I realize you're probably sick to death of hearing about PFCscams, but this might amuse you anyway: I just got a phone call from a heavily-accented call-center voice purporting to be part of an energy-saving campaign by my electricity provider, Hydro-Quebec. They promised to send me a gadget which I would plug into any outlet and which would reduce my electricity consumption 30-40%.
(Initially I thought it might be a Kill-A-Watt or similar, which I would actually use, or could if my ancient inefficient appliances didn't belong to my landlord.)
When I asked how it worked, they claimed it contained "three special capacitors" and that it reduced some sort of ill-defined stray currents in my wires, and that it would reduce what was read on my electricity meter by the above 30-40%. Initially they gave the impression they were going to just send it to me, which I would have gleefully accepted so that I could dissect it and demonstrate its non-function. But it transpired that they were actually offering me a "great deal" and a "once in a lifetime offer" - yes, those are the words they used - of 50% off on its $400 price.
Once it was clear I wasn't going to get a piece of hardware for skewering, I suddenly found I had better things to do. I called Hydro-Quebec and they know there are people doing this, they had a security department number to hand (which referred me to the Canadian Anti-Fraud Office, which isn't open), but I was kind of surprised to get it at my home number.
Anne
Yes, I am just a little tired of bogus power savers, having written about them here, here, here and here on Dan's Data, and here, here, here, here and here on this blog.
But it bears re-re-re-repeating, here and elsewhere, because people are still selling these things (and removing all doubt in the comments of relevant blog posts...), and innocent people are still buying them. The more frequently this message is repeated, the more of a public service it does:
Magic power savers that're somehow meant to substantially reduce your household (or small business) electricity bill by hazily-described means involving capacitors, power factor or even stranger allegedtechnology are, withoutexception, scams. Power factor is a real thing and so is power factor correction, but household and small-business electricity consumers are almost never billed by power factor - spinning-disc electricity meters can't even measure it - and magic one-size-fits-all power-factor-correcting gizmoes don't actually even do what they're supposed to. The components inside these things aren't necessarily even connected. So even if you were billed by power factor, these gadgets would not improve it.
I have, to date, not had the pleasure of some guy with an Indian accent trying to sell me a magic power saver over the phone. Indian dudes ringing the doorbell and trying to get me to change my electricity supplier, yes; phone solicitations for power savers, no.
(The door-to-door guys are probably having a pretty bad time. I presume someone's making out like a bandit hiring Indian kids for a "working holiday" in beautiful Australia, then leaving the unfortunate workers stuck in yet another of those godforsaken semi-scammish door-to-door sales jobs that only pay by commission and have all sorts of outrageous requirements designed to soak up what money the poor bastards do manage to make. The door-to-door electricity guys, here in Australia where the power industry is still well enough regulated that there are no real "scam" providers as far as I know, are kind of like the Kirbyvacuum or Cutco knife salespeople, selling a legitimate, if overpriced, product in an unpleasant way. They are, at least, not selling white-van loudspeakers, or fake health insurance to grandmas.)
My household has, however, been enjoying the attentions of another breed of Indian-accent phone-scammers. These guys, invariably identifiable thanks to the distinctive autodialer pause when you pick up the phone, were calling us a couple of times a week, though I think they've been quiet for a little while now. We may have finally persuaded them to stop, or perhaps they got busted. Or, more plausibly, they've submerged and departed for a while to avoid being busted.
Aaaaanyway, these guys usually say they're from Microsoft or something, and tell you there's something terribly wrong with your computer, and you need to go to their Web site and install some malware to fix the problem.
Anne (my Anne, not the Anne at the top of this post) has frequently asked these callers why they do not seek honest employment. The next time I pick up a call from them, I think I'll pretend to be racist.
"Is there, do you know, a single honest man anywhere in India? Clearly the British need to return and take you naughty little children firmly in hand once again. You silly little dusky monkeys, bless your souls, simply cannot grasp the white man's honour, can you? It's really not your fault; you simply cannot tell right from wrong. We blame ourselves, you know. It was foolish of us to trust you, with your tiny, adorable brains, to govern yourselves."
The Register had this story; it paraphrases a study from Pediatrics but includes this paragraph:
The incidents are no laughing matter, as a swallowed button cell can generate sufficient current to burn a hole in a child's oesophagus, from the inside, without the child displaying any obvious symptoms. Acid can also injure. Even batteries that appear depleted, inasmuch as they can no longer power electrical devices, can inflict these injuries.
Is it just me, or is the claim that a mostly-depleted button cell can "burn a hole in a child's esophagus" via electrical current a complete and obvious impossibility? By leaking strongly acidic or basic electrolyte I can buy, but by electrical action?
Charles
In brief: Yes, the problem here is burning, and it can be very serious. But it's not electrical burning, it's chemical burning, specifically as a result of electrolysis of tissue fluids. And if a battery makes it to the stomach, the swallower is likely to be OK; it's only if it lodges in the oesophagus that big trouble is likely to result.
Well, that's what I learned in the course of writing the following Wall O' Text, anyway.
Whenever you find yourself wondering about some oddball medical news, you should proceed directly to PubMed.
(This is particularly important if you got the news from a newspaper or TV show, many of which can be relied upon to get almost all science news solidlywrong. Mass-media science reporting is sometimes good, but it's veryoftenterrible, for surprisingly complex reasons. Whenever I hear some interesting-sounding science report on TV news, I try to remember the first five seconds of the report and expunge the rest of it from my consciousness, so I can look up what, if anything, has really been discovered, without wasting any neuron-connections on what some attractive ignoramus thinks is going on. See also, jazzed-up, dumbed-down reality shows, some of which make a real effort to get things right, and some of which don't.)
PubMed lets you search the Medline, and some other, medical research databases. You'll generally only get the abstract of each paper (and not even that, for some), and you're not tremendously likely to be able to find the whole paper for free anywhere (a situation which should change, and actually may). But a quick PubMed search will nonetheless give you a rough idea of the state of research on a subject.
If you lean on PubMed for evidence when you're having an argument with someone, the two of you are likely to end up playing what I call DuellingAbstracts, in which neither of you knows how good any of the research you're citing is, so you both just end up Bullshitting for Victory. All research is not of the same quality, and PubMed will cheerfully present you with numerous papers in support of almost anynuttyidea you like. (This is largely because Medline indexes many dodgy journals along with the respectable ones.)
Assuming you're not using the science for support, rather than illumination, you need to see how well a given piece of research was done, and how often it's been reproduced by other researchers, before you should cite it in a serious discussion. (At least few bad papers are the result of outright fraud. Unfortunately, though, a paper often has to be blatantly and quite famouslyfraudulent before it'll actually be withdrawn, though this situation is improving.)
But if you're just trying to see whether there's any research on, say, kids swallowing batteries, and you don't need more detail than you get from paper abstracts or letters written to medical journals (PubMed doesn't only index research papers), a couple of minutes on PubMed is all you need.
I was surprised to discover that there's actually quite a bit of literature on the subject of kids eating small batteries. I suppose it's the result of more and more consumer items that run from these tiny batteries. In 1980 you might have had a lithium coin or an alkaline LR44 in your calculator or wristwatch, or a silver-oxide cell if you were fancy, or a zinc-air battery in your hearing aid and maybe a mercury battery in your camera. But plenty of people didn't have one button cell in their house.
Nowadays, small remote controls, key-ring flashlights, laser pointers and umpteen other glowing tchotchkes run from miniature batteries, and it's easy to get the batteries out of most of these items. The only other thing you need to guarantee many tiny-battery-ingestion events is firm instruction from a parent that children must most emphatically not eat said batteries.
However it happens, kids are eating batteries, and the results can be quite serious.
I initially thought some danger might be posed by lithium batteries, which really do contain metallic lithium...
...which isn't as excitable as its relativesfurtherdowntheleftmost column of the Periodic Table, but which is still not something you want running around loose in your stomach. Lithium salts: Mood stabiliser. Metallic lithium: Mood ruiner.
In theory, stomach acid could eat through the casing of a battery, but in practice this doesn't seem to happen. Especially not with lithium cells, which are deliberately made very resistant to corrosion specifically to stop them from starting fires all over the place. The same goes for pretty much every other tiny battery; I don't know which of them have stainless-steel casings, but it seems they can be expected to pass through the gastrointestinal system pretty much intact, even if they do some damage on the way.
The mechanism for said damage does seem to be electrical, but not directly. Even a brand new button cell doesn't have a lot of power to deliver, and the harder you load a battery the less capacity you'll get, but swallowing a battery will give it a quite nice low-resistance pathway from one terminal to the other, and button cells all have terminals separated by only a millimetre or two. This means something close to the battery's full short-circuit current could flow through a quite small amount of tissue. The relatively large circumference of a coin cell will spread out the affected area a bit, unless the battery lodges in such a way that only part of its circumference has a good contact.
To see how much current that actually is, I threw together a battery-torturing apparatus...
...in which the twenty-amp current range of a multimeter, with about one ohm of resistance including the wires, stood in for the conductive lining of a human gut. I think one ohm is a pretty good figure to go with, here; human tissue is often not very conductive at all (put multimeter probes next to each other on your tongue and you can get a surprisingly high reading; more invasive test techniques are discouraged), but I think the internal mucous membranes, plus stomach acid or one or another salt, are both pretty conductive and pretty easy to damage.
My first victim was a tiny LR754 alkaline button cell, 7.9 by 5.4 millimetres in size, which had been sitting in my miscellaneous-battery drawer for a while but still had an open-circuit voltage above 1.5 volts. At the moment when I clicked the magnetic contacts onto the cell it produced more than 0.2 amps, but this fell to 0.1 amps after 30 seconds, 0.07 after a minute, and so on down the line until it was 0.01 amps at five minutes.
(Because I was using the super-low-resistance 20-amp range on the meter, the lowest current I could measure was 0.01 amps, and I wouldn't bet my life on the meter's accuracy either.)
Next I tried a CR2016 lithium coin cell, 20mm in diameter and 1.6mm thick. These cells are commonly used in Photon-type key-ring flashlights; red key-ring lights can run from one double-thickness CR2032, but blue, green and white LEDs need more voltage and so run from a series stack of two 2016s.
(Modern computer motherboards usually have a 20-series coin cell as their BIOS-setting backup battery. It'll probably be a CR2032, but in a pinch you can substitute a 2025 or 2016; the thinner cells should still fit the contacts. Don't stack thinner cells to fill the holder, though!)
The 2016's initial open-circuit voltage was 3.25V, but it managed less than 0.01 amps from the outset.
I thought I might have picked a defective or very old CR2016, but who cares, if the ceiling performance of shorted lithium coins isn't high enough to be a worry anyway? So I next tried to establish where that ceiling is by testing a beefy (by coin-cell standards) CR2430 (24mm wide, 3mm thick), which had also been on the shelf for rather a while and only started at 3.16 volts open-circuit, but which still should be able to easily beat any of the more common 2016s or 2032s.
The 2430's initial current was up around half an amp, but that lasted less than a second. It managed 0.16 amps after 15 seconds, 0.12 amps after a minute, 0.09 after two minutes, and kept going strongly (again, by coin-cell standards); it still managed 0.08 amps after four minutes, 0.06 after seven minutes, and was still managing 0.03A after thirty minutes, which was when I unshackled the prisoner from the wall and consigned him to eternity in the rubbish bin.
OK, so this cell managed to deliver something in the neighbourhood of a tenth of an amp for at least a few consecutive minutes. Voltage equals current times resistance, so if the current is 0.1 amps and the resistance is one ohm, there must be only 0.1V across the battery. (Voltage sag is normal in overloaded batteries.) Power equals voltage times current; 0.1 volts times 0.1 amps gives a miserable ten milliwatts of power, which even if it were concentrated in one small spot probably wouldn't, I think, directly singe even a baby's oesophagus.
My last victim was an alkaline LR44. I think this is the button battery most likely to end up inside a child, because it's both conveniently pill-shaped and very widely used. The one I chose started out at 1.57 volts open-circuit, and initially managed to deliver more than 0.3 amps into the short circuit. This, again, fell very rapidly, to 0.23 amps at 15 seconds, 0.21 at 30 seconds, 0.18 after a minute, and so on. At five minutes it was 0.12 amps, and just before ten minutes it suddenly fell from 0.07 amps to only 0.01, perhaps because of some internal failure caused by the short.
(The LR44 didn't get hot or leak, though. Modern batteries are extraordinarily good at not leaking, and only partly because we now use a lot of alkalines instead of carbon-zinc cells which corroded away their zinc casing as part of their normal operation. Un-leaking batteries are one of those things, like un-popping tyres, that now give so little trouble that people fail to even notice them any more.)
OK, let's suppose we've got a very beefy LR44 that manages to deliver 0.3 amps into one ohm for a significant amount of time. V equals IR, once again, I is 0.3, R is 1, therefore V is 0.3V, and V times I is a pathetic 0.09 watts. Again, this doesn't seem to me to be very dangerous.
One of the couple of kids who apparently managed to eat anLEDthrowie escaped without drama. This kid for some reason ate multiple magnets and batteries, but only the magnets then caused trouble.
Interestingly, there's a two-page guide to "Management of children who have swallowed button batteries", which was published in 1986 in Archives of Disease in Childhood, in PDF format here. It agrees with the newer papers that it's lodgement in the oesophagus that's the problem, but says thin lithium coin cells don't seem prone to lodge at all. And it also speculates that an increase in pH (an increase in alkalinity around the battery's anode) is what causes tissue burns, not simple electrical heating or leaking chemicals from inside the battery.
A swallowed battery is essentially electrolysing water wherever it comes to rest. That'll produce hydrogen bubbles on one terminal and oxygen bubbles on the other, but the salts that make saliva, gastric juices and tissue conductive will electrolyse too. Sodium chloride in water, or hydrochloric acid from the stomach, could give you chlorine bubbles along with the others, which would be bad news. Perhaps it's that, along with mechanical damage from the child trying to swallow the battery or cough it up, that causes fistulas and their life-threatening consequences.
Given the feeble numbers I got by short-circuiting miniature batteries, I agree that there really doesn't seem to be any electrical burning going on there. You'd just need more watts per conductive length than 1.5V and 3V miniature batteries can deliver. A twelve-volt A23 battery might do it; A23s have a stack of tiny button cells inside them, and used to be ubiquitous in small radio transmitters like car central-locking key-fobs and wireless doorbells, but are now being replaced by lithium coins. I bet a standard rectangular nine-volt battery could do it too, in the unlikely event that even a full-grown adult, let alone a child, somehow managed to ram one down their throat. There are rechargeable button cells as well, which like other rechargeables have a lot more current capacity than non-rechargeables of the same size, but they're rare enough that no child may ever actually have swallowed one.
There are variousotherindividualcasereports, ranging from the benign to the fatal, in the face of which one should remember that surely for every kid who ends up in hospital for battery-eating there must be a few who ate and later excreted a battery without any adult noticing. Or, at least, without any adult noticing until they changed that nappy.
Saving the best for last, here we have "an analysis of 8648 cases", the full text of which is available for free. The authors conclude, and also say in this slightly later paper (also online for free), that the severity of battery-swallowing injuries is getting worse, because of proliferation of 20mm-plus coin cells, which (in contradiction of the 1986 management guide) now seem to be the most dangerous. Misdiagnosis seems to be a major part of the problem, though, which shouldn't be too hard to fix since batteries show up loud and clear on an X-ray. Oh, and kids do manage to swallow AAA and AA batteries too; more than 5% of the 8648 cases involved "cylindrical cells".
These authors also say it's alkalinity - formation of hydroxide ions in tissue fluids next to one terminal of the battery - that "is now appreciated as the most important mechanism" in batteries damaging flesh.
So yes, swallowed batteries can "burn" the swallower, but chemically, not via resistive heating, which barely happens at all because these batteries can't deliver much power.
In the absence of complications like swallowed magnets, there only seems to be a danger if the battery lodges in the oesophagus. But 20mm and larger lithium coin cells are a good size to do exactly that, and if one does, there appears to be a good chance of very bad results. The authors of thosetwo meta-analyses says there's a 12.6% chance that a child younger than six swallows a 20mm-plus coin cell will "experience serious complications or death", but they base that primarily on the records of the US National Poison Data System and National Battery Ingestion Hotline (who knew?), which of course don't get to hear about battery-consumption that doesn't cause any problems and passes unnoticed.
Still, in the million-item list of things for parents of young children to freak out about, this doesn't seem like a silly one. I think parents could do worse than scan their house for remote controls, kitchen scales, toys and so on that have small and easily-removed batteries.
What the hell is going on in this "photo finish" picture?
Two sprinters are perfectly tying for third place and creating new track and field rules, but what I mean is what's going on with runner #2's Sideshow Bob foot, and runner #1's RobLiefeld foot. Runner #7 in the background looks pretty weird, too.
According to the New York Times, "the finish line cameras capture up to 3,000 frames per second". Do all of those frames look like this?!
TimT
The obvious way to implement a finish-line camera is, as the NYT say, to just run a movie camera at a huge number of frames per second.
This is not actually how most finish-line cameras work, though, primarily because of how shutters work.
A perfect camera shutter uncovers the film or sensor all at once, stays open for however long it's supposed to, then blocks the light, again all at once. You can try to implement something that works like this in electronics, or evade the problem by opening the shutter with the subject in darkness, briefly illuminating the subject with a high-speed flash, and then closing the shutter in darkness again. But that's no use for everyday photography or photo finishes, and making a physical object that works as an ideal shutter is pretty much impossible.
Instead, still and video shutters are implemented with "curtains", sliding plates, rotating discs, and various other things, none of which behave much like an ideal shutter when you need very brief exposure times, as is necessary if you need to see which runner, horse or car got over the line a hundredth of a second before the next one.
Most all-electronic cameras don't come anywhere near having an ideal shutter, either. Instead, they have a "rolling shutter" that scans across the frame, line by line or column by column, in a short but distinctly non-zero amount of time.
Rolling shutters aren't great for video, because things moving across the frame - because they and/or the camera are moving - will be in a different place as each new line or column of the frame is detected. This creates distinctive forms of distortion.
A rolling shutter will cause things that move through the frame relatively slowly to...
Things moving very quickly, like aircraft propeller blades, look far more disturbing if the exposure time is short enough that they aren't just a blur:
OK, so here we have examples of distortion created because the "hole" that lets light into the camera is changing in size, shape and location over a long enough period of time that it visibly interacts with moving objects in the scene being photographed. This is bad for everyday photography, when you don't want things you're shooting to look weird.
Looking weird is acceptable in finish-line photos, though, as long as you know what the weirdness means. The picture can be as freaky and distorted as you like, as long as you can tell who got to the finishing line first. (Or, in the case of the picture you're asking about, who got there third. Third place was, in this race, good enough to qualify the runner who got it for a place in this year's US Olympic team.)
For this reason, most finish-line cameras aren't super-high-speed movie cameras, but instead a kind of slit camera. A slit camera has a line-shaped lens, which exposes the film or electronic sensor line by line or column by column, not unlike the way a rolling shutter works. The critical difference, though, is that a slit camera can keep on going indefinitely. You can keep collecting image data, or keep spooling film past the slit, for as long as you have memory or film. The shutter never closes as long as the film or memory lasts, so it's impossible to miss any action between the frames.
Flatbed scanners are a kind of slit camera, and with modification can in fact be used as one; anything that moves around while the scan's being made, though, will look distorted. Move an object in the oppposite direction of the scanner head's motion, and that object will look shorter than it really is. Move it in the same direction, and it'll look longer. (Move it at the exact same speed as the scanner head, and the scanner will just keep seeing the same bit of the object for the whole scan, making the object look like an endless stripe.)
OK, so now imagine taking a flatbed scanner sensor and setting it up vertically, looking across a racetrack at the finish line. Start a "scan", and it'll authoritatively tell you when every body-part of every runner makes it to the finish, by simply showing that part of that person before any part of anyone else. The speed of the scan should be set to roughly match the speed of the runners, so they look generally the right shape, but any part of any runner that stays stationary relative to the scan rate - a foot on the ground, for instance - will seem long. Any part that's moving forward relative to the scan rate - a hand or foot coming forward, for instance - will seem short. Even if you mess up the scan rate so everyone looks wide or narrow, whatever part of whatever runner shows up first in the scan is the first to cross the finish line.
So let's look at this picture again. You can see that runner #4 got second place (whoever got first is off to the left somewhere), and #7 in the background is going to get fifth. Runner #2's foot got to the finish first, and because it was then planted on the ground it looks ridiculously elongated. Runner #1's left foot was moving forward as it crossed the line, and so it's shrunk.
Unfortunately for #2, the foot doesn't count. To win, your torso has to cross the line first. #2 has the first foot, #1 has the first hand and then knee, #2 has the first head... and then the foremost part of each of their torsos hits the line, so far as can be seen, at exactly the same time.
How the hell did "prune juice" ever come to exist, since a prune is a dried plum and you can't get juice out of dried fruit? Do they mash them up and add water or something?
Isaac
There's a loophole.
Plums grown primarily to be dried are called "prunes", even before they're dried. They can also be eaten fresh, or juiced. Presto, a warrior's drink.
And now, some Bonus Botanical Trivia:
Many people believe nectarines to be a peach/plum hybrid. They're not. They're a smooth-skinned strain of peach, sharing an ancestor with the plum somewhere back in the history of stonefruit, but otherwise unrelated.
Somewhat fewer people believe nashi pears to be an apple/pear hybrid. They're not. They're a natural species, or, at any rate, as "natural" as the apples and pears that humans have been selectively breeding for thousands of years.
(I am greatly amused by Creationist publications that show a magnificent spread of delicious fruit and veg that God in His wisdom has provided for us; the Jehovah's Witnesses have a really nice version of this in one of their numerous happy-pictured books and pamphlets. I always have a hard time finding anything in those pictures that hasn't been gigantically changed from a near-inedible ancestor by human intervention. Possibly the coconut. Good luck opening that with your bare hands, Adam.)
Lemons, on the other hand, are a hybrid, though a pretty ancient one. Genetic analysis (PDF) has shown them to be a hybrid of the bitter orange and the citron.
If you always thought that grapefruit were hybrids too, you'll now be amazed to learn that you were right. The grapefruit only dates back to the 18th century.
Many people are also familiar with the factoid that, technically, the banana is a herb. Banana taxonomy has always been a nuisance, but this bit of pub-trivia information is not actually worth much.
In everyday grocery-shopping terms the banana is obviously a fruit, but in botanical terms it can defensibly be described as a berry, while the botanical "herb" is any non-woody flowering plant, most of which are inedible. (And, by the botanical definition, each individual kernel on an ear of corn is a separate "fruit". Don't get me started on cashews.)
All of these games with definitions and clashes between scientific and everyday terminology are pretty pointless. They make about as much sense as saying that because people who make coins for a living may refer to all of their input metals as "bullion", it is therefore sensible to invest in copper by the ounce.
Another one: In everyday usage, hardwood means wood that is hard. In scientific terms, though, it just means wood from non-flowering flowering [it wasinevitable I'd get one of these wrong, wasn't it?] plants, so balsa wood is technically a hardwood.
Finally, and perhaps most interestingly, it turns out that the tomato is technically an amphibian.
My mom's always been a strong proponent of vinegar as a miracle cleaner for almost anything, floors, windows, clothes, you name it. She recently discovered bicarbonate of soda, too, and has been using that for all sorts of stuff too, like in the dishwasher instead of the special powder.
When I visited the other day, she was washing the floors with a bucket that had hot water, bicarbonate of soda AND vinegar in it. Apparently the fizz when you add the vinegar gives you more "scrubbing bubbles". Except I vaguely remember from elementary school that an acid and a base cancel each other out, the example given having been exactly this, vinegar and washing soda.
So was my mom just washing the floor with salty water?
Bicarb is NaHCO3, acetic acid is CH3CO2H. Acetic is the acid in vinegar - cheap "white vinegar", which is rather more economical for cleaning things than 50-year-old balsamic, contains nothing but nice clean industrial acetic acid and water.
The reaction is:
NaHCO3 + CH3CO2H -> CH3COONa + H2O + CO2
Those products are sodium acetate, water and carbon dioxide. The CO2 is invisible but heavier than air, and can be poured out of the reaction container to extinguish a candle, said candle being the most dangerous thing that exists in boringly-safe-science demonstrations.
Sodium acetate is sometimes used as a flavouring, because it tastes like salt and vinegar all by itself. ("Salt and vinegar" snacks in the USA are apparently likely to be flavoured with sodium acetate; here in Australia I think that's illegal for some reason. I don't think it's toxicity; sodium acetate is pretty innocuous.)
If you mix sodium bicarbonate and hydrochloric acid, HCl, then the reaction is the same except instead of sodium acetate, you get sodium chloride, which is everyday table salt.
(For this reason, bicarb is a very effective antacid. A teaspoon full of bicarb can turn nasty acid-reflux indigestion into a series of hugely satisfying CO2 belches in seconds. You'll have a pretty darn high-sodium diet, though, if like me you end up eating several spoonfulls of the not-that-bad-tasting-when-you-get-used-to-it substance per day. In that case, hie thee to a doctor and get yourself a prescription for one or another acid-production-reducing drug.)
You'd want to be careful making salt from bicarb and hydrochloric acid, though, because if you don't get your stoichiometry right and not add balanced amounts of the reagents, then there'll be left-over bicarb or hydrochloric acid at the end. This is also what will happen if someone decides to make a cleaning product out of bicarb and vinegar; they probably won't titrate the mixture, and so will have a surplus of one substance or the other. Surplus bicarb, as a base, will clean greasy things by, essentially, turning the grease into soap. Surplus vinegar, as an acid, will clean things by dissolving various kinds of dirt, like mineral deposits ("scale"), or rust.
For these reasons, and also the fact that plain water plus elbow grease can clean a lot of things pretty effectively (the basis for the popularity of "laundry balls", which don't actually do anything), people may come to the conclusion that a vinegar-and-bicarb concoction is a super cleaner, when in fact they'd be better off using a smaller amount of only one of the ingredients.
(At least, in this case, mixing the compounds will do no harm. Mixing bleach and ammonia, on the other hand, may greatly reduce the amount of time you spend doing household chores, on account of how you may now be dead.)
Oh, and sodium bicarbonate is not "washing soda"; that's sodium carbonate, Na2CO3, which is commonly used to "soften" hard water, which contains dissolved minerals that prevent soap from working properly. Sodium bicarbonate is "baking soda", named for its use as a leavening agent; if you mix bicarb into batter that's slightly acidic, the fizzy-neutralisation reaction occurs and creates lots of little CO2 bubbles in the batter. "Baking powder" contains dry bicarb and acid powder (usually tartaric acid). Add water, and the components react and fizz.
Getting back to sodium acetate, a supersaturated solution of it is used in "phase change" heat packs...
...which "freeze", liberating heat, when disturbed with the little clicker device inside, or when otherwise slapped around. You put the pouch in boiling water to re-liquefy its contents; the things can be used over and over indefinitely, as long as they don't spring a leak.
You can do something similar to this with numerous other fluids, but sodium acetate's properties suit it very well to the purpose. Even if you don't actually need a hand-warmer, I strongly recommend you buy one as a toy, since you can get them on eBay for about $5 delivered.
He came down from Queensland to visit us, and some other people, the other week.
And recorded some video, including some flying off Echo Point near where I live. Though with entirely too little buzzing of trees and tourists, or seeing how low he could go before the edge of the cliff tested the effectiveness of the copter's lost-signal configuration.
I am not in the Echo Point footage, because I was not there, because I am an idiot.
All I really know about it is that it's technically called "cyanoacrylate", but the "cyano" part makes me nervous. The last episode of Mythbusters I saw had them sticking stuff to other stuff with superglue (which they called "super adhesive" for some reason) and they were wearing gas masks while doing it.
Am I endangering my health if I superglue a teacup together without lots of ventilation? My son's just now started building model airplanes and tends to stare so close at the model I'm expecting him to stick a propellor to his nose soon; is HE going to be poisoned too?!
Eva
At some point in the next few thousand words I may answer your question, Eva. You know how it is with me.
The magic acronym (or possibly initialism) to remember whenever you want to know how strongly a given substance desires to kill you is "MSDS", for Material Safety Data Sheet. You can find an MSDS for just about anything, provided you know the name of the substance in question. You usually don't need to know the exact chemical name, either; brand names, especially of pharmaceuticals, often work.
One popular substance can have a large number of MSDSes for it, sometimes with different data, because, for instance, a product sold under the same name by different companies may be made with different constituents. MSDSes may also differ even when they're talking about the exact same substance, because different manufacturers and importers and so on may have different testing regimes, or may just plain get stuff wrong. Generally speaking, though, you can trust MSDSes, even if you can't find one for the exact brand of, in this case, cyanoacrylate (which is known to the relevant chemists, and many hobbyists, as "CA") you're worried about.
When I say "just about anything" above, I mean it. Here's an MSDS (in PDF format, like most online MSDSes these days), for skim milk. Including rather excessive first aid procedures to employ in case the substance is ingested.
Here's one, and another, for olive oil. More over-enthusiastic warnings; apparently you're not meant to allow olive oil to make direct contact with the skin. MSDSes for innocuous substances are often like this, possibly for reasons having to do with the covering of arses, or perhaps because there was no "zero hazard" box for the MSDS-maker to tick.
OK, enough silliness. Search for MSDSes for cyanoacrylate, plus a common brand name or two like "Krazy Glue", and you'll get hits like this, this, this and this. Here's a whole page of MSDSes for Loctite products, including various other glues and threadlocks. There's a "safety" section in the Wikipedia article for CA, too, plus some MSDS links at the end.
What all of these agree on is that CA products of various kinds, from the water-thin stuff used to wick into gaps in plastic models through to various non-runny gel-type versions, are not nearly as poisonous as you'd think from their alarming "chemical" odour. The fumes are an eye and mucous-membrane irritant, and if you're sticking a whole room worth of furniture to the ceiling as they did on MythBusters then you'd be nuts not to wear some kind of breathing protection, but this stuff really isn't that bad. I don't think it even releases much in the way of horrifyingly deadly gases if you burn it, though again, this is not recommended.
(With regard to the title of this post, glues that people sniff to get high in a rather dangerous manner are generally based on some kind of solvent with psychoactive effects, though usually not effects that people living a life somewhere above rock bottom would consider worth the damage. Glues with no such solvent, like CA, PVA, hide glue or epoxy, often aren't particularly bad to inhale, which is just as well since they won't even get you high.)
Part of the reason why superglue isn't very poisonous is that its "set" state, a hard polymerised lump, isn't toxic. It's still listed as an "eye irritant" when hardened, but only in the way that sand is. And CA really wants to polymerise. All actual CA glue contains "inhibitor" chemicals in addition to the CA itself, to stop the stuff from instantly turning into a lump of plastic in the bottle. Several common compounds in the world, chief among them water, will "kick" CA into polymerising. And since your eyes and mucous membranes and so on are all rather damp, any CA vapour that hits them polymerises instantly.
Now, this is still not a good situation, since having a very thin layer of plastic accumulate inside your nose and on your eyeballs is not most people's idea of a good time, but the body can deal with tiny amounts of the stuff with no trouble. (This also means that all you probably need as the abovementioned "breathing protection" is a damp cloth tied around your face.)
You can take advantage of the effect water has on CA to accelerate its bonding, by for instance breathing heavily on the two pieces of something you're gluing before bringing them together, or even by spitting on the glue, in extremis. That won't give you a very good bond, but if you're in a hurry, it'll do. You can also sprinkle bicarbonate of soda on the glue, or dribble CA onto bicarb, to get an instantly set, hard but brittle filler material. (It's basically Bondo for plastic spaceships.)
There are also liquids, known as "CA accelerators" or "kickers", that give you an almost instant full-strength bond when they touch CA. You generally put glue on one piece, a spritz of accelerator on the other, then bring them together and zap, instant gluing of two parts that you didn't quite bring together straight, god damn it.
I'm not sure how much variation there is between the different accelerators; these days I just buy whatever's cheapest on eBay. Note that CA accelerator tends to be rather volatile and thus prone to liberate itself from the spray-bottle faster than many people can use the stuff. I recommend you keep the sprayer in a Ziploc bag.
The fact that there are substances that kick CA better than water does is the base for products like the one described in this MSDS, which is for a CA formulation used for fingerprint "fuming". You can do this neat little science trick with any CA, not just special expensive law-enforcement CA:
One thing hobbyists discover pretty quickly about CA, especially if they're using accelerator as well, is that the polymerisation process is exothermic. The glue gets warm as it polymerises, the increased temperature speeds up the polymerisation, and with enough glue and enough accelerator (or just CA by itself, if it's on something with a lot of surface area - cotton is particularly bad) the result is boiling polymerising CA. I don't trust any hobbyist who hasn't emptied five whole dollars worth of discount-store superglue into a very disposable container in the back garden, then added some generous squirts of accelerator, and stood well back.
This is another CA hazard. If you spill a lot of it on your cotton-denim jeans (or somehow just manage to deliberately use an unusually large amount), the profoundly crappy time you'd reasonably expect to have in your immediate future may be made significantly crappier by some nasty burns.
Anybody who's ever used superglue will have stuck the wrong things together, though with any luck just one finger to another, not a square foot of garment to singed flesh. If possible, a good way to remove CA is mechanically, with sandpaper or a file or, for many glue-on-skin situations, a disposable razor. (Or you can just wait; as the outer layer of your skin naturally flakes off, the glue will go with it.)
CA can also be dissolved with acetone, but the MSDSes for acetone are rathermorealarming than those for CA. There are less toxic glue debonders out there too; again, please accept my very personal recommendation of whatever's cheapest on eBay and isn't just acetone.
(CA is also not just kicked into polymerisation by water, but also slightly soluble in it. So a long hot bath or shower may help you out, provided you have enough un-stuck limbs to be able to operate the taps.)
While I'm giving unrequested buying advice, as far as CA itself goes, I just buy it from discount shops. Given CA's irritating propensity to go hard in the bottle, I like the few-dollar cardboard oblongs with multiple little separately-bubble-packed tubes, the more and the smaller the better. Unless you've got an ongoing meaningful relationship with a local hobby shop - which I recommend; it's worth paying a bit extra for stuff if wise counsel on various subjects, or just hours of entertaining chat, is available in return - I see no reason to buy fancy brand-name CA for almost any job.
Getting back to that alarming cyano group which is indeed hanging off the few different, but effectively almost identical, kinds of CA molecule, it is in this case not much to worry about, but certainly is if it's hanging off something less complex, like a potassium or hydrogen atom. I find the lethality of various cyanide compounds almost amusing, since it's yet another sign of the absence of "intelligent design" of even this one planet, let alone the whole universe.
I mean, what's the element that's the basis of all life on this planet? Carbon. What makes up 78% of the planet's atmosphere? Nitrogen. (Don't miss this sample!) What do you get when the two of them get together? Cyanide, a deadly poison. It's sort of the opposite of the sodium-plus-chlorine thing.
And while I'm rabbiting on, I was also amused by MythBusters' and/or Discovery Channel's determination to call the glue they were using "super adhesive", a term that doesn't really exist in nature, to the point where a couple of slip-ups when someone said "superglue" anyway made it to air. This is in line with MythBusters' general self-censorship policy, in which no brands not integral to the myth are blurred or taped over or covered with new labels reminiscent of Repo Man.
Sometimes this policy seems to make little sense, though. In a recent special episode, MythBusters shot a .50 AE round from a Desert Eagle into watermelons, and they called the gun a Desert Eagle, even though there are various other firearms that chamber that round. But in the episode a while back where they demonstrated what a bad idea it is to wrap your hand around the cylinder of a .50 Smith & Wesson revolver when firing it, not one mention was there of the brand of that gun, though anybody familiar with the preposterous hand-cannon arms race of recent years could have mistaken a S&W Model 500 for anything else.
(If you haven't been watching the nutty progression of ever-more-wrist-smashingly-powerful handgun cartridges and the you've-gotta-be-kidding-me guns that shoot them, compared to which the action-movie-staple .50 AE Desert Eagle's .44-Magnum-ish bullet energy looks positively feeble, then you could be forgiven for thinking a short-barreled Model 500 was some kind of flare gun. I wonder if even this has been surpassed by now?)
The "super adhesive" thing is particularly nutty, though, since they could have just called it cyanoacrylate.
UPDATE: This post is now thankfully out of date; my mail's working again now.
Owing to circumstances beyond the management's control, the e-mail address dan@dansdata.com currently bounces.
While I wait for the server admin at m'verygoodfriends SecureWebs to undo whatever he did that deleted the account, you can contact me on my ISP address, rutterd@iinet.net.au, or of course just chatter cheerfully in the comments to this post.
I think PayPal donations to dan@dansdata.com will still work, but you may be thanked for your donation with an error-550 bounce message, which is kind of rude. Sorry about that.
for Victory. All research is not of the same quality, and PubMed will cheerfully present you with numerous papers in support of almost 
