This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Removing Film From Kodak. No dark-room is required for changing the spools. The operation can be performed in the open air, but to avoid all liability of fogging the edges it is advisable to remove the film in a subdued light. When the last film has been exposed in the kodak give the key about a dozen turns, thus covering the film with black paper again. Remove the spool from the kodak in exactly the reverse manner in which you loaded it. Be sure that the black paper is wrapped tightly around the spool of film; then fasten down the end of the black paper with the piece of gummed paper usually attached to the end of roll, or with a rubber band or piece of twine. It is further advisable to wrap this exposed film in black paper until you are ready to develop it. After removing an exposed film from the camera, take the empty spool from its recess and transfer to the winding side, bringing the slotted end of the spool, into which the key is to fit, opposite the keyhole and proceed to load the kodak with a new film, as at first directed.
Film Development. Read carefully the description of a dark-room which is given in Chapter II (Warm Tones On Gelatin Glossy Paper), in paragraphs 95 to 98. With very few exceptions the development of a film is the same as of plates, and you will need precisely the same outfit; viz., a good ruby lamp, four trays, a measuring glass, stirring rod, developer, and fixing chemicals.
199. Fill one of the trays nearly full of clear water and place this tray at your extreme left, on the developing table. Open one of the developing powders and dissolve according to the directions given in Chapter III (How To Proceed), paragraph No. 117; then pour this solution into a second tray placing the tray next to the water. Now close the dark-room door. To develop the film, unroll it and detach the entire strip from the black paper. Pass the film through the tray of clear water several times (see Illustration 24,) holding one end in each hand. This wets the surface of the film and enables the developer to come in perfect contact with the emulsion, when the film is placed in the developer. Now pass the film through the developer in exactly the same manner as you did while wetting it, but face down. Keep the film continually in motion, and in about one minute the high-lights (the strongest lights) will begin to show up darker. The unexposed portions will be distinguishable from the exposed, and in about two minutes you will be able to make out various objects in the picture.
Illustration No. 24.
200. An improvement on the ordinary tray for developing films will be found in the Ingento Film Trough. This trough is specially adapted for the developing of roll films by hand, as will be seen by Illustration No. 25. It is fitted with a rod adjusted near the bottom of the trough. The film is slipped underneath this rod and drawn up and down during the development, the rod holding the film under the solution all the while. This trough is seven inches long, and will accommodate all sizes of films from 5x7 down to the smallest. The trough is supplied with wood or metal base; the latter is preferable, as its weight prevents the trough from tipping over, while the wood base would need to be fastened to the table. When this trough is employed, it may be filled with water and used for wetting the film, after which the water is poured off and developer poured into the trough and the film developed.
Illustration No. 25.
201. If the film develops evenly it shows that all exposures were uniform, considering the amount of illumination - development may be completed without cutting them apart. The progress of development may be watched by holding the film up to the ruby light, from time to time. Read paragraph 124, of Chapter III (How To Proceed), to judge when development is complete. If some exposures on the film flash up more quickly than the others, cut the film apart with a pair of shears and place the film in a tray of clear water. The cut films may be immersed in the developer and developed in the usual manner, carrying the over-exposures farther than the others, in order to secure the proper amount of contrast. When each film is completely developed, transfer to the third tray and rinse two or three times with clear, cold water. Then place in the "fixing bath." (See paragraph 125.)