I was surprised by how many readers have large volumes of hydrofluoric acid in their labs. What do you use it for? Industrially, HF is used to make drugs, refrigerants, and plastics. It is used to purify aluminum and uranium. It can etch glass, remove impurities from silicon, pickle steel, and catalyze alkylation reactions in oil refining. Geologists and rock hounds sometimes use it to dissolve rock samples. You may have a little hydrofluoric acid in your home if you have certain rust removal or wheel cleaning products. Otherwise... why have jugs of it? If you have an answer, by all means, post a comment to the blog.
Another thing I found myself wondering was why a high school chemistry teacher would have a gas mask. Walt neutralizes the hydrofluoric acid with baking soda. That's nice and all, but just because the goo isn't corrosive, it doesn't mean the mess is safe. All that fluorine went somewhere. I don't think sprinkling any amount of baking soda would get me on my hands and knees with nothing except a mask, lab apron, and gloves between me and that toxic waste.
List of Elements in the Body | Photo Gallery of Body Elements
Photo: 65% of the mass of the human body is oxygen, shown here in its liquid form. (Warwick Hillier, Australia National University, Canberra)