Then, we calculated the chemical potential ∆µ CnAm (P ) in bulk electrolyte solutions containing 150 particles (composition given in Table ), as in our previous study but for pressure ranging from 0.006 to 1000 MPa. Because concentration depends explicitly on the volume of the solution, it is more convenient to use molality as the relevant metric. This quantity will be required as input to set up the osmostat in zeosils filled with water molecules at different pressure. At each value of pressure, the simulation was performed until 400 values of the protocol work had been gathered to construct the ∆µ CnAm (P ) relationship.