311. There are still other methods of preserving the plate for a long time between the time of coating and developing it. One of the best consists in the addition of a few drops of water to the collodion. The method employed in such cases is as follows: A good ripe collodion should be used, and new strictly avoided; to this, drop by drop, distilled water is added, equivalent to about two drops to each ounce of collodion; after the addition of each two or three drops, the collodion is well shaken, lest the precipitation of the cotton should occur; after this, carefully filter. There is much in the manner of adding the water, by small defilm; then 1 add silver, five grains to the ounce, pour it over the plate, when, to my delight, the picture comes out boldly and clearly. In order to get up intensity, add more iron and silver, after which treat it as usual with negatives. Any mode of developing generally practised will do, with the addition of silver; but without it, there is only a faint outline of a picture. I have never seen this recommended in any of the journals, but hope it will be fully tested by more skilled hands. - B. S. Cooper.

Every photographer is familiar with the risks of stains from partial drying of the plate, when a long time elapses between exciting and developing the plate. Here is a method the extreme simplicity of which will entitle it at least to a trial, and one trial will prove its utility. The plan is simply to flood the plate with a few drachms of distilled water previous to exposure, the water is then poured from the plate to a developing - glass, and must on no account be thrown away, for in this appears to lie the secret of success. After exposure, the plate is again flooded with the same water that was previously used, and which, after thoroughly moistening the film, is again returned to the developing-glass, and mixed with the required quantity of developer, and the development proceeded with as usual. Plates so treated will give pictures as clear and free from markings as if only exposed in the camera for a few seconds. - John L. Gihon.

311. In my own practice I have always been able to avoid this inconvenience by redipping the plate in the bath just before development, and I recommend this course as a cure for the evil. The quality of the pyroxylin has much to do with this, as also the salts with which the collodion is bromo-iodized; and it is a noticeable fact that in the bromide process with the bath this evil is much less in plates kept very long than in the ordinary bromo-iodide process. - Col. Stuart "Wortley.

Some of our best landscape photographers have been for some time developing in the field, and finishing up at home in the evening or next morning. The mode is as follows: After developing the plate, wash off with water; then flow over a solution of glycerin -

Water,..................

4 or 5 ounces

Glycerin,.....

1 ounce.

Alcohol,..................

1/2 "

Or you can dispense with water in washing off the iron, and flow on a solution of -

Glycerin,..................

1 ounce.

Water,..................

4ounces

Acetic Acid,..................

1 ounce.

Flow on like collodion and drain; then flow on a second time, and put the plate in the negative-box. In this way you lose no time in finishing up, but can keep on taking negagrees, and carefully shaking after each addition. Plates coated with collodion so modified will keep free from stains three hours in a moder-ately dry temperature,

812. Sometimes it is necessary, too, to keep the plates a long time after exposure before they can be developed and fixed; and, again, when they have been that kept, after - manipulation is required in order to bring them up to a proper printing quality. All these little niceties must be studied. In no branch of the art is the exercise of careful thought more essential than in this, provided yon are not content with indifferent results.

818. As to interior work, views of the interiors of churches, dwellings, factories, and what not, the manipulations are largely the same as tives. Plates with glycerin on them will keep a week or more with safety. When you reach home, wash off the glycerin, and fix in weak cyanide; then force up, if required, by 4 the well-known methods. - T. C. Roche. 812. I prefer, after fixing and washing, to flow over the plate a solution of

Acetic Acid,No.8,..................

1/2 ounce.

Water,..................

5 ounces

I then drain and flow over a solution of pyrogallic acid, No. 1, mixed with a few drops of acid silver, as per formula No. 2.

1. - Pyro,..................

60 grains,

water,..................

20 grains

Citric Acid,..................

20 grains

2. - Silver,..................

20 grains

Citric Acid, ..................

10 "

Water,..................

1 ounce.

This will bring the negative up to a good printing color, which will not change. Dry and varnish the negative. Keep the shield and camera free from dust in working, and take a general interest in your apparatus. - T. C Roche.

Take iodine one drachm, iodide of potassium one drachm; dissolve in twenty ounces of distilled water. This forms a stock solution of the color of good old port, and for use may be diluted six times. When the plate has been developed and washed as usual, flood it with this dilute fluid, and keep it on about half a minute; then wash again, and put in the drain-ing-box. The plates may be intensified at any time; but I prefer, on getting home, to let them dry in daylight on a rack, and if any further intensity is required (though this is not often the case), it is done either with iron and citric acid or pyrogallic and citric in daylight, and fixed as usual. I can scarcely give too much prominence to the importance of this matter. - Samuel Fry.

818. Sometimes it is necessary to take a view of an interior or of some object at a distance from the dark - room; in either case, when as much as two hours must elapse between the plate leaving the bath and its development, the only extra precautions to be observed are, collodion quite ripe, and if inclined to give stains, the addition of a little water, say one drop to the ounce, will cure it. Bath proper strength, free from organic matter, and rather acid. Allow the collodion to set well before putting the plate into the bath, and when in keep it the others, only the exposure must be very much lengthened, when one or the other of these hints as to the preservation of the plate will be found of use. The collodion may be modified to suit the lighting of the subject, and, as a rule, a weaker developer is used. In these times the wet plate is seldom used for interior work. See the lesson following.