Notes Upon Indigo is a comprehensive and detailed treatise authored by J. W. (John William) McRae, focusing on the cultivation, manufacture, and commercial aspects of indigo, one of the most significant dye plants in history. Drawing from years of practical experience and observation in India, the book offers an in-depth exploration of the entire indigo process, from the selection of land and preparation of soil, to the sowing, tending, and harvesting of the indigo plant. McRae meticulously describes the various methods of extracting and processing indigo dye, including the construction and operation of vats, the chemical principles underlying fermentation, and the techniques for achieving the highest quality product. The book also delves into the economic and social dimensions of indigo production, discussing labor management, the impact of weather and pests, and the fluctuating market conditions that affect profitability. McRae provides practical advice for planters, including troubleshooting common problems, improving yields, and adapting to changing technologies. Rich with technical details, historical context, and personal anecdotes, Notes Upon Indigo serves as both a practical manual for those involved in indigo cultivation and a valuable historical document illuminating the importance of indigo in colonial agriculture and trade. The work stands as a testament to the complexity and significance of indigo production in the 19th century, offering readers a rare glimpse into the science, art, and business of this once vital industry.