Measuring temperature of a gas inside a container does not prove the greenhouse effect.

You have to have sunlight being absorbed on a surface, that surface has to heat the atmosphere (0,04% CO2), then you need to double that to (0,08% CO2) and measure the changes in temperature of your surface.

All this experiment does is prove that pressure drives temperature (energy density actually), which is a basic physics. As CO2 is heavier then air.