Prout is principally remembered for his speculation concerning the chemical elements, while his other theoretical and experimental work in biochemistry has been generally forgotten, or ignored. In this thesis an attempt has been made to achieve an historical balance by examining both Prout's experimental and theoretical interests. The study is divided into two parts. In the first section, after a brief biography, Prout's contributions to experimental science are considered. A discussion of his development of apparatuses and techniques for organic analysis is followed by surveys of his work in the fields of urine chemistry, the physiology of respiration, and the chemistry of digestion. A full summary of an unpublished manuscript on sensation is also given. The first part ends with a short treatment of Prout's barometric interests. The second part is concerned with Prout as a theorist, and the transition is made through a study of his Bridgewater Treatise and his support for natural theology and vitalism. A detailed analysis of Prout's Hypothesis from 1800 to 1850 is followed by a final chapter which explores Prout's molecular theory and attempts to link together his theoretical ideas with his experimental work in the field of animal chemistry. Reasons for Liebig's success, and Prout's failure, to establish the science of biochemistry are also considered. Transcriptions of some unpublished manuscript material are given in appendices.