Image from: http://farm3.static.flickr.com/2013/1818381113_3ea6eeca57.jpg
I dont have much time tonight, because I have 8 papers to read for my 9:30am class. However, I had a good day and wanted to share part of it. Some folks in my lab and I are working on a project that involves trying to get DNA out of rocks that microbes are (presumably) living in. The rocks have been frozen, and the first step is to grind the rocks into a powder so that we can get at all the microbes that might be present within the rock's pores. The way we did this was very basic - mortar, pestle, and elbow grease. However, the key was not to let the rocks thaw out because we wanted to preserve the microbes as they were when the rocks were collected. In order to accomplish this we were pouring liquid nitrogen over the samples as we were crushing them in the stainless steel. Nitrogen is a gas at room temperature (~80% of what you breath in with each breath is dinitrogen, or N2). Nitrogen is a liquid at very cold temperatures, so when you put something in it, it freezes almost instantly. This makes it great for biology because you can freeze tissue samples before molecules start to react and change. LN2 (as liquid nitrogen is called) boils at -196 C (-321 F). When you pour it over something at room temperature it immediately starts to boil. I will bring my camera in next time I do this type of work (the above image is not mine, but gives the general idea) because it looked like a witches brew with nitrogen steam spilling over and down onto the floor as we worked. This is a similar (but more pronounced) effect to that created by dry ice (frozen N2). I really felt like I was in a Hogwarts potions class rather than a microbiology lab... awesome!