Unique device shows the relationship of pressure to temperature of a gas, allowing students to determine the value of absolute zero. The bulb is immersed in hot water, cold water, and a dry ice-acetone mixture. Temperatures and pressure readings are recorded. Pressure versus temperature readings, when plotted, provide a value of absolute zero. Bulb diameter 100 mm. Bicycle air pump and thermometer (thermocouple) with a -100 ºC to 100 ºC range are required, but not included.