Observation of thermo-mechanical equilibration in the presence of a solid 4He conduit

We observe a thermo-mechanical effect when a chemical potential difference is created by a temperature difference imposed between two liquid reservoirs connected to each other through Vycor rods in series with solid hcp 4He. By creating a temperature difference, $\mathrm{\Delta }T$, between the two reservoirs, we induce a rate-limited growth of a pressure difference between the two reservoirs, $\mathrm{\Delta }P$. In equilibrium $\mathrm{\Delta }Pvs.\mathrm{\Delta }T$ is in quantitative agreement with the thermo-mechanical effect in superfluid helium. These observations confirm that below $\sim$ 600 mK a flux-limited flow exists through the solid helium.