Boiling Seawater For Salt

[Turtle]

for their return trip east, lewis & clark & company replenished their salt by boiling seawater on the nearby washington coast of the pacific ocean. i'm about 150 miles from that beach as the crow flies, and i got to thinking about where i'd get salt around here on my own as it were. a little reading found this historical account of the practice, though it's not as old a thing as i'd imagined.

 

the learning channel

...In the Iron Age, the British evaporated salt by boiling seawater or brine from salt spri­ngs in small clay pots over open fires. Roman salt-making entailed boiling the seawater in large lead-lined pans. Salt was used as currency in ancient Rome, and the roots of the words "soldier" and "salary" can be traced to Latin words related to giving or receiving salt. ...

 

so my question is, what other elements & minerals would end up in my salt if i boiled it out of pacific ocean seawater? i was particularly wondering about mercury, what with it being in the fishes today but presumably not back in iron age days. what all would i get with my salt from boiling seawater?

[Qfwfq]

what other elements & minerals would end up in my salt if i boiled it out of pacific ocean seawater?

Making it into crystals is actually a great step to purification. Once you have monocrystaline chunks they tend to be mighty pure. Salts taken by evaporation from the sea, and then suitably washed, are among the purest.

 

If you want to do it manually you want those single crystals to grow big, you can achieve this by adding more brine as evaporation progresses until you got big big craystals. This way it isn't so slow to select them with tweezers and it makes less loss when you wash them out. then you can always break it into finer salt. Adding the less saturated brine, I would spoon it gently over the surface so it remains atop because it is lighter, so it evaporates more readily.

[Turtle]

Making it into crystals is actually a great step to purification. Once you have monocrystaline chunks they tend to be mighty pure. Salts taken by evaporation from the sea, and then suitably washed, are among the purest.

 

in saying "making it", "it" being "salt" & "salt" being singular, is this "salt" sodium chloride? then however you say "Salts taken by evaporation" and "salts" is plural, so what other salts beside sodium chloride would i get?

 

If you want to do it manually you want those single crystals to grow big, you can achieve this by adding more brine as evaporation progresses until you got big big craystals. This way it isn't so slow to select them with tweezers and it makes less loss when you wash them out. then you can always break it into finer salt. Adding the less saturated brine, I would spoon it gently over the surface so it remains atop because it is lighter, so it evaporates more readily.

 

mmmm....lewis & clark used open kettles & wood fires & probably weren't using spoons and tweezers. how is washing done, & what would i be washing out?

[Moontanman]

Turtle, when you evaporate sea water you get lots of salts, of course the lions share is sodium but you will also get Calcium, magnesium, sulfur, potassium, you can run it down to ever less significant concentrations and get all naturally occurring elements.

[Turtle]

Turtle, when you evaporate sea water you get lots of salts, of course the lions share is sodium but you will also get Calcium, magnesium, sulfur, potassium, you can run it down to ever less significant concentrations and get all naturally occurring elements.

 

i understand that. i want to know exactly what gets concentrated with a rudimentary open-pot boiling setup. presumably it's different than what you'd get in a pressure vessel and/or higher temps. also, won't the exact amounts & types of elements & compounds have different reactions under boiling than a different mix of elements & compounds? i mean, aren't there also chemical reactions going on between elements&compounds in the pot that change the outcomes of what gets deposited/crystalized?

 

then there is also the thing of historically recent ocean pollution & i still want to know about mercury and other toxic compounds like lead, arsenic, cadmium, etcetera that we have added since the industrial revolution. i'm no chemist, but i did find there are salts of mercury. are they sure to evaporate, or could they deposit with the other salts?

 

Mercury Compounds

[Don Blazys]

Quoting Turtle:

I want to know exactly what gets concentrated with

a rudimentary open-pot boiling setup.

presumably it's different than what you'd get in

a pressure vessel and/or higher temps.

 

Sorry Turtle, I couldn't find any useful information

on that in any of my books, or on the net.

(I'm no good at "search injuning" anyhoo.)

 

So...if no one else can find that information either,

then you just might have to conduct that experiment yourself !

 

Quoting Turtle:

Then there is also the thing of historically recent ocean pollution

& i still want to know about mercury and other toxic compounds like lead,

arsenic, cadmium, etcetera that we have added since the industrial revolution.

 

Well, I think the nutritional benefits of seafood far outweigh

the so called "harmfull effects" of small traces of pollutants.

 

Here's why...and this of course is just my own, personal opinion...

 

My favorite food has always been seafood.

Throughout my 60 years, I must have consumed at least 10,000 lbs of the stuff!

I never get sick, and I have never been to a doctor.

On a good day, I could pass for 40, even though I smoke, drink

and quite often get very little or no sleep.

 

I'm convinced that negative emotions are far more harmfull

to the human body than are small amounts of pollutants.

Thus, to worry about a teeny tiny trace of mercury in a tuna sandwich

probably does a lot more harm than does the mercury itself!

 

Don.

[Qfwfq]

in saying "making it", "it" being "salt" & "salt" being singular, is this "salt" sodium chloride? then however you say "Salts taken by evaporation" and "salts" is plural, so what other salts beside sodium chloride would i get?

:lol: Of course you could take it like a chemist and say the same principle applies for getting crystals of any cation-anion pair from supersaturated solution.

 

However, I was referring to available NaCl products, produced by different methods from different sources.

 

mmmm....lewis & clark used open kettles & wood fires & probably weren't using spoons and tweezers. how is washing done, & what would i be washing out?

They sure weren't concerned about industrial waste were they, back then. Neither would they have been concerened with efficiency when they could just chop down plenty of wood to keep the fires roaring. Other salts naturally occurring in the sea aren't such a big deal, especially if it's just to get back home and, mostly, back in those days the main value of salt was for preserving foods, by drawing moisture, very much done with large coarse crystals.

 

The trick with large crystals is the ease of recognizing those of different kinds of salt and also that any trash tends to be on the surface of the crystal, if it is regular and grown steadily. Because ordinary salt is very soluble, rinsing large coarse crystals carries the trash away along with the most superficial NaCl and leaves a good clean salt behind.

 

Speaking of solubility, many other kinds will crystalize before the solution is supersaturated for the NaCl that you want; you can work it, somewhat as in distillation, so as to separate out the less soluble ones. When a kettle has just got supersaturated for NaCl you can decant it and add the liquid solution to the final kettle, where the good crystals are growing.

[Moontanman]

Turtle, you have opened a can of worms that will be difficult to figure out the contents of.

 

Many many years ago i decided to not make salt but to make seawater. I found out it was not quite as easy as ordering various salts and adding them to freshwater. Sodium chloride is the most common salt in seawater by far, magnesium chloride would probably be number two but here is a ppm of various ions in seawater.

 

http://www.seafriends.org.nz/oceano/seawater.htm#composition

 

This how ever is some what misleading in that the chlorine ions are not all associated with sodium so it's difficult to add salts to freshwater and get an exact ionic match. Here are the major ions,

 

 

Element PPM

Hydrogen H2O 110,000

Oxygen H2O 883,000

Sodium NaCl 10,800

Chlorine NaCl 19,400

Magnesium Mg 1,290

Sulfur S 904

Potassium K 392

Calcium Ca 411

Bromine Br 67.3

 

As you can see after NaCl everything else drops off fast, various salts condense out of solution faster than others as well.

 

http://www.ehow.com/how_4894267_make-salt-seawater.html

[Turtle]

Turtle, you have opened a can of worms that will be difficult to figure out the contents of.

 

Many many years ago i decided to not make salt but to make seawater. I found out it was not quite as easy as ordering various salts and adding them to freshwater. Sodium chloride is the most common salt in seawater by far, magnesium chloride would probably be number two but here is a ppm of various ions in seawater.

 

http://www.seafriends.org.nz/oceano/seawater.htm#composition

 

This how ever is some what misleading in that the chlorine ions are not all associated with sodium so it's difficult to add salts to freshwater and get an exact ionic match. Here are the major ions,

 

 

Element PPM

Hydrogen H2O 110,000

Oxygen H2O 883,000

Sodium NaCl 10,800

Chlorine NaCl 19,400

Magnesium Mg 1,290

Sulfur S 904

Potassium K 392

Calcium Ca 411

Bromine Br 67.3

 

As you can see after NaCl everything else drops off fast, various salts condense out of solution faster than others as well.

 

 

thnx. i got my "eye-on" the can is about all i can say. :doh: :lol: i found that sea friends link too, and the concentrations for mercury, lead, & arsenic seem pretty low even if they did stay with the salt. :shrug: for the disaster scenario i had in mind that might necessitate making my own salt, some mercury in the salt will be the least of my problems. :lightning

mercury 0.00015 ppm

lead 0.00003 ppm

arsenic 0.0026 ppm

Note! ppm= parts per million = mg/litre = 0.001g/kg.

source: Karl K Turekian: Oceans. 1968. Prentice-Hall

[Qfwfq]

This how ever is some what misleading in that the chlorine ions are not all associated with sodium so it's difficult to add salts to freshwater and get an exact ionic match. Here are the major ions,

If that site wasn't lying about the ppm, a bit of stoichiometric calculation would do the trick. But...

Element PPM

Hydrogen H2O 110,000

Oxygen H2O 883,000

Sodium NaCl 10,800

Chlorine NaCl 19,400

Magnesium Mg 1,290

Sulfur S 904

Potassium K 392

Calcium Ca 411

Bromine Br 67.3

They can't be telling the truth because composition in ppm shouldn't tot up to any more than one million. After hydrogen and oxygen, a mere 7000 is left to go and the sodium alone goes well over the rim of the kettle...:shrug:

 

In any case the elements shown here are healthy enough in a diet and appropriate quantities of them are ok for drinking water, except that to be precise composition in solution is usually listed as ions/molecules. For many of the elements it makes a difference; oxygen for instance can be in H2O, in HO- or as dissolved O2.