Hans Eggenkamp studied geology and geochemistry at Utrecht University, where he wrote this book to obtain his PhD degree. After obtaining this degree he moved to the University of Reading (UK) to continue the study of chlorine isotopes as research fellow. Currently he is appointed at the Centro de Petrologia e Geoquimica of the Instituto Superior Tecnico in Lisbon (Portugal). The study of chlorine isotopes is still an important part of his work.