6. Conclusion

The sheer number of information systems mentioned in the various paragraphs might lead one to believe that the thermodynamicist or engineer looking for data is spoilt for choice. However, a closer look at the tables reveals that the main information sources are cited several times for one of their data modules or program libraries. A closer look at the contents of the databases reveals the difficulties inherent in all numerical and factual compilations:

• the limited number of compounds for which data are collected;

• the many missing values ;

• limited coverage of each field of application;

• the impossibility of consolidating reported values for the same product, either because the primary information is identical, or because the measurement conditions...