1	Measure the density of water by measuring mass and volume.
	Measure the density of steel by measuring mass and volume.
	Measure the density of brass by measuring mass and volume.

2	Measure the density of air - include error estimate.
	

3	Measure the bouyant force on brass in water, first roughly, then accurately.  FBD!

3	Using the Westphal balances:
	Measure the density isopropyl alcohol (or windshield-washer fluid, propylene glycol)
	Measure the density of water
	Compute the volume fraction of the solution.

5	[Time permitting] Compute the density helium (with FBDs) by measuring mass of
	balloon envelope, string tension, etc.