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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. 502, April 17, 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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Band 12.1868
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192 THE PHOTOGRAPHIC NEWS. [April 17, 1868. Antidote for CYANIDE.—The injurious effect on the skin produced by cyanide of potassium in electro-plating establish ments is completely arrested and ulcerous sores prevented by anointing the hands with a mixture made by incorporating protosulphate of iron in fine powder with linseed oil. Ul Correspondents. Punjab ee.—It is not difficult to cover a stout wire with gutta-pe rcha to form a dipper, but it requires constant observation to see that no portion of the gutta-percha gets removed, so as to bring the metal into contact with the silver solution. Take a strip of thin sheet gutta percha, -wide enough to meet round the wire, soften by immersion in boiling water, dry carefully, then envelop the wire, making the edges wrap over a little. The flame of a spirit-lamp or a piece of hot metal will then melt the edge of the sheet sufficiently to make it adhere like a soldered joint: or, another, and perhaps better, plan consists in taking the thin sheet gutta-percha like thin paper, and cut into narrow strips; heat the wire, and wrap round the gutta-percha spirally. When once covered, pass it through the flame of a spirit-lamp, and with moistened fingers press it down to cause all the edges to join. Repeat this process until a suf ficient covering is secured. As a rule, we prefer glass dippers, as they are most easily made, most easily repaired, and under no cir cumstances injure the bath. If a little gutta-percha or india- rubber be attached to the bottom, the risk of knocking out the bottom of a glass bath is avoided. SCIENTIA cum Arte.—The yellow spots in the print enclosed arc undoubtedly due to imperfect fixation. Vignettes are much more subject to risk of imperfect fixation than fully printed out prints, as you will readily perceive on a little reflection. The more per fectly a print is covered with dark objects the more perfectly all the chloride of silver in the paper is reduced, and the less there is for the fixing bath to remove. The more white there is in a print—as in a vignette, for instance—the more unaltered chloride of silver it contains when it is immersed in the fixing bath. Therefore, if the bath be rather weak, or a little exhausted, the vignettes, or prints containing most unaltered chloride of silver, will suffer first and most. Three ounces of hypo to the pint of water will give a somewhat weak bath, which will readily get somewhat inert after fixing a batch of prints. We prefer at least 4 ounces to the pint, and 5 ounces arc better, especially where vignettes are concerned. J. R. L. M.—The trustees, as we explained some time ago, have been acting under legal guidance from the first. The communi cation to which you refer was a tissue of mis-statements. Sub scribers could at any time obtain information from the trustees, as many have done satisfactorily. Non-subscribers have no concern in the matter. J. G. B.—A vessel for the nitrate bath made of pure silver might, of course, be used, but we cannot recommend it. The baser metal used in soldering would undoubtedly be attacked. Any excess of nitric acid would also act upon the metallic silver. A glass bath in a wooden case is quite safe, with fair usage, for travelling; or, wood lined with pure thin sheet india-rubber may be used. South Devon.—The solution of iodine 1 grain, iodide of potassium 2 grains, in water 1 ounce, is a stock solution, of which, for the clearing process to which you refer, something less than a drachm should be added to an ounce of water. A very dilute solution of iodine will serve to convert the abnormal deposit on shadows into iodide of silver; and this is all that is required. If any portion of the actual image is converted into iodide, it will, of course, be dissolved by hypo or cyanide, and so impoverish the image. P.—There are several toning baths which keep well and reduce very little; but only one, that we remember, that does not reduce at all. The sulphocyanide bath keeps well and does not reduce at all. Dissolve 1 grain of chloride of gold and from 46 to 60 grains of sulphocyanide of ammonium in 3 ounces of water. This may be used at once, or will keep any length of time. The acetate bath, containing 1 grain of chloride of gold and 30 grains of acetate of soda in from 4 to 8 ounces of water, may be used in a couple of days, or will keep for months; it yields a warm tone, and reduces very little. The lime bath, containing from 1 to 2 grains of chloride of lime and 1 grain of chloride of gold in 4 to 8 ounces of water, is best not used for a week after it is mixed, and will keep for months : ityields a black tone, and reduces less and less as it gets older. 2. To keep a plate moist after development, so as to intensify and fix at leisure, coat the film either with a mixture of equal parts of glycerine and water, or equal parts of golden syrup and water. We prefer the latter. This will keep the film moist many hours; after washing it off, the image can be further intensified, if necessary, or fixed at once, 3. If you will describe the details of your morphine operations, we can probably account for the failure. 4. When development is tardy with Mr. England’s plates, he adds a trace of ammonia to the plain pyro, which rapidly brings out an image. Beta.—You will find a full description of the «vitrified sheet india-rubber” and its probable applications upwards of a couple of months ago (February 7th). Actual experiment will be necessary to test its practical value. When it is ready for introduction into commerce we shall have more to say about it. We have examined a sample: it is something like goldbeaters’-skin, but a little thicker. It will be sold in sheets; the price we cannot state. W. J. A. G.—If morphine be used for preserving moist plates, all free nitrate of silver must be first thoroughly washed away. For keeping a plate twenty-four hours, perhaps the glycerine process is best; you will find it fully described on p. 231 of our Volume for 1867. If you describe in detail the operations you employ in the process which gives you so many failures, we can probably point out their origin. Waterloo.—You may, without serious results, use the same solu tions for plain paper which you employ for albuminized paper, although the solutions for one are not always the best for the other. The dirty yellow of the paper you forward is due to imper fect fixation, and arises, probably, from the use of an exhausted fix ing bath; it may possibly arise from keeping the paper sensitive some time before use, or, rather, before fixation; in which case a decomposition has ensued in the combination formed between the silver and the sizing matter of the paper, leaving a dirty, insoluble compound on* the body of the paper. This you may see on ex amining it by transmitted light. Plain salted paper has a right side and a wrong; the right side has the smoothest, finest surface. J. Taylor.—The letter has been addressed and forwarded. W. Crouch.—Your negatives having the appearance of positives instead of negatives is due to insufficient exposure and insufficient development. The negative of the print enclosed has either been much out of focus, or you have printed with the wrong side in contact with the paper. 2. You cannot tone after fixing, satisfac torily ; but you may, without danger, use sufficient light in toning to examine the progress fairly. A lamp or a candle would do no harm to the toning print, nor would an occasional glance by dull daylight. 3. If the film of the negative stick to the paper, there is little hope of preserving it. It is the result of imperfect varnish, or of using the negative too soon after varnishing. Let us hear further of your progress. You have no need to be discouraged with the results of your first week’s practice. J. Miller.—The IB long of the same maker will answer your pur pose best. The front lens may be used as a landscape lens. 2. No, to both parts of the question. J. C. G.—No. 1 is most suitable, and No. 4 least suitable. L. B.—The print is from an imperfect negative, thin and foggy, apparently; it is too lightly printed, and is over-toned; hence the grey, flat appearance which puzzles you. No amount of toning will gave you deep blacks without a sufficient deposit of silver to begin with. R. D. (Devizes).—Your doublet in preference to your single land scape lens for copying plans. 2. Willis’s process is a patented process. II. P. W.—We are not familiar with the especial lens you describe; but it doubtless requires the same treatment as similar portrait lenses. To use it for landscapes the back lens must be removed altogether, and the front lens reversed, so as to present its concave side to the landscape. The stops being placed in their ordinary places will now be in front of the front lens (which is screwed in the back cell) as nearly as circumstances permit, in the proper place. B. C.—The effect you describe is fog. It may proceed from a variety of causes; but most likely from the condition of the bath- Try, first, the addition to the bath of a drop or two of nitric acid- If that does not effect a cure, take a 10-grain solution of bicarbon ate of soda, and add a few drops at a time until the bath remains turbid ; then expose for a few days to the sun; filter, and, after adding a drop or two of acid, try again. The use of a newly- mixed collodion, or of newly-mixed developer, will conduce to fog* G. R. Fitt.—We will examine the precipitate, and report. Thanks for the communication on the Honey Process, which will appear in our next. « Lux Graphicus on the Wing,” and several other articles, are compelled to stand over until next week. Several Correspondents in our next. All Communications for the Editor to bo addressed to 15, Gough Square, Fleet Street, London, E.C. *,* All photographs forwarded to the Publisher for registration regeus attention at once ; but the pressure on our space sometimes comP in to defer the acknowledgment in this column. It should be oorn mind, therefore, that non-acknowledgment at once does not nec imply non-receipt or non-registration.
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