h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Why does salt sting a wound?

And why does it sting a slug?

Are there billions of tiny bees in it?

Seriously, salt contains sodium and chlorine. Chlorine makes my eyes sting. I know this from my experience in swimming pools.

I'm afraid that I'm answering one question by posing another one, e.g. why does chlorine sting? Sorry

The question about slugs is the easier of the two. Salt kills slugs simply by dehydrating them. Slugs use osmosis to bring in water into their bodies. Salt reverses the osmosis and leaches (pun intended) the water out of their bodies.


The question about why salt stings wounds is less clear. I'll just leave this link to a Reddit /askscience discussion.

http://www.reddit.com/r/askscience/comments/j5akk/why_does_table_salt_applied_to_a_wound_cause_pain/

I know about the dehydration thing. But salt does seem to make slugs hurt and recoil in a way that other desiccants don't. Talcum and sawdust, for example. I thought there might be a chemical reason.

Well, that might be related to the reasons discussed for the wound question, that it makes the tissues hypertonic (full of electrolytes) and reacts with pain receptors in a similar way to capsaicin.

I do know the answer to an unrelated salt question, why salt makes beer and soda water foam up.

Salt crystals have "perfect cubic cleavage" with 8 sharp corners on the cubic crystals. rough surfaces and sharp points create "nodes of nucleation", points where the carbon dioxide molecules can release from solution and return to gaseous form. It's not a chemical reaction, it's physical. If you dropped a bit of sponge or scouring pad into the beer or soda it would have a similar reaction.

why on earth would anyone want to put a scourer or a sponge into beer.... soem people... such a waste... My moneys on teh bees hidding in the salt....

Wouldn't you know, the silliest thing I could think of to say ended up being taken seriously.

I'm still wondering who talcum powders slugs - presumably that is the finest, perfumed variety?

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Wait... Also, do we actually know that slugs don't recoil at talcum and sawdust?

What we need is somewhere where you can find talcum powder, sawdust and slugs all in the same place. Any ideas?

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Wherever you find slugs, you can bring the talcum powder and sawdust to them. Or bring all three together in a lab.

I'm reminded of our local Texas Horned Toad Lizards, which when frightened or startled can squirt blood from their eye sockets. I've seen it stated about the horned lizard "if it is sufficiently frightened it can squirt up 1/3 of its volume of blood out of a pore near the eye (Middendorf and Sherbrooke 1992)."

Apparently these guys Middendorf and Sherbrooke must have taken a few of our cute little "horny toads" and scared teh bejeezus out of them in increasing stages of scariness.

http://youtu.be/pI5t_VmHWWI

I have a sunflower in my back yard.The other day I saw a big slug on it, but I threw the slug away. I might not be able to find it again, nor do I have sawdust and/or talcum powder.

Why is it that everywhere you'd expect to see a vast quantities of sawdust, ie places that do flat-packed furniture, such as Ikea, or DIY supplies, such as B&Q, are surprisingly spotless, but there's always somewhere nearby that sells hotdogs? Are the secretly made out of sawdust, and if so, can we see how the slugs react to them?

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I expect that any slugs here froze last night.

Salt acts as an antifreeze.

I'll remember that when my driveway ices up this winter....

Post 9 did actually give me the first full-on bellylaugh I've had for ages.

I'm losing track of this discussion.

It's cold out. Do I need to go and rub slugs on my car windscreen?

PP.

You have to run them through a blender first