A Manual Of Photography

TO GIVE THE SENSITIVE SURFACE TO THE PLATE. 245 grain, as much iodine as the bromine will dissolve till quite saturated. This point is ascertained when some grains oi the iodine remain undissolved. They may remain in the bottle as they will not interfere with the success ot the preparation. . . “ The bromide of iodine thus prepared, from its occupying so small a space, can very easily be carried, but in this state it is much too concentrated to be used. When it is to be emploi ed, pour a small quantity, say fifteen drops, by means of a drop- ping-tube, into a bottle containing about half an ounce ot filtered river water. It will easily be understood that the bromide of iodine can be used with a greater or less quantity of water without altering the proportion which exists between the bromine and iodine.” Chloride of iodine was first employed by M. Claudel, and is prepared by merely placing iodine in an atmosphere o chlorine. Chloride of bromine is made by mixing two drachms of a saturated solution of bromine with fifteen drops of strong muriatic acid and about nine or ten ounces of water. The Ilungarian mixture appears to be a similar compound o Por the following exceedingly convenient preparations we are indebted to Mr. J. Bingham, who has for some time with much success, devoted his attention to the improvement of pho- tographic processes. The following extracts are from the Philosophical Magazine for October 1816. “An Improvement in the Daguerreotype Process by the appli- cation of some new compounds of bromine, chlorine, and iodine, with lime.—All persons who have practised the ågoorreotype must have remarked that in warm weather a considerable depo- sition of moisture takes place upon the glass or slate cover used to confine the vapour in the bromine or accelerating p. This moisture must also necessarily condense upon the cod metallic surface of the plate during the time it is exposed to the bromine vapour. In fact, 1 have been informed by a number of professional daguerreotypists (and I have experienced the difficulty myself), that they were unable to obtain perfect pictures during the excessive heat of the late season, and a very clever and enterprising operator, who last year made a tour on the Continent, and brought home some of the finest proofs I have ever seen, entirely failed this season in obtaining clear and perfect pictures, from the constant appearance of a mist or cloud over the prepared surface. This appears to be caused by the deposition of moisture upon the plate, arising from the water in which the bromine is dissolved. Io obviate