The photographic news

• Bandzählung: 12.1868
• Erscheinungsdatum: 1868
• 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-id1780948042-186800009
• PURL: http://digital.slub-dresden.de/id1780948042-18680000
• OAI: oai:de:slub-dresden:db:id-1780948042-18680000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

Palestine, Greece, &c. The Vicomte de Ronge, in his mis sion to Egypt in 1863-4, produced six volumes of hand copies of inscriptions and 220 photographs. Professor Piazzi Smyth lately took 166 photographs at the Pyramids (many for the lantern) and 50 stereo views. Most of them were taken “ solely with a view to procuring aids to scientific enquiry.” They were produced on glass slips, 3 inches by 1 inch, exposed while in the bath, and they include eleven views in the interior of the Great Pyramid by magnesium light. He prefers stereo views taken with two cameras, and very justly urges the taking of distant objects with the cameras placed widely apart. This, I think, we might often do with advantage, using one stereo camera, first taking one half and then moving the camera and re-focussing for the second half. In this connection I ought to mention the labours of Thompson among the ruins of Cambodia; Fergusson and Hope in Indian achitecture ; and Svaboda at the Cave of Elephanta, likewisesin Mesopotamia and on the sites of the Seven Churches of Asia; Uelsby has illustrated some of the antiquities of South America; and a new work on Central America by Squier is, I believe, to be illustrated by 3,000 photographs, and any one acquainted with the elabo rated monuments of that country will admit that by no other means could fair representations be given. It would be tedious to enumerate the volumes bearing on antiquities which photography has illustrated, either directly by silver or other prints, or as furnishing a ground-work to the wood-cutter. In “ Sinai Photographed, or Contemporary Records of Israel in the Wilderness,” Lord Lyndhurst sug gested the application of photography “ as the only way so to certify their copies of the inscriptions as to silence cavil.” Noel Humphrey’s interesting work on the “ History of the Art of Writing ” is cleverly illustrated by photography. Our art-science has been employed, to some extent, in illustration of old coins and medals, also in copying old mosaic pavements on a reduced scale. Some time since Mr. Rejlander turned his attention to the ancient brasses for which our country is so famous ; and, by uper-imposing rubbings on sensitized paper, obtained copies same size as the originals. I am of opinion that negatives of the rub bings, reduced to a known scale, would yield equally useful and more convenient prints. Of the numerous works of antiquarian interest I will only mention “ The Ruins of Pompeii ”; but I may mention that, as its counterpart in this country, “ Uriconium," a photograph previously taken, was useful in enabling 120 columns of a hypocaust to be restored after they had been wantonly overthrown. Some of the details at Iona, and upwards of a hundred photographs at Melrose, have been taken, the latter em bracing everything of constructive or ornamental interest; and it is somewhat in this spirit that I would urge the copying, by photographic means, wherever practicable, of such works of antiquity as remain to our own day, as well for the purpose of study as for transmission, if possible (either in the form of negatives or prints), to posterity, to whom the originals may be partially or entirely lost. The portico of the Temple of Drudeia, on the Nile, was added by Tiberius, but against this recent acquisition may be set tbe fact that Egyptian monuments known to exist in the fourteenth century are now no more. Of some treasures of antiquity now lost, only rude representations have come down to us; for example, on the arch of Titus at Rome we have some of the sacred trophies from the Jewish Temple, and, in this country, drawings of the famed shrine of St. Thomas of Canterbury, only exist on portions of an un destroyed window, and in a partly burnt manuscript. The idea I have suggested may appear speculative, if not visionary; but who shall say whether our art-science may not be the means of much more being known hereafter of men and things as they existed in the nineteenth century than could have been had photography been unknown ? Lot me nclude in the words from the “ Essays of Elia ” :— “Antiquity! thou wondrous charm, what art thou? that being nothing, art everything ! When thou wert, thou wert not antiquity ; then thou wert nothing, but hadst a remoter antiquity, as thou calledst it, to look back to with blind veneration, thou thyself being to thyself flat, jejeune, modern! What mystery lurks in this retroversion? or what half Januses are we that cannot look forward with the same idolatry with which we for ever revert! The mighty future is as nothing, being everything! The past is everything, being nothing!” RESEARCHES ON DRY PLATES. BY M. CAREY LEA.* New Processes. I shall now proceed to describe the new processes referred to at the commencement of this paper. Several years ago I described a method of developing both positives and negatives with the aid of a lead-salt. I did not claim to have discovered that lead-salts impart additional activity to gallic acid, but I showed how this principle could be advantageously used. Gallic acid pre cipitates acetate of lead, and in the earlier experiments this muddy mixture was employed. I showed that clear solu tions could be got with acetate of lead by adding a sufficient quantity of acetic acid beforehand, which prevented pre cipitation ; and that with nitrate of lead no precipitation tended to form, even without the need of employing acetic acid. I showed that the effect of acetate of lead was so extraordinary as to multiply the power of the gallic acid fifty-fold, so that, instead of using gallic acid in the pro portion of 5 grains to the ounce, it might be reduced, with the aid of acetate of lead, even to 1-12th of a grain to the ounce ; and that in the proportion of l-6th of a grain to the ounce it was a very powerful developer. This method was not only extensively used, but, I am sorry to say, was ex tensively borrowed, with trivial alterations and somewhat scanty acknowledgments. In Paris it was made the founda tion of a secret process. Vials containing the two solutions were sold at the rather extravagant price of thirty-eight francs. Some of the contents having been forwarded to Dr. Schnauss for analysis, his examination resulted in showing that the materials used were precisely those which I had indicated. I have applied this principle in an entirely new direction, to the preparation of dry plates, instead of to developments, and with excellent results. A plate is coated with collodio- bromide, and is thrown, as soon as set, into a bath of acetate of lead, acetic acid, and gallic acid. It is then simply dried, without any other treatment, and so gives an ex cellent dry plate, very sensitive, and giving satisfactory negatives. The details are as follows :— In 16 ounces of ordinary acetic acid (not the glacial) dissolve one drachm of acetate of lead. Prepare also a 60-grain solution of gallic acid in alcohol. Both will need filtering ; both will keep a long time, probably indefinitely. To make a bath suitable for a 4-4 plate, take 1 ounce of the lead solution, l-4th of an ounce of the gallic-acid solution, and 6 ounces of water. Add the lead solution first. No precipitate or troubling will take place (unless, perhaps, in some water containing a large proportion of sulphates, in which case, either use distilled water, or filter and add a little more lead solution), and the bath is ready at once. It is better to prepare three such baths, for the plates are made so rapidly that, otherwise, delay will occur for want of a ba th to put the plates in. The collodion is the same as that>before recommended, viz., 8 grains bromide of cadmium, 2 grains bromide of ammonium, but with 7 grains pyroxyline to the ± ounce of alcohol and J ounce of ether. Sensitize with 16 grains of finely pulverized nitrate of silver to the ounce. The quality of the pyroxyline to be used is of very great * Continued from p. 162.