Volume 15 in this series continues the voyage of discovery started almost a decade ago. Chapter 98 adds significantly to an evaluation of systematic, experimental low-temperature studies of the ambivalent behaviours of cerium (ferromagnetism, antiferromagnetism, spin glass, superconductivity etc.) which depend upon its environment in materials. The conclusions arrived at should provide new data against which the theory can be advanced. The next chapter provides a review of rare earth carbides, emphasizing the thermodynamics, phase diagrams, crystal structures and physical properties. The binary rare earth carbides present an exceptionally wide range of compositions and structures both as solids and gas-phase molecules. Complex carbides with additional metal and non-metal components also receive attention. Metal-rich halides (i.e. compounds with an X/R ratio