Surface Tension of Mercury in the Presence of Gas Under Varying Pressures

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Abstract
Quincke's method with Worthington's correction was used. Contrary to the accepted values the maximum surface tension of mercury (515±7 dynes/cm at 31°C) is reached when only mercury vapor is present. A surface freshly created in a gas at 760 mm has a high initial tension approaching that when the surface is created in mercury vapor. The tension falls as the gas is adsorbed until an equilibrium value for a given pressure is attained. As the pressure is reduced the equilibrium value rises to a maximum which depends upon the nature of the gas. For instance, this maximum tension for mercury-hydrogen occurs at the critical pressure of 2.8 mm. If the pressure is lowered to stiction the tension remains unchanged so long as the mercury is not agitated beyond a certain amount. This maximum value for mercury-hydrogen is 441 dynes/cm which is less than the mercury-mercury vapor value of 515 dynes/cm. If the mercury-hydrogen is violently agitated when the pressure has been reduced to stiction the tension approaches 515 dynes/cm, the mercury-mercury vapor tension. Vibrating drop methods tend to give the vacuum value of the surface tension even when a gas is present at atmospheric pressure.