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Towler, John. The Silver Sunbeam. Joseph H. Ladd, New York: 1864. Electronic edition prepared from facsimile edition of Morgan and Morgan, Inc., Hastings-on-Hudson, New York. Second printing, Feb. 1974. ISBN 871000-005-9

Chapter XXXIV.
PRINTING BY DEVELOPMENT.

DURING the feeble light of winter in high northern or southern latitudes, as also in the preparation of enlarged views or portraits with the solar camera, printing by development is of very great utility. It is quite analogous to the operation of producing a collodion picture by the agency of a reducer; and the same materials in general are employed in the two branches.

Formula for the Salting Solution.
No. 1. With the Chlorides.

Chloride of sodium, (common salt,) 100 grains. Hydrochloric acid,
6 drops. Rain-water, 12 ounces.

Immerse the papers in this mixture and let them remain in it for two or three hours, then take them out and allow them to dry.

Formula for Sensitizing (Solution.

Nitrate of silver, 1 ounce.
Citric acid, 8 grains.
Distilled or rain-water, 8 ounces.

Float the papers on this solution for three minutes, and then suspend them on the varnished needles, or on a cord with clothes-pins. Remove all the fluid that accumulates on the lower side or on the corners. As soon as the papers are moderately dry they may be exposed beneath the negative or on the screen of the solar camera until a faint image appears. Beneath a negative in the rays of the sun, the time of exposure will not exceed three or four seconds; in feeble light a minute or more may be required. As soon as the print is sufficiently distinct, it is withdrawn and laid upon a piece of glass somewhat smaller in dimensions than the paper, picture side upward; two opposite edges of the paper are folded beneath the glass, and in this position the paper and the glass together are placed on the left side of a capacious gutta-percha developing dish.

Formula for Developing Solution.

Pyrogallic acid, 12 grains.
Citric acid, 6 grains.
Water, 6 ounces.

Of this solution take sufficient to cover the paper. Inclining the dish downward to the right side, pour in the solution; then dexterously raising the right side, the fluid will flow or may be made to flow over the whole surface without producing any lines of stoppage. This is very important, because any stoppage on such paper would be as injurious as on collodion prints. The development commences and proceeds as rapidly as on a collodion negative, and requires just the same amount of vigilance. As soon as the proper contrast has been attained, the further reduction is caused to cease by pouring off the developer into the sink or waste-tub, and then by washing at the tap. The washing must be performed with care and effectually. After this operation the prints are fixed in the following solution

Formula for the Fixing Solution.

Hyposulphite of soda, 1 ounce.
Water, 16 ounces.

The prints are kept in this solution until the whites are perfectly clear, which will require from ten minutes to half an hour. They are then taken out and submitted to the regular process of washing, in order to remove every trace of the hyposulphites.

Second Method with a Chloride and a Bromide.
Formula for Salting the Paper.

White of egg, 10 ounces.
Distilled water 15 ounces.
Chloride of sodium, 1 drachm.
Bromide of potassium, 1 drachm.

Dissolve the salts in the water and add the solution to the albumen, which has to be beaten up into a froth and allowed to subside several hours in cool place. The clear supernatant liquid is decanted carefully or filtered from the deposit into the appropriate dish for salting operations.

The papers are floated in the ordinary way on the surface of this bath for three minutes, and then hung up to dry on cords and attached by means of clean clothes-pins. After ´his operation the papers are put in a long tin box which is inserted in a deep kettle of boiling water, taking care that none of the water can get access to the paper, but that the paper is submitted through its whole length to the heat of steam; the operation is still more effectual if hot steam could come in contact with the albumenized surface; such an expedient is intended to coagulate the albumen. The omission of this part of the operation must not deter the operator from trying the process; the results will not materially be changed, because the coagulation can be effected in the sensitizing bath.

Formula for the Sensitizing Solution.

Nitrate of silver, 1 ounce.
Distilled water, 12 ounces.
Citric acid, 3 drachms.
Alcohol, 1 ounce.

The papers are floated on this bath from two to three minutes, and are then allowed to dry as usual. An exposure of from eight to ten seconds in the full sun will be sufficient; whilst as many minutes will be required in a weak light. The picture must be quite visible, or very nearly so, before it can be said that the exposure is long enough.

Developing Solution.

Gallic acid, 5 grains.
Distilled water, 2 ounces.

The operation of development is best performed in a glass or gutta-percha dish; the print is first moistened and then placed on the bottom of the vessel to which it adheres. The developing fluid, being poured on the inclined right-hand side, is flowed over the print almost instantaneously; if any part remains not covered, a slight, quick motion will easily bring the fluid over the part, or a glass triangle will cause the difficulty to disappear, dragging along with it sufficient of the fluid to cover the part denuded. The reduction is very rapid; and where the exposure has been about right, the development of the image will be complete in two or three minutes. In very cold weather it is better either to use a stronger bath or to warm the bath by floating it in warm water. Gallic acid in solution is very apt to become mouldy by keeping, and, consequently, a small piece of camphor, or a drop of oil of cloves, is mixed with the bath to prevent this sort of decomposition. An under-exposed picture develops very slowly, and by a long continuance of the action of the acid it becomes uniformly dark-colored without any gradation of tone; on the contrary, an over-exposed picture is developed with great rapidity, and has to be removed from the bath quickly to prevent its assuming a dark color over the whites. If printed deep enough in the shades, in such a case, the lights would in the mean while be completely spoiled. The best prints are those in which the gradation is all thoroughly and rather slowly brought out in the printing; these are afterward carefully washed and fixed in a weak solution of hyposulphite of soda, containing as follows:

Hyposulphite of soda 1 ounce.
Water, 20 ounces.

The prints remain in this solution for a quarter of an hour or so, and are again thoroughly washed. After this proceeding, if the tones are not satisfactory, the prints may be immersed in the gold toning-bath, in order to receive a gold deposit, which modifies the color. Any of the gold-toning formulas given will answer the purpose. If; in the operation of developing, etc., the whites are not clear, an improvement in this respect is effected by immersing the well-washed prints in a bath containing one ounce of chlorinetted lime to ten ounces of water.

Third Method with an Iodide.
Formula for Salting Solution.

No. 1. Nitrate of silver, 44 grains.
Distilled water, 2 ounces.
No. 2, Iodide of potassium, 7 drachms.
Distilled water, 2 ounces.

Dissolve the two salts, and then mix the solutions together, which will produce a precipitate of the yellow iodide of silver. Add to this a concentrated solution of iodide of potassium, until the precipitate is dissolved. The fluid is then ready for the bath.

Float the papers on this bath in the usual manner for about three minutes, or until they lie flat on the solution. They are then taken out and hung up to dry. After this proceeding they are floated in a quantity of rain-water, two and two together and back to back, for a number of hours, taking care to turn them over from time to time. The surface thus prepared assumes a very uniform but pale yellow color. The papers are again taken out and hung up to dry.

Sensitizing Bath. Formula.

Distilled water, 25 ounces.
Aceto-nitrate of silver solution, 4 drachms.

The solution of aceto-nitrate of silver is prepared as follows

Nitrate of silver, 1 ounce.
Acetic acid, 2 ounces.
Distilled water, 10 ounces.

Or the complete formula may stand as follows, where operators do not wish to keep a stock of the aceto-nitrate of silver

Distilled water, 25 ounces.
Nitrate of silver, 18 grains.
Acetic acid, 2 scruples.

The papers are floated on this bath for three minutes, and then taken out and' hang up to dry. Whilst the surface is still somewhat moist, they are exposed beneath a varnished negative, or on the screen of the solar camera, for a few seconds. The image in this case is quite latent. In dull weather, and when the light is very feeble, half a minute's exposure will suffice. The print is developed by pouring upon it, in the manner already indicated, a saturated solution of gallic acid containing about one third its quantity of aceto-nitrate of silver. If the development is very slow, the exposure has been too short; on the contrary, the development is quite rapid when the exposure has been too long. As soon as the print is completely brought out in all its details, it is immersed in water and very thoroughly washed in order to remove every trace of gallic acid.

The prints are then immersed in a solution of hyposulphite of soda as follows

Hyposulphite of soda, 2 ounces.
Water. 10 ounces.
Chloride of gold, 2 grains.

The prints do not change much by immersion in the fixing solution, if the time of exposure has been sufficiently prolonged; if the time has been too short, the dark color will become pale and red. If the tones of the shades do not assume a dark color in the developing solution, the cause may be attributed to the want of aceto-nitrate of silver in the gallic acid; and, as a rule to be observed, the aceto-nitrate is gradually added where the development or the intensity relax. If the toning in the fixing solution becomes inky, the gold may be omitted.

Method of Sensitizing by Means of Nitrate of Uranium. (The Process of Niepce de Saint Victor.)

The paper used in this operation has to be kept in the dark-room, or at least excluded from light, for several days previous to its employment. It is then floated, without any other preparation, on the following bath

Sensitizing Bath.

Nitrate of uranium, 1 ounce.
Distilled water, 5 ounces.

After two or three minutes the papers are removed from the bath, allowed to drain, and then hung up and dried. They will keep a long time when not exposed to light. The time of exposure beneath a negative varies with the intensity of the light; from one to ten minutes in the sun, and from a quarter of an hour to an hour in a feeble diffused light. The image is barely visible.

Developing Solution. No. 1.

Nitrate of silver, 1 drachm.
Acetic acid, 1 to 2 drops.
Distilled water, 2 ounces.

The development is very rapid. Almost as soon as the print is immersed in the fluid, the picture comes out and proceeds to its termination with great velocity. As soon as the development has advanced far enough, the prints are plunged into water, and thus washed and fixed at the same time.

Developing Solution. No. 2.

Chloride of gold, 10 grains.
Hydrochloric acid, 1 drop.
Distilled water, 12 ounces.

Prints are developed in this bath with more rapidity than in the preceding.

Another Method.
Sensitizing Bath.

Nitrate of uranium, 1 ounce.
Distilled water, 10 ounces.

Developing Solution.

Bichloride of mercury, 5 grains.
Distilled water, 12 ounces.

Pass the prints through this solution, and then wash them

very carefully, after which they are immersed in the following bath

Nitrate of silver, 2 drachms.
Distilled water, 12 ounces.

When the image is intense enough, wash the prints thoroughly and hang them up to dry.


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