The photographic news

• Bandzählung: 35.1891
• Erscheinungsdatum: 1891
• 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-id1780948042-189100009
• PURL: http://digital.slub-dresden.de/id1780948042-18910000
• OAI: oai:de:slub-dresden:db:id-1780948042-18910000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

attracted the attention of all; I think it was from Ger- many. They were portraits about 11 by 14, mostly heads, printed upon matt surface paper of some kind. I saw a great deal of them, and studied them with the greatest interest and profit. They were admired by all the best photographers who attended the Convention, not one of whom but gave them unqualified praise. They were cer tainly not sharply focussed according to the usual photo graphic standa: d, yet they were sharp enough for pictorial standards, and their great beauty was their truthfulness to nature. The retouching upon them was only just enough to remove the spots and blemishes due to the false render ing of colour by photography. This is another abuse which has done much to bring photography under condemnation from artists : over- retouching. You must do it when you make such extremely sharp negatives, particularly when you make large heads. The photographic texture is an exaggera tion of the natural texture, and the pencil of the retoucher must be use l ; and in getting rid of this exaggerated texture, the retoucher makes with his pencil another which is more unreal in its mechanical smoothness than the exaggeration of extreme sharpness. If you will use a portrait combination and do not stop down too closely, and use a diffused, subdued light, these exaggerations will not be seen, the retoucher’s woik will be much lighter, and you will have a consequent gain in truth. From what I have seen of the new isochromatic plates, they are going to make quite a revolution in both lighting and retouching. I have not used many of them, but I am quite charmed with what I have. The breaks in the gradations of the shadows, caused by the false rendering of colour, are absent entirely, and the retouching reduced to a minimum. The texture of the skin is softer and more truthful, and the general effect so superior, that before long they must take the place of all others. One of the best firms in the city is using them exclusively, and speaks in high terms of them. I have confined my remarks to suggestions; to write exhaustively would be out of place where there are so many other things to attract your attention. But I would like to impress upon all young photographers the import ance of studying art apart from photography, to be able to detect the untruthfulness of photography, for with untruthfulness there can be no true art. Remember you are catering for a public which every day is getting more critical as art education spreads, and to keep your place you must head the procession, not follow behind. THE RUSSIAN PLATINUM MINES. All the the platinum of Russia comes from one district, the government of Perm. In 1885 the output amounted to 110,635 ounces, and in 1886 to 184,336 ounces. Hitherto it has only been found in alluvial deposits, and is always associated with gold. The proportion of the two materials varies greatly, the platinum sometimes being in greater quantity than the gold, in other places not constituting above one per cent. The former deposits are the more profitable to work. The most important of these distinctly platiniferous deposits occur in the district of Nijni-Taguil, near the watershed of the Urals. All the platinum-bearing streams of this locality descend from Mount Solovskaia, which is composed of a serpentine rock. The rivers have greatly exceeded their present size in former times, orelse—which is more probable—have shifted their course; for the wide valleys in which they flow contain alluvial de posits of considerable extent, which are exploited for platinum, and to a less extent for gold. Between Mount Solovskaia and the diorite mass of Mount Blanche the surface is covered with rounded boulders of serpentine and peridotite rock. As these boulders decompose under the action of the air, they form a sand or gravel from which the metal can be profitably extracted. This is similar to what takes place in the weathering of the diamond-bearing peridotite rock of Kimberley, which is exposed to the disintegrating action of the atmosphere before being washed for diamonds. The platinum of the alluvial deposits occurs in grains, or pound of 10 Kgm. weight. The gravel often contains } ounce per ton of platinum, but can be profit ably worked forounce. The deposit near the banks of the river Martiane consists of a serpentine conglomerate, and is from 4 to 5 metres in thickness. Above is a thickness of 23 to 24 metres of barren ground, chiefly clay. Most of the alluvial auriferous deposits in which platinum is found are in the neighbourhood of peridotite rock, or of serpentine rock formed by the partial alteration of the peridotite. Thus, the River Mioss takes its source from a mountainous district mainly composed of serpentine rock, and accordingly the auri ferous deposits near the head of the river are rich in platinum ; but further down stream, as the serpentine formation is left behind, the gold becomes less platiniferous. Small nuggets of platinum are sometimes found embedded in pieces of ser pentine, of peridote, and of chrome iron ore, all constituent minerals of the peridotite rock, which there is good reason, therefore, to regard as the true mother rock of the platinum. The richest deposit of the Nijni-Taguil district is that of Avra- rinski, extending for a length of 2 Km., 20 to 60 metres wide, and of a thickness of 4 to 5 metres. Here the platinum is found to the amount of 4}, 5, and sometimes even 9 ounces per ton. The metal contains a small proportion of gold, about 0'26 Gm. per kilo, which is separated by amalgamation. The crude platinum left contains about 90 per cent, of pure platinum. From October, 1886, to August, 1887, the pro duction at Avrarinski was 40,475 ounces. The working of these deposits is to a large extent sublet by the proprietors to the peasants of the district, who are paid by the weight of metal obtained. They construct their own washing and other machinery, which is made of wood, and is of a very crude description. The conditions with regard to cost of living, wages, and so forth are, of course, very different from those obtaining in new countries, such as South Africa, where the precious metals are exploited. Sometimes the present beds of the rivers contain sufficient platinum to pay for working, in which case the course of the river is diverted, and the water power used for driving the machinery. A large part of the gold mining of the Urals is likewise carried on under the system of subletting, but where the mother rock—generally quartz or diorite—is worked, more expensive plant is required, and the work is carried on by the proprietors of the soil or by companies. — American Druggist. TRANSFERRING PRINTS TO GLASS. The Lithographer and Printer gives the following method whereby any chromo print, or even clipping from newspapers, any engraving, no matter in how many colours, or on what kind of paper, may be transferred to glass by different treat ment of the various kinds of paper. Place the object to be transferred, face downwards, upon a larger sheet of Manilla paper ; prepare a solution of from 1 to 3 per cent, of nitric acid in water, according to thickness and strength of paper, and how strong it was sized ; ordinary news papers, and printings and engravings on unsized glazed paper, require even less than 1 per cent, nitric acid. One of the pur poses of adding nitric acid is to remove the sizing out of the paper. This solution apply with a sponge to the back of your object to be transferred. Be careful not to overdo it ; you only want to render the paper soft, but not wet. Continue sponging with this solution until you see the printing plainly— that is, until the paper becomes quite transparent. Laying down the paper, first adjust the upper right-hand corner to the mark on the plate, hold it there with the tip of your finger, and adjust the left-hand lower corner, but be careful to avoid air-bubbles. The practical printer and litho grapher, of course, does not need this advice, but to the amateur it is very valuable.