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A friend of mine is wanting to make a mercury vacuum gauge, and was asking me if I had any idea where he could get a pound of mercury, and how much it would cost him. Anybody have any thoughts?
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Well, when I worked in the pharmaceutical chemistry department at KU, I'd have just ordered it from Perkin Elmer or somebody like that. I wonder if they'll sell to an individual?
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You can buy 500 g at from VWR for $588.91 CDN. 1 pound is 453.6 g so that's a little more than he needs. I don't know where you'd get it in the states, especially if you're a layperson. Mercury is a restricted product and if has neither the proper training nor the proper ventilated fume hoods he's going to have a hard time getting it. And a hard time not doing himself some serious harm.
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Turns out that his previous figure of "a pound" was vastly over estimated. He actually only wants 10 mL or so! Big difference there.
Anyway, I was able to register at the PerkinElmer site and qet a quote of $79/500 mL. Whether they'd actually ship that to me without some kind of proof that I was a legitimate business with a legitimate need for it or not, I have no idea.
Yeah BtL, I agree that there are some fairly enormous safety risks involved for him here, and have told him as much. Right now he's fairly unphased by this, and thinking of finding someone who does heating and air work, and seeing if they have any old thermostats lying around with mercury switches inside them. I suspect that he'll decide to just buy a mercury vacuum gauge, as they're commercially available, once all is said and done.
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I'm really trying to impress on you how much of a bad idea this is, Noemon. Mercury evaporates much faster than you'd expect it to and is a heavy metal and extremely toxic. It has a health rating of 4 (the highest poison) and a contact rating of 3 (life threatening if exposed to skin) and a pound is a heck of a lot of mercury. It's also a pain to work with, it doesn't move like any other liquid he'd be familiar with. If he does work with it keep it away from heat and other metal surfaces as it has some pretty nasty reactions with those things. (and cyanogens, hydroxides and some carbonyls, but those are probably less of an issue).
Basically, if he doesn't have a proper lab and is properly trained there's a good chance he'll kill himself and whoever stumbles into his workspace and tries to help him.
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Unless he has access to a hood, protective gloves, and a mercury spill kit, I'd tell him to quit dreaming.
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I'll let him know BtL. I already have, actually, but I'll let him know with the level of detail that you've provided.
You know, when I was a kid I broke a mercury thermometer once, and had a fairly entertaining afternoon spent on the kitchen floor playing with it, until I finally knocked it into a crack in the floor and lost it. Kind of makes you shudder to think of the danger kids will inadvertantly put themselves in, doesn't it? It's really a miracle I survived to adulthood (this is just one of many, many things I did as a kid that could have gone dreadfully wrong).
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Unless he buys a whole lot of thermometers it's a moot point. Like I said, it's a restricted product and I doubt a company will sell it to him. It's just not worth their risk.
Yeah, I worked in a lab where a girl dropped one of our 400 degree C thermometers on the floor and didn't bother cleaning it up. Nobody knew until walking by her bench and found the broken glass on the floor, the mercury already evaporated. I know people who still pipette by mouth, people who keep their lunch in the biohazard fridge, and any number of other things. Nothing breeds contempt like familiarity.
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How long would it take the amount of mercury in a typical early 70s thermometer to evaporate? I remember playing with my blob of mercury for at least a couple of hours, but if it evaporates that quickly I must be misremembering.
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Just a quick comparison for your friend, Noemon. Potassium Cyanide (and we're all familiar with cyanide) also has a Contact safety rating of 3 but only has a Health safety rating of 3. That's something he might take notice of.
As for the evaporation rate, it's expressed as a ratio so it's unitless. Mercury is a 4 (when BuAc (butyl acetate) = 1). By comparison ethanol is around 2. So mercury evaporates roughly twice as fast as ethanol. Most of the times you see mercury it's something like Mercury Acetate. Something that's less volitile. I don't actually know what's in thermometers, but now that I think about it I doubt it's pure mercury.
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Bob, I think it is pure mercury, unless you get the red thermometers. This is because it is the surface tension and expansion and contraction properties of pure mercury (Hg2) that the thermometers were based on in the first place.
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I understand the science that gave way to the thermometer, Banna . It's just thinking about this safety stuff that got me wondering about it. Of course, you do read about children dying after playing with broken thermometers every now and again so I suppose it is very possible.
What is the red one, anyway?
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A school in DC was contaminated when some stupid, stupid kids stole some and spread it around everywhere. At least one kid painted her hands with it.
They closed the school for a while, and decontaminated a bunch of houses.
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When I was in elem. school, some of us kids went over and dumpster dived at the local phone company (switching?) center [it was a one-room, one-floor building filled with brightly colored wire).
In addition to bits of wire and circuit boards (exciting finds for a nine and ten year olds), one of the kids knew that if you cracked open these little plastic cases that were in the dumpster they had about a kidney bean-sized amount (sorry -- can't picture fluid amounts very well) of mercury in them. All the kids though it was so cool. We had a vague sense that it was dangerous so we cracked the cases over a Dixie cup. But some of the kids actually poured the mercury out on their hands and played with it.
I did not -- I was a rather cautious child. In fact, I stayed well away from it.
I wonder how that one kid knew how to find the mercury.
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Long live ear thermometers. Fast, easy, hard to misplace, unlikely to be a source of broken glass and spilled mercury, and incapable of being placed in the rear.
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Well, I spent most of my lunch hour trying to talk the guy out of trying to build his own mecury vacuum gauge. We'll see how successful I was. He's agreed to at least price commercially available models before attempting to build one on his own, but he's not happy about it, as he says that he feels like he could improve on the design of the ones he's seen (this is the guy I've talked about before who is incredibly mechanically gifted, and would have made a brilliant engineer had he decided to pursue it instead of going into first auto repair and then computer networking).
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I didn't know vacuum gauges used mercury in them.... I guess I should ask my boss - he'd know.
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brandy is an amber color liquid, that contains a lot of ethanol so it makes sense. You've got to have something that shows up well against a clear background.
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Pure mercury can't be absorbed through the skin, Ic. And a small drop in a large classroom shouldn't concentrate the air enough to cause significant harm. But there are two dangers. The first is your body's ability to deal with it once it enters the blood stream. Mercury dissolves readily in blood and if it gets into red blood cells it gets oxidized into Hg2+, effectively trapping it inside the cell. Which may seem bad (and it certainly isn't good) but is better than what happens in some more metabolically active cells where it gets methylated. MeHg is able to directly take part in many biochemical reactions and can cause a plethera of different problems, especially if it works its way to your brain. The greater the concentration of mercury in your body the more likely some gets methylated (although any concentration could be).
The other risk is that Mercury is a pretty reactive metal and a number of its other forms are also toxic. So if you're playing with a blob you're not really in control of what other compounds it's coming into contact with. HgS, for example, is really toxic.
Noemon's friend could be fine. Many people are fine after handling mercury directly. Many people are also fine after working with radiation with no shielding but it's generally considered to be too much of a risk to be worth it.
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Good news--my friend found plans online to build what he wants to build using water rather than mercury, so potential disaster averted.
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I'm actually amazed that he listened to me enough to even research non-mercury alternatives. He's probably the most stubborn, hard headed person I've ever met. Great guy though.
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I once broke a thermometer, and that stuff is hard to clean up. It turns into little balls that roll around. You can't mop it up- it has to be coaxed.
Exactly how much mercury is dangerous?
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I paid extra when I ordered lab supplies a few years back to get the red alcohol thermometers instead of the mercury ones. (Not sure if they're still a bit more expensive, but they were 5 years ago.) I just remember very well the comment made in one of the lab-safety-for-HS-lab-instructors manuals I had read: spilled mercury poses a minimal risk for students, who are exposed to fumes for less than an hour (generally); but a large risk to the instructor, who is exposed all day.
Besides, when they break (and it is when, not if, of course), the alcohol ones don't need special precautions to clean up.
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. It's just thinking about this safety stuff that got me wondering about it. Of course, you do read about children dying after playing with broken thermometers every now and again so I suppose it is very possible. ![[Roll Eyes]](rolleyes.gif)
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FG
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