This volume on silicon nitride covers electrochemical behavior, colloid chemistry and part of the chemical reactions. Silicon nitride is characterized as a reactant. The most important types of reactions are reactions with metals and reactions with metal oxides under nonoxidative conditions. Other types of reactions include thermal decomposition, effects of radiation, tribochemical reactions and reactions with other metal nitrides. Not only are results reported for pure silicon nitride but also for ceramic silicon nitride materials, which may contain up to 20 % additives.