Silver prints must be thoroughly washed from the free nitrate of silver before toning. If this injunction is obeyed in each and every case, the prints after being finished will keep pure and white, and not turn the least yellow with age. In alum eliminating the above must be adhered to. Prints in my possession of my own and others, made in 1873, are as good to - day as the day they came from the alum solution, eight years ago. - John R. Clemons.
256. In acidifying the prints, a little warm water facilitates the reddening of them very wonderfully. The plan I have adopted for keeping the toning - bath warm is similar to that for the silver bath; the same pan will answer for both. Unless there is a very large number of prints, it will only be necessary to fill the pan with warm water; but if necessary, the gas - or coal-oil stove can be used for this also. In this case, care must be taken to prevent the bath from becoming too warm, as the action will not only be uneven, but also flat and gray, with a tendency to measles. The fixing - bath may be made up of warm water, and all the operations are through, with far more satisfactory results; and, as regards comfort, I will leave it for those who have tried this and the ice - cold solution to judge. - H. A. Webb.
257. Now sufficient scope is given for the exercise of judgment and taste. Do not hurry. More prints are spoiled by making the gold solution strong in order to tone rapidly, than in any other way. This caution should be observed, and the prints turned over and over, so each one may be carefully watched, and withdrawn from the solution as soon as it arrives at the proper color or tone. The prints are not acted upon just alike, some becoming toned much sooner than others, hence the necessity of " going slow."
258. Operators differ in their tastes as to the most desirable tone to secure One prefers a warm or chocolate tone, while the rich, black, vel-
257. A solution of chloride of gold. What can this do? Gold is what might he called an ascetic metal; it likes to live alone. In other words, it is easily reduced from its salts to the metallic state. So when this sheet of paper, covered all over with silver salts, is brought into a solution of chloride of gold, the silver, having a great attraction naturally for chlorine, and the gold parting willingly with its chlorine, it is no more than can he expected to find the chlorine leaving the gold and uniting with the silver, forming, of course, chloride of silver; the dark subchloride, when the silver has been reduced to the subchloride by the action of the light, and the white chloride when the silver is unaltered, and then the gold, having lost that which held it in solution, has nothing to do but come down as a precipitate of metallic gold, and so metallic gold is deposited upon the picture. - H. M. McIntire.
Placing the whole number of prints, to be toned by a given quantity of gold, in the solution at once insures more complete utilization and equalization of the toning agent through the entire number of prints. The large surface exposed to the action of the toning-bath at once prevents rapid reduction, and there being in the bath nothing but the prints to precipitate the gold, the toning takes place with deliberation and uniformity. - W. H. Sherman.
The toning should be done in a quite iveak and even light, and at a little distance from the window. An idea of the quantity of light required may be had by bearing in mind that all you wish is to see distinctly and clearly, without any guessing. Take a couple of dozen prints, and let them lay in your bath solution, face up, but under the surface, and keep them in motion while in it; the action is as follows: At first the prints will not perceptibly change, but very gradually the high-lights and half-tints of the face will lose their red tint, and will commence to border on the rich purple, and then they will quite quickly arrive at that stage when they are to be removed to a bath of running water. - Charles W. Hearn.
258. After washing away the nitrate of silver from the print (for the reason that the nitrate would only cause a useless waste of gold), we place the print in the toning - bath. Now the chloride of silver cannot be toned by gold I Why? Because the chloride of silver will not take any of the chlorine away from the chloride of gold. But the subchloride will take a little; enough to change it from the subchloride, AgaCl, to the chloride AgCl, that is, one atom of chlorine for every atom or molecule of the subchloride. This accounts for the bleaching which usually takes place - the violet subchloride being changed to the chloride, which is white. But, if the bath be acid with hydrochloric acid, the subchloride is quickly changed, vety tone of an engraving is liked best by others. For the last, use this toning bath:
Acetate of Soda,.......................
Chloride of Gold, .......................
Nitrate of Uranium.......................
The gold and uranium, both baying an acid reaction, must be neutralized with bicarbonate of soda separately before being added to the bath. dissolve the salt and acetate of soda in the water; than dissolve the nitrate of uranium in one ounce of water and add bicarbonate of soda, until neutral. Add this to the first solution and then neutral gold solution suffient to tone in about fifteen minutes. Where a warm, brown tone is desired, the uranium may be omitted. This bath should be made several hours before use.But a few prints should be toned at a tin and they should be kept agitated while in the solution, for, if they rise to the top and remain there for a minute or two, a red patch will be the result, and the picture spoiled. Air - bubbles between the prints will also cause red spots. To prevent these, lay your prints in one at a time.
259. It is believed that the toning - bath most in use, and the one with which all varieties of tones may be secured, is the one first given in section 258. But this is not the only way, a choice being given by soma to and then some of the suboxide gives way, and is converted into the chloride again. Hence the more hydrochloric acid the more bleaching. But the toning takes place upon suboxide of silver, which is being converted into the chloride by the chlorine of the chloride of gold, and the gold takes the place of the silver thus removed. - W. H.Sherman.