Independently of the very rich and agreeable tones which may be produced by the process which I am about to describe, it has the property of affording permanent pictures, not liable to that change by time to which pictures produced by the use of the ammonio-nitrate solution are certainly liable. I have upon all occasions advocated the economical practice of photography, and the present process will be found of that character; but at the same time I can assure your readers that a rapidity of action and intensity are hereby obtained with a 40-grain solution of nitrate of silver, fully equal to those gained from solutions of 120, or even 200, grains to the ounce, as is frequently practised.
In eight ounces of water (distilled or not) dissolve forty grains of common salt, and the same quantity of muriate of ammonia.[[6]] Mix this solution with eight ounces of albumen; beat[[7]] the whole well together, allow it to stand in tall vessel from twenty-four to forty hours, when the clear liquor may be poured off into a porcelain dish rather larger than the paper intended to be albumenized.
Undoubtedly the best paper for this process, and relative quantity of chemicals, is the thin Canson Frères' but a much cheaper, and perhaps equally suitable paper, is that made by Towgood of St. Neots. Neither with Whatman's nor Turner's papers, excellent as they are for some processes, have I obtained such satisfactory results. If the photographer should unfortunately possess some of the thick paper of any inferior makers, he had far better throw it away than waste his chemicals, time, and temper upon the vain endeavour to turn it to any good account.
The paper, having first been marked on the right-hand upper corner of the smooth side, is then to be floated with that marked side on the albumen. This operation, which is very easy to perform, is somewhat difficult to describe. I will however try. Take the marked corner of the sheet in the right-hand, the opposite corner of the lower side of the paper in the left; and bellying out the sheet, let the lower end fall gently on to the albumen. Then gradually let the whole sheet fall, so as to press out before it any adherent particles of air. If this has been carefully done, no air-bubbles will have been formed. The presence of an air-bubble may however soon be detected by the puckered appearance, which the back of the paper assumes in consequence. When this is the case, the paper must be carefully raised, the bubble dispersed, and the paper replaced. A thin paper requires to float for three minutes on the albumen, but a thicker one proportionably longer. At the end of that time raise the marked corner with the point of a blanket pin; then take hold of it with the finger and thumb, and so raise the sheet steadily and very slowly, that the albumen may drain off at the lower left corner. I urge this raising it very slowly, because air-bubbles are very apt to form on the albumen by the sudden snatching up of the paper.
Each sheet, as it is removed from the albumen, is to be pinned up by the marked corner on a long slip of wood, which must be provided for the purpose. In pinning it up, be careful that the albumenized side takes an inward curl, otherwise, from there being two angles of incidence, streaks will form from the middle of the paper. During the drying, remove from time to time, with a piece of blotting-paper, the drop of fluid which collects at the lower corner of the paper.
In order to fix the albumen, it is necessary that the paper should be ironed with an iron as hot as can be used without singeing the paper. It should be first ironed between blotting-paper, and when the iron begins to cool, it may be applied directly to the surface of each sheet.
To excite this paper it is only needful to float it carefully from three to five minutes, in the same way as it was floated on the albumen, upon a solution of nitrate of silver of forty grains to the ounce. Each sheet is then to be pinned up and dried as before. It is scarcely necessary to add, that this exciting process must be carried on by the light of a lamp or candle.
This paper has the property of keeping good for several days, if kept in a portfolio. It has also the advantage of being very little affected by the ordinary light of a room, so that it may be used and handled in any apartment where the direct light is not shining upon it; yet in a tolerably intense light it prints much more rapidly than that prepared with the ammonio-nitrate.
The picture should be fixed in a bath of saturated solution of hypo. The hypo. never gets discoloured, and should always be carefully preserved. When a new bath is formed, it is well to add forty grains of chloride of silver to every eight ounces of the solution.
A beautiful violet or puce tint, with great whiteness of the high lights, may be obtained by using the following bath as a fixing solution: