Abstract
I have reanalyzed the thermal-relaxation-time experiments made by Reinstein and Zimmerman on a mixture of cerium magnesium nitrate and solid He3, which supposedly showed a spin-spin thermal contact across the boundary. It has been found that some of the assumptions made in the original interpretation are suspect. A new interpretation, based upon a magnetic-field-dependent phonon bottleneck in cerium magnesium nitrate, is presented.