I haven’t tried doing many “do it yourself” projects from the internet, and so I wasn’t entirely prepared for what I was getting myself into. The steps given on the website I was working off of were pretty simple:

1. Get a jar
2. Put something absorbent on the bottom of the jar
3. Add some alcohol
4. Let sit for a while
5. Put on dry ice
6. See trails of awesome!

I believe I can confidently say I messed up every one of these steps in some way or another. Fortunately I learned a few things and got the contraption working in the end. This post however, is not about that. It is about all the things that can go wrong while you are trying to make a cloud chamber from instructions you get online.

Getting a Jar:

I am still unsure as to what the ideal jar for this project might be, but I have a few criteria that might aid in selecting an appropriate one. Firstly, the jar should Square sides, or at least as square as possible, and it should be as easy to see through as possible. The clear sides should be self-evident; the roundness issue surprised me though. The curved sides really distort what you can see through the jar and will make using the device later quite a headache.

The jar should also have a good, airtight seal. At first I entertained the idea of using a plastic container, but most do not actually retain a seal once they’ve been opened. I would also worry about the plastic becoming brittle in contact with the dry ice, though I cannot speak with any authority on that matter.

Finally, the jar should either be already empty, or filled with something delicious that you wouldn’t mind eating. Wasting food isn’t good, but neither is trying to eat through a jar of Salsa Con Queso single handedly.

Putting something in the jar:

This is where I had the most trouble. It does not sound like a horrible task, but the devil is in the details. First, the directions I was following said to put the cloth in the “bottom” of the jar. I interpreted this to mean the bottom as it was lid down on the block of dry ice, meaning on the lid. A little common sense (or just looking at the diagrams) would show this to be a bad idea, but I did it anyways. The directions also recommend attaching the cloth using a clip of some sort, and if that fails, one could resort to epoxy. At first, I did not have any ideas for how to fashion a clip, so I leapt right in with super glue (which I figured to be just as good as epoxy).

Super glue was a bad choice for two reasons. Firstly, it does bad things to anything plastic or rubber its vapors come in contact with. In my case, this happened to be the all important seal on the lid. After that, I could no longer get an air tight seal on the jar. The second problem was mostly cosmetic, and actually kind of cool. If super glue is heated, it releases vapors that will bind to oils left on a surface. According to the internet, this technique is often used by CSI labs for preserving fingerprints. In my case I, for some reason that I no longer remember, closed the jar while the glue was drying and when I went to check on it, I discovered my fingerprints highlighted throughout the inside of the jar.

Putting the alcohol in the jar, and letting it sit:

This part of the project did not cause me a whole lot of problems, though when I first attempted the project I did not understand the importance of letting the jar sit for 15 minutes. The goal seems to be letting as much alcohol as possible vaporize in the jar before the dry ice causes it to condense. This can be sped up by heating the jar. I used a halogen desk lamp to do this, and it seemed to work pretty well. This is when I noticed that I had messed up the seal on the jar though. It started making squeaking noises as the pressure rose from the evaporating alcohol and the gas started escaping.

After I realized the experiment wasn’t going to work, I decided the best way to dispose of the alcohol vapor would be with fire. Plus I figured it would be interesting to photograph. The exposure is several seconds long, and the bright streak is the match I lit it with.

Figure 1: For Science

The Dry Ice:

By this point, I already knew that the experiment wasn’t going to work, but I felt compelled to try it anyways, because I had already gotten the dry ice. When I put the jar on the ice, it immediately started making the same squeaking noises as before as air escaped back into the jar. Looking closely I noticed little jets of mist where the air was disturbed, but it was quickly evident that I would not be seeing any cosmic rays or anything of the sort. With that attempts officially a wash, I decided to play around with the dry ice a little bit, and I discovered a few interesting things. First of all, everybody (including myself) warns to be very, very careful with dry ice, because it can give you frost bite very quickly. What I think is interesting though, is that it did not provide the warning signs that I encounter with other cold materials. Anybody who has ever licked a light pole in sub freezing weather (It took me until college to try that one) can tell you that your tongue, or rather the saliva on it, will freeze and stick very quickly. The same is true for touching a fresh ice cube in the freezer: your fingers will stick to it. I notice that I use that as a sign that I need to immediately stop what I am doing or else I might be in for a bit of pain. Oddly, with dry ice, this doesn’t happen. If I touched anything touching the dry ice, such as the pan it was in, my fingers would start sticking, but if I bumped the block itself, nothing would happen. I think this makes it more dangerous, because while it still causes damage, and it does so more rapidly than most cold things you encounter on a regular basis, it does not give warning that it will mess you up. I suppose the moral of the story is that the people who tell you not to do are often right, but not for the reasons you might expect.

I did discover one fun thing while I was playing with the dry ice. I started by putting water directly on the block of dry ice, and once I got a drop to stay on, I watched it freeze. Instead of freezing into a regular shaped drop like I would expect, it formed sort of a Hershey kiss shape as the expanding ice pushed up through a contracting hole. There are some resources that talk about this sort of phenomena happening in birdbaths and ice cube trays, and some instructions for attempting to create “ice spikes” of your own, but I thought it was interesting to have stumbled on the concept in a completely different way.