For the longest time, mercury amalgamation was the choice for getting gold out of rock. Baser metals like silver, copper, and lead would be found in sulfide or oxide ores which would have to be reduced to drive off the offending substance. Gold, on the other hand would be more or less pure – it was often alloyed with silver or copper but none of those pesky sulfides or oxides.
Gold ore processing was largely a mechanical process, grinding the gold-bearing rock to powder then passing it over a riffle table with mercury in the bottom of the riffles. The gold particles, being heavy, would sink to the bottom of the riffles where it would amalgamate with the mercury there. The fairly solid amalgam would be periodically dug out of the riffles and sent to a refinery where the mercury was separated and sent back to the processor, and the gold refined to a more pure form.
(Man this is getting long-winded) As you can imagine, the recovery of the mercury was not 100% efficient. When I lived in Carson City, I was near the Carson River, just upstream from where the mills for the Comstock Lode were located. The mills are long-gone with just the foundations remaining, but it is highly advised against eating any fish caught from that point downstream for quite a ways due to their mercury content, methyl mercury being the chief worry.
I personally have never handled mercury. I have pictured myself on my deathbed saying, “Okay, bring in that Hg flask – I’m ready.”
I remember playing with mercury, from broken thermometers, when I was a kid in the 50s, before people knew about the danger. I remember having a blob of it on the palm of my hand, then smashing it into lots of little droplets. Then moving the droplets close together, and as soon as they touched they immediately became one new drop. I don’t recall any particular sensation from holding it though, just the sensation of it rolling around on the skin.
What everybody says–playing with mercury was fun. Dip your finger into it, it sort of massages your finger in a way that water doesn’t, and it feels wet. Take your finger out, and it’s dry! Hold it in the palm of your hand, it rolls around.
It splits a lot more easily when it’s warmer so it’s more dangerous then, so we weren’t allowed to pass it around for too long. I think the science teacher kept it in a chilly place–not the refrigerator, but someplace cool.
We also turned several pennies into shiny silver pennies.
>Yeah… how’d you do that, anyway? I’d always heard it could be done, but everytime I tried it the mercury just rolled away from the penny.
Cup the penny and a 5 to 10 mm blob of mercury in the palm of one hand and keep rubbing the penny and trying to push the blob up against it with the other index finger. It doesn’t feel like the mercury is grabbing onto the copper, but it still works. Though, I haven’t done this since pennies started being copper plated instead of solid - anybody know that it still works on new pennies?
and can add a sensation: due to its extreme density, plunging your hand into it will give you a squeeze like your hand in a bucket of sand…the mercury is pushing your hand to the surface: everything floats in mercury.
It didn’t look like there was any water used, it all seemed to be pure mercury. The fountain is actually contained in a glass box to contain the vapours. I assume the air inside is saturated. It did seem that the mercury was pumped in a cycle. The pump would need to be fairly strong and/or large, I would think.
Ok, using mercury instead of KY is all fun and games, but when you coat pennies in the stuff and release them back into general circulation (for kids to stick up their nose or whatnot), isn’t that dangerous?
Man dead from mercury exposure, while trying to reclaim gold. This is why even though people don’t die just because they handled it, you should not use it if possible. I wish I could find the U.S. funded Peruvian expeditionary report to Congress I once stumbled upon. It described the gold extraction rooms which were full of mercury, and the health of peóns working there. The process implementation as described was unbelievable even for that period.
Most people have mercury *amalgam *in their mouth, don’t they? All bound up (probably) safely with other metal? Not quite the same thing as liquid mercury.
Oh. I have no idea. From what was said, it sounded like someone was smooshing mercury onto the penny to coat it in a layer of mercury like I might do with Play-doh. I didn’t realize he was talking about making the mercury chemically react with…the copper?
Mercury has the odd property that it alloys with most other metals from contact at room temperatures. The reason the coating on the mercury penny seems more or less permanent is that the mercury forms an amalgam with the metal in the coin. Mercury amalgams can emit mercury vapor over time, too, but I seriously doubt that occasional exposure to a mercury coated penny really represents any significant danger - the amount of actual mercury picked up by the penny has to be tiny. As noted, many of us have carried dental amalgams around in our mouths for years, and they DO emit some mercury vapor over time. Most studies suggest that hysteria over dental amalgams (widespread, just google for it) is just that, though - hysteria.
I was just looking up stuff about mercury yesterday. Mercury occurs in deposits throughout the world and it is harmless in an insoluble form, such as mercuric sulfide, but it is poisonous in soluble forms such as mercuric chloride or methylmercury (from Wiki). Where “thermometer mercury” falls into this is unknown to me, but I played with A LOT of mercury when I was a kid. We’d smash a bunch of thermometers and get a big-ass ball of mercury about the size of a quarter and would have all kinds of fun with it.
“Thermometer” mercury is pure metallic mercury, so I guess it can end up in any form, depending on what molecules it happens to react with in your body, or elsewhere. It’s clearly not harmless, but as has been noted, the worst danger seems to be prolonged exposure.
