Liquid Nitrogen Smoke Cloud!

Among my favorite new pieces of science equipment are my liquid nitrogen dewars. A dewar is a special container designed to store liquefied gases. It is like a special thermos but much larger. When you have a dewar and are trained in safely handling one, you can do science experiments with liquid nitrogen.

Liquid nitrogen is a super cold liquid version of nitrogen. It is so cold that is boils at −320 °F. That is 352 degrees colder than the temperature that makes water freeze. And it is even colder when it is still a liquid! That’s cold!

My first dewar after filled for the very first time! It weighs over 100 pounds filled and is being loaded into the Yuckmobile with a forklift!
My second dewar is the one I use for shows. It is much smaller an has a blue wrap. My sometimes co-host Luke is shown with it here!

One of my favorite demonstrations with liquid nitrogen is making a ‘smoke cloud.’ The smoke is actually a nitrogen being released as a vapor. In this demonstration, you poor warm water into a container of liquid nitrogen. The extreme temperature change causes the nitrogen to turn into a vapor immediately, and if you watch closely, you can see little chunks fly out, which are piece of a ice that were instantly frozen by the liquid nitrogen. That’s really, really cold!

Making a ‘smoke cloud’ with liquid nitrogen

Follow this blog or subscribe to the Yuck Science youtube channel to see more liquid nitrogen demonstrations soon!

Public Science – Elephant Toothpaste!

Elephant toothpaste foam swirling in front of Empires13 mural

I hit the streets again and did some elephant toothpaste demonstrations with passersby in front of a really cool mural near downtown Houston. Check out the video below!

Elephant toothpaste is getting to be a really popular science demo! It is a chemical reaction using hydrogen peroxide and a catalyst to increase the release of oxygen. The oxygen in caught in dish soap, creating the foam. I use potassium iodide as the catalyst and a really strong hydrogen peroxide for a really big effect, but those chemicals require careful handling. You can try the demonstration safely at home using the instructions below!


  • Empty plastic bottle, or experiment with different sizes and shapes of containers!
  • Dry yeast packet (found on the baking aisle of the grocery store)
  • Warm water
  • Liquid dish soap
  • 1/2 cup 3% or 6% hydrogen peroxide
  • Measuring cups 
  • Measuring spoons
  • Safety glasses
  • Plastic sheet or container to catch the foam . . . or try it outside!


  • Use safety glasses because hydrogen peroxide can irritate your eyes.
  • Gloves are a good idea too, at least for clean up!
  • Place your plastic bottle on your plastic sheet or container, or do the experiment somewhere that will be okay if you have a spill.
  • Mix one tablespoon of yeast and three tablespoons of warm water together. Stir for about 30 seconds. Set aside.
  • Measure 1/2 cup of hydrogen peroxide, and carefully pour it into the bottle.
  • Add a nice big squirt of dish soap into the bottle and give it a light swirl to mix. Soap creates the foam, so don’t skimp here!
  • Add a few drops of food coloring directly into the hydrogen peroxide, Or if you want to give your foam stripes like toothpastes, put the drops along the inside rim of the bottle’s mouth. Let them drip down the inside of the bottle without mixing them. 
  • Pour the yeast mixture into the bottle, and watch your reaction!

Hopefully, you saw lots of bubbles and foam when doing your demonstration! When the hydrogen peroxide comes into contact with the yeast it starts breaking down into water and oxygen. Oxygen is a gas and it gets trapped as bubbles in the soap, creating the foam. The reaction continues as long as there is some hydrogen peroxide and yeast left.

You can try this with different-shaped containers, as you see me do in the video above! What happens if you use a bottle with a narrower or wider neck, or a container with no neck? Have fun!

Public Science – Downtown Houston Mentos Geysers!

Today, I took the Yuck Mobile on the road and did a science demonstration in a park near downtown Houston with a sweet family and a very nice man visiting from Atlanta, Georgia! We made six Mentos geysers with Diet Coke!

This is a physical reaction caused by the Mentos speeding the release of carbon dioxide gas. Notice how the streams are all different sizes? The reaction depends on the number of Mentos that actually make it into the bottle, how quickly they move through the soda, and also the freshness and temperature of the soda.

If you would like to see more public science videos, be sure to follow this page or subscribe to the Yuck Science youtube channel.

PS. Making Mentos geysers is the only thing I do with diet soda. The artificial sweetener aspartame is a neurotoxin and is just terrible for you! I don’t drink Diet Coke or any other sodas, either.

Student Art

Occasionally, students share drawings inspired by the show.  Here is one of a girl getting covered in slime!  If you would like to submit a photo of your drawing to be published here, you can ask a parent to help you send one.  Be sure to do your very best . . . a lot of people might see it!



How to Make Slime

The number one question kids ask at the end of each show is what’s in the slime!  There are many, many different recipes for making slime.  The one I use, I call “theatrical slime” because it is somewhat different from the types used in science experiments.  It is completely non-toxic and non-staining, and it is even safe to eat (though I wouldn’t recommend it).  Perfect for sliming your friends!


6 quarts of water

1 box of corn starch

green food coloring


Pour water into a large pot.  Stir in corn starch, breaking up any clumps.  Add 5-6 drops of food coloring, or more if you like.  Bring to a boil (with parent supervision).  Reduce to medium-low heat and let simmer for 20-30 minutes, or until slime begins to thicken.  Rinse the pot before the slime dries so it will be easier to clean.  LET IT COOL THOROUGHLY before use.  When I need slime in a hurry, I add ice at the end.  Makes one big bucketful, or enough to slime yourself and a friend.

Souvenir Merchandise

Yuck Game Show t-shirts and other merchandise are available through Cafe Press.  These items were made available for the kind folks who ask for souvenir items.  The prices are set by Cafe Press, and I have opted to receive any of the money from purchases to keep prices at least somewhat low.