And you can see that gas is going into your tank because the gauge is moving. It sounds pretty elementary - but why is it that there is no such indication on your butane tank?

Those who have the tank delivered at home have no idea how much butane they are getting - and are just relying basically on the goodwill of the butane vendor.

And what about when you go personally and fill up your cylinder - how can you know that you're getting the true value? That's what we wondered in the middle of all this talk about butane standards - and so today we did an interesting experiment: we took an empty 50 pound cylinder, made sure it was empty, weighed it empty and then went to fill it at a local butane vendor.