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The photographic news
- Bandzählung
- 14.1870
- Erscheinungsdatum
- 1870
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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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- SLUB Dresden
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Zeitschrift
The photographic news
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Band
Band 14.1870
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- Titelblatt Titelblatt -
- Sonstiges Preface -
- Ausgabe No. 592, January 7, 1870 1
- Ausgabe No. 593, January 14, 1870 13
- Ausgabe No. 594, January 21, 1870 25
- Ausgabe No. 595, January 28, 1870 37
- Ausgabe No. 596, February 4, 1870 49
- Ausgabe No. 597, February 11, 1870 61
- Ausgabe No. 598, February 18, 1870 73
- Ausgabe No. 599, February 25, 1870 85
- Ausgabe No. 600, March 4, 1870 97
- Ausgabe No. 601, March 11, 1870 109
- Ausgabe No. 602, March 18, 1870 121
- Ausgabe No. 603, March 25, 1870 133
- Ausgabe No. 604, April 1, 1870 145
- Ausgabe No. 605, April 8, 1870 157
- Ausgabe No. 606, April 14, 1870 169
- Ausgabe No. 607, April 22, 1870 181
- Ausgabe No. 608, April 29, 1870 193
- Ausgabe No. 609, May 6, 1870 205
- Ausgabe No. 610, May 13, 1870 217
- Ausgabe No. 611, May 20, 1870 229
- Ausgabe No. 612, May 27, 1870 241
- Ausgabe No. 613, June 3, 1870 253
- Ausgabe No. 614, June 10, 1870 265
- Ausgabe No. 615, June 17, 1870 277
- Ausgabe No. 616, June 24, 1870 289
- Ausgabe No. 617, July 1, 1870 301
- Ausgabe No. 618, July 8, 1870 313
- Ausgabe No. 619, July 15, 1870 325
- Ausgabe No. 620, July 22, 1870 337
- Ausgabe No. 621, July 29, 1870 349
- Ausgabe No. 622, August 5, 1870 361
- Ausgabe No. 623, August 12, 1870 373
- Ausgabe No. 624, August 19, 1870 385
- Ausgabe No. 625, August 26, 1870 397
- Ausgabe No. 626, September 2, 1870 409
- Ausgabe No. 627, September 9, 1870 421
- Ausgabe No. 628, September 16, 1870 433
- Ausgabe No. 629, September 23, 1870 445
- Ausgabe No. 630, September 30, 1870 457
- Ausgabe No. 631, October 7, 1870 469
- Ausgabe No. 632, October 14, 1870 481
- Ausgabe No. 633, October 21, 1870 493
- Ausgabe No. 634, October 28, 1870 505
- Ausgabe No. 635, November 4, 1870 517
- Ausgabe No. 636, November 11, 1870 529
- Ausgabe No. 637, November 18, 1870 541
- Ausgabe No. 638, November 25, 1870 553
- Ausgabe No. 639, December 2, 1870 565
- Ausgabe No. 640, December 9, 1870 577
- Ausgabe No. 641, December 16, 1870 589
- Ausgabe No. 642, December 23, 1870 601
- Ausgabe No. 643, December 30, 1870 613
- Register Index 619
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Band
Band 14.1870
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16 THE PHOTOGRAPHIC NEWS. [JANUARY 14, 1870. certain it is that the texture and tone of the old prints would not be accepted by the general public ; and equally certain it is that an albuminized print will not be found to possess the rich bloom of its nativity after a fourth of five-and-twenty years have elapsed. At the Manchester Society, amongst other interesting topics, was a conversation on Durand’s sensitive paper. Mr. Sanderson remarked, that he had accidentally left some pieces in the printing-frame for six weeks, which, however, toned well, and gave prints which did not suggest that the paper had been kept more than two days: a capital testimony to the keeping qualities of the paper. At other societies interesting meetings were held, but not calling for especial notice. EXPERIENCES OF AN EXPERIMENTALIST. BY WILHELM GEUNE. Introductory Remarks. During the lengthened period I have been engaged in photographic labours and research, I have been successful in collecting together a large number of practical results which . will doubtless interest, and also be of some value to, your . numerous class of readers. My very multifarious labours were confined to the chemical and purely technical branches of photography, and it is from this field of investigation that I propose to make a series of communications, which will not, however, contain the details of distinct processes or formulae, but will partake more of the nature of a statement of facts or practical results, capable, I trust, of beneficial application by my brother photographers. I shall not follow any particular order, but shall enumerate the subjects one after another as they occur to me, turning from plate cleaning to etching upon glass, from the preparation of enamel paper to the recovery of silver from residues, from photographing in natural colours to the production of direct negatives without development, &c.; and in this manner I hope to invoke the interest of all in some way or another. Experiments in Connection with Photography in Natu ral Colours and with Collodion Plates, which are at once Developed in the Camera. The fact, established beyond doubt, that chloride of silver under certain conditions is capable of being impressed by colours—which are reproduced by it—of similar tint; and that even iodide of silver has been known, on some occa sions, in the wet collodion process, to evince a similar capa city, induced me to institute an investigation into this inte resting matter ; and my efforts, although unattended by suc cess, have afforded several practical and interesting lessons. The several methods already adopted and made known by investigators into this branch of the science I shall as sume my readers to be acquainted with, inasmuch as a de scription of them is to be found in this Journal. The best results are obtained by means of silver plates treated with chlorine, but experiments with these plates have been very limited, on account of the expense of the same, and the trouble involved in preparing them. For these reasons I myself was deterred from their employment, and therefore adopted the idea of using for the purpose the very fine metallic film afforded in the wet collodion process. This method, which answers the purpose well, places within the reach of all the power to observe and examine into the im pression made by colours upon chloride of silver. A well cleaned glass plate is coated with collodion and sensitized in the ordinary manner, then exposed to diffused light for a few seconds, and afterwards developed with iron. "When fixed and washed, there is present upon the plate a fine precipitate of metallic silver, and if to the developer a few drops of sulphuric acid have been added, the silver as sumes a very light tint, and rests upon the collodion film. The plate is dried, and then exposed to chlorine vapouruntil it has become of a violet tint, a point easily determined by observation through the transparent glass. For experiment upon paper, the white precipitated chlo ride is first converted by means of diffused light into tho violet chloride of silver, and then placed upon the paper ; but, owing to the substance of the latter, no very accurate in vestigation can be made with it. My manner of proceeding is to employ a silver plate— prepared as above described by means of the wet process — and to place this in a solution of chloride of iron or chloride of copper, or in a mixture of permanganate of potash and hydrochloric acid. The silver quickly changes into white chloride of silver, which, after washing in water and drying, may easily be coloured violet by diffused light. This is subsequently placed under coloured glass and exposed in the sunlight, when the colours will be found to be reproduced with much accuracy. In order to reproduce natural colours with wet collodion, with iodide or bromide of silver, therefore, I have made many experiments, which demonstrate that the problem is,by these means, capable of solution in a very simple manner, as, indeed, all who follow in my footsteps will be able to affirm. I employ, for the purpose, a camera used in the produc tion of collodion positives, and, in lieu of the negative, place therein a highly-coloured transparent picture upon a black ground—such as a bunch of flowers, &c.—so that all light which enters the lens passes through the coloured plate. With the different collodions and various pyrogallic acid developers in general use plates may, in this manner, be obtained, which, after fixing and drying, show colours, which, if weak, are still very distinct, and which are visible either by transmitted or reflected light. By using collodion containing but a fourth part of the usual iodizing solution, and over-exposing the same, the results are even more marked. Pure bromide collodion also furnishes some very interesting results. By developing with an acid iron solu tion, very definite colours may be obtained, the red and blue being especially striking. This research I was regretfully compelled to discontinue, and very many experiments may still be made before this field of investigation can be regarded as exhausted. Attention to slight details and minute particulars will, no doubt, be instrumental in bringing about a practical solution of the beautiful problem of photographing in j colours, for an im possibility it lemains no longer. /Through the medium of these experiments, I finally acquired an experience which, for other purposes in photo graphy, may possibly be put to some practical use. I became possessed of the idea that, in order to obtain a better result in regard to chromo-photography, it would be well if the colours could be developed at once in the camera by light, as in the case of chloride of silver. This I achieved by changing the general older of the manipulations through which a plate passes before an image is created. Iodide of silver, light, and a reducing agent, are necessary to the pro- ; duction of a photograph: two of these employed together i are without effect, but the presence of the third at once de- ■ velops a picture. In a general way, we employ first iodide of i silver, then light, and then the developer or reducing agent; . but I altered this order, taking first the iodide, then the • reducing agent, and subsequently used the light to bring s out the perfect result. 3 A plate is collodionized and sensitized in the usual man- 3 ner, treated with a pyrogallic acid and alcohol solution, and - then exposed in the camera; a perfectly developed picture is thus obtained, on opening the dark slide, requiring 1 to be fixed. 1 From this result much may be learnt, for enlargements . upon paper by the development process ; and for photo- i graphing out of doors this mode of operating would be use- a ful, inasmuch as the fixing of the negatives may be consider- - ably delayed. For cameras which serve at the same time as . laboratories, and in cases where it is of importance to watch 1 the gradual action of the light, this modification would also y be advantageous. I will, at some future time, come back to this question, in order to discuss it more fully
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