hard boil an egg - app. 5 minutes. Allow it to cool. Dissolve as much alum as will dissolve in about a tablespoon of vinegar. Alum is found in the pharmacy or in the grocery store with pickling supplies. Use this solution to write on the eggshell using a toothpick. Once the egg is dry, it will look perfectly normal. When the shell is later removed, the writing will be visible on the egg's surface. Note: although alum has been used for years in pickling, it is no longer considered as safe as it once was (aluminum compounds may be linked to Alzheimer's Disease) so it is best not to make a habit of eating too many of these eggs. Also note that this trick doesn't always work. It seems to depend on the egg used. I am going to do some experiments with different brands of eggs (free range and otherwise), boiling times, etc. If and when I find the "secret" to making this work every time, I will add it here.
This requires a dry white hen's egg at room temperature. Hold an egg near a candle flame to cover it with soot. It will need to be completely covered. This is tricky, because if the egg is a tiny bit damp the soot will easily flake off on to your fingers as you turn the egg. Be careful not to burn yourself! Once the egg has a nice black sooty coating, gently immerse it in a bowl of water. If it is completely covered, the carbon in the soot repels the water and holds a fine film of air. This will give the egg a silvered mirror appearance.
Eggs are surprisingly strong and will stand up to forces applied evenly to them. They don't stand up so well to uneven forces, which is why they crack easily on the side of a bowl or break when they hit the ground. Hold an egg, completely surrounding it with your hand. Squeeze it, making sure that the pressure is even all around. You should be able to squeeze it very hard without breaking it (do this over a sink or bowl just in case). The egg may break if it is already slightly cracked, or if you are wearing a ring.
The empty shells are also fairly strong. If you are able to break eggs so that the shells are halved, top to bottom, set aside 4 half shells, rinsing them out and letting them dry. Trim off the jagged edges with scissors. They should all be about the same height when sitting open end down. Carefully set them under the corners of a large book. You should be able to add quite a few books before the shells finally reach their limits.
Bruce Weertman writes:
OK now for the magic trick...
I saw a magician do a long trick with this and was quite amazed!"