Pyrogallic Acid Developer. Prepare the following: solutions:

1. - Distilled Water,....................

500 parts.

Pyrogallic Acid,....................

3 "

2.Ordinary Water,....................

500 parts

Bromide of Ammonium,....................

6 parts

Ammonia,....................

10 "

A.Water....................

10 "

Ammonia,....................

10 "

B. - Water,......

20 parts,

Bromide of Ammonium,....................

10 parts.

These last two solutions, A and B, being used only in very small quanmay be; but if the same sample of potass oxalate be neutralized by the addition of oxalic acid, the resulting negatives have all the printing density required, with beautiful and clear shadows. Although the same sample of plates may be used, that with the alkaline potass oxalate gives thin and foggy negatives. If every photographer who uses the ferrous - oxalate developer would test his potass oxalate before using, he would then know the true power of his developer, and have it more under control than in working by rule of thumb. - A J. Jarman.

The apparatus for preserving ferrous - oxalate developer consists of a pickle-bottle, in the cork of which are inserted two tubes. One tube is bent for delivery of the solution into a tray when required for use. The other is a thistle-headed funnel through which to pour it back into the bottle. A layer of paraffine protects it from the air. In using this bottle the mouth is applied to the funnel, and air is blown through it to expel the liquid through the delivery tube. - T. H. C.

333. Successful development depends upon - 1. Extraneous circumstances, that is, accommodation, light, and mechanical contrivances, on which points I have nothing here to say. 2. Proportions of the reagents employed. 3. Length of time employed in the process. 4. Like success in everything else - -brains. Upon this last essential depends the success of the entire operation. Now, in blindly following out the printed instructions of a plate manufacturer, or the confidential directions of some friend at headquarters, who knows all the "bigwigs," brains can play no part, so that nothing is left for our brains but to comprehend the rationale and practice of Nos. 2 and 3.

Every one knows that " pyro gives density, ammonia detail, while bromide keeps the tity, are kept in bottles having a drop-tube. To develop,make a mixture of equal parts of the first two solutions, No. 1 and No. 2. If the posure is good, this mixture is sufficient to completely develop the print shadows clean and checks over - hasty development; " but how many put their knowledge to any use? Our friend, Mr. Phocus, has had a field - day. In bit slides he has plates bearing the " latent images " of a landscape or two with fine distances, a duke's country - seat, a waterfall in deep shadow, and perhaps a happily - caught cloud effect In his dark - room be finds Mr. Collodion's printed instructions, thus:

Fig . 87.

Fig . 87.

Pyro

2 grains.

Water

1 ounce.

Ammonia liquid, fifty per cent, solution, . .

2 drops.

Bromide of Potassium, five per cent, solution.

2 "

or something of that kind, and straightway makes up enough of these solutions to develop all his negatives. He is surprised to find his landscapes nearly clear glass, bis mansion-house almost a success (barring, perhaps, the foilage of a splendid and characteristic elm), his waterfall as hard as if it were an icicle, and his cloud - nil! " Would he be surprised to hear " that if for his landscape he had doubled bis pyro and halved his ammonia, if for his house and tree he bad reduced his bromide, if for his waterfall he had halved his pyro, doubled his ammonia, and modified his bromide, and if for his cloud he hud halved the whole lot, he would have got a negative uniform and probably fairly good? The moral is this: When you have a subject wanting in contrast - such subjects are rarely under-exposed - use as much pyro as you like, only as much ammonia as will bring out all detail, and as much bromide as will keep the shadows clear. When you have strong contrast, keep down the pyro and with it the density, and do not counteract the ammonia with too much bromide. When making cloud negatives for printing into landscapes, remember that you only want the image clearly defined, any further density simply causing waste of time in the double printing. Of course many will say, " Oh I I knew all that before." I say, "Then do it I " - Andrew Pringle.

I prefer to develop very slowly, as one has more control over results, and therefore adopt the following method. My alkaline developer is made of a solution of -

Pyrogallic,..............................................................

3 grains.

Bromide of Ammonium,........................................

30 grains

Strong Ammonia,........................................

1 drachm.

Water........................................

10 drachms.

These solutions being kept separate. The pyrogallic will keep a considerable time if a drop of nitric acid be added, as recommended by Mr. W. Bedford. Now to develop. Before placing the plate in the dish, rub round the edge a piece of white wax. This is a great preventive to frilling at the edges. Put in a measure, for (say) a cabinet size plate, one ounce of pyrogallic, and add eight or ten drops of the bromide solution, and the same quantity of the ammonia. Pour this over the plate (no previous wetting is necessary). Watch the result, and if the right exposure has been given, the image will come out very slowly; if necessary to hasten the development, and to get the proper intensity, a few more drops of ammonia and bromide may be added, or, if under - exposed, ammonia only. A useful form of dropping - tube, and which I always use, is made by the following method. A piece of quarter-inch-bore glass tube, four inches in length, is held over the flame of a spirit - lamp

Although it is believed that the ferrous - oxalate developer will, erelong, be the one most used for the bromo - gelatin plates, still the amount of experience with pyro that has been published by the fraternity abroad, leads to the feeling that it ought to be given a place here. Pyro will, sometimes, place a power in your hands when its compeer may not be so and one end sealed, except a small hole about the size of a pin. Over the other end a small red rubber pipe must be placed, about three inches long. Place a cork in the end, and it is ready for use, and may always remain in the solution ready to hand; by pressing the rubber tube it will take up sufficient liquid, which can be dropped in the exact quantity required by pressing the tube between the finger and thumb. Sometimes I develop with iron, which is conveniently used in the following way: A saturated solution of sulphate of iron, an ditto of oxalate of potash, using four parts of the latter to one of the former; when using the iron I prefer to wet the plate before developing. - Wm. England. Make two stock solutions, and label them No. 1 and No. 2: