PREPARATION OP DAGUERREOTYPE PLATES. 253 
ART. LIII.— « NEW MODE OF PREPARATION OF THE DA- 
GUERREOTYPE PLATES, BY WHICH PORTRAITS CAN 
BE TAKEN IN THE SHORT SPACE OF FROM FIVE TO 
FIFTEEN SECONDS, ACCORDING TO THE POWER OF 
LIGHT. Discovered by A. Clacjdet, in the beginning of May, 1841." 
Communicated by the Marquis of Northampton, President 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 color, I take it out and 
pass it for about two seconds over the opening of a bottle 
containing chloride of iodine, and immediately I put it again 
in the iodine box, where it acquires very soon the yellow co- 
lor, which shows that the plate is ready to be placed in the 
" camera obscura. I have substituted for 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 operat- 
ed in ten seconds with the same apparatus which, without 
any chlorine, required four or five minutes when using 
only the original preparation of Daguerre : I have obtained 
an image of clouds in four seconds." 
London, Edinburgh, and Dublin Philosophical Journal 
