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The photographic news
- Bandzählung
- 27.1883
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- 1883
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- Hochschule für Grafik und Buchkunst Leipzig
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Zeitschrift
The photographic news
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Band
Band 27.1883
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- Titelblatt Titelblatt I
- Register Index III
- Ausgabe No. 1270, January 5, 1883 1
- Ausgabe No. 1271, January 12, 1883 17
- Ausgabe No. 1272, January 19, 1883 33
- Ausgabe No. 1273, January 26, 1883 49
- Ausgabe No. 1274, February 2, 1883 65
- Ausgabe No. 1275, February 9, 1883 81
- Ausgabe No. 1276, February 16, 1883 97
- Ausgabe No. 1277, February 23, 1883 113
- Ausgabe No. 1278, March 2, 1883 129
- Ausgabe No. 1279, March 9, 1883 145
- Ausgabe No. 1280, March 16, 1883 161
- Ausgabe No. 1281, March 22, 1883 177
- Ausgabe No. 1282, March 30, 1883 193
- Ausgabe No. 1283, April 6, 1883 209
- Ausgabe No. 1284, April 13, 1883 225
- Ausgabe No. 1285, April 20, 1883 241
- Ausgabe No. 1286, April 27, 1883 257
- Ausgabe No. 1287, May 4, 1883 273
- Ausgabe No. 1288, May 11, 1883 289
- Ausgabe No. 1289, May 18, 1883 305
- Ausgabe No. 1290, May 25, 1883 321
- Ausgabe No. 1291, June 1, 1883 337
- Ausgabe No. 1292, June 8, 1883 353
- Ausgabe No. 1293, June 15, 1883 369
- Ausgabe No. 1294, June 22, 1883 385
- Ausgabe No. 1295, June 29, 1883 401
- Ausgabe No. 1296, July 6, 1883 417
- Ausgabe No. 1297, July 13, 1883 433
- Ausgabe No. 1298, July 20, 1883 449
- Ausgabe No. 1299, July 27, 1883 465
- Ausgabe No. 1300, August 3, 1883 481
- Ausgabe No. 1301, August 10, 1883 497
- Ausgabe No. 1302, August 17, 1883 513
- Ausgabe No. 1303, August 24, 1883 529
- Ausgabe No. 1304, August 31, 1883 545
- Ausgabe No. 1305, September 7, 1883 561
- Ausgabe No. 1306, September 14, 1883 577
- Ausgabe No. 1307, September 21, 1883 593
- Ausgabe No. 1308, September 28, 1883 609
- Ausgabe No. 1309, October 5, 1883 625
- Ausgabe No. 1310, October 12, 1883 641
- Ausgabe No. 1311, October 19, 1883 657
- Ausgabe No. 1312, October 26, 1883 673
- Ausgabe No. 1313, November 2, 1883 689
- Ausgabe No. 1314, November 9, 1883 705
- Ausgabe No. 1315, November 16, 1883 721
- Ausgabe No. 1316, November 23, 1883 737
- Ausgabe No. 1317, November 30, 1883 753
- Ausgabe No. 1318, December 7, 1883 769
- Ausgabe No. 1319, December 14, 1883 785
- Ausgabe No. 1320, December 21, 1883 801
- Ausgabe No. 1321, December 28, 1883 817
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510 THE PHOTOGRAPHIC NEWS. L August 10, 1883. 1st. Take some highly-polished zinc, thickness No. 8 or No. 10; choose the smoothest sheets, free from streaks and defects. 2nd. Clean the plate in the water containing three per cent of hydrochloric acid, and get rid of all bubbles of hydrogen. 3rd. Render it hygroscopic in the bath of iodine, gallic acid, and phosphoric acid, indicated in the previous des cription of the process of photo-engraving in outline. 4th. Next wash the zinc in running water, and dry care fully between blotting-paper. 5th. When quite dry, coat it with coal-tar pitch, eight per cent, dissolved in pure benzine ; as soon as spread, it may be heated in the dark up to the temperature of 50° C., and allowed to dry until, upon cooling, it is no longer sticky. 6th. Expose behind a positive plate having soft half tints. 7th. Control the exposure with the help of slips coated with coal tar, it is more rapid than bitumen. 8th. Develop as before with turpentine and benzine, and finish the process in petroleum and one-tenth its quantity of spirits of turpentine. This new bath by forming a light homogeneous varnish gives a chemical grain well suited to the half-tints of the tar. Next cause the plate to rotate so that the mixture of petroleum and turpentine may be uniform in texture and almost entirely evaporated. Heat the plate again up to 50° or 60° C., and allow it to cool. 9th. To engrave the image thus obtained™on the zinc with all its half-tints, make use of the following bath :— Pure water 100 grammes Water saturated with sulphate of copper ... 50 „ Sulphuric or bydrocloric acid... 3 ,, Bubbles of hydrogen will be disengaged from all the little points constituting the chemical grain of the plate, and at the same time particles of copper will;bejdeposited in their place, forming a positive image, which must not be touched while in the bath. As soon as the image is well formed in copper, it can be removed and placed in water, frequently changed. It may next be wiped between blotting-paper, and dried in the open air. 10th. Remove the insoluble coal tar and non-adherent copper with a brush soaked in benzine. Rinse with clean benzine, and wipe well with a soft cloth so as not to scratch it. 11th. To ink the plate, coat it with varnish or oil and fatty ink, so as to fill up the grain of the picture-heating it if necessary. 12th. Rub the plate with a damp flannel to remove superfluous ink, and print off in a press for line-engraving if the lines are deep, or in a lithographic press if but slightly indented. The depth of the lines in the plate depends on the thickness of the coal tar film. This process is most ingenious, and the various operations it admits of are more easy to execute than describe. Captain Biny will finish these experiments by determining the proportional chemical grain for heliographic plates in a simple and economical manner. Leon Vidal. CLINICAL KNOWLEDGE. BY THOMAS C. STRICKLAND. A FEW years ago photographers weighed out the iron for deve loper, and were careful to pulverize it in a mortar. To-day most all make a saturated solution, or weigh the iron and put it into the water without pulverizing. By either method the labour of pulverizing is saved. Not much in that, you may say. But when you come to think of it rightly, you will find that it was so in those days for want of thought. No benefit was derived from pulverizing; not even time. Some fifteen years ago I knew a photographer who kept a customer waiting until he sent a boy five miles for a mortar. He depended on his written formula, and that said—pulverize. Strange as it may seem, he had never thought of the why. And even to-day things as foolish are oftener done than most would care to own. Not three months ago an instance occurred regarding a copying tube fully as absurd. I do not advocate that every man who works in the dark room should be a thorough chemist; but he should know all about the chemicals he uses. The reason is obvious. The list is not so very long. And a study of them that will enable you to give the. why intelligently, will add reputation to your work. And that means more gold in your pocket. Now, water is a familiar element, and one much used in the dark room. A tolerably pure water may give good results. Many a time the bath is boiled, sunned, and condemned, when the fault was in the water. A strip of glass an inch or two wide i by three long, and a lamp, is sufficient to test for iron and earthy matter. If, upon evaporating a drop, only a ring or two is left upon the glass, it contains but little earthy or saline matter. But if a crust is left, it is called loaded. And if that crust is brownish, it contains iron. Use litmus paper to test for acid. Water has great power of solution, and is essential in the processes of art, as well as a sustenance of animal life. Moun tains of stone give way to this power, and wherever it is, a change is going on—dissolving here, depositing there. On account of this power, it becomes what is termed impure. Particles of matter possess powers of attraction and repulsion. And a knowledge of these regarding particular elements give rise to the useful “ dodges,” as they are called, yet they are no more or less than principles in chemistry. Some substances have great affinity for each other, and readily unite ; alcohol and water, for instance. But when so mixed the individual elements lose their name and individuality, and the compound is given another name. By the way, some men have a strong affinity for the two named elements, but I hope no artist does, for when saturated he also loses his individuality, and is given another name. Take nitric and hydrochloric acid, mix, and the result is a new solution. This will dissolve gold, and even if you buy your gold, and prefer to do so from press of work, it will pay you to make a small quantity just for the practice. To dissolve as much as a gold dollar piece take : Nitric acid 1 drachm Hydrochloric acid 3 drachms Water 3 ounces After the gold is dissolved, add carbonate of soda until a green precipitate is formed. Filter and add 36 ounces of water. The fact is, if you would have a thorough knowledge of the chemicals of the dark room, you must experiment. With prac tical work you become familiar with tne action of the different drugs. Probably you were not aware of the powerful agents used in toning. I have noticed that parties using dry plates, who never used wet plates, however intelligent they may be, are more at sea when trouble comes than those who for years used wet plates. Though a wet-plate worker may have never made dry plates, if he has been a thinking man, he knows what he is about when handling a dry plate. When you get iron from your dealer, if it has effloresced, you condemn it. You detect it at once, from your past knowledge of how it should look. The brilliant green crystal had given place to a dull grayish powder. So it is with every chemical we use, if we will only make a knowledge of them as familiar. A knowledge of the repulsion between different particles of matter is useful in many ways in everyday work. For instance, if you use the cheap tin pan to develop dry plates in, and it becomes rusty, and you have not time to re-varnish, grease or warm slightly and run beeswax over. Working blindly is not business. Even in the cities you will find men using pine trays with glass bottoms, which is a useless expense. However, even to use one with glass bottom is far ahead of a few years ago. It’s no difference what material your tray is made of, if it is not porous, and is of itself, or covered with a substance having no aflinity with the solution it is in tended to hold.—St. Loais 1'hooographer. Eorxespondence. STAINED SENSITIVE FILMS. Sir,—I have just received the last number of your excellent journal, and I find in it an article and a repro-
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