John Stenhouse: Contribution to the study of active charcoal, lichens, and alkaloids

John Stenhouse (1809-1880) carried a large number of experiments
comparing the adsorbing power of wood and animal charcoal for the gases ammonia, hydrogen sulfide, sulfur dioxide, and carbon dioxide, as well as their decolorizing and oxidation ability. e results led him to suggest that charcoal could be used to absorb the small amount of infectious matter floating in the atmosphere of unhealthy locations (as was the belief in those days). Consequently, he designed a charcoal air filter consisting of a thin layer of charcoal powder enclosed between two sheets of wire gauze, as well
as personal respirators to be used over the mouth or nostrils and mouth. Stenhouse also studied the dyes present in lichens, particularly in the varieties of Orchella weed Rocella tinctoria, Rocella Montagnei, Gyrophora pustulata, and Lecanora tartarea. He described the extraction, purification and analytical procedures of the different dyes and discovered a series of intermediate compounds, among them, alpha and beta orsellic acids, roccellinin acid, erythreselic and usnic acid, pico-erythricin, pseudo-orcin (erythromannitol), erythromannitol pentanitrate (an explosive), betorcinol (a homolog of orcinol). Stenhouse proved that it was possible to obtain, artificial alkaloids using
as starting materials the highly nitrogenated compound principles (i.e. albumen, fibrin, legumin, etc.) found in all plants, known to be as rich in nitrogen as the corresponding animal compounds. He also developed an analytical procedure for detecting quinic acid, discovered the presence of sparteine in a variety of vegetables and the active principle connesine (wrightine) in the seeds of the tree Wrightia antidysenterica.