Dielectric constant of ${\mathrm{N}}_2$, C${\mathrm{O}}_2$, N${\mathrm{H}}_3$ and S${\mathrm{O}}_2$.—By an improved heterodyne null method previously described, measurements were made of the dielectric constant at atmospheric pressure of the carefully purified gases, over a range from 300° to 400° from just above the liquefaction point. These results as well as all others found by the author are represented by the Debye equation $(\epsilon -1)vT=AT+B$, where $\epsilon$ is the dielectric constant, $T$ the absolute temperature, and $v$ the specific volume. The values found for $A$ are.000958 (C${\mathrm{O}}_2$),.000768 (N${\mathrm{H}}_3$), and.001433 (S${\mathrm{O}}_2$); and for $B$ are.003 (C${\mathrm{O}}_2$), 1.740 (N${\mathrm{H}}_3$), and 2.167 (S${\mathrm{O}}_2$). The anomaly observed by Jona and attributed to association was not observed except possibly to a slight degree in N${\mathrm{H}}_3$. The values of the electric moment of the molecules calculated from the constant $B$ differ from Jona's values by 7 percent. It is believed that the explanation of the difference is to be based on the fact that the anomaly is not due to association but to surface effects on the metallic plates of the condenser. The values obtained for the electric moment are, in c.g.s., e.s. units×${10}^{18}$,.06 (C${\mathrm{O}}_2$), 1.44 (N${\mathrm{H}}_3$), and 1.611 (S${\mathrm{O}}_2$). The small value for C${\mathrm{O}}_2$ differs from zero by an amount which is less than the experimental error.

• Received 1 November 1925

DOI:https://doi.org/10.1103/PhysRev.27.455