Sometime in the late 1980s or early 1990s, my mom bought me a chemistry set. I was in grade school, but I remember thinking it was pretty cool. I also remember being slightly disappointed (particularly after being told that I could only play with it in the garage) that there was nothing in there that could actually blow up.
Many of us are nostalgic for the lost golden era of certifiably dangerous children's chemistry sets. Even if we weren't alive when that era occurred, we're still, sort of, vicariously nostalgic. At the BBC, Alex Hudson has a story about what was really in those misty colored chemistry sets that have lodged themselves into our cultural memory. Along the way, we learn that their demise was only partly to do with unfounded safety fears—some of the fears were founded, for instance, and in other cases, money and seemingly unrelated legal issues got in the way of fun.
By the 1920s and 30s children had access to substances which would raise eyebrows in today's more safety-conscious times. There were toxic ingredients in pesticides, as well as chemicals now used in bombs or considered likely to increase the risk of cancer. And most parents will not need to be told of the dangers of the sodium cyanide found in the interwar kits or the uranium dust present in the "nuclear" kits of the 1950s.
Most will know cyanide as a deadly poison, but one of its main applications is in gold mining. It can make gold dissolve into water.
...Used often to test the presence of starch, the iodine solution once seen in kits is now regulated as a list I chemical in the US because of its use in the manufacture of methamphetamine. It can also be lethal if more than 2g of pure iodine is consumed.
Karen sez, "Instructables user kazmataz has figured out how to freeze alcohol using liquid nitrogen, and made her own cocktail popsicles."
CAREFULLY pour your liquid nitrogen into the container, making sure to not hit the top of your pops. You want enough LN2 to go about halfway up your pop molds.
While that's continuing to bubble away, pour some more LN2 into your smaller container. Delicately pour a little bit on top of your popsicles. It will all evaporate away, so don't worry about consuming any - this is just to ensure things freeze evenly from all sides.
Let the whole thing sit for a few minutes, or until the popsicle sticks seem firmly in place.
**pro-tip: besides just sitting there, and watching the popsicles slowly freeze (booooooring), feel free to carefully move the container around, to keep the liquid nitrogen moving. It speeds up the freezing process a little.
Geekdad has a bunch of tips for using the round power-cells from a dead laptop battery. These cells, called "18650s," look like AA batteries, but have very different characteristics. Your laptop battery will contain lots of these (I have a mongo long-lived Thinkpad battery that I use while travelling with nine cells), and if any one of them dies, the whole laptop battery is rendered useless.
18650s are incredibly powerful and volatile, so be careful, because it's easy to blow 'em up or start a fire. That said, they're awful handy-dandy for providing a very long charge for very bright LED flashlights, or for powering your RC vehicles.
By the way, a good quality LED flashlight is incredibly bright. I tried to take some pictures and video to demonstrate just how bright, but you really have to see this with your own eyes, in person to appreciate it. And the LED is incredibly power-efficient, so it runs for a very, very long time on a single charge. It’s easy to see that the future of household lighting is not compact fluorescents, but LEDs...
In the video, I’m actually powering the Arduino as well as the motors, and I’m surprised it works. Motors tend to create a lot of electrical noise, and I’ve read about many other people who ran into trouble using a common power source for their Arduino and their motors. I presume I’d start seeing trouble if I was driving a heavier load than those little Lego motors.
In this video, you'll learn how to use an ultraviolet LED to kickstart a chemical reaction capable of sending a cork flying halfway across a lecture hall. It's a hazardous science demonstration! Hooray!
Quick note: The sound quality gets a little sketchy at times. If you click on the CC option in the lower-right corner of the player window you'll be able to read the English subtitles.