The Nature of the Conductivity of Insulating Oils

It has been shown in a previous paper how the methods developed in the study of conduction of electricity through gases could be applied to determine the nature of the ions present in liquids and solids. In the present paper these methods have been applied to the measurements of the space charge set up in insulating oils by a steady electric field, which were recently performed by Whitehead and Marvin. The procedure is as follows: the shape of the curve shows that the current must be considerably below three-fourths of the saturation current. It is possible to fit the curve closely by assuming the Langevin constant to be $\beta =36\mathrm{}\pm 10$. From this the number of ions present in the normal state and their mobility can be calculated, which turns out to be 3.5 · ${10}^{-6\mathrm{}}$ ± 50% cm/sec per volt/cm. With the assumption that the mobility is inversely proportional to the viscosity, the mobility of these ions in water would be 1.2 ${10}^{-4\mathrm{}}$ cm/sec per volt/cm or in the usual units 12. If one assumes that Lorenz's results for organic ions can be applied these ions should have approximately 110 atoms. From the boiling point of the oil one would conclude that the molecule of the oil contains about 45 atoms.