Spotted a few days ago at a DIY centre in my hometown in Ireland - some sacks of sea-salt imported from the Dead Sea. This seems a good starting point for a LAB discussion page - despite today being Friday the 13th?; however isn't there that old tradition of throwing a pinch of salt over the (left?) shoulder to ward off, or counter-act, some bad luck?

The little excerpt here from the printing on the salt sacks exhibits a whole world of salt connections: including landscape, culture, elemental processes....Dead Sea...life giving...created by the sun...rainwater on the plastic sack (water cycle)...even a bit of religious practice...

Such complexity from a simple compound.

The next entry will be on the subject of ritual salt routes.

....and finally, from an interesting lecture on creativity from John Cleese:

"tolerate that slight discomfort and anxiety that we all experience when we haven't solved the problem..."

CONSOLIDATED COMMENTS:

12 Comments

LAB- Exchange Gallery

LAB

Below we have two case studies from this week and a couple of questions:

Natasha

My project is about preservation. I am preserving old dolls and toys and other objects, maybe even photos and displaying them in an old dark wood cabinet

My question is, is there a certain ratio of salt to water to grow crystals on these objects to get the best results?

Issy

My project is about historical value of salt. The idea of the word 'Salary' coming from salt because of it's huge value in the past. I am making a range of jewellery from jewellery from charity shops and new findings, along with salt and food colouring. At present I am experimenting creating a whole brand, with photos and my salt/ food colouring photos that you have seen.

My question is; do you know what has made my paintings go transparent and how to keep them that way? Would they work on a light box or dry out?

Cassie

We are also looking at preservation of salt and the 'Sin Eatters' in Wales and more information on the value of salt. Have you found any information regarding this in your research? We are really looking forward to the visit to the Salt Silos and the Cornish Salt Company and are very excited about the ideas of recording photographically, as film and sound too.

Tuesday, April 24, 2012 - 06:24 PM

Antony

Hi LAB...and especially Natasha

I’ve done a little searching and am copying something to you (below). In answer to your query, it seems to me that first you need to maximise the concentration - ie getting the most salt dissolved. The advice is that a higher temperature water is good for this, and also boiling-off some water would be good. However - for the crystal formation, lower temperature is better, so maybe place in the fridge once the solution has cooled down?

One of the links at the bottom talks about a ‘seed crystal’ as well...

Good luck !

Also - to all - the links at the bottom could be interesting in preparation for the field trip next week?

Question : “My son is growing Salt crystals for his science fair project. He wanted to see if the temperature will effect the rate of growth of the crystals. He has 2 test samples, one at room temperature and the other in a lower temperature using the refridgerator. The test sample in the refridgerator started growing crystals within 3 hours. The room temperature sample took 8 days before it started growing crystals. Can you explain why they grew faster in the lower temperature? Are the crystals forming at a lower temperature from evaporation, or are they solidifying? If this is the result why does salt melt ice?”

Answer 1: Crystals tend to accumulate when the concentration of salt in solution exceeds the solubility. In this state of growing crystals, the solution is called "supersaturated". Supersaturation can be achieved by quickly changing the solubility, or by changing the concentration.

One way to change solubility is by changing the temperature. As temperature increases, some salts become more soluble, some become less soluble, and some maintain a relatively constant solubility. Here is a chart illustrating this principle:

http://galileo.phys.virginia.edu/education/outreach/8thgradesol/TempSolubility.htm

One way to change concentration is by evaporating the water (and leaving behind the salt ions in solution). Did you observe any change in the water levels in his containers, especially the room temperature container? Was there any crust around the rim just above the water level?

Here is a page that discusses the competing processes of dissolution and precipitation:

http://dwb.unl.edu/teacher/nsf/c09/c09links/www.chem.ualberta.ca/courses/plambeck/p101/p01181.htm

Many people tend to think that dissolution and precipitation are exclusive processes (only one happens at a given time), but, in reality, they both occur simultaneously. The different rates of the processes often give the appearance to the human eye that only one or the other is taking place.

AND:

Answer 2: I am going to assume that the experiment consisted of two solutions of table salt (NaCl) and water, with equal concentrations of salt mixed up in the same way (esp if any heating was involved), in identical containers, etc -- that is, all variables controlled except for whether the solution was kept in the refrigerator or at room temperature.

Q: Can you explain why they grew faster in the lower temperature?

It makes sense that the solution would crystallize more quickly at a lower temperature because the crystalline state is more ordered. When molecules and atoms are at a higher temperature, they have a higher average kinetic energy, i.e. they are moving around more quickly. This makes it hard for them to enter and remain in an ordered, solid state. This is the same reason that a pure liquid such as water will crystallize below its freezing temperature and melt above. The same thing happens with most amorphous (non-crystalline) solids such as butter -- above some temperature, they become liquid. However, with the salt in your experiment, the two states are "crystalline solid" and "in solution" (rather than liquid). When the experiment is done, it might also be interesting to compare the sizes of the crystals obtained at the two different temperatures.

Q: Are the crystals forming at a lower temperature from evaporation, or are they solidifying?

It's difficult to say without being certain of your experimental setup and seeing photos. If the crystals that have formed are under water, then no, they are not being formed by evaporation. They have precipitated out of the solution. If the only crystals you can see are on the inside of the container above the water line, then that sounds like evaporation. (Evaporation should occur more quicker at the higher temperature, other things being equal, but the humidity levels inside and outside of your fridge are almost certainly not the same.)

Q: If this is the result why does salt melt ice?

Think of it this way: in your experiment, the crystals that are forming are made of salt -- there is no water in them. In the case of salt helping ice to melt, the crystals are made of water. So, even though the same two substances are involved (although road salt is often not NaCl), two different processes are occurring. The general idea is that atoms from the salt wiggle their way in between water molecules, making it more difficult for them to stay in their ordered, crystalline structure. Thus, less kinetic energy (a lower temperature) is required to induce melting.

Here are some resources for further reading:

http://chemistry.about.com/od/growingcrystals/ht/saltcrystals.htm

http://antoine.frostburg.edu/chem/senese/101/solutions/faq/why-salt-melts-ice.shtml

http://www.pa.msu.edu/sci_theatre/ask_st/030492.html

http://en.wikipedia.org/wiki/Road_salt#Road_salt

Thursday, April 26, 2012 - 10:43 AM

Antony

And here's some extra advice from Andrew Fielding, who is an expert on the heritage of salt working. Andrew will be demonstrating the making of sea-salt in Penzance in May.

http://www.aandafielding.blogspot.co.uk/

First for Natasha:

"A STRONG BRINE, SATURATED IF POSSIBLE WILL GIVE THE BEST AND FASTEST RESULT. BUT THE SALT NEEDS TIME TO BE SUCKED UP AND AROUND THE OBJECTS AND THEN IT WILL START TO EVAPORATE. THE LONGER YOU LEAVE THIS THE BETTER, SO START DOING THIS NOW AND YOU WILL HAVE A GOOD RESULT BY JUNE.

TAKE SOME PHOTOGRAPHS AT REGULAR INTERVALS AND YOU CAN RECORD HOW THE PROCESS HAPPENS.

YOU NEED A LARGE RESERVOIR OF BRINE SO IT DOESN'T DRY OUT AND STOP THE PROCESS."

and then for Cassie

"I'VE NOT DONE ANY RESEARCH INTO 'SIN EATERS', I'VE HEARD OF BREAD AND MILK BEING INVOLVED.

PART OF THE LINK WITH SALT MIGHT BE CONNECTED WITH THE TRADITIONAL GIFTS OF WELCOME BEING BREAD AND SALT

http://en.wikipedia.org/wiki/Bread_and_salt

SO THAT THE END OF LIFE WAS LINKED WITH THE START OF LIFE.

HOUSE WARMING GIFTS WERE TRADITIONALLY BREAD, SALT AND EITHER WINE OR A BROOM."

Friday, April 27, 2012 - 10:52 PM

Cat

Sin Eaters - I found this:

In some part of Wales a very extraordinary rite was observed. "When a person died, the friends sent for the sin-eater of the district, who on his arrival places a piece of salt on the breast of the defunct, and upon the salt a piece of bread. He then muttered an incantation over the bread, which he finally ate; thereby eating up all the sins of the deceased. This done, he received the fee of two shillings and sixpence, and vanished as quickly as possible from the general gaze; for as it was believed that he really appropriated to his own use and behoof the sins of all those over whom he performed the above ceremony, he was utterly detested in the neighbourhood -- regarded as a mere Pariah -- as one irremediably lost."

-- From Welsh sketches, by Ernest Silvanus Appleyard

Monday, April 30, 2012 - 11:09 AM

Cat

And this from www.walesonline.co.uk  

Terry Norman, secretary of Ammanford History and Archaeological Society has spent the last 20 years researching and documenting the rich written and oral histories of both Ammanford and Llandeilo in Carmarthenshire.

Among the intriguing tales is the account, based on a biography of a Welsh Preacher, Christmas Evans, of the ritual of eating the sins of the dead.

"The sin-eater would be summond and would place a plateful of salt covered with a slice of bread upon the breast of the deceased.

After the recitation of appropriate charms over the body, the sin-eater would then proceed to eat both bread and salt, and wash them down with a tankard of beer. It was generally believed that the sins of the deceased were transferred to the unfortunate wretch through his consumption of the salt and bread. A paltry sum of sixpence or a shilling would then be paid to him before he was was driven over the threshhol to the sound of oaths, and threats never to return again."

What this has left me wondering is whether this is the same Christmas Evans who inspired Bedwyr Williams' marvellous performance character of a one-eyed, slightly tipsy methodist preacher!

Monday, April 30, 2012 - 11:50 AM