主题：道家武功学习记 -- 长河落日圆

M. G. Bulmer and G. D. Forwell

1956

How salty are sweat, tears and that stuff that you use to soak your contact lenses compared to, like, the ocean?

--The Fat Man Who Never Came Back (talk) 15:09, 24 February 2008 (UTC)

The salinity of sweat is examined in this paper by Bulmer and Forwell. It depends on the sweat rate, but seems to be between 30 and 120 molar equivalents per litre.

Sancho 15:23, 24 February 2008 (UTC)

The salinity of seawater is about 3.5%. Most of that's sodium chloride. Tears have the same osmolality as the body's internal fluids, containing a mixture of salts. (An isoosmotic solution of sodium chloride – as used in normal medical saline solution – contains about 0.9% sodium chloride: about 150 millimolar.)

TenOfAllTrades(talk) 17:13, 24 February 2008 (UTC)

salinity of bodily fluids is the same as the salinity the ocean was, when our distant ancestors crawled out of it; they had to carry that environment around with them for their cells to function. meanwhile, however, the earth continued to wash minerals down off the land into the ocean, so that now it is much saltier than it was then, and than we are; and the organisms that stayed behind have had to adapt to that.

Gzuckier (talk) 18:27, 26 February 2008 (UTC)

The same as when our ancestors crawled out of the ocean? Are you sure? Wouldn't it be more likely to be the same as when cellular life forms established a clear separation between what was inside and what was outside the cell, i.e. some two billion instead of 500 million years ago? Or possibly when multicellular life evolved? See Timeline of evolution. I was unable to find any source internally or externally about rate at which ocean salinity has risen. Is anything known at all on such large time scales?

--NorwegianBlue talk 20:41, 26 February 2008 (UTC)

Ocean life is good at expelling salt from the interiors of their cells. I think a better scientific explanation is that there is an ideal salinity for certain biochemical processes, and the cell tries to maintain that level.

Nimur (talk) 22:46, 27 February 2008 (UTC)

Thank you. And now for another salty question....

Do all salts taste "salty?" Are there any edible, nutritious salts besides NaCl?

--The Fat Man Who Never Came Back (talk) 17:49, 24 February 2008 (UTC)

'Nutritious' is a matter of quantity. Chronic excess consumption of sodium chloride is linked to high blood pressure, heart disease, and other ailments. Acute overdoses of sodium chloride can be fatal.

To answer the question you're probably asking, potassium chloride is often used as a salt substitute for individuals on sodium-restricted diets. Its oral toxicity is quite low (comparable to that of sodium chloride).

TenOfAllTrades(talk) 17:56, 24 February 2008 (UTC)

What are the most toxic salts? Are they salty as well?

--The Fat Man Who Never Came Back (talk) 18:01, 24 February 2008 (UTC)

You'll have to test and report back.

On a somewhat more serious note, there are a lot of different salts, and they will have a wide range of tastes. Salts of zinc reportedly have a bitter, astringent flavour. Cyanide salts have an odour of almonds—tasting is discouraged. Calcium carbonate is the bulk of most calcium antacids; it has a chalky taste. Sodium citrate is acidic and tart. Alkaline salts may have a soapy taste or mouthfeel. The list is practically endless.

TenOfAllTrades(talk) 19:24, 24 February 2008 (UTC)

Also see Taste#Saltiness, which could use references.

--Allen (talk) 20:19, 24 February 2008 (UTC)

I stumbled upon a paper on this subject recently, but I'll be damned if I can remember what keywords I was searching the journals with. If I recall, it's the chloride anion which actually triggers the "salty" flavour, and different counterions (sodium, potassium, etc.) affect how strongly salty something may taste. If I find the article, I'll get back to you.

Sockatume (talk) 01:37, 25 February 2008 (UTC)

check out Sea Salt. That tends to have all kinds of salts mixed up in it.

Furmanj (talk) 01:54, 25 February 2008 (UTC)

Also check out Salt (chemistry)#Tastes.

Sockatume: from personal experience, potassium chloride tastes much saltier than sodium chloride and has a very unpleasant aftertaste. Calcium carbonate has no taste. Potassium nitrate, the main component in gunpowder, tastes slightly alkaline. Sodium bicarbonate, baking soda, also tastes alkaline and sodium carbonate is unbearably so. Lithium oxide turns into lithium hydroxide upon contacting water, and therefore tastes very caustic. Iron oxide is obviously tasteless. Again, all of this is from personal experience and may not be reliable.

--Bowlhover (talk) 06:42, 25 February 2008 (UTC)

Other edible salts include Epsom salts and sal ammoniac. Magnesium chloride tastes more salty than salt, and Calcium chloride is pretty harmless. potassium sulphate and sodium sulphate taste less salty but are also harmless in small quantities. PS don't eat lithium oxide or lithium hydroxide as they are very damaging to flesh.

Graeme Bartlett (talk) 12:18, 25 February 2008 (UTC)

Yes, don't eat sodium carbonate either. It is used as washing soda and tastes extremely, extremely alkaline.

--Bowlhover (talk) 17:26, 26 February 2008 (UTC)

That is superb--tasting notes for salts of every sort. I love the Science reference desk.

--The Fat Man Who Never Came Back (talk) 02:21, 26 February 2008 (UTC)

There was an episode of Good Eats that focused on salt, it aired back in 2004. Alton Brown talked about all the different kinds of salts depending on where they come from, how they're processed, etc...

-- MacAddct 1984 (talk contribs) 15:03, 25 February 2008 (UTC)

I love Alton Brown. But I'm sure he was talking about different kinds of table salt. I was asking about different types of chemical salts.

--The Fat Man Who Never Came Back (talk) 02:21, 26 February 2008 (UTC)

See also Monosodium glutamate (MSG), also known as E621. It is used as a food additive because it stimulates the umami taste receptors. I heard a story on this podcast that suggested a link between the huge increase in the consumption of MSG and the obesity epidemic, based on studies in rats, but according to our article, this correlation was not found in humans.

--NorwegianBlue talk 22:02, 25 February 2008 (UTC)

I am confused by the claim that iron oxide is flavorless. Rusty nails taste different from plain nails, and the difference is iron oxide.

Edison (talk) 05:30, 26 February 2008 (UTC)

Sorry, iron oxide is not flavourless. It has a mild taste that I can't accurately describe; it's been a long time since I've tasted rust.

--Bowlhover (talk) 17:26, 26 February 2008 (UTC)

Salts of heavy metals such as lead are very toxic (often more toxic than the pure metal). See Lead(II) chromate, for example.

Nimur (talk) 22:47, 27 February 2008 (UTC)