6 CONCLUSIONS

Corrosion products associated with artifacts can provide information about original composition and the environment in which they were preserved. Two- and four-dimensional phase diagrams contribute to an understanding of the chemical-microbiological and historic environments. In cases where Eh and pH are the critical independent variables and where changes in concentrations of other ions do not fundamentally change the corrosion process, two-dimensional phase diagrams can be used. In more complex processes where corrosion products have finite solubility, it is necessary to construct four-dimensional figures with two-dimensional projections. Four-dimensional diagrams and projections have not until recently been used in corrosion science.

ACKNOWLEDGEMENTS

The authors acknowledge Michael Marron of the Office of Naval Research, Code 1141MB, for financial support. David Mohr, Naval Coastal Systems Center, and Patricia Wagner, Naval Oceanographic and Atmospheric Research Laboratory, provided technical assistance. NOARL Contribution Number JA 333:081:90.