The apparatus can be used to demonstrate the three historically important special cases
The two most important parts of the gas laws apparatus are a variable gas volume with a controllable temperature – and a sensitive manometer.
The gas volume is divided into a fixed and a variable part where the variable part corresponds to the measurement range of the manometer. The variable volume is constituted by a plastic syringe that is controlled by a spindle with a crank handle.
The manometer is a liquid manometer with demineralized water as the manometer fluid. With a meter stick for reading the positions of the liquid surfaces, it is possible to measure pressure differences in a range of about ± 900 mm water column (approx. ± 9000 Pa). The precision of the measurement is about 1 millimetre water column – i.e. a relative precision around 1-2 ‰.
During development of the gas law apparatus we have tried to minimize the "dead" gas volume that cannot be kept at the same temperature as the rest. For example, we use a connection hose between the gas volume and the gauge whose internal volume is only 1 mL.
Gas law apparatus