Magnetic and Thermometric Properties of ${\mathrm{Na}}_3$[${\mathrm{C}\mathrm{e}\left({\mathrm{C}}_7{\mathrm{H}}_3\mathrm{N}{\mathrm{O}}_4\right)}_3$] · 15${\mathrm{H}}_2$O in the Millikelvin Range

Measurements of the 16-Hz susceptibility of a powdered ${\mathrm{Na}}_3$[${\mathrm{C}\mathrm{e}\left({\mathrm{C}}_7{\mathrm{H}}_3\mathrm{N}{\mathrm{O}}_4\right)}_3$] · 15${\mathrm{H}}_2$O (CDP) sample, in the shape of a right-circular cylinder with diameter equal to height, have been made as a function of the Johnson noise temperature $T_{\mathrm{J}}$ of a resistor in the range 2 to 20 mK. Pure liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ was used for thermal contact between the CDP and the noise thermometer in a demagnetization cell. The results are compared with similar data for cerium magnesium nitrate (CMN). CDP appears, like CMN, to have an anomalously low thermal resistance to pure liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$.