Subject: Balloon lift calculations with different gases...

How do you calculate the lift generated by hydrogen, helium, or 
(theoretically) a vacuum in a balloon (probably mylar)?  How high 
could such balloons rise, given an ideal situation and a standard 
mylar or similar balloon material?  What difference does a hot gas 
make over a cold gas?  What other gases could provide lift in our 
atmosphere (i.e. are lighter than air)?

Re: Balloon lift calculations with different gases...