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Metal

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knightmare
1074044.  Wed May 14, 2014 3:56 am Reply with quote

Metals are not always heavier (density) than water. Lithium, for example, and it's density of about half of water, will float while gradually reacting with the water.

 
ConorOberstIsGo
1074382.  Thu May 15, 2014 8:25 am Reply with quote

Mercury is used as a bed on which to cook glass. This was the revolution which meant flat glass no longer had to be blown.

 
Simon1066
1080386.  Tue Jun 17, 2014 10:50 am Reply with quote

Molybdenum is a trace metal, like copper and zinc, essential for life.

Sexual reproduction couldn’t occur on planet Earth for billions of years because of a lack of these trace metals in the environment.

About 1.9 billion years ago a new continent was formed on Earth called Nuna. Vast quantities of magma pumped up into the crust to form granite. Rock records shows that the erosion of this granite provided a source of these metals for organisms to start reproducing sexually.

They are central to many of the metabolic processes that occur in more complex life.

s: http://www.newscientist.com/article/dn21947-sex-born-from-hard-rock-and-heavy-metal.html#.U6BcF_ldWSo

Molybdenum, when added to steel, makes an incredibly strong alloy. It was not widely used until the 20th century - applications include armoured plating and munitions. However some Japanese swords of the 14th century had been found to contain enough of this element to be considered a type of Moly steel. The swords have incredible strength and corrosion resistance, but it is thought that the blacksmith who chanced upon adding this to iron took his secret to the grave.

s: nature’s building blocks, John Emsley, OUP.

 
djgordy
1080396.  Tue Jun 17, 2014 12:04 pm Reply with quote

Simon1066 wrote:

Sexual reproduction couldn’t occur on planet Earth for billions of years because of a lack of these trace metals in the environment.



Sharp intake of breath.......

 
Marsupial Bob
1080799.  Thu Jun 19, 2014 7:39 pm Reply with quote

ConorOberstIsGo wrote:
Mercury is used as a bed on which to cook glass. This was the revolution which meant flat glass no longer had to be blown.


Actually, float glass is almost exclusively made using a bed of molten tin, and most of the early patents for it use tin. I think lead was used somewhere, but I can't for the life of me remember where.

If you were to float molten glass on liquid mercury, the surface layer of mercury would get hot enough to vaporize. Not only would that quantity of mercury vapor kill you in a fairly unpleasant manner, it would also be a lower density than both the underlying liquid mercury and the overlying glass, so your lower glass surface would be uneven.

 
ConorOberstIsGo
1080940.  Fri Jun 20, 2014 5:39 pm Reply with quote

Marsupial Bob wrote:
If you were to float molten glass on liquid mercury, the surface layer of mercury would get hot enough to vaporize.


I had considered this so should not have used the word 'is'. I still believe molten Mercury 'had' at some point been used in this fashion.

 
Marsupial Bob
1080943.  Fri Jun 20, 2014 6:10 pm Reply with quote

I'm not aware of any attempts at manufacturing float glass using mercury, but then I only have a passing familiarity with glass manufacture after the 18th century. The commercially viable patents are all for tin as far as I know, but outside of the major players (Pilkington) it's not something I've particularly looked into in detail.

I would be somewhat surprised though if mercury was on the list of attempted methods, particularly given how recent a development float glass is. I wouldn't be completely shocked - there have been a lot of industrial uses of mercury that were, in retrospect, utterly terrible ideas - but definitely surprised.


There is a thing called mercury glass, but it's a coating rather than a sheet-glass production method. It's essentially just a mirrored glass produced with a tin amalgam. They quit doing that at some point in the 19th century for the same reason amalgam gilding fell out of favour: the process tends to kill you, and somebody finally found a better method.

 
Efros
1080944.  Fri Jun 20, 2014 6:52 pm Reply with quote

Francium, the ultimate alkali metal, is radioactive and presumably highly chemically reactive. I say presumably as not a lot of it has been gathered together at one time to test it. If you look at the physical properties of Francium you'll find a fair bit of guesswork and extrapolation but very few hard facts. There are estimated to be about 30g of Francium in the whole of the Earth's crust at any time.

 
Posital
1080951.  Fri Jun 20, 2014 9:53 pm Reply with quote

Gallium

Applying a bead of gallium to the surface of an aluminium can destroys the structural integrity of the aluminium when it's adsorbed after a few hours at room temp. See the video in the link.

Something doable for the show...

 
'yorz
1080955.  Sat Jun 21, 2014 1:12 am Reply with quote

Very! Great find, Posital! The process probably needs a bit of speeding up; body temperature-only would take too long. A hair dryer?

 
Troux
1080957.  Sat Jun 21, 2014 1:39 am Reply with quote

'yorz wrote:
Very! Great find, Posital! The process probably needs a bit of speeding up; body temperature-only would take too long. A hair dryer?

Editing.


So many destructive uses for gallium....

 
Efros
1080969.  Sat Jun 21, 2014 4:13 am Reply with quote

Gallium melting in a hand.

https://www.youtube.com/watch?v=VFV81xripUc

 
brunel
1080992.  Sat Jun 21, 2014 9:20 am Reply with quote

Posital wrote:
Gallium

Applying a bead of gallium to the surface of an aluminium can destroys the structural integrity of the aluminium when it's adsorbed after a few hours at room temp. See the video in the link.

Something doable for the show...

There's a certain xkcd article that is rather apt: http://what-if.xkcd.com/50/

 
'yorz
1080995.  Sat Jun 21, 2014 10:20 am Reply with quote

Wonderful stuff, brunel. Easy to understand for simpletons like me. :-)

 
Morbius
1081004.  Sat Jun 21, 2014 12:38 pm Reply with quote

Astronomers use the term metal to describe everything that isn't hydrogen or helium. This leads to the property metallicity is the proportion of an object's mass that isn't made up of hydrogen or helium.

 

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