The Quintessence of Irving Langmuir is the first full-length biography of Irving Langmuir, accompanying the book entitled The Collected Works of Irving Langmuir. The major focus of this book is on Langmuir’s early life, including his family background and experiences that shaped his exceptional character and profession. This text also provides some of Langmuir’s technical works and reviews of other scientists regarding his work. This particular topic is to present Langmuir as a scientist. This book will best serve those interested in Langmuir’s life and contributions.