The plant that softens stone.

originally posted by: Harte

An acid will react with limestone so it's possible to use acid to shape the surface of limestone.

Harte

True. But it will change the molecular structure of the (surface of) the limestone.


And, of course, this is the reason why we can easily show whether any rock has been "softened" by any plant or indeed anything else. Or, as others have suggested. somehow broken up and reconstituted.

If rocks had been softened we would known in the same way that we know if a bone has been in a fire. And thats about as easy as archaeology gets!

originally posted by: AndyMayhew

originally posted by: Harte

An acid will react with limestone so it's possible to use acid to shape the surface of limestone.

Harte

True. But it will change the molecular structure of the (surface of) the limestone.

Assuming there's any such treated stone left on the surface.

Anyway, I'm not advocating for the idea. Just wanted to point it out to Admirethedistance that a stone's surface can be removed this way.

Everything doesn't have to be done with saws and chisels alone. Even granite can be "softened" - in the sense that heat can change the surface to make for easier carving. I think this may have been utilized for some of the obelisks in Egypt - both in quarrying and in carving the the highly precise glyphs to be found on them.

Harte

a reply to: AdmireTheDistance

Well, that would depend on both the acid used and the mineral component of the rock it was attempted on, wouldn't you agree? I bet that HydroFluoric acid (HF) as well as some other common acids would perform quite well at least against some types of rock.

It's been a while since my chemistry classes but as I recall the effect would be a combination of how reactive the acid would be with the mineral content of the stone and the strength of the acid one would have available. Chemical erosion is recognised factor in landscape erosion I belive - correct me if I'm wrong. So that acids might dissolve minerals in rock, thereby making them easier to shape, shouldn't be very controversial.

So using some sort of chemical to aid in a mechanical process, let's say drilling a hole in a rock, doesn't seem so far fetched if one found the right acid and the right rock. So I'm afraid I don't see how one might conclude that it won't work in general. It might not work in some situations, granted, but I suspect it might work quite well in others.

Now, if one could find some chemical way to make one's work more effortless, I find it very possible - even probable - that this would be something that people in earlier times would take advantage of if they knew about it.

We accept that people, even in prehistoric times, managed to do some pretty advanced processing of raw materials. Glues, for instance, and tar production - which is not all that easy to make. So why should they not make use of acids?

I think this is quite plausible. If there is something I'm missing here, feel free to educate me. I'll accept any logical and plausible explanation why this will not work, that has an explanation of why that holds water.


BT

originally posted by: Harte

originally posted by: AdmireTheDistance

originally posted by: MissMilkyWay
Although this doesn't provide any further information, it seems to be further proof of the rock softening process. I think if you can master this, you can do anything.

Don't be naive. That guy is a good sculptor and artist, but he hasn't magically softened stone. Those are just carvings. Try and find a 'before' picture of the raw material used to create any of those.

originally posted by: beetee

If I try it and it does work I'll try to document it.

It won't.

An acid will react with limestone so it's possible to use acid to shape the surface of limestone.

Harte

That's a good point, and one I hadn't considered. The artist may well have utilized such a method on some of those works. Some of them, however, are clearly not limestone (or sandstone, which I believe will also react with some acids). I'd be willing to bet that those were done via chiseling and sanding. Nice pieces of work either way.

a reply to: AndyMayhew

I was wondering, are you aware of any studies that have looked into the possible use of chemical compounds in stone shaping in prehistory? I am just curious because I have not. The conventional wisdom is mechanical force was used almost exclusively to shape stone, and I have a sneaking suspicion that if one just accept this the molecular structural changes you describe might not even be looked for.

I, for one, have always been amazed by the kind of effort that would be requred to, for instance, drill a hole into a hard rock. Many of the "battle axes" of the neolithic for instance, which are very beautifully shaped and many with drilled holes. I know it can be done with sand and water and patience, but have any looked for molecular changes in artefacts such as these?

Just curious.

BT

Edit: After refreshing my chemistry I think igneous rocks (like granite) would be very difficult to work chemically, so no obvious short cut for the battle axes made out of these kind of rocks then. Chemical working of limestone seems feasible though.

originally posted by: beetee
a reply to: AndyMayhew

I was wondering, are you aware of any studies that have looked into the possible use of chemical compounds in stone shaping in prehistory?

Link to paper about the use of fire in AE: [url=http://www.academia.edu/8533249/Fire_on_the_Rocks_Heat_as_an_Agent_in_Ancient_Egyptian_Hard_Stone_Quarrying_co-authored_with_Tom_Heldal_]link[/ur l]

No studies on chemicals that I know of. Even if they were used, it's highly unlikely any evidence would remain on the stone after a century of rains, etc.

Harte

Link entry not working, so:

www.academia.edu...

Harte

a reply to: Harte

Thank you. I will give it a read :-)

BT

a reply to: Harte

Very interesting read. I guess fire quarrying is pretty well established an ancient practice, but I must admit to not having heard anything about it in an egyptian context before - not that I'm very knowledgeable about egyptian prehistory other than in a very general sense. I know they used a lot of granite, and was duly impressed with that (and still am), but I have to concede that I never gave much thought to how they quarried it.

I guess this method could have been used in South-America as well, but probably not by the bird OP started this thread about :-)

Thanks again.

BT

originally posted by: beetee. So why should they not make use of acids?

So they had a super strong acid, which melts rock

here's my question

What material was the acid container made from

originally posted by: beetee
After refreshing my chemistry I think igneous rocks (like granite) would be very difficult to work chemically, so no obvious short cut for the battle axes made out of these kind of rocks then. Chemical working of limestone seems feasible though.

I worked in the granite industry for several years, and the only chemical I know of that will really do anything to granite is hydrofluoric acid. It'll slowly dissolve most of the minerals and leave pits in granite, but it takes a long time, and is incredibly dangerous to work with.

originally posted by: Marduk
What material was the acid container made from

Wasn't the original claim that ancient peoples had learned it from watching birds rub acid onto the sides of cliffs, to make holes to nest in? Screw the containers, I want to see those birds!

a reply to: Marduk

Well, that is of course a practical conisideration, but I suspect something that could be overcome. Hydrofluoric acid was, after all, discovered back in 1771 by a swede who produced large quantites of it (and probably died from exposure to it as well). Acids will, as you are probably aware, not react to absolutely every material. I read of some horrible experiment once where some researchers exposed Guinea Pigs You can read the abstract here if you have the stomach for it to HF to see how lipids (fats on the skin) would act as a barrier to the acid. Some acids could also, conceivably, be produced in situ by mixing components that would negate the need for it to be stored in its reactive state (I think this is sometimes done with HF in the oil industry).

So I guess if you knew how to produce a very potent acid (or chemical of any ilk) you would soon learn how not to store it, and after a few deaths I guess someone would figure out a way to store it more or less safely. It is also a regrettble fact that the term "worker safety" throughout history didn't always mean what we take it to mean today.

I'm not suggesting the ancient Inkas had HF, but merely that if they knew how to make a potent acid they would probably manage to store it as well.

BT

a reply to: beetee

Well, I didn't realise I was asking for rampant speculation on something which has no supporting evidence whatsoever, lol

I was simply asking, what would you store an acid in which can eat through stone in an age where glass hadn't been invented




This is all a bit stupid anyway, the wall at Sacsayhuaman is most often claimed to have been shaped by this unknown method by fringe writers and in fact, its construction technique is absolutely understood, no acid required.

If you have a bit of a common sense think about it, its nonsense, to claim, that you could shape rocks with acid to fit together precisely into a wall. Because Acid isn't that discriminatory, you couldn't use it to shape rock that way. I could buy that some ancient culture used something acidic to form a nice patina, but claims like these about lost technologies are usually born out of a modern persons credulity and refusal to accept the truth.
i.e. I couldn't build a wall like that, so therefore, no one else could.

So I realise that we are drifting a bit from the poor bird at this point, but just to answer your question about storage I guess this would be dependent on what kind of virulent chemical compound I was required to store.

Let's say it's an acid that reacts quite strongly with silicates but is rendered inert by lipids such as fat. Maybe I would try a container lined lavishly with fats. Maybe I'll lose a worker or two to the toxic fumes or acid burns but I would just claim that the gods have claimed their sacrifice and the Great Inca would say no more about it. Perhaps.

Now, as to wall construction (sorry OP but I'm going to just say a little more about walls because I really haven't been able to get anywhere with the bird) , I realise of course that a great many things are thought to be well understood. What that actually means is that there are theories that are widely accepted as plausible, but it hardly means that these are truths. Theories are there to be challenged after all, not merely accepted. I realise we are not going to cause any paradigm shifts from a thread on an internet forum, but let us at least give the whole "things are thus" line of scientific reasoning a well deserved kick on the shin.

Now if I was building a great big wall out of rocks that needed to fit closely together, and I knew about a substance that could weaken the surface of the stone enough to remove say the inconvenient lump or impresicion, I would certainly try to utilise it somehow. Certainly if the alternative was to spend several hours grinding with sand or chiselling away with a relatively weak metal tool.

I'm not claiming the Incas did this, I am merely suggesting that it is plausible if the right chemical was known.

BT

originally posted by: beetee
I'm not claiming the Incas did this, I am merely suggesting that it is plausible if the right chemical was known.

BT

Seems to me, that you don't really have an answer. Your claim about saving time on shaping blocks for a wall for instance, tells me that you aren't very familiar with limestone,
Limestone is very soft and easily carved by hand tools

nor are you familiar with limestone construction techniques,
Its very easy to carve the edges from limestone and this can be achieved in minutes, not hours

nor are you familiar with the Amerindians culture.
They had lots of manpower, very few Elites, who gave the orders, tens of thousands of workers

There's a pretty good video here which shows how easy it is to carve limestone, obviously ignore when he gets his electric tools out



Using acid, would have lengthened the time it took to build the wall, not shortened it.

a reply to: Marduk

Seems to me, that you don't really have an answer.

This is, of course, true. I don''t have an answer, and I always become a bit suspicious when we claim to have all the answers to something that went on more than 500 years ago. Now, this is perhaps a fault in me, but my experience is that all studies of something as complex and bewildering as human behaviour must approach the subject with a certain degree of humility. We should perhaps allow ourselves the luxury of a little bewilderment now and then.

Your claim about saving time on shaping blocks for a wall for instance, tells me that you aren't very familiar with limestone,
Limestone is very soft and easily carved by hand tools

Again, this is true. I am not very familiar with limestone. And certainly not working with very large blocks of it in building projects. Now, I know that limestone is relatively soft, and easily carved. And I've come across this beautiful little video which shows limestone cutting with (admittedly steel) saws, and this shows that cutting and shaping it is fairly easy.



Your video, which shows someone working with marble, is also an interesting video. Now, marble is methamorphosed limestone, which means perhaps that working with it will be a bit different than working with limestone.

Interested parties can read a little more here Limestone and marble.

I am not a stonemason, but perhaps a stonemason would know the difference in working with these two materials. I would suspect that marble would be a little more brittle than limestone, due to its chrystalline nature, but I as I have not worked with these materials I really could not say. Perhaps you have some insights?

nor are you familiar with the Amerindians culture.
They had lots of manpower, very few Elites, who gave the orders, tens of thousands of workers

Again, this is true. I am not very familiar with the AmerIndians cultures. I would, respectfully, contend however, that there seems to have been a lot of different societies over a very long time, so this seems to be a pretty complex subject matter. I agree that they might have learned from each other, which is after all one of the ways humans gain new knowledge (as demonstrated right in this very thread), and they seems to have been fairly innovative and organised. Thus, perhaps, the term AmerIndian culture have some merit, although it seems unwise to assume they all did things the same way. (Which, of course, you don't claim). Further, from what I can see - not being an expert - there were some pretty good stonemasons among them.

Now, with regards to manpower and the degree of control the elites had over this potential workforce, you again have a good point. Some of the elites in some of the societies seems to have exercised a lot of control - at least most of the time.

This, of course, makes building all sorts of walls easier. There is nothing, after all, like ten thousand workers to get a job done, if one can manage to get organised properly.

Atahualpa, the Inca ruler who had the misfortune of meeting Fransisco Pizzaro, allegedly had an army of about 80000 soldiers, just to pick a name at random. There is an article on Atahualpa and on Wikipedia which also perhaps hints at the underlying complexity of the political entity he controlled: Atahualpa

So, we have a lot of workers, and we have a lot of power. We have limestone (but other building materials as well such as granite) and now we can build our wall. Regardless of this, which I grant you is not very controversial in my eyes, we are still left with some pretty hefty construction work. Now the Great Leader may not have cared much about this, but I am willing to stake a few beers on the guess that the people actually tasked with building the wretched thing probably did care a bit. Anything that might have aided them in this process would, I suspect, be very welcome.

Which leads us to your final point:

Using acid, would have lengthened the time it took to build the wall, not shortened it.

Now, this is a very valid point, if correct. And to me, at least, this is where the whole thing will either fall apart as so much bad masonry (if you will forgive the pun) or rise as an intriguing possibility worth at least some consideration.

And, not being a mason, I really cannot answer this. I might also point out that I am not necessarily married to it being an acid - if it exists at all. But here is why I thought it could, potentially, have some merit (again if it exists):

We have these large stone blocks that we need to fit on top of each other, closely interlocking, and we are not going to use mortar. So, we need to shape them very carefully to fit each other with great precision. Some of these blocks have a hefty weight. Now, how would we do that? It it was me, and I was limited to chisels and sanding, the easiest way would perhaps be to cut them in sequence from the same source then reassemble in place with a bit of sanding. Now, this would ensure an almost perfect fit, right out of the quarry, but I suspect it would not always be feasible because accidents (and imperfections) happen.

In such acses I would need to carefully measure and align a block from another source, which is again not undoable, but again requre a lot of careful work. And every so often things would not line up, because humans do make mistakes and blocks are damaged and chipped during transport.

Now, if there was a paste that I knew about, that would weaken the surface of the rock here and there so that the sheer weight of the rock would crush the inconvenient knob and lump with less effort than was required otherwise, I can assure you that I would use it.

There is a little information about Inca stonemasonry here and here for those who want to read more - and there are some references to source material as well, which is alway a neat way to discover more.

As you have previously stated, there are no mention anywhere from what I've managed to read so far about any kind of chemical used, and that could mean that someone actually did look into this and found no sign of etching or weakening that could point to something other than mechanical force being employed. But it could also mean that nobody really thought to check if this might have been done, because why would they if they already understood how the wall was built and no chemical was requred. Which, I shall concede, it wasn't.

But it might have been convenient.
And we still don't really know if such a compound can be made, and if it would save us any work if it could.

But, allegedly, there is a certain species of bird.... ;-)

BT

originally posted by: beetee
But, allegedly, there is a certain species of bird.... ;-)

Was it a mocking bird
haha

a reply to: Marduk
Plant softening stones:



Harte

originally posted by: bluwindRD
Well when talking about the spurs its worth bearing in mind that many spurs were made of silver, which is a lot softer than metal and reacts easier with acid.. perticually nitric acid if memory serves me correctly.

Nice one, good shout! It made me go do some research and then join this forum having read this magnificent thread!

It turns out that oxalic acid is pretty good at leaching silver too, as seen in this paper:
www.iaeng.org...

"The choice of oxalic acid over other leaching agents is due to possible 100% silver recovery; low toxicity; high efficiency on product purity; short retention time; reusability; low CO2 emission; simple smelting process for the sludge."

a reply to: Fortyball

I hope you realise that you are responding to a post made five years ago by a poster who hasn't posted at this website for two years.

And if anyone in this thread knew anything at all about animal behaviour then they would know that no bird has ever been reported using any tool in this manner, their use of tools is strictly restricted to shaping twigs for nests and in one species alone, using small rocks to break open eggs
There is a reason that we use the saying "bird brained"

Expecting a bird to understand the use of acids in softening rock is science fiction...