This applet replaces the FORMS-based interface residing at http://www.geology.washington.edu/~ghiorso/MeltsCALC/ .

The applet is a client that uses socket-based communication to send requests to a standalone server program operating on the web server which provided the applet in the first place. The server performs the requested thermodynamic calculations or component transformations and returns the data to the client applet for display. The server is currently written in C, not in java. The applet performs the following functions:

• For solid phases of more than one endmember,
  • Converts composition in mole fraction of endmembers to weight percent oxides, an exact calculation.
  • Converts composition in weight percent oxides to mole fractions of endmembers by least squares. (If composition cannot be exactly transformed, the program gives nearest guess and also returns residual; nearest composition is not guaranteed to be legal)
  • Given T, P, and mole fractions of endmembers, computes the following thermodynamic data:
    • Gibbs free energy G (standard state, mixing, and total),
    • Enthalpy H (standard state, mixing, and total),
    • Entropy S (standard state, mixing, and total),
    • Heat capacity Cp and its temperature derivative (standard state, mixing, and total),
    • Molar volume and its first and second derivatives with respect to temperature and pressure (standard state, mixing, and total),
    • for each component, activity and chemical potential (standard state, mixing, and total).
• For simple, pure solid or vapor phases, given T and P does the above thermodynamic calculation.
• For a silicate liquid phase, given T, P, and composition in terms of weight percent oxides, does the above thermodynamic calculation.

For complex solids, the "Calculate thermodynamic properties" option provides a warning if composition is metastable or unstable with respect to exsolution into coexisting phases. Thermodynamic data are still calculated for such compositions. This is not currently implemented for the component transformations because they don't require specifying P and T.

For pyroxene, you may need to add a tiny amount of Ti and Al to get the program to accept the composition as legal.

Here is a TODO page , and a CHANGELOG for the applet. The applet lives here.