On the measurement of the thermal conductivity of liouids by a non-stationary method

Synopsis In 1949 in this journal 1) a paper appeared dealing with a non-stationary method for measuring the thermal conductivity of liquids. This method, indicated first by Stalhane and Pyk 2), was based upon the temperature rise at a certain distance from an electrically heated wire, producing a constant heat flow into the liquid. Results obtained by using this method were found to be unreliable. The time during which convection does not disturb the measurements appeared to be too short to apply the proposed mathematical approximations. E.g., neglecting the ratio of the specific heats per cm3 of the liquid and the heating wire (cϱ/c0ϱ0) is not allowed. In consequence of a more rigorous mathematical treatment the method has to be changed to yield the correct results as its application to a series of experimental data shows. As the necessary changes mean a serious drawback of the original method it is suggested to lengthen the time during which measurements are possible by rotating the vessel containing the liquid about the heater to suppress convection.