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THE PHOTOGRAPHIC NEWS. Vol. XXVII. No. 1274.—February 2, 1883. CONTENTS. PAGE Carbon Printing 65 About Highly Sensitive Emulsions. By Dr. J. M. Eder 65 By-the-Bye.—Douceurs 66 On Expression-Photographs. By'William Peek 67 On Latitude in Exposure. By C. Ray Woods 67 From Traves to Hanover. By J. H. T. Ellerbeck 68 On a New Light. By Leon Warnerke 70 Notes on Photography. By E. Howard Farmer 70 PAGE Notes 72 Patent Intelligence 74 Twelve Elementary Lessons on Silver Printing. - 76 On Gradation in Gelatine Negatives. By Edwin Cocking 77 Correspondence 78 Proceedings of Societies.— London and Provincial Photogra phic Association—Photographers* Benevolent Association 78 To Correspondents 80 24 parts 80 grammes II. » » 24 5 500 60 parts 500 To this is added, Nitrate of silver Water surface by gently rubbing it with a solution of wax in benzole, say about five grains to the ounce. Mr. J. K. Johnson was, during his life, a constant con tributor to the Photographic News, and he possessed a mind of remarkable originality ; many important inventions being due to him. His reputation as an inventor rests mainly on his type-founding machine, this being the first machine of the kind which turned the letters out quite ready for use, and not requiring any subsequent trimming. Doubt less many of our readers have seen these machines in action at the National Printing Office, in Paris. Although the carbon process is now open to the world, or rather it will be so to-morrow, we imagine that very few will care to manufacture tissue for their own use, excepting fo experimental purposes ; this manufacture being one especi ally unsuited for profitable working on a very small scale. transfer method is of little value to the general photographer, as, when he takes his negative, he generally does not know whether silver prints or carbon pictures will be required. Many important improvements, besides the double transfer process, are embodied in Johnson’s specification. The grinding of the pigments with a small proportion of gelatine, so as to facilitate their perfect admixture with the bulk of the gelatinous preparation, is a matter of con siderable importance in the practice of tissue making, as it obviates the necessity of specially grinding the colour for each batch of tissue which is made. The coating of long lengths of paper with the composition by a continuous process is another improvement due to Johnson, this method being invariably adopted at the present time, rather than Swan’s or Spencer’s process with separate bands or strips. The use of flexible supports for development is referred to, and in connection with this matter we may mention that we have found that the thin and fine-surfaced macintosh linen, or so-called “ syphona-cloth," is one of the best flexible materials on which a carbon print can be deve loped. It is advisable to slightly wax the india-rubber I. Bromide of ammonium Bromide of potassium Iodide of potassium Water Simeons’ hard gelatine ABOUT HIGHLY SENSITIVE EMULSIONS. BY DR. J. M. EDEE, How to produce emulsion that will give No. 25 on War- nerke’s sensitometer is a question we are interested in just now. Scolik does it in the manner following. He makes an emulsion with ammonio-nitrate of silver, as I have indicated in my “ Modern Dry Plates,” and adds to it some iodide of potassium, warming up to a temperature of 50° to 55% C., instead of 35°. His formula is as follows :— Ammonia as much as necessary to form ammonio- nitrate of silver. Scolik digests, then, for a period of from half to three quarters of an hour, at a temperature of about 50° C., taking care to agitate repeatedly during the time, for otherwise the silver bromide will be precipitated in the form of sediment. The emulsion is then finished. The advantage of this modusoperandi lies in the circum stance that iodide, which is added, permits the raising of the temperature in the cooking operation ; the iodide acts, indeed, the rle of a restrainer. The plates from such emul sion are best tieated with the Edwards’ glycerine developer. The fixing is rather slow, and the negatives somewhat thin, so that they usually require to be intensified. Plener, as the readers of the Photogbaphio News know CARBON PRINTING. Although the gelatino-pigment method, as practised on a large scale by the Autotype Company, is almost invariably referred to as carbon printing, it does not always merit the title; as occasionally earthy or other pigments, entirely free from carbon, are employed in the manufacture of the tissue. The misnomer is, however, likely to remain in general use, as photographers are ordinarily extremely con servative as regards names. To-morrow, the 3rd instant, will mark an era in the history of carbon printing, as from this time forward, all which is of real importance in connection with the process will be open to the public, and no longer hampered with patent rights, the double transfer patent of Johnson lapsing on this day. The fundamental patent of Swan, which expired in February, 1878, covered the single transfer process in its entirety, and a germ of the double transfer method ; but he employed an india-rubber cement in order to make the gelatinous film adhere to its temporary support, the subse quent application of benzole or some similar solvent being then necessary before the finished picture could be separated. Johnson found that the exposed tissue, after being softened by immersion in cold water, would adhere sufficiently to any impervious surface, if a squeegee is used to establish contact in the first instauce ; and it is this discovery which has given to carbon printing much of its present commercial importance. It is quite true that large carbon printing establishments mainly adopt the single transfer process, reversed negatives being then made use of; but the single