Visible Gas? Answered
I wan't to fill a chamber with hydrogen, have a chamber of the same size linked with it, with a heavy visible gas in it, then as I pump out the hydrogen the heavy gas displaces it and I can see when I need to stop pumping and refill with hydrogen. What gas can I use, I know just about any visible gas will work because hydrogen is the lightest, but it would be nice if it was heavier than average air so I could allow air to flow into my heavy gas chamber to displace it. Or can I just die the air with some kind of smoke from my smoke machine.
Yes hydrogen is extremely explosive, so this would be on a very, very small scale with hopefully 0 oxygen.