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Author Topic: lead glass  (Read 52410 times)

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Offline NevB

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Re: lead glass
« Reply #60 on: June 23, 2020, 08:06:01 PM »
Going back to the original question I was pondering recently whether you could identify lead glass by its density in gms./cm3. So looking it up I found soda glass is anything up to 2.4gm./cm3 and lead glass is anything from 3.19gm./cm3 usually up to 4.00gm./cm3 and even 5.9gm./cm3. It's easy enough with a regular solid object to work out its volume in cm3 and divide it by its weight in grams but something like a glass is more difficult. If you can part fill a container with water, mark the level and then submerge the piece in the water and mark the new level. The amount of water displaced gives the object's volume which can then be divided by its weight to give its density. Although it's difficult to do this accurately I tried this with something that was marked as lead crystal and it seemed to work but I'm prepared to be shot down in flames! 
You can't fool me there ain't no sanity clause. Chico Marx.

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Offline Ekimp

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Re: lead glass
« Reply #61 on: June 23, 2020, 08:47:15 PM »
Hi again  :). As you say, measuring the volume of displaced water directly can be a bit difficult to do accurately. I think a better way is to do it entirely by weight.

You suspend the item you are investigating from scales by wire or similar and read the weight when suspended in air. You then lower the item, still suspended from the scales, into water until itís entirely submerged and then read the weight again.

If for example it weighs 1000g in air, and 600g in water, then it has displaced 400g of water or 0.4l volume (in fresh water). Obviously you have to be careful of bubbles in the glass and trapped air. I used this method to determine the density of a glass elephant and it worked quite well (although I had to estimate the volume of a large internal cavity).

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Offline NevB

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Re: lead glass
« Reply #62 on: June 24, 2020, 08:09:28 AM »
That is another good method, it avoids trying to measure the small differences in water height which might only be a few millimetres.
You can't fool me there ain't no sanity clause. Chico Marx.

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Offline sph@ngw

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Re: lead glass
« Reply #63 on: March 11, 2021, 06:02:56 PM »
Weight is really the key factor, and the real way ( not simple) is to do specific gravity test.

The normal method of determining specific gravity is to weigh the specimen dry (DW), then to suspend the specimen in water on a string, and to measure the weight pulling on the string (WW) (specimen weight suspended in water). Then you subtract WW from DW, and divide the difference into DW.



Lead is a heavy metal, and lead glasses weight more, by up to 30% for a similar size and

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