# Homework Help: Historical information on density

1. Oct 20, 2005

### koroljov

This may or may not be the correct forum to ask this, but let's ask it anyway.

I am looking for historical information on density.
It is so that densities can not be added lineary:
A material containing 10% of material 1 and 90% of material 2 will not have a density of 10% * the density of material 1 + 90% * the density of material 2.

I'd like to know who was the first that realized this.

(any other historical information on density is also welcome).

2. Oct 20, 2005

### Diane_

While it's not strictly speaking density, Archimedes' Principle is related.

http://en.wikipedia.org/wiki/Archimedes
http://physics.about.com/cs/fluiddynamics/g/archimedes.htm [Broken]

This may get you started.

Last edited by a moderator: May 2, 2017
3. Oct 20, 2005

### Cyrus

Aha, I have re-read the site and have to change what I said. He probably did not do the experiment to determine if the kings crown was made of pure gold by simply using the law of the lever and the displacement of water. The problem with that method is that it is too small of a displacement of water when comparing pure gold to gold-silver alloy. To overcome this, he balanced the known gold and the crown on a lever. Then he put the lever into the water. If it remained level, then they both had the same volume. The Crown is quite nice too!
http://www.math.drexel.edu/%7Ecrorres/Archimedes/contents.html [Broken]

Last edited by a moderator: May 2, 2017
4. Oct 21, 2005

### koroljov

That's a good one. I should have thought of that one. Thanks.

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