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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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- Public Domain Mark 1.0
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- urn:nbn:de:bsz:14-db-id1780948042-187000001
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- http://digital.slub-dresden.de/id1780948042-18700000
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- oai:de:slub-dresden:db:id-1780948042-18700000
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- LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
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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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ing block from a negative by means of a bichromated gela tine film and the electrotype process. The details which reached us when the process was announced were only suited to the reproduction of subjects in line or stipple; but here subjects from nature are attempted, gradation being obtained by a grain resembling the texture of a woven fabric, a veil of such a character being evidently interposed between the photographic negative and the gelatine film during exposure. Very delicate or perfect results cannot, it is to be feared, be obtained by such methods. In this country we have not seen any recent progress in photo-block printing, if we except the steady improvements made in his method by Mr. Dallas. It is a somewhat singular fact that with several photo block processes in existence, apparently capable of yielding good work, and especially suited to reproductive processes, so little has been done in utilizing any of them in commercial enter prise. This fate, indeed, seems to attend photo-mechanical printing processes generally in this country. The Photo- galvanographic Company, and Mr. Pretsch’s methods, utterly failed as commercial projects. Mr. Woodbury’s photo-relief process, having had three starts commercially, has again come to grief, and the Company is now in liqui dation. That this is due rather to the unsuitable hands into which it has fallen than to any inherent defect in the process, is made manifest by the fact thatin Paris, where it has been taken in hand by a first-class engraving and publishing firm, Messrs. Goupil and Co., it is working successfully and satisfactorily. In photo-lithography, Mr. Osborne failed to stimulate commercial enterprise to take up his process in this country, which, taken to America, was readily appreciated, and he is now directing a large and successful establishment belonging to a company which was at once formed to work the process. These facts are not encouraging to experimentalists in this country engaged in working out such processes ; but we believe their time will come. CHEMICAL "HALATION” IN ECLIPSE PHOTOGRAPHS. In noticing the admirable photographs of the recent solar eclipse obtained under the superintendence of Professor Henry Morton, wo mentioned the existence of the line of increased reduction on the sun’s disc in immediate contact with the dark image of the moon, as probably due to photo graphic causes. From the appearance of the prints, the in creased deposit seemed to us to have been due to the reduc tion on the sun’s image of the nitrate of silver belonging to that part of the plate where the dark edge of the moon had not impressed the plate sufficiently to determine reduction upon it. In a correspondence with Professor Morton on this subject, he pointed out that there were circumstances which threw doubt on this explanation, especially mentioning the fact that the phenomenon was recorded by the thermometer tls well as by photography. In a letter just received from Professor Morton, recording some experiments undertaken to decide the question, he remarks, “ Your explanation of the bright line in the pho tograph is, I think, the true one and he forwards a proof of an “ artificial eclipse picture ” produced in the course of his experiments which aptly verifies the explanation in question. We subjoin the communication on the subject, which Professor Morton intends to publish in the Journal of the Franklin Institute for the present month :— “ Cause of Bright Line on Partial-Phase Eclipse Pictures. By Professor H. Morton.—During the progress of the eclipse of August 7th. I observed on the negatives taken during the partial phase by the section of my party with which I had located myself, a decided increase in the opacity of the silver deposit in immediate contact with the advancing edge of the moon. When, after our return to Philadelphia, all the negatives taken by the other two sections were handed over to mo, I found the same characteristic appearance varying only slightly in degree, to distinguish all of them, and this had, of course, been noticed by those engaged in making the pictures. In fact, many remarks have been made upon this point, and some deductions drawn from it. “ On the paper prints prepared from these negatives this local density produced a line of light in contact with the moon’s limb. “ An appearance similar to this had been observed by Professor Alexander, in the photographs taken during the eclipse of 1860, as also by Mr. De la Rue, and while ascribed by Professor Challis and Professor Alexander to a very rare lunar atmosphere, had been explained by Mr. De la Rue and the Astronomer-Royal, as a subjective effect The Astronomer-Royal had, moreover, shown, in papers published in the Monthly Notices of the Royal Society, 1863, November 13th, and 1864, June 10th, that no such effect would be produced by a lunar atmosphere, were it present. He, therefore, very justly discards such a supposition, and, by satisfactory experiments, shows that the light line in the prints under his examination is an optical illusion, and not an existing fact. “ These experiments, however, when applied to good prints of our pictures, did not show the same results, and, beside, the actual opacity of the negatives seemed to preclude the above explanation as one accounting for the entire effect. “ I therefore made the following experiment: I converted one of the solar pictures, taken soon after first contact, into a crescent, by pasting partly over it a dark circular piece cut from another print. This showed a faint line of light such as results from contrast, and which was, no doubt, found in the pictures examined by the Astronomer-Royal. “ I then had this artificial eclipse-picture photographed (through the kindness of Mr. James Cremer), when nega tives were produced showing a dense deposit along the lunar edge, and giving prints which showed a bright line in the same place far more decided than that seen in the artificial original. “ It thus appears that the effect observed in these eclipse pictures, while not due to any lunar inflection of sunlight, is also not due to an optical effect of contrast solely, but is in great part due to a chemical action which may be explained by what we know of the chemical reactions concerned in the production of a negative. “ It is well known that the development of a negative depends upon the presence of free nitrate of silver in the film, and that a great strengthening or intensifying may be pro duced by re-immersion in the silver bath, and a second application of the developer. Now, in the present case, part of the plate representing the dark edge of the moon, and, therefore, not acted upon, furnishes a reservoir of nitrate of silver, imbibed by the collodion film, which, during the development, penetrates for a short distance into the portion representing the luminous area of the sun, whose supply of free nitrate was exhausted by the reaction which occurred at the first moment when the developer was applied. “ My conclusion, then, is, that while a certain effect in the paper prints is, and was on former occasions, due to ‘ con trast,’ yet in the present instance the peculiar appearance of the negatives, and most of that seen on the prints, is the result of a chemical action such as I have described, and does not represent any celestial phenomenon. The appear ance of a bright line in the same place, which has been noted by several observers, is, we believe, due simply to the contrast of the sharply defined lunar edge, which produces the faint line above-mentioned, in the artificial eclipse picture before described.” ONE PRINT FROM TWO NEGATIVES. A novel form of double printing has just been patented in America by Mr. Egbert Guy Foux, of Baltimore. It con sists not in producing one picture from a series of negatives of different parts of the subject, but of producing one soft picture by the superposition of one negative over another,
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