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THE PHOTOGRAPHIC NEWS VoL. XXVII. No. 1315.—November 16, 1883. CONTENTS. PAGE Gelatino-Bromide Paper for Positive Pictures 721 The Nature of Green Fog 722 Sulphur and some of its Reactions 722 The Woodburytype Process 723 “ By-the-Bye ’’—Studio Furniture 723 Photo-Lithography and Photo-Zincography. By Major J. Waterhouse, B.S.C 725 French Correspondence 726 About London with a Camera. By W. Cobb 727 PAGE 730 730 730 732 735 736 736 A FenousOxalate Developer. By Norman Macbeth, U.S.A,... 727 Notes 728 Patent Intelligence Isochromatic Plates. By Greenwood Pim, Correspondence Proceedings of Societies Talk in the Studio To Correspondents The Photographic News Registry GELATINO-BROMIDE PAPER FOR POSITIVE PICTURES. First Article. Scientific pursuits of all kinds have their innings, to use a common phrase, during which time large numbers of the scientiSeally inelined are enlisted in the ranks to recruit and augment the failing forces ; for it is a pretty generally admitted fact, even in science, that unless there is con tinually some new discovery or re-discovery—it matters little which—to keep up the high temperature of popular excitment, those having no fixed purpose in view, to induce them to study any particular subject, more than superficially, are usually attracted to the latest novelty, irrespective of the branch of science to which it may be long. Electricians have had their innings, and a good one, too ; now the sister science, photography, is preparing to take the front rank. Recent discoveries have enabled her devotees to secure the passing realities of the moment in a manner surprising the whole scientific world. The attraction photography offers to the man of even limited scientitic attainments is very great indeed—he obtains a result, something more than problematical, giving him courage to labour further in the field of research. Increas ing her ranks rapidly, and as rapidly making discoveries and improvements, one need not be surprised if some of the processes, ancient and modern, are not familiar to everyone. In a recent leader entitled “ Printing on Gelatino- Bromide Paper,” it was observed that the method of preparing and working such papers had been previously published, and was no doubt familiar to the reader. This may be a correct conclusion to arrive at—no doubt it is, as far as old hands are concerned—but if one might take as an example a question recently brought before the members of one of our most advanced photographic societies—i. es, how to obtain a successful coating of gelatino-bromide emulsion on paper—neither the replies nor the discussion which followed would make it seem probable that a satis factory method of working is generally known beyond the environs of the manufacturers’ premises. It is our purpose in this article to deal with the amateur side of the question ; or, in other words, to describe the details of the process in such an elementary manner as to enable those with time at their disposal, and the inclination, even without any previous knowledge in this branch, to prepare paper for their own use. Many amateurs prefer making the plates they use to those they procure from commercial sources : then why not try making bromide papers? Both operations can be performed at the same time, thus the inconvenience of getting everything ready for the one operation might very well serve for performing both ; we say inconvenience advisedly, because the number is limited of those who have so far completed their arrange ments as to be able to produce plates of varying sizes and high standard quality, in quantities, with the ease and certainty of the manufacturers. Neither is the professional photographer an exception; hence it is more profitable for him to purchase of the manufacturer than to waste, to him, valuable time in striving to obtain a good result. Amateurs and beginners especially will, however, prefer being made familiar with the details. The primary consideration is to obtain a suitable base upon which to spread the sensitive emulsion. As in albumenizing, so also in this process, a good quality of paper is indispensable, or objectionable spots and other markings make their appearance on developing. Even when Saxe or Rive papers have been employed, black spots and stains are frequently met with. For this reason a preliminary coating or substratum becomes a necessity, thus forming a covering over any metallic particles or other foreign bodies in the pulp. There is also another reason equally important why a substratum should be used, and that is, to fill up the pores of the paper, thus presenting a smooth surface capable of easy and firm attachment to the sensitive compound, and thereby keep ing the image on the surface. The amount of sizing in ordinary photographic papers has been hitherto regulated to suit the requirements of albumenizers ; but there is not the least doubt, if a sufficient demand be created, there would be no difficulty in obtaining a suitably-prepared paper, available alike to the experimentalist and the manu facturer of the commercial article. The choice of substrata cannot be said to be limited ; either of the following answering the purpose :— Nelson’s No. 1 gelatine 1 ounce Water ... ... ... ... 10 ounces Dissolve, filter through swansdown, and add— 30-grain sol. of chrome alum ... 20 minims 10-grain alco. sol. of salicylic acid... 60 ,, Or best Bermuda arrowroot ... 1 ounce Albumen 1 ,, Water 24 ounces Mix the arrowroot with a small quantity of cold water, afterwards stirring in the remaining quantity of water : boil, stirring well until transparent; when cool, add the albumen, also a similar quantity of salicylic acid, as in the previous mixture. Or, Good starch 1 ounce Water (boiling) 24 ounces Salicylic acid, same as above. Mix starch into a fine paste with a small quantity of cold water; add boiling water; boil for a couple of minutes, and add the antiseptic,