The camera back is taken into the operating room, from which all white light is carefully excluded, the plate removed from the camera back, and laid, albumen side upwards, on the fixing stand; as much distilled water is now poured on it as the surface will hold, taking care that every part of the sensitive surface is covered with the liquid; allow the water to remain on the surface for one minute, then pour off and drain slightly; replace the plate on the stand, and pour over the surface so as thoroughly to cover every part, the pyrogallic solution (made as described at page 192, and carefully filtered just before being used); allow this to remain on the plate for one minute, then drain off into a perfectly clean measure, and add to it an equal bulk of silver developing solution, page 192; mix these thoroughly together with a glass rod, and then pour the mixed liquids over the plate; allow them to rest until the picture begins to appear, which generally takes about from three to five minutes; then pour off and on repeatedly, until the developing fluid becomes opaque, which then contains floating particles, and these, if allowed to do so, would settle on the plate, to the injury of the picture; but this may be prevented by brushing the surface with a camel's-hair brush frequently during the development. When this opacity of the developing fluid takes place, drain all the fluid off the plate, and thoroughly wash with water; then mix another quantity of pyrogallic and silver developing solution in the same proportions as before, and pour this on and off the plate as before, until the picture appears sufficiently intense, and the middle shades well brought out; when this takes place drain off, and wash with water, so as to clean the surface thoroughly, and the plate is then ready for the next step, "fixing the image." Should the picture begin to develope in less than three minutes after the application of the mixed developing fluids, thoroughly drain the plate, and wash well with water, then continue the development with a solution of three parts pyrogallic solution and one part silver developing solution; but should the picture not begin to appear in five minutes, the addition of half a drachm of the albumen bath solution to each ounce of mixed developing solution will be necessary, in order to obtain the middle shades and the required intensity. It may be stated, as a guide, that the best negatives which the author has produced occupied from ten to twelve minutes in developing. _Fixing the Image._ The plate, having been thoroughly freed from the developing fluid by careful washing, is now placed on the fixing stand, and the surface covered by the fixing solution, made as described at page 192, being poured over it. In a few seconds the yellow opalescent color of the film will begin to disappear, and its complete removal may be hastened by blowing gently on the plate, so as to disturb the fluid.