Poor man's "Liquid Nitrogen"

FREEZE THE DAISY! Here's yet another science video that's "Not For Kids." It's for science teachers and physics demonstrators. You have to know the safety precautions dealing with cryogenic fluids in order to not injure yourself while doing the demonstration. So, watch the video but don't mess with it unless you know you're doing. This time we're going to make our own liquid nitrogen at home. It's not real liquid nitrogen. It's "Poor Man's" liquid nitrogen. We need... a couple pounds of Dry Ice, and something to chop it up Oh, um, dry ice will last many days if you wrap it up in Emergency Space Blanket. Aluminized Mylar. Also we need a 2-liter pop bottle, a small bottle that fits inside, and ninety nine percent isopropyl "rubbing" alcohol. scissors, big ones or little tiny scissors, and that's it. Poke a bunch of holes in the bottom of the small bottle, and in the sides. Now of course this isn't liquid nitrogen. I was thinking about the difference between dry ice and liquid nitrogen, and I realized that dry ice doesn't make good thermal contact. If it was only a liquid, it would probably work just as good as liquid nitrogen for most of the science demonstrations. So we're going to chill down some alcohol, and use that instead. Use scissors to cut the tops off both of the bottles then test-fit the small one inside the larger. We're going to chop up dry ice into half-inch chunks. then fill the space between the bottles evenly with dry ice several inches deep. Chop up the dry ice however you want. I use a butcher block in the sink. and... keep the dry ice in a bag so all the little pieces don't end up getting lost. Lots and lots of little half-inch chunks. And of course you could save lots of time by buying the pellet type of dry-ice instead of chopping it yourself. Most welding supply stores will have the pellet rather than the block type. Keep the center bottle all the way down, and distribute chunks evenly, so it doesn't get off to the side There. There's three or four inches thick of the chunks and then slowly pour in the 99% rubbing alcohol into the dry ice itself. Oh, you can use seventy percent but it soon freezes into a thick gel. Ah, also this is not like liquid nitrogen, in that the liquid nitrogen beads up off of your skin. This stuff sticks. So don't put your finger in it. It's like "cryogenic ***." You want about two inches deep in there so you have plenty of room to stick in flowers, and leafs and rubber balls. Okay, it's mostly stopped boiling, so it's down in temperature. FREEZE THE DAISY. Thin objects freeze very quickly. Knock all alcohol off and... Frozen flower! Ready? OOPS. Yep, it shattered pretty good. Little pieces all over. Another frozen flower... Here's an un-frozen one. No it doesn't shatter. And I've got a couple of cherries down there. That's where you need the tongs: to get stuff back out. Instant-frozen maple leaf from the front yard. I couldn't find any rubber super-ball in my collection, but we have cherries and grapes. Nope, didn't shatter. Let's try again. Oh... don't put in your mouth. It will freeze to your tongue like a flagpole. Nope. It's more like a stone.