We were curious about exactly what the helium gas outlets, captured in our pick for Photo of the Day by volcanojw, were for in the Library of Congress — and boy are we really glad we asked. Volcanojw has pretty much the coolest job ever; she’s a Research Chemist with the LoC and has been working with daguerreotypes for the past few days. She told us she’s trying to figure out:

• What did 19th century photographers use as plate bases for their daugerreotypes?
• Can we tell what the tarnish is on his plates?
• Can we treat the tarnish without destorying the image?
• Do multiple sensitizations change particle size/distribution?
• How can we clean off organics (like bugs) without destorying the image?
• Can we use hyperspectral imaging to re-create what an almost-gone image once looked like by using UV and infrared light?

Got all that? Science! (NB: The helium gas isn’t used in her work, they’re just in the lab.) Volcanojw’s answers are all way cooler than the story I was going to tell about my crazy high school chem teacher turning on all the gas outlets in our room and lighting them on one unusually cold day (ridiculously unsafe lab practices aside, it did, in fact, get pretty toasty in there). Drool over volcanojw’s job, or just make your gas jokes, in the comments.