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  The research archive of Gary W. Ewer regarding the history of the daguerreotype

The following notice appeared in the August issue of "The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science." (London; Vol XIX, No.122) and was included in the section titled "Recent Improvements in Photography": ----------------------------------------------------------------- 5. "New mode of preparation of the Daguerreotype plates, by which portraits can be taken in the short space of time of from five to fifteen seconds, according to the power of light, discovered by A. Claudet in the beginning of May 1841." Communicated by the Marquis of Northampton. Pres. R.S. "My improvement," says the author, "consists in using for the preparation of the plates, a combination of chlorine with iodine, in the state of chloride of iodine. I follow the preparation recommended by Daguerre. After having put the plate in the iodine box for a short time, and before it has acquired any appearance of yellow co- lour, I take it out, and pass it for about two seconds over the open- ing of a bottle containing chloride of iodine; and immediately I put it again in the iodine box, where it acquires very soon the yellow 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." ----------------------------------------------------------------- aug1-95

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