The photographic news

• Bandzählung: 24.1880
• Erscheinungsdatum: 1880
• 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-id1780948042-188000001
• PURL: http://digital.slub-dresden.de/id1780948042-18800000
• OAI: oai:de:slub-dresden:db:id-1780948042-18800000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Bemerkung: Exemplar unvollständig: Seite 1-82 in der Vorlage nicht vorhanden
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

OcTOBER 22, 1880.] THE PHOTOGRAPHIC NEWS. 513 To prevent confusion, it will, perhaps, bo as well to give the original formula, which stands thus Solution No. 1. Pyrogallic acid 1 ounce Glycerine 1 ounce Spirits of wine (methylated) 6 ounces Solution No. 2. Liquor ammonia -880 1 ounce Bromide ammonia or potassium ... 60 grains Glycerine 1 ounce Water 6 ounces Solution D (developer). Solution No. 1 1 ounce Water 15 ounces Solution A (accelerator). Solution No. 2 Water 1 ounce 15 ounces To use for a properly exposed plate, take equal parts of each solution D and A. In solutions Nos. 1 and 2, white sugar or honey may be substituted for the glycerine. The proportions given above for a properly exposed plate leave nothing to be desired, unless the plate be apt to give thin flat images, in which case solution D will be best compounded of— No. 1 2 ounces Water 14 „ A still being the same. On the contrary, when the density is likely to be too much, as little as half-an-ounce of No. 1 to 15J of water may be used. By thus modifying the pyro gallic solution, any desired degree of density may be obtained, and, as to the exposure, the solution is regulated in the same manner by using less or more as the exposure has been long or short. To develop a plate, the exposure of which it is antici pated has been far too much or is very uncertain, it is best laid in a dish and covered with the requisite quantity of pyrogallic solution mixed for a weak plate with (say) two ounces of solution ; now add one dram of solution A, and allow to act for a minute or two, repeating the dose until the image begins to appear. When the image begins to appear, the dish may be covered up and left for five or ten minutes, when, on examination, a good negative will be the result. A more elaborate method, and, perhaps, more reli able, is to make up solution No. 2 in two solutions, keeping theammonia and bromide separate, diluting the concentrated solutions as usual with water, and then going cautiously to work, adding the full quantity of bromide to the pyro gallic, but only adding sufficient of the dilute ammonia to start the action ; then leaving the result to time. Under exposed plates can be managed by a reversal of the above method, using solution D weak, as directed for dense plates, and using double the amount of ammonia solution to bromide, but always in a dilute state. Do not be in a hurry ; give the plate time ; and, if you arc impatient, cover up the dish and go away for a time: on your return you will see a far better result than if you had tried to hurry the process. To develop a picture containing violent contrasts, mix equal parts of D and A, and add five times the bulk of water ; place the plate in, and give about half-an-hour to an hour to be finished in. After the image has been properly developed, the next stage is to well wash it, back and front, and then immerse in a tolerably strong solution of alum. The functions of this solution are twofold : first, as a guard against frilling in the subsequent washing, and also to clear out of the film the remaining pyrogallic from the developer, and avoid red stained shadows. The time of immersion is immaterial, so long as no less than three minutes are allowed. After again washing, the plate is removed to the hyposulphite for fixing; the strength of the hyposulphite is rather im portant, as, if too strong, the film will frill; and if too weak, the time of immersion is too long ; about half satu ration is the best strength. If any tendency to frill bo suspected, the plate ought to be immersed in a solution of chrome alum upon leaving the hyposulphite bath; after this, wash thoroughly under the tap, and then place in a grooved tin box containing clean water, which ought to be constantly changed for three or four hours. Now if, after rinsing, a weak solution of cyanide be flowed over the film, and well washed off, the image can be easily and readily intensified by means of pyrogallic and silver. Some photographers complain of the difficulty of getting sufficient density in their negatives; but, if care be used, and attention paid to the strength of the developer used after developing the first of a batch, little or no trouble ought to be experienced in getting just the proper amount of density. If, however, as may sometimes happen, the negative is not dense enough, if only a little be required, pyrogallic and silver will give it; but if the lack of density be considerable, then Edwards’ formula for mercury inten sifier is the very best that can be used. Do not on any account (except for copies of drawings, &c.), use the plan of bleaching with mercury, and then blackening with ammonia, as there is so little latitude that the best result is difficult to attain with the mixed mercury, potassium, and hyposulphite solution. The colour of the negative after immersion is so near the old collodion colour that it is easily managed, and, if not used too strong, is perfectly under control. With careful manipulation a gelatine negative need never be stained; but as it sometimes happens that they do get stained, especially in intensifying, it will be as well to men tion that one of the first remedies that ought to be tried, and which, in most cases, will be found efficacious, is im mersion in fresh hyposulphite. A weak solution of hydro chloric acid in alum water will also remove stains. Weak solution of cyanide in almn water will remove silver stains contracted from sensitive paper. The most obstinate stains can be removed by using a mixture of common salt and sulphuric acid, as directed by a formula published in the News a short time back. When this paper was projected, I intended to give some account of the characteristics of different makers’ plates, and with that intention procured from various sources half plates by Wratten and Wainwright, Rouch, Mawdsley, Swan, Fry, the Britannia, Archer, and Bennett. Each plate was exposed in the studio as rapidly as possible, two cartes on each; but the result was that all plates in the market will give good negatives, providing care be taken to use them intelligently; and if a fresh batch does not give the same results with the same developer as a previous one, alter the developer to suit. In conclusion, I might mention that it is not necessary to use a fresh lot of developer for each plate, but that four ounces will develop at least six plates, when done one after the other ; also, that over-dense negatives can be reduced by a weak solution of perchloride of iron, followed, after thorough washing, with hyposulphite; or else the negative may be bleached by immersion in a solution of bichloride of mercury. The “ Topic ” for next week will be, «My Infant Studies,” by T. G. Whaite. ON INSTANTANEOUS SHUTTERS.—A NEW ONE. BY VINCENT BEECHBY.* It was with very great pleasure that I found myself once more surrounded by the members of the old Society and many of the well-known faces, and all the old harmony and activity present at the meeting. The principal subject of the evening seemed to be instantaneous photography, and two very ingenious shutters were exhibited by Mr. M. Noton and Mr. A. Coventry. Having • A communication to the Manchester Photographic Society.