After an experiment has been selected in the stockroom and placed on the table, a gas cylinder can be selected by clicking on any of the eight gas cylinders next to the table. For the balloon, pressure, and temperature experiments, this will bring the cylinder to the front of the room with a gas regulator attached to the cylinder and will connect a copper line to the experiment. The regulator consists of (1) a solenoid valve (the green Open Valve button), (2) two pressure gauges, (3) arrows for adjusting the regulator pressure, and (4) the Return Tank button which is used to return the tank to the other cylinders. Clicking on the Open Valve button will open the solenoid valve and allow gas to flow into the experiment at the pressure specified on the left pressure gauge on the regulator. (The pressure gauge on the right measures the pressure of the gas in the tank and is fixed.) Clicking on the solenoid valve again will close the valve. Clicking on the blue and red arrows will increase (red arrow) or decrease (blue arrow) the regulator pressure. Note that when a cylinder is first selected after starting the simulation, the regulator pressure will be initially zero and no gas will flow when the valve is opened. Also note that the units of pressure on the pressure gauge are kPa (outside scale) and psi (inside scale) relative to atmospheric pressure. If the selected cylinder is still attached when zoomed in on an experiment, then the number of moles of gas in the experiment will be adjustable.