Note: This is related to H1-24: Speed of Sound in Helium. These can both be used in a single class, but can require some time to switch over. This can be a good project for in-class discussion, giving students the opportunity to make predictions and discuss while the gas is changed. This can also be an opportunity to introduce concepts related to measurement uncertainty and propagation of error. For a shorter demonstration, use H1-26 alone to make a single measurement.