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The photographic news
- Bandzählung
- 6.1862
- Erscheinungsdatum
- 1862
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- Englisch
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- F 135
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- Hochschule für Grafik und Buchkunst Leipzig
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- Hochschule für Grafik und Buchkunst Leipzig
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- Bandzählung
- No. 217, October 31, 1862
- Digitalisat
- SLUB Dresden
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Zeitschrift
The photographic news
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Band
Band 6.1862
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- Register Index 619
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Band
Band 6.1862
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THE PHOTOGRAPHIC NEWS. [October 31,1862. From the analytical results presented, the most different formulae may be calculated with equal probability. In the present state of our knowledge in respect to these bodies, we must abandon every formula by which their atomic constitu- tion is said to be expressed.” If this be true (which I have not the least doubt of), the quantity of albuminate of silver, which is formed by using any particular albumenizing mixture, can only be ascertained by delicate and careful experiment as to the combining power of dried albumen and nitrate of silver. As an inspection of the tables I have given suggests many important questions, I must defer their consideration to a future time. ♦ NEW METHOD OF PRINTING. BY II. COOPER, JUNR.* Though I hope the time is not far distant when resinized paper will take the place of albumenized, yet there is a good deal to be done in the former process before it can ac complish the wished-for result. I have the honour to lay before you this evening a few specimens of my progress; and if you will kindly listen for a few minutes, I should like to make a few remarks on the different methods I have employed, and on the disadvantages and drawbacks at present existing in the process, as I think that it is a better way to remove them, than to forget the faults, and point out the beauties. A good many faults arise, not exactly from careless manipulation, but from a want of knowledge of the peculiar requirements of the process. For after having gained a little skill in the processes we employ, we are apt to wonder why we cannot succeed all at once with a new one ; forgetting, for the moment, all the difficulties and disappointments we met with in that which now appears so easy. For instance, after I had printed some dozens upon resinized paper, I lost numbers by not printing deeply enough. And what is more vexing, after a hard day’s printing, and that to all appearances successful, than to see all the batch becoming gradually faint in the toning bath, without a hope of preventing it ? The prints should be left in the printing frame till a good part is quite green with bronzing ; and even if the lights become faintly tinted,’ it will be of no consequence, as they will become quite white again in the toning. Many will say, “ But that is a great disadvantage; look at the time a print takes to get bronzed like that, why I shall only be able to print one half the number from the same negative!” But you must not forget that the resinized paper is very sensitive to light, and that as many prints may be produced upon it in the day, as upon albumenized paper. I have received many enquiries whether the bath should be acid, neutral, or alkaline. I recommend a strong bath very slightly acid with nitric acid, hardly sufficient to be detected by litmus paper. My reason for this is, that a very unstable salt is formed in the paper, which causes it to decompose very quickly, and the more alkaline the bath, the sooner the paper becomes spoilt. In very warm weather, the paper should be sensitized and fixed within twelve hours; but if it be very cold, twenty- four hours may elapse. I have also received complaints from several, that they have not been able to get warm tones. Sensitizing on an alkaline bath is very apt to render the prints cold, as well as to decompose the paper. The use of a new toning bath is also conducive to blueness. I find that a bath prepared as I recommended in the first instance— acetate of soda and chloride of gold made at least twenty-four hours before using—is the best to obtain rich warm tints. The prints prepared with chloride of cadmium seem much poorer than those prepared with a more soluble chloride such as cal cium or magnesium. On this account, 10 grains is about the quantity of chloride of cadmium soluble in alcohol of 8'35°; this is equal to a much less quantity of chloride of sodium, * Read at a meeting of the North London Photographic Association, on October 22nd. as the chloride of cadmium has a much higher equivalent of its base than sodium. Being moreover locked up in a resin it does not, in my opinion, form as much chloride of silver as it would if it were employed in albumenized paper; by in creasing the quantity of chloride of silver in the paper, the prints become much more vigorous. To effect this, I have em ployed the chloride of calcium and magnesium, which, as I have just remarked, are more soluble in alcohol. There is another advantage over cadmium in the two mentioned chlorides, they are very soluble in water, so that any that remains in the paper undecomposed is easily removed. The prints before you marked calcium and magnesium, contain 15 grains to the ounce. Some of the specimens, as you will see, are salted only on one side. I thought of this method when I was endeavouring to get more vigorous prints; but since using chloride of calcium I have discarded it, as it is much more trouble than the formula I gave at first; but as you may like to know the details, I will shortly run over them. The paper, to begin with, is immersed in a solution of frankincense and mastic, made according to directions given in The Photoorapihc News for October 3rd, with the exception of the chloride, which must be omitted. When the paper is quite dry, float for two minutes or more upon a 15-grain solution of chloride of sodium. Float on ths nitrate bath for three to five minutes. After the prints arc finished they should be immersed, before mounting, in the resin solution that was used in the first preparation, to thoroughly encase all the particles forming the imago. I would recommend that all prints on resinized paper should bo immersed in a weak alcoholic solution of mastic. This does not give the prints a varnished appearance ; but they will glaze much finer in the rolling. I have found an ap plication of enamel to the prints, after they are mounted and rolled, is very efficacious in giving depth and transpa rency to the shadows; but it has also a disadvantage of causing the prints to assume a highly glossy appearance, which is highly inartistic and very like albumenized paper; it also slightly injures the whites. The want of trans parency and brilliancy is one of the points I would call your attention to in the resinized paper. Another is the peculiar granular appearance of the prints after rolling, particularly papier Saxe. The cause of this is obvious—the uneven thickness of the paper. The resin is, as it were, io little hills, and when the paper is passed between the rollers, the tops of them get crushed down and polished, leaving the valleys untouched. With a thin sample of papier Rive, that I had some little time back, it was hardly perceptible. From the pieces of prepared paper now before you, you will perceive that papier Saxe possesses the gran ular appearance in the first instance ; this also is caused by the uneven texture of the paper. The flat appeal ance of some of the specimens is owing to the want of depth in the shadows to which I have called your attention. To better show the failings of the process, I have brought a few prints on albumenized paper from the same negatives. As regards printing by development, about which I was very sanguine at first, I have not been able to get on at all well, the proofs being very motley. I have not had much time to devote to this branch of the process, but I hope, during | the next few weeks, to resume my experiments in this di rection. One fact with regard to it worth mentioning is, that the paper when prepared with a chloride, and a small quantity of a neutral citrate, receives the actinic impression very rapidly, so that it has to be exposed a much less time, than is usually requisite for this method of printing. Only the faintest trace of an image should be visible. I bring two proofs which have been the most successful at present. After removal from the pressure frame they were soaked for one hour in distilled water, and then developed in the. fol lowing. Saturated solution of gallic acid one ounce, distilled water half ounce, acetic acid 5 drops, and 10 drops of a 30-grain solution of nitrate of silver. They were then toned and fixed in the usual baths. You will not be asto nished at the stains on the back, when you hear that upon ’ Octo I ’ rmoval water, sc left the: intouclu 1 could < produce io print I hav slution perfect! Bring ] dust or ; strong i paper, i omitted tinned 1 in the 1 i dissolve : the pap the free brillian of an h I ing fra: soak be a, a ci rapidly hyposu it into I evap acetic filter i I will a] in prac quick! tot th in who any qi you ai NJ IODr glass iodine When iodide tion. Tin from coppe it oft the ii obtai chlor much iron cadm parir iodid aists of io acid. In it co iinpi anot adva prie as ft Ii
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