The principle consists in sampling of a known volume of chlorine (about 100 ml) obtained by gasification of liquid chlorine. Absorption of the chlorine by a 2% zinc amalgam in the presence of 1 ml of saturated sodium chlorine solution. Measurement of the residual, non-condensable gases such as H2, O2, N2, CO, CO2, etc. Calculation of the volume of chlorine from the difference from total volume, refereed to 100 ml of vaporized sample. The apparatus used is shown diagrammatically in the figure. The safety measures for working with chlorine are listed.