A Manual Of Photography

SIMPLIFICATION OF THE DAGUERREOTYPE. 257 Daguerre, I placed it, without removing the iodine, in a vessel of chlorine ; the picture was obliterated, and very speedily blackened. On exposing this black plate to light, it almost instantaneously whitened. This is mentioned to show the extent of curious subjects which photography opens out for examination. The apparatus for the Daguerreotype shown in the vignette, may be enumerated with advantage. 66. a. Is the camera obscura, with the screen upon which the image is seen, and by which the focus is adjusted, partly raised; and when this is accurately determined a screw is shown by which it is secured. b. Silver plate and edges for the same. c c. Are bromide and iodine boxes of walnut, enclosing each a stout porcelain pan : each pan is furnished with an air-tight glass cover. On the upper edge of each box is a groove for holding the plate. On withdrawing the glass cover of the iodine pan, the plate is exposed to its action, and the colour produced is observed by holding a sheet of white paper in sucli a position that its reflection may be seen on the plate, which enables the 8