Bubbling Witches' Brew: Scientifically Scary

About author / Christine Gable

Culinary enthusiast; kids cuisine and slow cooking; magazine recipe developer; professional writer. Her simple recipes are great for family dinners.

Before kids, Halloween used to almost be a bother. It seemed like just another chore, to make sure that I had a basket of treats to hand out to the little ghosts and goblins.

Fast forward thirteen years later—after life with kids—and my entire experience of Halloween has evolved. Halloween, a bother? Certainly I was too young to be such a fuddy-dudd. Amazing what fun and learning kids can bring into your life.

Take, for example, making punch for a Halloween party. While you could just go with soda or regular punch, it’s a prime opportunity for making some creepy scientific discoveries. That’s what happened when we discovered dry ice. It’s the perfect Halloween experiment since it creates plumes of white eerie vapor when it comes in contact with warm liquid. And the warmer the liquid, the more it bubbles and blurps when it’s dropped in.

Yet beware, little ghouls and goblins: dry ice is so cold, that you have to wear gloves to touch it, or it will burn your skin. One other trick to dry ice is finding a supplier. Search for the supplier nearest you here.

We have to drive about 20 miles to the nearest supplier, a bulk foods market. Usually a few phone calls to restaurant supply houses or bulk food suppliers will put you in touch with a local company that carries either bricks or pellets of dry ice.

What exactly is dry ice? It’s frozen carbon dioxide. And it’s really, really cold: -109.3 degrees Fahrenheit to be exact. (That’s -78.5 degrees Celsius.) It’s really important to wear heavy gloves so that you don’t get burned when handling it also. Sure, the cold temperature makes it great for transporting frozen items long-distance—it arrives intact without any wet melted mess of regular ice. How come?

This is where the scary science applies: Dry ice sublimates. This means that as it breaks down it turns directly into carbon dioxide gas rather than a liquid like regular ice. Voila—it keeps perishables cold, with not a trace left behind. Plus, it evaporates into vapor quickly, so obtaining it as soon as possible before you need it is vital for having enough left. One year I bought it too far ahead of time and when I opened the bag, there were only a few pellets left. It had seemingly evaporated into thin air—and where I thought I had a whole bag full of dry ice, I really had almost none left. So try to buy your dry ice within 24 hours of using it—the sublimation rate is five to ten pounds every 24 hours in a typical ice chest.

Another safety consideration when using dry ice is ventilation. Always make sure the room you’re using it in is well ventilated. Remember, this is carbon dioxide that you’re releasing into the air. Levels above 5 percent in the normal air can be toxic (normal air is composed of 78 percent nitrogen, 21 percent oxygen and only 0.035 percent carbon dioxide). So don’t transport it in a closed vehicle or use in a small-unventilated space.

That said, do have some fun and try the excellent experiments here, which will also answer questions for young, inquiring minds as to how dry ice is made.

Or try what my kids did: drop the dry ice pellets into bedtime bathwater. With a variety of cups, containers and playtime teakettles, they had a bubbling, good time in the bath. (Just remember to open the window and caution them about getting it directly against their skin.)

Here’s hoping you all have a scientifically scary Halloween!

Serves/Makes: 24

• 1 bottle (64 ounce size) grape juice
• 2 bottles (2-liter size) lemon-lime soda or ginger ale

***Fun floaters***

• frozen grapes (eyeballs)
• ice cubes