ome of the earliest quantitative measurements were performed on gases. One early study was conducted by Robert Boyle in 1662.
Robert Boyle employed a J-shaped piece of glass tubing that was sealed on one end. A gas (air) was trapped in the sealed end of the tube and varying amounts of mercury were added to the J-shaped tube to vary the pressure of the system. Boyle systematically varied the pressure and measured the volume of the gas. These measurements were performed using a fixed amount of gas and a constant temperature. In this way Boyle was able to examine the pressure-volume relationship without complications from other factors such as changes in temperature or amount of gas.
The manometer that was employed in the previous experiment can also be used to perform Boyle's experiment. A small amount of air is trapped in the sealed end of the manometer. The scale that is used to read the height of a column of mercury can also be used to read the height of the column of air. (You will need to estimate the position of the top of the tube, which is curved.) The inside diameter of the tube, 4.286 cm, and the height of the column of air can be used to calculated the volume of air.
The pressure of the gas will be varied in exactly the same manner as Robert Boyle varied the pressure: mercury will be added or removed from the open end of the manometer. After changing the pressure (by changing the amount of mercury in the manometer), the pressure and volume are recorded.