A Manual Of Photography

THE DISCOVERY OR M. DAGUERRE. 43 completed before the thermometer läs —— 55° Cent. (131° Fahr.) This is, however, always known by observing the sketch through the 8 After each operation the apparatus is care- fully cleaned in every part, and in particular the strips of metal which hold the plate are well rubbed with pumice and water, to remove the adhering mercury and iodine. The p a e now be' deposited in the grooved box, (hg- 11), in which it may be kept, excluded from the light until it is convenient to perform the last hxm^ 11. operation. cess has for its object the removal Fifth operation.—Ims process tue further of the iodine from the plate of silver, w 1 action of the light. . , □ for this A saturated solution of common salt y to be placed ha trough of water plunging and withtowmg» immediately ; it is then to be pluugu if it was not saline solutions, which would act upon the draw mg it it previously hardened by washing in water. To assist the effect of the saline washes, the plate must moved to and fro, which is best done by passing ".wiregenerte the plate. When the yellow colour has quite disappeare plate is lifted out, great care being taken that re impi of not touched, and it is again plunged à water A -} warm distilled water, or very pure rain-water bo le 1 äe being provided, the plate is fixed on an me i L ^ The water is poured in a continuous stream over àepià drops of water whieli may remain upon I drying they moved by forcibly blowing upon wishes the driving, would leave stains on the drawings, tarnishins and and it only remains to preserve the silver from tarnishing ana in the daguerreotype P^wasTZ“ by the polished surface of the silvia, an - bering mercury, which will not bear the slightest rubbin .10 preserve these sketches, they must be placed in cases of paste board, with a glass over them, and then framed in wood, they are now unalterable by the sun s light.