Our apparatus can be seen in the picture above. On the left is the actual canister of gas held by a clamp attached to a ring stand with pressure gauge on the outside. Just to the right of that is the water pump/heater. This device pumped water at different temperatures through the clear glass tube above and to the right. In the center of the picture mounted on the gray stand is the Central Scientific Thermal Equation of State and Critical Point Apparatus No. 32019. This piece of equipment allowed us to vary the volume of the container in which the gas became trapped by liquid mercury. The round pressure gauge gave us the pressure inside the enclosed volume in MPa. The orange hose below the pressure meter and connected to the three-opening glass jar to the right created the vacuum seal inside the Central Scientific device. A good vacuum seal enables one to read more accurately the pressure inside the closed volume where the trapped gas molecules exist. The rubber tube that extends out of the picture to the right eventually reaches a vacuum pump responsible for the good seal. The contraption sticking out of the middle prong in the glass jar is a thermocouple. It notified us of when our vacuum seal was good enough to begin taking data that would be accurate.
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