Re: What does salt contain to be able to float an egg?

To understand this, you have to think about why things float (or sink).

The property that is important is the *density* which is the mass (or you 
can think of weight) per volume.  So a solid piece of iron has a very high 
density, air has a very low density, and water is somewhere in between.  
Things that have a higher density than water (rocks, coins) will sink in 
water, while things with lower density than water (ice, most wood) will 
float.  That is true for anything floating in any liquid (the liquid 
doesn't have to be water) -- it all depends on whether it is more or less 
dense than the liquid.

An egg is about the same density as water.  But if you put salt in the 
water, you are adding mass to the water without changing the volume of the 
water very much.  So a liter of normal water would weigh about 1000 grams, 
but a liter of salty water might weigh 1050 grams (depending on how much 
salt you put in).  Since the density of the egg doesn't change, making the 
water more dense makes the egg more likely to float.  Anything that 
dissolves in water (like sugar) would have a similar effect as long as it 
increased the density.

Scientists sometimes use this same principle when they need to know the 
density of some liquid -- they use objects of known density and see if 
they sink or float in the liquid.

Allan Harvey
"Don't blame the government for what I say, or vice-versa."