316 



colour, which shows that the plate is ready to be placed into the 

 camera obscura. I have substituted to the chloride of iodine, 

 chloride of bromine, and have found nearly the same result ; but I 

 prefer chloride of iodine as producing a better effect ; and besides, 

 on account of the noxious smell of bromine. 



" The result of my preparation is such, that I have operated in ten 

 seconds with the same apparatus, which, without any chlorine, re- 

 quired four or five minutes ; when using only the original prepara- 

 tion of Daguerre, I have obtained an image of clouds in four 

 seconds," 



