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The photographic news
- Bandzählung
- 7.1863
- Erscheinungsdatum
- 1863
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- Englisch
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- F 135
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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. 256, July 31, 1863
- Digitalisat
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Zeitschrift
The photographic news
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Band
Band 7.1863
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- Register Index 619
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Band 7.1863
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364 THE PHOTOGRAPHIC NEWS. [July 31, 1863. If necessary, I can electrotype direct upon my material; but as this might lead to tho discovery of part of my process, I prefer to make a different kind of matrix. I should have been glad to have taken out a patent, in order to grant licences, but as the lawyers say no patent is valid till ■well litigated, I prefer to run the risk of competition, which after all is of more benefit to the Arts than monopolies such as tho present Patent Laws permit. THE DIFFICULTIES OF LIME TONING. BY JABEZ HUGHES. In last week’s News appeared a letter signed "Cha-meal- ion,” written apparently “ half in joke but all in earnest,” complaining of the difficulties encountered in using a lime toning bath. I cannot say I am surprised at the narra tion of failures, as I know from experience how difficult it is to work a lime toning bath without mealiness. As “ Cha-meal-ion" is evidently a person of intelligence and experience, there must be some weak point, though glancing at what has been written on the subject I cannot detect it. Mealiness, however, is not peculiar to the lime toning baths, though it certainly has a greater tendency to be shown with their use. For this reason I do not think the lime toning process will ever be in general use. I have practised this process for a considerable time, and have had the opportunity of seeing it worked out by my several assistants. I have been at some times elated with the beautiful result, and at others depressed with the miserable failures ; and the general conclusion I draw is, that more pains and skill are required to produce good results with it than with the usual ones containing acetate, phosphate, or carbonate of soda. “ Cha-meal-ion" may rest assured that others have had their failures as well as himself, but few have so fiankly and jocosely proclaimed them. I do not think that any of the toning baths depend for their proper working on such delicate conditions as this chloride of lime one. When I first purchased the late Mr. Lacy’s business I found a German printer there using the lime toning ; and, keeping a photographic depot and selling albumenized paper, as I did, I naturally wished to introduce my own wares, but the printer told me “ dere vas only von kind of baper dat vould do, and I must have dat.” Many quires of paper were found on the premises, good paper for other toning processes, but I was told that “ it had all been dried, and vos bad ; it did not suit the doning bath.” When I proposed to print in another house I alarmed the printer, who exclaimed, “ I must have de same vater ; dere is only von vater dat vill do vor de brinting, ’specially vor de doning bath.” In this manner I was introduced to the peculiar conditions under which the lime toning bath could be successfully worked. It would scarcely be necessary to give “ Cha-meal-ion ” a fresh formula, after he has failed in those already published, or I might refer him to the new edition of my Manual, in which the subject is discussed, but the truth is that there cannot ever be a complete formula, because the minor modifying causes cannot be embraced. Let “ Cha-meal-ion,” however, try and work out a formula for himself. Let him take two solutions; one of saturated solution of carbonate of lime, say three ounces, and one of saturated solution of chloride of lime, say two ounces. Mix these two solutions in the proportions given, and add forty-five minims of the mixture to one grain of chloride of gold in solution. This bath, diluted to, say, eight ounces of water, may be used imme diately, but will be better for waiting twenty-four hours. Wash the prints as usual, and tone them. If they are mealy, reduce the proportion of the chloride of lime, or in crease the proportion of carbonate of lime. If the prints are not mealy, out refuse to take a black tone and become blue, increase the chloride of lime until the black tones are obtained. If too much chloride of lime is used, mealiness is set up instantly, before toning even begins. Upon the harmonious proportion of the chloride of gold, chloride of lime, carbonate of lime, the amount of free hydrochloric acid in the gold solution, as well as the nature of the albu menized paper, depends the tone of the print. It will thus be seen that a formula that succeeds in one persons hands may easily fail in another’s. The so-called, satu rated solution of chloride of lime may, in “ Cha-meal-ion’s" case, contain more or less than in mine; the same with the carbonate; and the acidity of the gold solution will be quite variable, to say nothing of the nature of the paper. Can it be surprising, then, that a “ Cha-meal-ion” may fail where an Ommeganck succeeds ? The Parkinson formula is one that he worked out himself from the Ommeganck; he does not pledge himself it will succeed with others, he only knows it is just the thing for himself. The formula I have proposed for “ Cha-meal-ion ” to start with is successful with me just now, but next week, if I open a fresh ream, I may find the new paper requires a variation of the toning bath to suit it. To conclude, I would urge on “ Cha-meal-ion ” and others who may wish to try the lime toning, that they must make a liberal allowance, in following the formulae of others, for those minor circumstances that influence the result—that they must trust rather to the general spirit of the instruc tions than the precise details. I trust that “Cha-meal-ion” may find some of the hints given to be useful, and as a proof that clear and brilliant prints without any mealiness can be produced by the lime toning, I enclose a few. Ryde, 1. W. PHOTOGRAPHIC CHEMICALS: Their Manufacture, Adulteration, and Analysis. If it is desired to obtain pure manganate of potash in tho crystalline form from mineral chameleon, it is dissolved in a small quantity of pure water, the solution decanted from a little sesquioxide of manganese which may be deposited, and evaporated over oil of vitriol under the receiver of an air pump. Green crystals will be deposited, which are the salt in question. These crystals are decomposed by water, yielding a red solution of permanganate of potash and brown peroxide of manganese, caustic potash being separated at the same time. The formula for this decomposition being as follows:— 3(KO,MnO.) =KO,Mn,0,+2KO +MnO 2 . When free potash is present the decomposition is not so rapid, and hence, when the crude substance is dissolved in a large quantity of water, the decomposition taking place gra dually causes the liquid to assume various colours. The solution is dark green at first, but rapidly changes through blue, violet, and purple, to carmine red, in proportion as the excess of potash is removed from the salt by the water, and by the carbonic acid of the air. The changes occur with greater rapidity if the water be in large excess, or if it be hot. Permanganate of potash is always prepared from the man ganate, by making use of the reaction shown in the above equation. This salt can be purchased at most chemists’, both in solution and in the crystalline form; but as some of our readers may wish to prepare it for themselves, we give the process which we have found most effectual ; it is the one originally recommended by Gregory. Add to a finely divided mixture of 8 parts of peroxide of manganese and 7 parts of chlorate of potash, a solution of 10 parts of hydrate of potash in a very small quantity of water; evaporate to dryness, during which a small quantity of mineral cha meleon is formed; ignite the finely pounded mass in a crucible till the whole of the chlorate of potash is decom posed (for which a low, red heat is quite sufficient); reduce the semi-fused mass to coarse powder, and boil it in several times its weight of water. An insoluble deposit will bo formed, which allow to subside and separate by decantation. Evaporate tho clear solution rapidly, during which time a
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