Suche löschen...
The photographic news
- Bandzählung
- 6.1862
- Erscheinungsdatum
- 1862
- Sprache
- Englisch
- Signatur
- F 135
- Vorlage
- Hochschule für Grafik und Buchkunst Leipzig
- Digitalisat
- Hochschule für Grafik und Buchkunst Leipzig
- Digitalisat
- SLUB Dresden
- Lizenz-/Rechtehinweis
- Public Domain Mark 1.0
- URN
- urn:nbn:de:bsz:14-db-id1780948042-186200003
- PURL
- http://digital.slub-dresden.de/id1780948042-18620000
- OAI
- oai:de:slub-dresden:db:id-1780948042-18620000
- Sammlungen
- Fotografie
- LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
- Bemerkung
- Seite 1-72 fehlen in der Vorlage. Vorlagebedingter Textverlust.
- Strukturtyp
- Band
- Parlamentsperiode
- -
- Wahlperiode
- -
- Bandzählung
- No. 193, May 16, 1862
- Digitalisat
- SLUB Dresden
- Strukturtyp
- Ausgabe
- Parlamentsperiode
- -
- Wahlperiode
- -
-
Zeitschrift
The photographic news
-
Band
Band 6.1862
-
- Ausgabe Ausgabe 73
- Ausgabe Ausgabe 85
- Ausgabe Ausgabe 97
- Ausgabe Ausgabe 109
- Ausgabe Ausgabe 121
- Ausgabe Ausgabe 133
- Ausgabe Ausgabe 145
- Ausgabe Ausgabe 157
- Ausgabe Ausgabe 169
- Ausgabe Ausgabe 181
- Ausgabe Ausgabe 193
- Ausgabe Ausgabe 205
- Ausgabe Ausgabe 217
- Ausgabe Ausgabe 229
- Ausgabe Ausgabe 241
- Ausgabe Ausgabe 253
- Ausgabe Ausgabe 265
- Ausgabe Ausgabe 277
- Ausgabe Ausgabe 289
- Ausgabe Ausgabe 301
- Ausgabe Ausgabe 313
- Ausgabe Ausgabe 325
- Ausgabe Ausgabe 337
- Ausgabe Ausgabe 349
- Ausgabe Ausgabe 361
- Ausgabe Ausgabe 373
- Ausgabe Ausgabe 385
- Ausgabe Ausgabe 397
- Ausgabe Ausgabe 409
- Ausgabe Ausgabe 421
- Ausgabe Ausgabe 433
- Ausgabe Ausgabe 445
- Ausgabe Ausgabe 457
- Ausgabe Ausgabe 469
- Ausgabe Ausgabe 481
- Ausgabe Ausgabe 493
- Ausgabe Ausgabe 505
- Ausgabe Ausgabe 517
- Ausgabe Ausgabe 529
- Ausgabe Ausgabe 541
- Ausgabe Ausgabe 553
- Ausgabe Ausgabe 565
- Ausgabe Ausgabe 577
- Ausgabe Ausgabe 589
- Ausgabe Ausgabe 601
- Ausgabe Ausgabe 613
- Register Index 619
-
Band
Band 6.1862
-
- Titel
- The photographic news
- Autor
- Links
- Downloads
- Einzelseite als Bild herunterladen (JPG)
-
Volltext Seite (XML)
1861 tingve itine b I albuv” My av5 lit vis! lai. tken IS focus, S’ ttedW lectio*.* rs of 0 ‘i vesr he ! t tbal n0 as™ tes of* retat?” ssociZ ir de start* s and* f the? h me ofe issodi' left to' ctiop" • eting • g tbe iove hepe5) lot We t)a May 16,1862.] THE PHOTOGRAPHIC NEWS. 239 in a bath of chloride of platinum, one per thousandth of water ; the proof to remain in this bath only a few seconds, anil as soon as it becomes darkened and of sufficient vigour, it must be immediately removed and washed in abundance of water. By this method, the greater portion of the picture is retained on the surface of the paper. The vigour of the proof may be augmented by drying it very rapidly, and Tarnishing it with wax. On the preparation of positive paper, M. Davanne makes the following remarks : — “ Among those who prepare albumenized paper, some are accustomed to add acetic acid to the albumen, or soluble acetates, or perhaps in certain fermentations of albumen, acetic acid is spontaneously evolved; in any case the pre sence of acetic acid in the paper must have a prejudicial in fluence from giving rise in the silver bath to the formation of needle-like crystals of acetate of silver, which remain cither on the surface of the proofs, or on the surface of the negatives, and thus cause the loss of one or both. “ This result has frequently occurred to me under circum stances which I think it will be useful to describe in order to guard photographers from similar annoyance. For seve- ral days I made use of a payer charged with a soluble ace tate; the acetate of silver formed remained either on the Paper or dissolved in the bath, when the latter becoming Weak, it was filtered into a dish, and before sensitizing any paper on it, it was sufficiently strengthened by a concen trated solution. Some sheets of paper were sensitized on this bath in the feeble light of the laboratory, and all the negatives and the positives taken from them during the day Were covered with fine, needle-like crystals, which became blackened in the light, and would have caused me to lose ’ll my negatives if 1 had not prevented it by quickly wash ing them. Analysis showed that I had to deal with acetate of silver; the acetic compounds could be derived only from the preparation of the paper. But the question arose, how epuld they be formed so suddenly in such abundance, while the temperature had not varied perceptibly, when the bath gave none the day previous, and only on the next day when I had added to the bath a fresh quantity of solution ? The reason is, simply that, contrary to what happens with most of the other salts of silver, the solubility of acetate of silver is much less when the nitrate of silver is more concentrated, And that at the moment when in a positive bath almost Curated with acetate of silver, but not yet crystallized, a Concentrated solution of nitrate is added, there is an imme- diate general formation of acetate crystals, which are after- Vards deposited upon the proofs. By observing this fact "e find a ready means of remedying this accident:—We ’’M, when we desire to restore the bath to its original Srength and volume, first add the necessary quantity of dry litrate of silver. After it is dissolved in the bath, it is left in the cold night air ; next day we begin by filtering the bath, to separate the crystals which have formed, and not till then the necessary quantity of water. In this manner we first make a very concentrated bath, which allows of the greater portion of the acetate of silver to be deposited, and ' y hen it is subsequently diluted there is nothing to fear from crystallization. With regard to the keeping of sensitized positive paper, II. Kriine remarks:—Our practical experiments on this sub ject fully prove that sensitized papers are not perfectly pre served in boxes by drying alone, but that it is indispensably necessary to continually maintain a small quantity of gaseous chlorine, which converts the molecules of silver recently reduced into chloride of silver. This is why we have never been able to preserve our strongly albumenized paper when sensitized in boxes with chloride of calcium only, while in boxes supplied with chloride of lime we have obtained very sa is actory results. A mixture of these two substances—• Chloride of calcium 3 parts Chlonde of lime 1 part will enable us to preserve both sensitized paper and unfixed positives during a much longer time than is usually required, for, of these two substances, the latter constantly exhales the paper of all its sizing, and also diminishes the sensitive- chlorine gas ; the first keeps it constantly dry. It must not be omitted to state that too much gaseous chlorine deprives ness of the chloride of silver, that is, brings it to the state of pure chloride of silver, without excess of nitrate. The paper thus preserved tones much more readily, and assumes much richer hues in the chloride of gold. The traces of nitric acid, which are disengaged during the preservation of the paper, seem to us, without any remarkable inconvenience to the paper, provided these are well washed before toning, for the proofs preserved in this manner remained pure and white, without the slightest yellow tint. We cannot say the same for those preserved with chloride of lime alone; for these proofs always assume, after a time, a yellow line in the white portions, especially when the chloride of lime has, in conse quence of long service, become moist or aqueous. The more the paper is impregnated with salted albumen, or the more the albumen holding salt converted, by sensitizing into chloride of silver, the more difficult the preservation of the paper becomes, and the more chloride of lime must be added to the calcium in the boxes: the thinner and more superficial the albumen is, the whiter the paper remains, even without artificial preservation, when merely kept in a press. A paper, with the albumen coagulated before sensi tizing, always keeps better than one not coagulated; for the albumen, like all organic substances, decomposes the salts of silver into metallic silver more slowly when the albumen is coagulated than when it is in a soluble state. HOT DEVELOPMENT FOR DRY PLATES. Dear Sir,—The present rage for hot developement is calculated to do more harm than good to the novice in photography. I have for some time past used heat in developing collodio-albumen plates, but only when the exposure has been short, and the plates newly prepared. Extreme care must be employed in the manipulation, otherwise, foggy pictures will unquestionably be the result. My plan is to apply first a plain strong pyro solution, and if the image does not soon appear, to flood the plate with hot water, and go on again with the pyro, until all the details are well out, when citric acid and silver must be added to the developer, and the hot water discontinued. The mistake often made, is a too liberal use of the hot element, irrespective of the exposure, and the continuance of it, after the silver has been added to the developing solu tion. I enclose a stereograph from a negative taken last Monday at six o clock in the evening. There was a good light, and my intention was to give about 3 minutes exposure, but in order to illustrate my method to a friend, I exposed only 45 seconds, and produced a fair negative. Now, if I had con tinued the exposure to 3 minutes as originally intended, and proceeded to employ hot water in the development, I should have ruined my negative at once. When the exposure has been moderate (say about two- thirds the time a dry plate usually requires), then mix the pyro with warm water, and proceed very cautiously to work. Hot water is very excellent to fall back upon in case the picture develops tardily, but great discretion must be used in its employment Perhaps these hints may be useful to some of your readers. —I am, yours very truly, John H. Underwood. Jieech Cottatje, Sale Green, Cheshire, May Vith, 1862. [The stereograph enclosed is a very fine one, and evidently from a good negative. The tone of the print is very charming. We should be glad to know something of the paper, printing and toning employed. Ed]
- Aktuelle Seite (TXT)
- METS Datei (XML)
- IIIF Manifest (JSON)