Summer students are showing up at academic and industrial labs around the country right about now. A certain percent of them will blow something up within the next three months, and that percent will be several standard deviations above the ka-boom rate of the other lab members. I'm not trying to say mean things about summer students. I merely speak the truth.
I had a summer undergraduate working with me for a while in grad school, and he taught me several lessons, of varying utility. One day he needed some dry benzene for a reaction, so I helped him set up a still in my hood. One-liter round-bottom flask, some benzene, a little sodium. My intern, who I'll refer to as Toxic John, put a heating mantle on the thing and turned it on.
A little while later, I walked past my hood and noticed that the stuff was boiling merrily. A bit too merrily, actually - it was really hopping around in there. I turned down the Variac (basically a big dimmer-switch type AC transformer that's used to step down the voltage to equipment like heaters) and went on my way. But I came back a little while later, and it was still rolling away in there.
If anything, it was worse. I turned down the Variac again, wondering just what was going on, and why my guess about the inital setting had been so wrong. A few minutes later, things hadn't improved much. The benzene was really leaping around, splattering and erupting. I looked a little more closely at the Variac this time, and noticed something that had escaped me: the heating mantle wasn't plugged into the damn thing at all.
Nope, it was plugged right into the wall socket, as some of my experienced readers will have guessed. As soon as I noticed that, I dropped the lab jack that was holding the heating mantle, which gave me a good look at the glowing red coils showing through the woven glass lining. I could feel it on my face like a sun lamp. Cursing, I pulled the thing out of my hood and heaved it into the hallway, right into a shopping cart that we kept out there for visits to the stockroom.
I went looking for Toxic John as the mantle popped and clicked. It was cooling down, but I wasn't. "John!", I shouted (I was pretty crabby back in grad school), "you plugged the mantle into the wall! No wonder it looked like a volcano in there!"
"What's the matter," he asked me. "Benzene doesn't burn, does it?" "Doesn't. . .burn. . ." I said slowly, as a nearby post-doc put a warning hand on my shoulder. "Well," said John, making his case, "it's inert to bromination!" That line of reasoning didn't impress me much, and as I recall, I told him that if he had any more insights like that we were going to find out if he was inert to bromination himself. Then I went off looking for the professor who'd just taught him sophomore organic chemistry, to let him know that his work, once again, had been in vain.