抄録
Relative humidity of the gas in equilibrium with saturated salt solution has been used as the fixed point of the scale of relative humidity. Lithium chloride is important to this aim for low relative humidity. But the reported values of the relative humidity in equilibrium with saturated lithium chloride solution are different each other. In this investigation, therefore, the value was newly determined using an improved direct method. Saturated lithium chloride solution and pure water are kept in the same temperature and the vapour pressures in equilibrium with them are measured respectively with U-tube manometers. Then, the relative humidity in equilibrium with saturated lithium chloride solution is given in the ratio of the liquid head differences of each manometer. This method has the following advantages: 1) Value of relative humidity can be obtained independently of the acceleration of gravity and the density of the liquid for manometer. 2) Accurate measurements of temperatures of saturated lithium chloride solution and pure water are not necessary a s long as both of them are kept in the same temperature. 3) Accurate measurement of relative humidity is comparatively easy.
Relative humidity in equilibrium with saturated solutions of several salts other than lithium chloride were also measured by this method.
