Letter, 'On the optical characters of certain alkaloids associated with quinine, and of the sulphates of their iodo-compounds' from William Bird Herapath to [George Gabriel] Stokes Herapath describes specimens he has obtained of the perfectly pure alkaloids quinidin [quinidine] and cinchonidin [cinchonidine], noting that quinidin possesses the phenomenon of fluorescence or 'epipolic dispersion', while cinchonidin does not. Annotations in pencil throughout. Marked on front as 'Amend to pencil alterations'. Subject: Chemistry Received 8 January 1856. Communicated by Stokes. Written by Herapath in Bristol [England]. This letter was published in full in volume 8 of the Proceedings of the Royal Society as 'On the optical characters of certain alkaloids associated with quinine, and of the sulphates of their iodo-compounds. By William Bird Herapath, M. D., in a letter to Professor Stokes, Sec. R. S. Communicated by Professor Stokes'. 6 January 1856