Suche löschen...
The photographic news
- Bandzählung
- 27.1883
- Erscheinungsdatum
- 1883
- 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-id1780948042-188300004
- PURL
- http://digital.slub-dresden.de/id1780948042-18830000
- OAI-Identifier
- oai:de:slub-dresden:db:id-1780948042-18830000
- Sammlungen
- Fotografie
- LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
- Strukturtyp
- Band
- Parlamentsperiode
- -
- Wahlperiode
- -
- Bandzählung
- No. 1285, April 20, 1883
- Digitalisat
- SLUB Dresden
- Strukturtyp
- Ausgabe
- Parlamentsperiode
- -
- Wahlperiode
- -
-
Zeitschrift
The photographic news
-
Band
Band
-
- Titelblatt Titelblatt I
- Register Index III
- Ausgabe Ausgabe 1
- Ausgabe Ausgabe 17
- Ausgabe Ausgabe 33
- Ausgabe Ausgabe 49
- Ausgabe Ausgabe 65
- Ausgabe Ausgabe 81
- Ausgabe Ausgabe 97
- Ausgabe Ausgabe 113
- Ausgabe Ausgabe 129
- Ausgabe Ausgabe 145
- Ausgabe Ausgabe 161
- Ausgabe Ausgabe 177
- Ausgabe Ausgabe 193
- Ausgabe Ausgabe 209
- Ausgabe Ausgabe 225
- Ausgabe Ausgabe 241
- Ausgabe Ausgabe 257
- Ausgabe Ausgabe 273
- Ausgabe Ausgabe 289
- Ausgabe Ausgabe 305
- Ausgabe Ausgabe 321
- Ausgabe Ausgabe 337
- Ausgabe Ausgabe 353
- Ausgabe Ausgabe 369
- Ausgabe Ausgabe 385
- Ausgabe Ausgabe 401
- Ausgabe Ausgabe 417
- Ausgabe Ausgabe 433
- Ausgabe Ausgabe 449
- Ausgabe Ausgabe 465
- Ausgabe Ausgabe 481
- Ausgabe Ausgabe 497
- Ausgabe Ausgabe 513
- Ausgabe Ausgabe 529
- Ausgabe Ausgabe 545
- Ausgabe Ausgabe 561
- Ausgabe Ausgabe 577
- Ausgabe Ausgabe 593
- Ausgabe Ausgabe 609
- Ausgabe Ausgabe 625
- Ausgabe Ausgabe 641
- Ausgabe Ausgabe 657
- Ausgabe Ausgabe 673
- Ausgabe Ausgabe 689
- Ausgabe Ausgabe 705
- Ausgabe Ausgabe 721
- Ausgabe Ausgabe 737
- Ausgabe Ausgabe 753
- Ausgabe Ausgabe 769
- Ausgabe Ausgabe 785
- Ausgabe Ausgabe 801
- Ausgabe Ausgabe 817
-
Band
Band
-
- Titel
- The photographic news
- Autor
- Links
- Downloads
- Einzelseite als Bild herunterladen (JPG)
-
Volltext Seite (XML)
242 THE PHOTOGRAPHIC NEWS. APRIL 20, 1883. beautiful emulsions with this gelatine, have managed to get them washed or dialysed, and the plates coated and dried, exposed, and an image developed of such quality as would gladden the heart of the wet collodion man, when oh, horrors ! eruptions seem to be taking place, the film lifts in places, floats up all along one edge, half the film wraps over on to the other half, and, at a slight inclination of the developing dish, the films floats off, and with a flop goes down the sink 1 N ow, what is the cause of this ? We are told that gela tine is a complex substance liable to organic changes. Just so, and changes are most likely to occur in the presence of heat ; but what the precise change is that takes place in an emulsion which behaves as we have just described, it is very difficult to say, but it is called frilling. It is really, more correctly speaking, disintegration. There are yet other appearances which are more akin to real frilling; they are the blistering of some films which rise up in countless bubbles, of various sizes, sometimes all over a plate, some times around the pouring-off corner. These we attribute to incipient disintegration or destruction, or to the presence in the bulk of the otherwise perfect emulsion of a certain per-centage of spoiled gelatine, which, without actually producing the worst results, is sufficiently injurious to point to the desirability of eliminating all such traces of danger. A mild form of the defect is where a slight puckering will show itself without actually loosening the film or ex tending to the edges of the plate. This and the blistering just named may be got over with considerable certainty by careful washing and then soaking the plate in alcohol. But we are anticipating. The committee of the Club might judiciously have amended the title of the discussion, aud made it “ On the Causes of Frilling in Gelatine Blates: their Prevention and Cure,” for, as might have been fore seen, the discussion resolved itself into the means for pre vention and cure. The Club fortunately numbers among its members several gentlemen who have made a great study of gelatine, and the information elicited was very useful ; in fact, could be obtained from no other source. Several well-known workers described their methods of working, the speakers being of two distinct kinds—those who pre pare and develop their own plates, and those who only develop commercial plates. The latter section have, of course, the opportunity of avoiding some of those diffi culties which beset the enthusiastic and determined amateur who feels that he cannot claim the entire work unless he prepares his own plates. Among commercial plate manufacturers there are many whose plates will not frill nor be subject to any surface disturbance under any ordinary treatment such as gelatine plates usually undergo. The means adopted by these makers to prevent “ frilling, &c.,” may be scientific or secret; that is scarcely the object of these remarks, but we desire to communicate, for the general benefit, such information as may be useful. In the use of commercial plates, if there is the slightest tendency to frilling in any form, the means generally adopted are the use of chrome alum in the developer; or a preliminary soaking in chrome or common alum ; im mersion in saturated solution of common alum after deve loping ; in fact, alum at every possible or convenient stage. We need scarcely say that the action of alum and of chrome alum is to render gel tine insoluble in ordinary water. There are other substances which have a similar action, but none are so innoxious as the alum salts. In the deve lopment of commercial plates of repute and known pro perties, probably in ninety-nine instances in a hundred, the observance of simple preventive measures will avoid any trouble or danger to the films; but this does not apply in the case of amateurs or experimentalists, to whom we must look for every real advancement in processes. We have already instanced the case of emulsions made with No. 1 photographic gelatine, concerning which at the meeting named, it was pretty generally admitted that plates made with No, 1 photographic, usually developed with readiness a soft yet vigorous image ; and although in the discussion a well-known gelatine man argued that this did not, of necessity, imply but that hard gelatines might be made to act similarly, yet there is no doubt that, as was said by more than one of the speakers, if we could only make our emulsions with a gelatine similar to No. 1 photographic, we should thereby embrace some very valu able properties, and it would be desirable to experiment in that direction. Whereas, the mere portrait or land scape man, who has to develop bought plates, has few difficulties to overcome, which he may circumvent by the use of alum and alum salts, or by hardening the water by Epsom salts (a penny packet in a pailful of water), and the avoidance of rain or soft water, the experimenter has troubles of quite a different nature. In all the processes in which the gelatine is subjected to heat, decomposition, disintegration, or frilling are liable to arise; we say liable, not of necessity, but at times and seasons. Whether we emulsify or boil with only a tithe or the whole of the gelatine, it will depend upon the character of that gelatine whether we need adopt any preventive measures. If we attempt to boil the whole of an emul sion made up with No. 1, we get an emulsion as rotten as rags, and probably no precautions will save us from that result. If we make an emulsion on the precipitation plan, we may employ No. 1 with confidence, for then it needs only one liquefaction. Also, Plener’s system would enable us to use the softest of gelatine. But if we employ a soft gelatine, or any gelatine where a risk is run of encountering the defects we have pointed out, it will be very prudent to use preventive means. Two celebrated makers stated it as their practice to use chrome alum in the emulsion itself, added in liquid form to the emulsion when liquefying before coating. One gentleman said he had found one-eighth of a grain of chrome alum per ounce of emulsion was a sure preventive of frilling under ordin ary circumstances, and another speaker said that his prac tise was to use one-sixteenth of a grain per ounce. These apparently homoeopathic doses of chrome alum may seem almost useless, but it must be borne in mind that the action of chrome alum on liquid gelatine is very great, and that there is also a continuance of the action ; that is, plates prepared with a chrome alumed gelatine will con tinue to harden by age, whereas a gelatine minus the chrome alum will be almost unchangable. This points to the limit in the employment of the chrome alum being very low. It is a notorious fact that certain plates of commercial make develop much more rapidly than others, and yet the respective films, and the sensitiveness of the various makes, do not favour the idea that the softest gelatine makes the quickest plate, and the most easily developed ; on the contrary, a plate may be made with a soft gelatine, which is so loaded with chrome alum as to be exceedingly slow to develop, and the chrome alum may be in such great excess beyond what is requisite, as to appear to slow the plate. The fact is, the film is im pervious by the developer. Notwithstanding, it may prove of very great service to our readers to kuow that they may employ almost any gelatine if, knowing its characteristics, they use the pre cautions of one-eighth of a grain of chrome alum per ounce of emulsion ; it is possible certain cases may permit of even more, without deterioration of the plates. Now that we have such very perfect methods of emul sion making—that is to say, boiling with as little as two grains per ounce; the precipitation methods; and the ammonio-nitrate process, not to name Plener’s mechanico chemical method—we may reasonably hope to see No. 1 or any soft gelatine used with entire immunity from frilling. MUYBRIDGE’S NEW INVESTIGATION. As we mentioned recently, Mr. Muybridge is about to undertake a further investigation into the subject of animal mechanics and locomotion, and the results he
- Aktuelle Seite (TXT)
- METS Datei (XML)
- IIIF Manifest (JSON)