itspip wrote:
When I was planning on being a teacher, during my student teaching the co-op teacher had me pour about 25mL of waste acetone into the sink. I think his thought was that it would evaporate just fine. In the first class he had me showing off a Tesla coil and specifically had me show that it could ignite a paper towel. Rather than continue to hold a burning piece of paper as it reached my arm I dropped it into the sink. There was a nice 'woompf' as the acetone that we had forgotten about released its energy.

That woke me up and got the students to all pay attention to my every word that day.

Years ago I was using a hand held tissuemizer and homogenizing samples and had to virtually take apart and clean the thing after every sample to avoid contamination. After removing the barrel exposing the stainless rod with teeth at the end I thought it would be a good idea at this point to stick it in the acetone beaker and pull the trigger. Little did I know at the time that the rod could not support that sort of force without that external barrel. The moment I pulled the trigger that rod bent practically 90 degrees, flipped the beaker and a spark from the tool (or just the contact) sent a 5 x 5 fireball off on the bench in front of me. Luckily it was gone as fast as it appeared and I just had to tamp out a little of the benchtop paper that was burning. Singed my moustache a bit but other than that was fine. I quit cleaning the tissuemizer like that in the future.