The Lycurgus Cup

August 31, 2013 5:08 PM

This 1,600-Year-Old Goblet Shows that the Romans Were Nanotechnology Pioneers. The Lycurgus Cup appears opaque green under normal light, but the ancient dichroic glass vessel transforms to a translucent red color when lit from behind. Roman artisans achieved this by impregnating the glass with particles of silver and gold as small as 50 nanometers in diameter. Inspired by the cup, modern researchers have created the world's most sensitive plasmon resonance sensor. [Via]
posted by homunculus (28 comments total)

I am always impressed by the delicate metalwork done by ancient civilizations. Amazing technology.
posted by annieb at 5:52 PM on August 31, 2013

What I want to know is how they managed to make particles of gold and silver that small. You can't grind them; they're ductile and the particles would merge together under pressure.

In modern times we make such powders through chemical precipitation, but that requires powerful acids that the Romans didn't know about (like nitric).
posted by Chocolate Pickle at 6:05 PM on August 31, 2013 [3 favorites]

What I want to know is how they managed to make particles of gold and silver that small.

Maybe they just used gold dust straight from the mine?
posted by Sys Rq at 6:12 PM on August 31, 2013

Sigh. I use this example all the time in lectures (mechanism of the glasses' color has been understood since the 1990's); however, the Romans were NOT nano-pioneers. They likely stumbled upon this glass through empirical trial and error, like most pre-19th century materials 'scientists'.

The art is beautiful and raunchy*, and the post-hoc science is great. Just don't impute understanding where there was none.

Also - ScienceDaily SUCKS: That Liu paper was 'inspired' by the lycurgus cup as much my arse was inspired by a curry. This is a well established field - surface plasmon tuning by some sort of geometric confinement or proximity other nanoparticles, then slap a biomolecule on there and get a sensor reading - maybe parallelize it somehow by putting lots of them down on a chip - there are THOUSANDS of papers about using surface plasmon materials as biosensors. The fact that they get a single wavelength is nothing impressive really.......Hint: it's published in a meh journal. Grrrrr.

The fact that some postdoc....or worse the PI...... saw the lycurgus cup and could wank this entirely-unrelated approach off as an 'inspiration' to science-popularizers is a testament to said popularizers complete lack of understanding of the field and their credulous acceptance of dubious metaphors and boilerplate funding-enabling bullshit about 'lowcost biosensors' 'therapeutic antibody screening for drug discovery ' - which are not likely to be impacted by this particular tiny advance. Grrr x2.

OK. Back to looking at pretty cups

ffs, the story on the engraving is much better than the breathless nanowank. From wikipeda:

* Most cage-cups have a cage with a geometric abstract design, but here there is a composition with figures,howing the mythical King Lycurgus, who (depending on the version) tried to kill Ambrosia, a follower of the godDionysus (Bacchus to the Romans). She was transformed into a vine that twined around the enraged king and restrained him, eventually killing him. Dionysus and two followers are shown taunting the king.

posted by lalochezia at 6:17 PM on August 31, 2013 [41 favorites]

I love reading about stuff like this. Too often, I get it stuck in my head that "ancient" cultures were inferior in their intelligence and abilities. A misinformed prejudice, I know, but not easy to fall into. Then I get a little reminder that no, just because they didn't have pocket computers, they still had the same grey matter to develop wildly intricate ideas. Just not as much history yet. (and then I like to think about how humans from the same amount of time forward will look at us and wonder how we came up with X.)
posted by [insert clever name here] at 6:17 PM on August 31, 2013 [1 favorite]

I suppose the cavepersons at Lascaux chose their pigments after first measuring the particle size of the pigments then deducing what color they would be after reflecting light from a fire. The part that really kept Ugg up at night was that the color temperature of the fire was dynamic and varied, but no one had yet invented numbers, so predicting the flame color based on the chemical composition of the burning materials prior to starting the fire was just such a chore using only hair and blood on the side of a flattish log.
posted by Stonestock Relentless at 8:10 PM on August 31, 2013 [9 favorites]

I went googling around to see if I could find out how they got the particles so small. Most references to the cup say this is unknown, but someone in a comments thread asserted that they dissolved the silver and gold in mercury, painted it on in a thin layer, and let the mercury evaporate. I don't know enough about chemistry to know if this is plausible.

Also, I assume the first time someone made glass like this, they had no idea they were going to get this colour-changing property, and were just hoping the silver and gold would make it nice and sparkly or something.
posted by lollusc at 8:15 PM on August 31, 2013

ffs, the story on the engraving is much better than the breathless nanowank.

I know nothing about nanowanking, but the engraving is absolutely incredible. The lattice connections between the top and bottom layers is so fragile. How dood they dood that?

It must have taken months to finish this. One false cut....
posted by BlueHorse at 8:29 PM on August 31, 2013

Imagine how much effort must have gone into learning to make alloys. Some things may have been just dumb luck; like maybe getting charcoal into the iron you are smelting and getting started on the road to steel.
posted by thelonius at 8:30 PM on August 31, 2013

Maybe they just used gold dust straight from the mine?

Gold Dust is about the consistency of sand. Much too coarse to cause this effect.

...they dissolved the silver and gold in mercury, painted it on in a thin layer, and let the mercury evaporate.

I don't believe it. Mercury doesn't evaporate that rapidly.
posted by Chocolate Pickle at 10:15 PM on August 31, 2013

Also, mercury has ridiculous surface tension; you can't "paint" it into a thin layer. I doubt that mixing silver and gold with it would change it drastically enough.
posted by Chocolate Pickle at 10:22 PM on August 31, 2013

So they had better concrete than us, they knew nano plus they outlawed circumcision. The descent of man.
posted by telstar at 10:47 PM on August 31, 2013

Yes, but they declawed their cats.
posted by brundlefly at 11:37 PM on August 31, 2013

Mercury evaporates fairly quickly when it is boiled.
posted by Brocktoon at 12:00 AM on September 1, 2013

the Romans were NOT nano-pioneers. They likely stumbled upon this glass through empirical trial and error, like most pre-19th century materials 'scientists'.

Why must 'scientists' always show distain for engineers? Sometimes the cart is in front of the horse, usually because the horse has not yet arrived. Edison "invented" the electric light bulb and Goodyear "invented" vulcanisation of rubber through the same patient, trial and error, test and observe process the Romans used to "invent" a lot of other things. Edison wasn't a scientist, but he was a pioneer and it seems to be that the Romans might deserve similar credit for having developed a manufacturing process taking advantage of something "scientists" would not stumble upon for another 1500 years.
posted by three blind mice at 1:20 AM on September 1, 2013 [3 favorites]

The part that really kept Ugg up at night was that the color temperature of the fire was dynamic and varied, but no one had yet invented numbers, so predicting the flame color based on the chemical composition of the burning materials prior to starting the fire was just such a chore using only hair and blood on the side of a flattish log.

Ugg figured it all out in the end.
posted by homunculus at 1:42 AM on September 1, 2013

three blind mice: Why must 'scientists' always show distain for engineers?

In this specific case, the claims of 'nanotechnology pioneers' are pretty wildly over the top, and I suspect that's what lalochezia is responding to. I'd also say there's a vast distance between this, which was most likely a single process that happened to be cool, and the sort of systematic exporation-on-a-theme and refinement that Edison, or Roman concrete engineers did.

I think part of the frustration (for me at least) is that it's so easy for bad journalism to look at stuff like this, and declare the Romans 'nanopioneers', as if there's a large body of knowledge behind something like this. It's a short step from there to the idea of 'Ancient Secrets', which leads to a lot of woo.
posted by Runcible! at 1:42 AM on September 1, 2013 [4 favorites]

Serendipity has always been a part of science and discovery.
posted by marienbad at 2:37 AM on September 1, 2013

I speculate that the glassworkers gilded some glass, ground that up, diluted it with some more glass, ground that up, and continued the process until they were satisfied. They may have done the same with the silver, perhaps coating the glass with a mercury-silver amalgam and then driving the mercury off by distillation. Anyway, I bet the melt-grind-melt process is the way they produced the nano-particles.
posted by Joe in Australia at 3:43 AM on September 1, 2013 [1 favorite]

If you google lycurgus nanotechnology freestone you will find the paper that the rotten piece of journalism was sourced from. It is quite informative.
posted by BenPens at 4:51 AM on September 1, 2013

Cup is believed to date from 290-325 A.D., so it's 1700 years old, not 1600.
posted by beagle at 5:43 AM on September 1, 2013

Chocolate Pickle, butter of gold is a mercury / gold amalgam that you can indeed paint onto a surface to be gilded.
posted by pajamazon at 5:51 AM on September 1, 2013 [2 favorites]

"...having similar shape and properties as the Lycurgus cups displayed in a British museum."

Cups plural aside, that's THE British Museum, motherfuckers.

I had never heard of this before, and now I am going to take myself down to the BM next week to see it. Thanks!
posted by corvine at 6:02 AM on September 1, 2013

Yes, mercury is fantastic at forming amalgams with most other metals. It's a shame it's toxic, because it is probably the funnest metal there is.
posted by Joe in Australia at 7:31 AM on September 1, 2013 [1 favorite]

Aha! I knew I'd read something about this: Art of Gilding - Materials - Leaf.
Lots of other interesting pages there, too, like Fire Gilding, in which "butter of gold" (thank you pajamazon) is used to paint metalware. I don't know whether that technique works with glassware, though. Anyway, hand-made gold leaf can be thin enough to be transparent. So take a few gilded tesserae, grind them and throw them into the mix. That sounds as though it would work nicely.
posted by Joe in Australia at 7:42 AM on September 1, 2013

Why must 'scientists' always show distain for engineers?

As Runcible! points out, my disdain is for the reporting, not the craftsmanship - also the "ancient secrets woo" linkage which gets my blood-a-boilin'.

TBM's points are well taken about the cart before the horse: I think that lots of science is based on not knowing mechanism and detail in anywhere the depth we think we do - cf. drug discovery and pharmacological action. This being said, these discoveries are made in a intellectual framework, and for there to be real science, there must be some sort of framework there, or at least attempt to discover said framework., always unerstanding that the framework can be revised or discarded.

I consider myself a scientist-engineer hybrid, as I test far too few hypotheses to be a Real NIH scientist (TM), and do quite a bit of "if it works, we use it" molecular engineering labwork.
posted by lalochezia at 8:23 AM on September 1, 2013 [1 favorite]

Chocolate Pickle: "...they dissolved the silver and gold in mercury, painted it on in a thin layer, and let the mercury evaporate.

I don't believe it. Mercury doesn't evaporate that rapidly.

It does at elevated temperature.

Chocolate Pickle: "Also, mercury has ridiculous surface tension; you can't "paint" it into a thin layer. I doubt that mixing silver and gold with it would change it drastically enough."

That's exactly how goldplating was done prior to electroplating. It's documented in De Re Metallica from 1556, but known much longer than that.

Joe in Australia: "So take a few gilded tesserae, grind them and throw them into the mix. That sounds as though it would work nicely."

Nope, you're still talking about gold objects (single painted surfaces of glass debris) far too large, by orders of magnitude.

I'm guessing they painted the gold on a blown bulb, then reheated it and blew it much bigger. The gold would fracture fairly evenly into islands. If needed, the bulbs could then be smashed, a fresh bulb rolled in the resulting grit, and the process repeated, for an X-squared reduction in gold island sizes. The gold contained in-matrix would probably contribute very little to the optical effect; only the gold on-surface (where the index of refraction boundaries were high) would likely be useful - but there's still a LOT of that.
posted by IAmBroom at 2:45 PM on September 3, 2013

The glass-blowing trick is a good one, but gold leaf can be as thin as a few hundred atoms thick. I found gold leaf sold commercially which is about .1 microns thick, not far from the reported particle size of 70 nanometers. My understanding is that the process used to beat gold hasn't changed much, and I presume that (a) you can make even thinner gold leaf if you try; and (b) the process of applying the leaf to an object, grinding it, melting it, mixing it and so forth would add further stretching and dispersion.
posted by Joe in Australia at 4:58 PM on September 3, 2013 [1 favorite]