The photographic
process called Daguerreotype was
fictitious by Louis Jacques Mandé Daguerre.
He collaborated with Niepce to the improvement of the
photographic process and, in the 1831, he discovered that a sheet
of silvered copper, exposed to the vapors of iodine, formed one
layer of silver iodide sensitive to the light on his surface. 
Only after subsequent six years
he discovered that the imprinted image on the sheet, for be well
revealed, must be treated with vapors of mercury, and then washed
with an assembled and hot solution of chlorinate of sodium.
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