Daguerreotype
Unique, unduplicatable, laterally reversed monochrome picture on a metal plate. Silver coated copper plate sensitized in iodine vapor and developed with mercury vapor.
A reverse wet collodion process using a thin metal plate that has been previously coated with silver, invented by Louis Jacques Daguerre in 1837.
Result of years of experimentation when Niepcé produced an image on a treated metal plate.