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Huge coughed up some electrons that declared:

Not intending to disagree - I don;t know anything about glass flow anyway: but *what* was all that stuff about in my 5th form physics books, where they said that glass flow was detectable in stained glass in some older cathedrals, to quote from memory "glass was found to be a mm or two thicker at the base than the top after about 900 years".

Curious...

Cheers

Tim

Reply to
Tim S
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... and at the sides, and at the top, and and various places in the middle too... because that's how glass was made in those days.

As I said, it's one of those urban legends that just won't let go.

Daniele

Reply to
D.M. Procida

Naah, me neither.

It was fitted that way...

Reply to
Huge

But if you do want to see a very slow liquid "in action" try this

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Reply to
Andy Burns

Daniele,

So what about the old farmers who were once breeding cows with only three legs so that they could:

A - Milk them easier. B - As a safety measure (even had elf and safety in them days) - so that if they tried to kick the farmer they would fall over.

But as farmers then were losing cash when they sold them (the cows were a bit short on leather and meat) they returned to breeding four legged ones - always said farmers were tight fisted!

Now is that an 'urban' or a 'country' legend, or could it even be a bit of folklore - or even a fact?

By the way, can you get glass wedges anywhere, as I'm stuck for a few to hold the sagging glass up in one of my windows?

Big Grin

Reply to
Big Grin

Alan,

Now you have made such a dramatic statement, please prove absolutely convincingly by scientific methods that I am wrong - please supply all calculations and experimental data to confirm your theory.

Now, if that is your theory that glass is not a liquid, then please go to the bottom of the class for lack of effort.

Now a question for you - what is the most prolific solvent?

Big Grin

PS do *YOU* know where I can get some glass wedges from to hold up my sagging window glass?

It's starting to get bloody draughty in here now. and I don't want to replace it as I'm not sure that the new glass won't suffer the same fate. :-(

Reply to
Big Grin

Have you forgotten to turn the windows every two years like you should?

Reply to
dennis

Dennis,

I've tried turning them upside down and that does the trick for a while - but then it starts to sag again.

Bloody annoying having to turn the stuff every million years or so! *eg*

I really must leave this modern technology alone and go back to milking my three legged cows. ROLFL

Big Grin

Reply to
Big Grin

Do they show evidence of devitrification? (I'd expect the glass to be a little cloudy or even have visible crystals.)

What's always struck me about the myth that glass (which does have the molecular organisation of a liquid) flows is how, supposing that it flowed, could the rearrangement of molecules that that entails avoid hitting the more stable crystalline arrangement, at least microscopically? And once it starts crystallising, it'll keep going, just as if you have super-cooled water, a tiny disturbance can make it turn to ice in a twinkling (not that undisturbed glass is going to do anything quickly).

Reply to
Jon Fairbairn

Indeed. I think the truth is that glass is a supercooled liquid, but no, it doesn't flow at room temperatures at all appreciably even in 1000 years.

Reply to
The Natural Philosopher

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