When he noticed that his health was being affected by the 'wet' collodion's ether vapor, Maddox began looking for a substitute. He suggested in the 8 September 1871 British Journal of Photography article "An Experiment with Gelatino-Bromide" that sensitizing chemicals cadmium bromide and silver nitrate should be coated on a glass plate in gelatin, a transparent substance used for making candies. Eventually Charles Harper Bennett made the first gelatin dry plates for sale; before long the emulsion could be coated on celluloid roll film.