A Study of Thermoelectric Methods for Determining Isotonicity

It is proposed that the isotonicity of a given aqueous solution shall be expressed as the weight per volume percentage of a sodium chloride solution found by a study of suitable colligative properties to be isotonic with it.Methods developed during the last decade for the electronic amplification and recording of thermal electromotive force values in the microvolt range suggest the advisability of making increased use of thermocouples and thermopiles in the study of colligative properties.It is the purpose of this paper to discuss the application of thermoelectric methods with emphasis on various modifications of the Hill-Baldes techniques for determining isotonicity by detecting and measuring slight differences in temperature arising from differences in vapor pressure of thermally isolated samples exposed in constant humidity chambers.Several modifications of thii technique are described, and the factors involved in the design of instruments for conveniently measuring isotonicity at any selected temperature are discussed.