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
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• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
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• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

THE PHOTOGRAPHIC NEWS. Vol. XL No. 460.—June 28, 186". CONTENTS. Keeping and Dating Bromo-lodized Collodion 301 Critical Notices 302 Photography at the French Exhibition 304 Mr. England's Modification of the Collodio-Albumen Process ... 305 M. Adam-Salomon’s Portraits. By Nelson K. Cherrill 305 Report of the Commission Appointed to Award the Prize of 8,000 Francs Presented by the Duc de Luynes for the Bc'st Photo Mechanical Printing Process... 303 Paper Negatives. By Prof. Towler 309 PAGE On the Cause of the Central Spot, or Flare," in Photographic Lenses ; and on a New Form of Wide-angle Rectilinear Lens . entirely Free from this Defect. By Mr. Dallmeyer • 308 On a Substitute for Ground Glass in the Camera. By Victor G. Bloede -- 310 Correspondence—Origin of Photo-Lithography—Retaining the Specimens of Operators 310 Talk in the Studio 311 To Correspondents 312 KEEPING AND DATING BROMO-IODIZED COLLODION. WE have often expressed a conviction that a collodion con taining a fair share of a bromide as well as an iodide would not only keep a long time without deterioration, but was often improved by the ripening process due to age. The value of this ripening in one aspect was recently illustrated by the experience stated at the Photographic Society by Mr. Hughes, in relation to the importance of using ripe collodion for long exposures ; but the freedom from fogging, under the circumstances then detailed, is by no means the Bole or even the greatest advantage secured by age. In many cases several other very speci tic improvements in the quality of the collodion are effected, and, besides increased cleanness, a more homogeneous and even film, a more bril liant image, and also increased sensitiveness are attained. This claim of increased sensitiveness will be greeted with considerable incredulity by some photographers, lor loss of sensitiveness with increase of age has been one of the commonly received canons of collodion photography; and with good reason. Krom causes un necessary here to trace, the first ten years of collodion photography in this country was marked by an influence which materially retarded its legitimate progress. The use of bromides in negative collodion, now acknowledged as of Buch vital importance, was then under a ban. Certain makers of most undoubted excellence used iodides only, but kept secret the details of their formulae generally. Chemists and writers on collodion, taking the best collodion in the market as their standard, strove to imitate it, emulating its defects as well as its merits, instead, as teachers, of setting up a higher standard. It is true that very early indeed Dr. Diamond published a formula in which the bromide played an important part. Sir John Herschel, Mr. Crookes, Mr. Berry, and others, advocated the use of bromides, alone or in conjunction with iodides. But still iodized collodion bore sway : the most persistent, if not the wisest, autho rities constantly advocated iodides alone, and condemned the use of bromides; and the time was when we stood alone amongst journalists as the advocate of bromides as well as iodides in negative collodion. All this has been changed, and the use of bromo-iodized collodion is universal. But the old idea has not passed away without leaving some traces of its influence behind it. As a rule, a simply iodized collodion is in its most sensitive state within a day or two after it is iodized, and daily becomes less so until, in time, it is simply useless, a few months being the outside keeping time during which it is of any value for ordinary work. Hence the habit was established of send ing out the plain collodion and its iodizer in separate bottles, so that they might be mixed from time to time as required, no more being got ready for use than would be used in a few days, or weeks at most. Many photographers thus acquired a habit of believing in the danger of using old collodion. Now we repeat a conviction which we have expressed before, and which is based on careful experiment and long observation, that a properly made bromo-iodized collodion will keep good ready for use, and without loss of sensitiveness, for years ; that it is in all cases better for keep ing for some months ; and that an injurious decomposition in plain collo:lion often takes place which does not take place in the presence of bromo-iodides. We are not now about to discuss any theory of the subject, but are confining ourselves strictly to facts. We shall for the present content ourselves by narrating some interesting facts in the expe rience of others, merely remarking that they are quite corroborated by our own experiment and observation. In the brief narrative we subjoin we shall avoid the men tion of names, for obvious reasons. The details were recently related to us by a photographer of very great skill and high reputation himself, as some experience he had repeated and confirmed, related to him by another photographer whose work is admired, and whose skill is acknowledged, throughout the world. Some nine or ten years ago the latter- gentleman, having accepted a commission from a publishing house to produce some photographs of scenery some thou sands of miles from England, proceeded to his destination with a good stock of the collodion in the highest reputation at home. Unlike a good Madeira or sherry, the collodion did not improve with a sea voyage, and his first attempts to obtain presentable negatives were a lamentable failure. Day after day passed in futile attempts to obtain decent results, without success. Fresh baths were made up, fresh deve lopers prepared, fresh bottles of collodion mixed; and, alas! fresh failures incurred, Satisfied from exhaustive examination that the collodion was the real delinquent, he was for the time, unfortunately, not nearer to an end of his difficulties, as, knowing the evil, he had no idea where to find a remedy. He was working many miles from a town of any kind, and ten years or more ago collodion was not one of the articles commonly kept even in towns of importance. Fortunately, he ascertained that a chemist in a town at sixty miles’ distance kept some photographic materials. That evening he took train for the town in question, and obtained of the chemist two samples of collodion for which he was agent. Returning to his work, after having travelled one hundred and sixty miles, the first thing in the morning be tried a plate with one of the samples of collodion. The negative was perfect—the first perfect one of the scenery he had travelled thousands of miles to photograph. Each nega tive in succession, out of this bottle of collodion, was in all respects satisfactory, and, when it was finished, once more the journey was taken. The second sample was not tested, the first having proved everything that could be desired; and the whole stock of this kind which the chemist possessed