CHAPTER VI.

LANDSCAPE PHOTOGRAPHY ON PRESERVED COLLODION AND COLLODIO-ALBUMEN.

The Collodion process may be applied with success to landscape Photography; but as the plates become dry and lose their sensitiveness shortly after their removal from the Bath, the operator will require to provide himself with a yellow tent or some portable vehicle in which the operations of sensitizing and developing can be conducted. As it is a point of great importance in the Collodion process that the plate should receive exactly the right amount of exposure in the Camera,--a few seconds more or less sufficing to affect the character of the picture,--many will submit to much trouble and inconvenience in order to have the apparatus complete upon the spot at which the view is taken.

The object of the "Collodion Preservative Processes" is to maintain the sensitiveness of the film for a certain length of time after it has been excited in the Bath. There is some difficulty in doing this, because if the plate be allowed to dry spontaneously, the solution of free Nitrate of Silver upon the surface, becoming concentrated by evaporation, eats away the Iodide of Silver, and produces transparent spots.

Some operators have attempted to use a second plate of glass in such a way as to enclose the sensitive film with an intervening stratum of liquid. The difficulty however of separating the glasses again without tearing the film, is considerable.

In the process of Messrs. Spiller and Crookes, the property possessed by certain saline substances of remaining for a long time in a moist condition was turned to account. Such salts are termed "deliquescent," and many of them have so great an attraction for water that they absorb it eagerly from the air: the solution having been formed, the water cannot entirely be driven off except by the application of a considerable heat.

More recently, Honey has been employed by Mr. Shadbolt.[52] This substance can scarcely be termed deliquescent, but it possesses, like other uncrystallizable sugars, the property of remaining moist and sticky for a long time. Honey is, according to the Author's views, superior to inorganic deliquescent salts as a preservative agent, from its possessing an affinity for Oxides of Silver, and thus acting chemically in communicating organic intensity to the image.--Collodion plates when kept long in a moist and sensitive state often give a pale and blue image, even although the Nitrate of Silver be left upon the film; and neither Nitrate of Magnesia nor Glycerine appears capable of supplying the deficient element, both being nearly or quite indifferent to the Salts of Silver.

[52] A claim has lately been advanced by Mr. Maxwell Lyte to be considered as the discoverer of the Honey Process. This gentleman appears to have worked simultaneously with Mr. Shadbolt, and to have anticipated him in publishing; but the object of Mr. Lyte's process was rather to increase the sensibility of the plates than to confer upon them keeping qualities.

THE HONEY AND OXYMEL KEEPING PROCESSES.

When the weather is cool, Collodion plates may be preserved with tolerable certainty for a few hours, by simply applying Honey to them in the state in which they are taken from the Nitrate of Silver Bath.

The best pure Virgin Honey should be obtained by dripping it immediately from the comb. This point is of importance, since if the sample of honey be of inferior quality, or adulterated, the process may not succeed. The quantity of water to be added will vary with the consistence of the honey, from about an equal bulk to two parts: it should be sufficient to make the preservative solution pass slowly through filtering-paper.

After the plate is removed from the Nitrate Bath, it is to be drained and wiped on the back in the usual way. The Honey is then poured along the edge in such a manner as to form a broad wave which forces the Nitrate of Silver solution before it and covers the film. Next drain the plate into a measure and pour on a second portion of Honey as before. This second dose may be used again for the first application to the succeeding plate.

Lastly, stand the glass on blotting-paper in a dark place for about a quarter of an hour or twenty minutes, and wipe the lower edge before putting it into the plate box.

The exposure required will probably be about four or five times as long as that for new and sensitive Collodion, or twice as long as the exposure required for old and brown Collodion.

Before applying the developer, immerse the plate in a Bath of rain-water for five minutes, moving it about occasionally to soften the honey. This will probably be sufficient for plates which have not been kept longer than four hours, and beyond that time the process is not considered certain, since the Honey exercises a slow reducing action upon the Nitrate of Silver.

The solution of Pyrogallic Acid may be used of the ordinary strength, with a full dose of Acetic Acid. Only a faint image comes out at first, but on pouring over the plate a fresh portion of the developer with two or three drops of the Nitrate Bath added to each fluid drachm, it may be intensified to any extent.

Fix with Hyposulphite of Soda, and wash in the usual way.

When the process fails, from heat of the weather or other causes, the image will probably be feeble and red by transmitted light, and the shadows defective and misty. This is especially likely to happen when the Nitrate Bath is very old and contains much Acetate of Silver; or when the same portion of Honey is used more than once, and has undergone partial decomposition by the action of the Nitrate of Silver. The use of _pure_ Honey, free from mouldiness and fermentation, will, _in cool weather_, almost certainly ensure success.

_A modification of the process when the plates are to be kept over four hours._--In this case the whole, or the greater part of the Nitrate of Silver must be removed before applying the preservative agent. Wash the sensitive plate in water in the manner described for the Oxymel process in the next page. Then apply the syrup as before, using it as thick as possible. Honeyed plates, free from Nitrate of Silver, may commonly be kept for five or six days; often much longer. Dr. Mansell, who has employed this process with great success, speaks of _temperature_ as a point to be attended to. In hot weather the same length of keeping properties will not be attained.

_Use of Oxymel for preserving Collodion plates._--The principal difficulty in the employment of Honey in Photography, is its disposition to ferment, or to become mouldy. Fermentation occurs most readily in a dilute solution, and will be obviated by using the syrup as thick and free from water as possible. Mr. Llewellyn employs "Oxymel," which is a mixture of Honey and Vinegar, as a preservative agent. This substance will keep even in dilute solution for a long time without decomposition; and, being very readily removed from the plates, does not interfere with the development of the image. The preparation of Oxymel is described in the Vocabulary,