Any developer that will work on any plate will work on Hartley's the same. But he claims that all published developers given by dry plate factories are right if the exposure is. Unless the exposure is right, or nearly so, a failure is almost sure to occur. Hartley's plan of developing, while using the same chemicals, is on a different theory, making the developer suit any exposure, no matter how long. It is impossible for any one to so accurately judge the time needed as to suit a standard developer; he must make the developer to suit any exposure, and by the following plan you can take any number of plates and not know the time of exposure or amount of light on subject at time of exposure, and if there is plenty of time, no matter how much, you can make a nice negative by this plan of developing.

Pyrogallic acid is used to give strength to the negative, and should be according to the amount of silver in the emulsion. The smaller the quantity of silver, the smaller the quantity of pyro. The more silver, the more pyro. If more pyro is used than should be for the amount of silver, there will be green fog; if the proportion is right, the plates will be clear in the shadows and no green fog.

The ammonia is used for detail. The bromide is used to correct over-exposure. Citric acid is used to keep the pyro from oxidising.

(a) Pyrogallic acid .. .. 3 gr.

Citric acid...... 1 gr.

Water .. .. .. .. 1 oz.

(6) Ammonium bromide .. 48 gr.

Ammonia ...... 3 oz.

Water........ 3 oz.

Take enough of the pyro solution in your developing tray to well cover the plate; let it remain in this solution for a few seconds; put 2-3 drops of the ammonia solution into your developing cup; pour pyro solution out of dish into cup containing the ammonia, then pour contents of cup on to the negative; in a few seconds the image will begin to appear. Repeat the operation of adding the ammonia, drop by drop, until you get all the detail out.

Remember that the pyro gives the strength; the more pyro, the more strength; the less pyro, the less strength.

Ammonia gives the detail: the more time, the less ammonia. Therefore, if you take plenty of time and commence with very little ammonia, you will get a fine negative. Always commence with not more than 2 or 3 drops of ammonia solution, then, no matter what the time is, you have the plate under control. It takes about 5 minutes to develop a dry plate properly. If you use the oxalate developer, use it on the same theory as the pyro. Oxalate in the place of pyro; iron in the place of ammonia; only you must add the iron to the oxalate- not the reverse. Oxalate gives the strength and iron the detail. If you commence slow, you need not use any bromide in either case. As bromide is only used to correct over-exposure, it takes off part of time, the same as when it is not washed out of the emulsion. Fix in hypo and wash as usual.

List Of Articles Needed

Washing box; heating box, for melting and filtering emulsion; dipping thermometer; oil stove; racks, for drying; Swiss or Heinrich's gelatine; Hartley's silver; ammonium bromide; pure soda carbonate; citric acid; alcohol; chrome alum, one quart pitcher; one quart bowl; half-gallon pitcher; one- gallon bowl; several small pitchers, for flowing; silver knife or horn spatula.

Cleaning And Preparing The Glass

Soak the glass in lye, well wash, and put into strong nitric acid; wash and albumenise same as in the wet process, using the albumen a little thicker. Do not add any ammonia, use a few drops of nitric acid instead.

Another way - Rub the glass over with the following solution: Soda silicate, 1 oz.; water, 30 oz.; rub dry with tissue paper.

Another way is to use the glass without any substratum. This is less trouble and just as good. Do not polish, simply rub off dirt with. dry cloth. If the emulsion does not flow readily, on account of plates being too cold, you can assist the emulsion to the edges with a glass rod or your finger. If air-bubbles get on the plate, break them with pieces of filtering paper. The greatest cause of failure is too much light in flowing and drying the plates. Also dust is a great enemy. Fog, if not from light, comes from free silver left in the emulsion. An emulsion of this kind can be made all right by putting it again into the brine, leaving for a few hours, and washing as before. The temperature of the brine should be 60°-70° F. (16°-21°C). Make all your plates in spring for summer use, and in the fall for winter use, as it is much more pleasant. Do not have the flowing room over 80° F. (27°C.) - 60°-70° F. is better. Plates that have been exposed to light and not developed, can be soaked in a solution of potash bichromate, washed, dried, and they are as good as before exposure. Be sure and keep plates dry. Dampness is a great enemy to the dry plate. Plates that take a long time to dry are apt to frill.

If you wish to make a more intense negative than this formula gives, use same amount of gelatine and less silver; if you want a less intense negative, use more silver and same amount of gelatine.

Always use the same number of grains of ammonium bromide in the brine as you use silver in the gelatine, and reduce or increase the soda carbonate . and citric acid in same proportion you reduce or increase the silver. Always use the same amount of gelatine. Any water that is fit to drink is fit to make emulsion. Water that is strong of lime is not good.

For subjects with not much contrast, such as children and fair complexions in light drapery, use 5 percent. of ammonia iodide in the brine. For dark draperies and dark complexions, use all bromide.