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The photographic news
- Bandzählung
- 12.1868
- Erscheinungsdatum
- 1868
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- Englisch
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- Hochschule für Grafik und Buchkunst Leipzig
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- Hochschule für Grafik und Buchkunst Leipzig
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- Bandzählung
- No. 488, January 10, 1868
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Zeitschrift
The photographic news
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Band
Band 12.1868
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- Titelblatt Titelblatt I
- Kapitel Preface III
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- Register The Index To Volume XII 619
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January 10, 1868.] THE PHOTOGRAPHIC NEWS. I The ribs and veins in prints made from undried loaves appear as sharply-defined dark lines, and the whole appearance of the prints is superior to those made from dried leaves in which the ribs and veins are represented by comparatively ill-defined white lines. The maple leaf of the accompanying illustration can therefore be easily surpassed by any reader by printing from a freshly-plucked leaf. The reason of the difference alluded to lies in the fact, that the ribs and veins, whilst filled with the fluids which they convey, are transparent, and allow the light to pass through and make a record Heisch amongst the number—who have maintained from the first that theoretically there was nothing in the present system of toning and fixing more conducive to permanency than in the old system, conducted properly. We believe that prints produced by either system, if properly treated, have a fair tenure of permanency; but we believe that the present system is safer, that there is less risk of sulphur- toning and imperfect fixation, than in the bath in which the toning and fixing functions were combined. The fading prints, of late so common, are chiefly due to careless or ignorant treatment in fixing and washing, especially to the repeated use of the same fixing bath after decomposition has commenced. We are not about to enter into the question in detail, however, now, but simply to call attention to an interesting article by Professor Towler, which we reprint on another page. Our American confrere bespeaks for the old bath of hypo and gold reconsideration, as possessing in some respects undoubted advantage in results over the present method. Alkaline toning processes have the tendency to bleach the prints sometimes in an excessive degree, whereas in a bath of hypo and gold this bleaching process is exercised in a much slighter degree. We wish to suggest to experimentalists who may be disposed to try toning on the old principle, that to be safe the solution should be neutral, and that a subsequent immersion for a short time in strong, fresh solution of hyposulphite is desirable. If freedom from bleaching be the chief advantage desired, that can be perfectly obtained by the use of the toning bath of sulphocyanide and gold, in which no appreciable reduction akes place. It is to be admitted that the subject of sulphur-toning remains to the present time very imperfectly understood, and that from general experience, rather than from theoretical necessity, it is held in dread. Sulphide of silver is usually of a fine black colour, and very permanent; but the form of it with which photographers are unpleasantly familiar is of an unpleasant yellow, or greenish tint. That this is not necessarily the case we all know: we are familiar with fine black prints, produced many years ago, which remain un changed now. We have before us at this moment some prints we received from Carl Meinerth, of New Hampshire, U.S., five years ago. They were described as having been toned by immersion for eighteen hours in an old toning bath of hypo and gold made eight months before ; and that after fixing they were only washed for one hour. The prints were some of a rich purple, and others a pure neutral black with perfectly pure whites, the prints being vignettes. They were toned just five years ago, and they present no change now : the whites remain pure, and the blacks rich and deep. The permanency seems, indeed, beyond challenge. This is one of many such facts familiar to old photographers, and which render further examination into the causes of such permanency desirable. In gathering leaves for photographic purposes, some care should bo taken to procure perfect and characteristic specimens. The margins should be kept as free from overlapping as possible when the leaves are placed in the printing-frame or pressed. Some are more easily managed if very slightly wilted, but gene rally the sooner they are subjected to a slight pressure the better. A portfolio or ordinary atlas, supplied with sheets of printing paper, should be taken to the woods, in which the most delicate one—as the maiden-hair, fine-haired mountain fern, &c.—can be placed as soon as plucked. Many leaves can be printed from with out pressing or drying, as forest loaves, many ferns, columbine, anomono, black currant, &c.; but when the pines of the leaf may bo expressed by the pressure usedin printing, and stain the sensi- tivo paper, it will be necessary to subject them to some pressure between the folds of bibulous paper. They should not, however, be dried as for an herbarium. LEAF PRINTS BY PHOTOGRAPHY* The sun has been both draughtsman and painter from the time when " the morning stars sang together and all the sons of God shouted for joy ; and “ leaf-prints ” have been amongst his most favourite works. It was not, however, until the present century that ho entered into the service of •nan to work to order as a draughtsman and printer, and . af-prints were amongst the earliest specimens of his powers when he entered upon his task under man’s guidance. Some, of the earliest experiments in securing images on chloride of silver were produced by superposing leaves, lace, and similar objects on the prepared paper, fac-similes of which, in white or a light tint, were obtained on a black ground. Singularly enough, although such a mode of pro cedure might have many interesting applications, it has re ceived since but slight attention or further development. # Leaf Prints : or, Glimpses of Photography, by Charles F. Himes, Ph. D. (Philadelphia Benerman and Wilson). Professor Himes, in a handsome little volume, introduces this mode of working to the public as a valuable aid in the study of botany, pointing out the beauty of its application, and giving detailed instructions for putting it into practice. In an introductory chapter he points out the great value of leaf-prints as an aid to the student. “ One great object,” he remarks, “ of the study of botany is to enable the student to recognize readily the individuals of the surrounding of flora, to call them by their names, and to arrange them according to their degrees of kinship. The number and distinctness of the characteristics of a plant, often concentrated in its leaf, and the comparative ease with which the story written in the leaf can be deciphered, make the study of its morpho logy peculiarly important and interesting to the beginner in botany.” The photographic image obtained by printing by superposition—using the leaf as a negative—renders the character of the leaf most perfectly, clearly indicating not only the general formation, but tracing accurately its vena tion and detailed structure. An admirable illustration of this is given in the photographic plate published in the work, containing a leaf of the Acer daaycarpum, one of the common maples of America; a leaf of the Polygonatum mul- tiflorum, or Solomon’s seal; and an example of the maiden hair fern, or Adiantum pedatum, all printed on one piece of albuminized paper. On the value of the study of leaf structure, and the facility which photography offers for assisting such study, Profeseor Himes further remarks,— But the fronds of the ferns reward in the highest degree the study of leaf morphology. Almost all specific and generic charac teristics are found in them, when the nature of the fructification, the shape of the sori, their position, &c., is considered, all of which can be perfectly represented by the photographic method used for the illustration, in which the marginal fructification is beautifully rendered. Thus the plate of this, one of the lower orders of vege tation in our earth’s flora in pre-Adamic times, is written in the impressions of its leaves upon the rocks. They tell that during the carboniferous era, when the vast beds of coal wore stowed away for the subsequent use of man, the ferns which at present seem only to serve to relieve, by their freshness and beauty, the waste and gloomy places, preponderated in number of species and genera, and in some of their representatives, even in our zone, aspired to the dignity of treehood, as they now only do in the tropics. One of the most important points in commencing the pro duction of leaf-prints is the selection of suitable leaves to act as negatives, and on this subject Professor Himes gives apt instructions. To secure the most definitely marked re sults in printing, vigorous leaves gathered late in the season answer best, those gathered in the spring being least in tense. The dried leaves of a hortus siccus may be used, the specimen-plate having been printed from such ; but freshly- gathered leaves give the best results. Here are some hints for the selection and treatment of the leaf negative :—
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