The photographic news

• Bandzählung: 11.1867
• Erscheinungsdatum: 1867
• Sprache: Englisch
• Signatur: F 135
• Vorlage: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: SLUB Dresden
• Rechtehinweis: Public Domain Mark 1.0
• URN: urn:nbn:de:bsz:14-db-id1780948042-186700008
• PURL: http://digital.slub-dresden.de/id1780948042-18670000
• OAI: oai:de:slub-dresden:db:id-1780948042-18670000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

THE PHOTOGRAPHIC NEWS. VoL. XI. No. Vl^.—October 11,1867. CONTENTS. PAGE On Keeping Bromo-Iodized Collodion 485 Cabinet Portraits 486 Critical Notices 487 A Few Further Hints to Photographers on the Production of Christmas Cards, etc., etc. By a Practical Man 487 Photography in California 488 Hints for the Operating Room 488 On a New Action of Light. By M. Niepce de St. Victor 489 Photography in the County Court 489 PAGE The Trials of the Wife of an Amateur Photographer 490 Correspondence— Foreign Science — Retouching with Lead- Pencil—Retouching Negatives—Commercial Dry Plates ... 491 Proceedings of Societies—Photographic Society of Marseilles— North London Photographic Society 493 Reports on Photography at the Paris Exhibition 495 Talk in the Studio 496 To Correspondents 496 ON KEEPING BROMO-IODIZED COLLODION. About three months ago we referred to the advantages to be gained from keeping a stock of collodion, bromo-iodized, some months at least prior to using it. Since then wo have had many communications from readers anxious to put the suggestion to the test, and from the observations made it has occurred to us that a few more hints as to the conditions were desirable. An esteemed correspondent, Mr. J. M. Turnbull, has just favoured us with the results of some experience in this direction, and as his letter suggests some important considerations, we print it before proceeding to further remark. He says :— “ Sia,—An article in the News of June 28, on Keeping and Dating Collodion, attracted my attention ; since then I have made various experiments on old collodion, the results of which I lay before the readers of the News. The article iu question contains several statements which will be new, and even startling, to many old photographers, it being a very general belief that collodion iodized even a few months is not nearly so sensitive as a collodion newly iodized. The statement that collodion is preferred iodized from two to three years, even though strictly true, is, in many cases, very apt to mislead; a great deal depends on the way it is kept. If collodion is kept iodized in dark rooms and studios under varying temperatures, as it generally is (and sometimes exposed to light), it will decompose as much in one year as it will do in three if kept in a cool, dry atmo sphere, and not exposed to light. “ In making these experiments I procured from a brother photo a sample of an English maker’s collodion, which had Men (as he said) ‘ allowed to get too oldit had been iodized about three years, and was kept in his dark room iu studio. On trial, it gave, with the usual exposure, a very fair negative, but somewhat deficient in detail in the shadows ; on varnishing the negative, the varnish partially dissolved off the film and image, making streaks iu the direction the varnish was poured oft', and leaving the negative nearly use less for printing. “ On trial with another well known English maker’s collo dion, iodized between two and three years, nearly the same results were arrived at, only in this case rather worse, a part of the film leaving the plate while lifting it up and down in the bath. After exposure and developing, and while wash ing in the usual way, nearly all the rest of the film left the plate. Subsequent trials gave nearly the same results on var nishing. In another trial, the greater part of the image was dissolved out, leaving only the ghost of a negative. With these results before me, it is my opinion that keeping collo dion iodized for long periods (more especially if exposed to varying temperatures and light) induces some change in the collodion which rots the film and renders it soluble in the alcohol of the varnish. With regard to sensitiveness between o’d iodized collodion and new, I find that the oldest iodized sample I have of my own make (iodized nearly twelve months) works cleaner and gives a rounder and denser nega tive, but without any appreciable differenc in quickness, than the same nearly newly iodized. “ I am in the habit of making my own collodion; I find it is the best way, and would recommend others to do the same. Some years ago I was much troubled with bad samples of commercial collodion, some of which, notwith standing their great recommendations, were fit for nothing but cleaning plates ; since then I have made my own, and have never had to waste a single ounce. It is better (unless the pyroxyline is wanted in large quantities, and the opera tor has had some experience in making it) to buy the pyroxy line from some respectable photographic dealer, who would supply a constant quality. I have tried a great many differ ent formula; with different iodides, but the formula I use and recommend is as follows :— Sulph. ether (sp. gr. 725 to 730) ... 2 ounces Alcohol (sp. gr. 810 to 815) 3 „ Soluble cotton 25 grains. The ether made from methylated spirit is both cheap and good. The alcohol used may be cither pure or methylated, but if of a higher specific gravity than 820 and upwards, the collodion will be too watery, and give a reticulated film. In some formulae equal parts of ether and alcohol are given, but it gives a very contractile film, and one which is more likely to split off on drying. To each ounce of plain collo dion the following is added :— Iodide of ammonium ... 2} grains Iodide of cadmium 2 „ Bromide of cadmium ... ... ... 1 grain. When a good sample of cotton is made or procured, enough collodion should be made to last for a year or two. If the collodion is not wanted iodized at once, part of the alcohol should be kept out, the iodides dissolved in it, and used as required. More bromide may be used, but will not give so dense an image ; but for some subjects—as light drapery in portraiture and dark foliage in landscape—the bromide may be very advantageously increased, and the iodides propor tionately diminished. “ With a collodion made after the above formula, and with proper lighting and exposure, no difficulty will be expe rienced in getting negatives which need no organic element in the developer to give them intensity, all which will tend to keep the photographer’s mind easier and his pocket heavier. “ J. M. TvRNBULL." It will be seen that, in the main, the experience of our correspondent corroborates that we stated in June, especially in relation to the sensitiveness and general working qualities; but he calls attention to another element on the question,