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The photographic news
- Bandzählung
- 6.1862
- Erscheinungsdatum
- 1862
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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. 189, April 17, 1862
- Digitalisat
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Zeitschrift
The photographic news
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Band 6.1862
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- Register Index 619
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Band 6.1862
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184 THE PHOTOGRAPHIC NEWS. [April 17, 1862 to th vertical dipping-bath is of a very inconvenient form for cleaning, and when made of an opaque material, for ascer taining with certainty whether it be really clean. Glass and white porcelain ware are the most satisfactory in this respect, as the dirt can be seen upon their surface ; but the cleanli ness of baths made of the other substances named must be taken a good deal on credit. The form of a vertical dipping-bath is naturally in a great measure determined by its intended use. It must be a deep trough larger all ways than the plates that are to be sensi tized in it, and of little breadth so as to economise the silver solution. There should be no sharp interior angles or corners, as the dirt collecting in these is difficult to clean out, so they should be carefully filled in and rounded. The interior surface should be smooth, because asperities en courage the deposit of the dissolved iodide of silver from the liquid. Finally there should be a spout ox - lip to facilitate the emptying of the bath without spilling any of the solu tion. Few of the vertical dipping baths generally manu factured fox' sale fulfil completely all these conditions. Vertical porcelain baths, as mostly made, approach nearest to the desired conditions of form and surface, but the interior angles are rarely rounded off sufficiently to make the cleaming of them an easy operation. If this fault were corrected they would be very perfect baths, and leave little to be desired. The cast glass baths of commerce, do not, I think, as a rule, come up to the standard of workmanship we have a right to expect from the trade which can produce the exquisite mousseline wine glasses which we see upon our dinner tables anil the beautiful apparatus that aid the experiments of the chemist and electrician. They are characterized by a smooth internal surface, and generally also by the absence of any interior angles, which qualities render them very valuable, and causes their deficiences to be the more regretted. The great thickness of the material is probably one cause of their high cost, which fox- large baths is almost prohibition for a poor person ; but] believe this excessive thickness is a mistake when given with the idea of increasing the strength of the vessel, because thick glass castings from their necess arily inferior quality, and the greater difficulty in annealing them, are frequently more liable to fracture than those of lighter substance or of blown glass, even where great care is taken in their manufacture; and also because photographic baths intended for the studio from their very nature are so little exposed to rough usage that precautions to give them extra strength seem unnecessary. Where we consider the thinness of the glass of some of those large bells which are used inverted as aquaria, containing often four to five gallons of water, and which are employed with safety for that purpose, it seems needless to more than double that thickness for vessels intended to hold one or two pints. Again, they are generally made too broad from back to front which necessi tates a larger- quantity of bath liquid then should be required. Three quarters of an inch, inside measurement is amply sufficient in my opinion, but if it be found that some customers prefer broader baths, I think a certain proportion should be made each way so that the purchaser may have the opportu nity of choosing for himself. Also the sides in many cases are not parallel to those opposite, and frequently both sides are curved, sometimes inwards, sometimes outwards. It is held by some to be advisable that the front side of a dipping bath should be slightly curved outwards, that the collodion may not be rubbed against it. I am hardly of opinion that this is necessary, as such an accident can only arise from the extreme carelessness of an operator, and such a form largely increases the quantity of liquid required to fill the bath ; but in any case the side against which the back of the plate is to rest must be flat, as if it curved outwards it would have a tendency to push the plate off the dipper, and for either side of a bath to curve inwards, which happens from the soft casting bending while being annealed, is clearly bad. Lastly, glass baths, as now supplied to us, have no lip, and when they are very full it is a matter of considerable diffi nperature or 01 property witho" , ng baths. In 1 d 12, I i. desiy value in general practice for dipping exceptional cases when such a property may be desl would be best to employ one made of porcelain. this material, that it will bear a temperature of oV Fall, without injury, but this is a ] (To be continued.) SOME EXPERIMENTS WITH A NITRATE B- BY VALENTINE BLANCHABD. , J Some time ago, during some experiments made told refractory bath to abandon its wayward conduct an I to the first i result made ployi tion i ’hops Us m six pei rest s turnet Very f to al negat to al iron s quisit these Btart 1(1 th Velope Iti Conta‘ “est r Th. accele I'ears devel, the b rally doned prove that - the o ounee and j tail t II upon Th taine nate • was i for a acid 1 negat a lias diatel proto there tive ] It alkali long work is sui ordin Henn curiot I desi who stunil hath Soi just 8 was i The 1 good tinuet at present I am of opinion however that a very effective % more satisfactory bath can be made of blown glass, in. same manner as cheap tumblers, which are blown iol mould. In point of strength blown glass is as superiot cast glass, as wrought iron is to cast iron, therefore ag diminution in the thickness might be allowed with S®’ and as such an article would be easier to manufacture® the thick unwieldly castings now supplied, it would prob be made better, more workmanlike in fashion, and " agreeable to the eye as well as better suited to its purr I do not think it necessary to do more than allude to built glass baths which have (fortunately) long ceased 111 a part of the apparatus used in photography. They’ always a source of misfortune and vexation, though it ‘ be admitted they were at least as much sinned again’ sinning, for they were generally constructed with ? science or care, and cemented with a material, often uns® for such a purpose. Uequieseat in pace. Gutta percha baths have been much praised, and eq) much abused, according as the writergot a pure gutta P bath, or one made with an adulterated or unclean spec of the gum. A clean, pure gutta percha bath may be’ without the remotest danger; but it is very probable I many baths of good gutta percha, have been conde® from impurities having collected on their surface, eitl the mould in manufacture, ox- otherwise during use, w combining with the nitrate of silver, have spoiled the liquid. The great drawback to gutta percha for a v dipping bath, is the impossibility of ascertaining wit; taintyif it be clean which is rendered still more important the tenacity with which some chemical stains adhere t material. (We all know that gutta percha trays can! used for developing wax paper negatives, because the df upon them, which always occurs in that process, can" with certainty cleared away, and the silver is cons" being thrown down on the tray instead of on the picb A simple sensitizing bath liquid, does not give any def that cannot be' rubbed oft'with ease, therefore * clean, a pure gutta percha bath may safely be used, more than ordinary care should be taken in washing, frequently, as the eye cannot examine every part of 11 detect dirt as in a glass or white porcelain bath. The objection to the form of the gutta percha baths of cot’ is the sharp inside corners and angles, which are d to clean out. They might easily be corrected. These . are especially valuable to the landscape photographer, | they can be carried about without danger of breaking-, The same remarks apply to ebonite baths as to 1 percha. I am not aware of any advantage they ha" the latter. Great stress is laid in the announce# 1 '’: culty to return the liquid into the bottle without spilling® of it, unless a syphon is employed. Seeing the excellence to which glass manufactures b arrived, I am sure that there would be no difficulty!, obtaining a cheaper and more suitable glass bath if 1 makers were better acquainted with the shortcoming’, those now manufactured, and the real requirements of * case. They cannot do better than take for models fo cast glass bath some of the best gutta percha baths with 5 only difference of having care to round off all the i corners and angles, the same as in the cast glass baths w
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