Name: 4 Things We've Forgotten How to Make
Uploaded: 2022-04-14T09:06:10.000Z
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History is full of things like personal histories, languages,  and even whole technologies and  

techniques that we no longer remember.  But one of the coolest things about archaeology 

is that it gives us a chance  to re-learn things.

So here are four examples of really  cool technology we kind of lost,

how scientists are using modern techniques  to study and re-learn them, and,

ultimately, why these techniques  nearly disappeared.

One of the first examples of impressive  ancient engineering is Roman concrete.

Rome built some truly epic buildings, and  many of them are still around today,

like the Pantheon.  Roman concrete was incredibly durable,  

especially when we're talking about its  use in marine environments,  

like building harbors.   Building something that can last thousands  

of years in wave-wracked seawater  is truly impressive.  

But with the decline of the Roman empire,  people seem to have more or less  

stopped using this super durable  concrete on a wide scale.  

And for a long time, we didn't really know  what made this concrete so durable.  

I mean, we knew just a tiny bit.   For instance, thanks to recipes  

recorded by people like Vitruvius,  historians knew that the Romans used  

a different recipe than modern concrete.   Concrete, in general, is a mix of aggregates,  

like little bits of rocks or brick,  water, and cement, and varying that recipe  

can change its physical properties.  The Romans used a particularly  

involved mix of aggregate  along with lime, seawater, and volcanic ash.  

But not just any ash: It was a  special kind called pozzolana,  

which was dug up near Naples.   This mix seems to be special,  

since people would actually pay  to import this ash when they were  

what actually made this mix special.  In a study published in 2017, scientists  

decided to find out.  They got samples in the  

form of long, cylindrical cores  that had been drilled out of Roman ruins     

and then used a microscope and X-rays  to look at the minerals inside.  

They found that the answer to the  incredible durability of Roman concrete 

lies in the chemistry inherent in the concrete,  in large part thanks to the mix of both seawater  

and that special volcanic ash.      Silica and aluminum oxide from the  

pozzolana reacts with lime and the seawater  to create crystals of a mineral called  

concrete and makes it less likely to crack.  Even better, further exposure to seawater causes  

the growth of more tobermorite,  explaining why Roman concrete did  

so well in coastal projects.   But if this was such cool tech,  

how did the whole world  just kind of seemingly forget about it?  

Well, in this case, the answer  partly has to do with demand.  

In short, with the collapse  of the Roman empire,  

the nearby demand for this kind  of mega-engineering went away.  

It no longer made sense to  build quite as grandly  

or to pay for the special pozzolana  to be dug up and shipped.   

With less demand, the knowledge  of how to make this concrete  

started to fade away.  It didn't entirely disappear,  

we have examples of engineers still reaching  for pozzolana long after the Romans fell,  

but it may have become more of a  trade secret or kind of oral memory  

rather than a codified recipe.  It was only later, in the 1700s,  

that science kind of formally recognized and “re-discovered” it again.

The moral is that technologies  exist in context. 

When it made sense for Roman concrete  to be widely used, it was. 

When it wasn't, it faded into memory.  Speaking of being widely used, 

Roman concrete might make a further  resurgence sometime soon.  

A number of scientists have suggested that  the formula, or something similar to it  

using coal ash, might be a good  candidate for marine uses today,  

and produce fewer carbon emissions.  Now onto something softer…Dhaka muslin  

was a thin, high-quality fabric  that came from what's now Bangladesh.  

It had been produced for centuries before  eventually becoming a big hit in Europe  

in the late 1700s.   The material was made  

of a special variety of cotton  that grew along the Meghna River,  

which had very short, easily frayed threads.  This made the material kind of a beast to  

work with and turning it into fabric required a convoluted, 16-step process 

that would have required multiple households.  One step could only be done on boats,  

for instance, as the material needed to  

be a certain level of humidity. The payoff of all this work,  

however, was incredible.  The material was very light and thin. 

It was said that you could fit 18 meters of  fabric into a pocket-sized snuff box and it  

could apparently reach thread counts  around 800-1200 threads per square inch. 

But by the 1900s, it seems to have disappeared. So why'd we stop making it? 

In short, because the British  East India Company or EIC  

made it impossible for farmers  to make a profit off of it. 

In the 1700s and 1800's, the EIC effectively  took over large portions of India 

and started to muck with the system.  One thing they did, for instance,  

was to put the farmers into terrible  financial situations where it was really  

easy to go into irrecoverable debt.   In the meantime, British manufacturers flooded  

the market with inferior look-alikes.  The end result was that the farmers,  

no longer able to make a stable living  off it, abandoned the practice.  

And without people to continue growing it,  the variety of cotton it was based on went  

Dhaka muslin was a thing of the past.  That said, scientists are trying  

to renew the industry.  Luckily, the technique was  

written down, so we do know how to make it,  but we still need that special cotton.  

And although it doesn't grow anymore, we  may be able to kind of recreate it.  

And it's all thanks to leaves  preserved at the Kew Gardens.  

Scientists could extract  the DNA from those leaves  

and form a genetic signature for this plant.  Then it was off to the races, they started a  

scavenger hunt for the closest wild plant  near that one river and found one that's a  

potential cousin or descendant.   Today, they've grown those plants  

and are making something  close to the original garments again.  

So what can we learn from Dhaka  muslin's disappearance?  

Again, it kind of comes down to economics,  but in this case, specifically, trade and  

colonialism were disrupting the industry.   We can see this in other places too.  

The Haya in Africa had a unique way  of making a very high-quality steel 

and were doing it long before many  other people had the technology,  

but the technique was nearly lost in the 1900s  

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4 Things We've Forgotten How to Make

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