The Properties of Slow Canal Rays is a scientific book written by Arthur Jeffrey Dempster and published in 1916. The book is a detailed study of slow canal rays, a type of ion that is produced in low-pressure gas discharge tubes. Dempster was a physicist who made many contributions to the field of atomic and nuclear physics, and this book is one of his most important works. The book begins with an introduction to the properties of slow canal rays and their behavior in gas discharge tubes. Dempster then goes on to describe the methods he used to study these ions, including the use of electric and magnetic fields to manipulate their motion. He also discusses the equipment he used to measure the properties of slow canal rays, such as ionization chambers and electrometers. The bulk of the book is devoted to a detailed analysis of the properties of slow canal rays, including their mass, charge, and energy. Dempster also describes the behavior of these ions in different types of gas discharg