Harper's Young People, May 30, 1882 / An Illustrated Weekly

by Various

Of course you will use the dry plates. I say of course, because for the amateur they are cheaper, more convenient, produce better results, and afford a wider latitude of subject than the wet plates. We will suppose, then, that you have provided yourself with a good camera and lens, chemicals, plates, baths, and all that go to make a complete outfit.

Your first trouble will be with your dark room. It must be absolutely dark; the faintest ray of white light will destroy the most perfectly timed picture. Any closet will do, so long as you can have perfect darkness and room to work. The most luxurious dark room I ever saw was ten feet square, provided with hot and cold water, and lighted by two large windows with panes of ruby glass. The gold-colored glass looks the same, but is worthless for photographic purposes. On the other hand, I have worked in a closet two feet deep, by the dim light of a single ruby lamp. But in photography as in everything else the "golden mean" is preferable.

If kept in a perfectly dark box, the dry plates need not be developed for months. Travellers often change plates, and even develop and fix them, at night, in their rooms, by the aid of a ruby lantern. As the changing of plates is an operation which consumes but little time, this may be done with safety, but we would recommend the young photographer to make use of his dark room for the process of developing.

Besides the pans, or baths as they are called, for the chemicals, you must have in the dark room a supply of clear water, and a vessel in which to throw it after it has been used. Dry plates require frequent washing, as we shall see further on. Your dark room must be, then, of moderate size, free from white light, provided with clean water, and free from dust. If it is dusty, you will have minute specks on the picture. The plates must be kept in this room, and must be transferred to and from the plate-holders here.

Next comes the business of mixing the chemicals. There are several different formulas for the development of dry plates, but I have found the ferrous-oxalate developer to be the simplest and best. The most convenient way to prepare the solutions is to take two common glass preserve jars, put in about a quarter of a pound of neutral oxalate of potash in one, and about the same amount of protosulphate of iron in the other; then pour on warm water, and let the crystals dissolve.

It makes no difference how much water you put in; the object is to get a "saturated" solution; that is, a solution in which the water has absorbed all the chemical matter it can take up. After the chemicals have had time to dissolve—say fifteen or twenty minutes—filter the solutions into separate bottles, and cork them tightly, to keep out the dust. Always filter all your solutions before using them; even filter the water if it is not perfectly clear. Cleanliness is a prime necessity in photography, and the amateur can not be too careful.

Now comes the "fixing" solution, which is made by dissolving four ounces of hyposulphite of soda in twenty ounces of water. Filter into a bottle, and cork it until used. Make at the same time a saturated solution of common alum, and use it for washing the plates after taking them out of the developer, and before fixing. Directions are given by many involving the use of cyanide of potassium, tartaric acid, bromide of ammonia, and the like; but it is better for the beginner to use as few chemicals as possible. More pictures are spoiled than saved by inexperienced doctoring.

After your chemicals are all prepared, put a plate in your holder, or wooden box with slides, one or more of which accompany every outfit. Focus your camera on some object; a row of buildings, the side of a house, or a board fence is preferable for this experiment. Take off the cap, and pull the slide about half of the way out. Expose about six seconds, and pull out the slide the rest of the way. Expose this six seconds again, and replace the slide. You now have two exposures, of six and twelve seconds respectively, on the same plate. This is for timing the lens. It is impossible to give any definite rules for the time of an exposure; experience must teach this.

In a gallery where the surroundings are the same and the light varies but little, it is comparatively easy to determine how long a plate should be exposed in the camera. But in out-of-door work the amateur must take into consideration the state of the weather and the atmosphere, the presence or absence of reflecting surfaces, such as a stretch of sand-beach, a sheet of water, or the proximity of a light-colored building, and time the plate accordingly.

After you have taken the test-plate, return to your dark room, and pour into the bath four ounces of neutral oxalate, and mix with it one ounce of iron solution. Take the plate from the holder, wash it in cold water, and drop it into the mixture. The image will begin to appear in from three to five minutes. After it has become clearly defined, wash it again in cold water, and put it in the alum solution for a few minutes. Another washing, and it is ready for the fixing solution, which will keep the picture from turning black, as it would otherwise do, if exposed to the light.