Thermal Conductivity Method for Following the Electrolytic Separation of Hydrogen Isotopes

Abstract

A RAPID and accurate method for determining the concentration of deuterium in small quantities of hydrogen gas is needed in order to be able to follow readily the separation of hydrogen isotopes during electrolysis of solutions containing heavy water. Methods dependent on the thermal conductivity of the gas are particularly attractive for this purpose, and a micro-method of this type using the gas at about 0·04 mm. pressure has been described by A, and L. Farkas¹. In attempts to apply this method, however, we did not succeed in finding conditions yielding reliable results of the accuracy required ; and, from a consideration of the factors influencing thermal conductivity, operation at a notably higher pressure seemed more promising, since the measurement then rests on a simpler and more definite physical basis². A method has accordingly been developed using gas at 10 cm. pressure. About 10 c.c. of gas at N.T.P. is needed for a determination, but the probable error is only about 0·1 per cent of deuterium.