I was working on my cloud chamber today, and I ran into two problems: A) It's not working :) To be more specific, I used compressed air to get the bottom extremely cold. The structure itself is a small plastic throw away cup, with a sponge with 91% alcohol stuck to the top. The bottom (the open end of the cup) is covered in a thin metal plate, and I spray the air onto that. It gets really, really cold. However, I was unable to see any tracks. Is this because i don't havea radioactive source? I thought I might be able to see a muon or positron every now and then, but I guess not... Also, once I was done, a purplish liquid was remaining in the cloud chamber. Could this be a product of the difuroethane from the duster and the isopropyl alcohol? I'm not sure about this. The purple liquid. I got it into a tube as soon as it came, since I'm still not sure what it is. http://imageshack.us/a/img525/7906/20121122131134.jpg [Broken] The set up of the cloud chamber. It looks nasty right now, but that's mostly because of the liquid. Metal bottom, sealed with plasticine. Sponge on top. Black background. http://imageshack.us/a/img831/1209/20121122131226.jpg [Broken] Any help would be appreciated! UPDATE: The liquid is definitely primarily alcohol based. I did some tests, and it's definitely flammable (don't have much left now, lol), and smells like alcohol. I'm just not sure what gives it the purple color.