The Eclectic Alkaloids, authored by John King and first published in 1910, is a seminal work that delves into the study of alkaloids—naturally occurring chemical compounds found in plants that have profound effects on human physiology. This book is part of the broader Eclectic Medicine movement, which emphasized the use of indigenous plants and natural substances in healing practices. King’s work stands out for its comprehensive analysis of alkaloids, focusing on their extraction, preparation, and therapeutic applications.​

In the book, King categorizes alkaloids into various groups based on their chemical structures and physiological effects. He provides detailed descriptions of specific alkaloids, such as morphine, strychnine, and quinine, elucidating their origins, properties, and uses in medicine. The text also explores the methods of isolating these compounds from plants, highlighting the importance of purity and concentration in their medicinal efficacy. King’s approach reflects the Eclectic emphasis on empirical observation and the practical application of botanical knowledge.​

Beyond the chemical and pharmacological aspects, The Eclectic Alkaloids offers insights into the historical and cultural contexts of alkaloid use. King discusses the contributions of notable figures in the field, such as William Stanley Merrell and Alexander Wilder, providing biographical sketches that underscore the collaborative nature of Eclectic Medicine. The book also addresses the controversies and debates surrounding the use of concentrated plant extracts, known as resinoids, and their place in medical practice.​

The Eclectic Alkaloids serves as a valuable resource for understanding the intersection of chemistry, botany, and medicine in the early 20th century. It reflects a time when medical practitioners sought to bridge traditional herbal knowledge with emerging scientific methods. While some of the practices and theories presented may have evolved or been superseded by modern research, the book remains a testament to the enduring quest for knowledge and the application of natural substances in healing.