"On Sulphonfluoresceïn and Some of Its Derivatives" by C. W. Hayes is a scientific publication written in the late 19th century. This dissertation was presented for the degree of Doctor of Philosophy at the Johns Hopkins University, focusing on the chemical compounds associated with sulphonfluoresceïn, particularly its preparation, properties, and various derivatives. The work explores the synthesis of sulphonfluoresceïn and the structural implications of replacing certain functional groups while examining experimental results and methodologies related to these chemical compounds. The book delves into the significant experimental work aimed at synthesizing ortho-sulphonbenzoic acid and subsequently sulphonfluoresceïn through reactions with resorcin. It outlines various methods employed to prepare the desired compounds, including the oxidation and reduction processes that influence the properties of the resultant substances. The discussions include crystallography, solubility characteristics, and the optical properties of sulphonfluoresceïn, showcasing its weak green fluorescence in different conditions. Additionally, the dissertation offers insights into the modifications and reactions of sulphonfluoresceïn derivatives, highlighting the complexities of working with such chemical entities, and concludes with a summary of the findings regarding its composition, solubility, and acidity. (This is an automatically generated summary.)