The photographic news

• Bandzählung: 12.1868
• Erscheinungsdatum: 1868
• 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-id1780948042-186800009
• PURL: http://digital.slub-dresden.de/id1780948042-18680000
• OAI: oai:de:slub-dresden:db:id-1780948042-18680000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

168 THE PHOTOGRAPHIC NEWS. [April 3, 1868. Uo Gorrespondents. To Agents and Advertisers.—Next Friday being Good Friday, the PHOTOGRAPHIC News will be published on Thursday, April 9th. Advertisers should send in their Announcements not later than Wednesday, the 8th. EDUCATOR.—The causes of collodion giving a thin transparent film may be various : deficiency of pyroxyline, deficiency of iodide, or lack of porosity or permeability in the film will cause it. The Ratter cause may be the result of the use of a pyroxyline giving a horny, repellent film, or the use of anhydrous solvents; if the latter, the addition of a drop or two of distilled water to each •ounce of collodion will remove the defect; if the former, time will be the best cure. If deficiency of iodide is the cause, it may be remedied by the addition of about half a grain of iodide of cadmium to each ounce ; but this is rarely required. The addition of a little more pyroxyline is often of service in securing a creamy film and a vigorous negative. About a grain of good pyroxyline to each ounce of collodion will often effect an improvement. J. H.—Wo recommend common sheet glass as most suitable for a studio, being cheapest and least liable to change under the action of light. If a small space is to be covered, a Id-ounce glass will be sufficient; if a larger space, a stronger glass (say 21-ounce) is better. Z. H. A.—The proportion of acetate of soda you use is very exces sive. The usual formula is 30 grains to 1 grain of chloride of gold; you are using 600 grains. You also use the bath too weak; 10 ounces of water to each grain of chloride of gold will give a very dilute bath; 5 ounces of water are sufficient. The tendency of excess of acetate of soda will be to prevent the keeping of the bath, causing it to become gradually inert, and tone slowly and imperfectly. F. F.—A ridge-roof room, with the side and roof facing north, glazed, and the other side opaque, will be best. The space you have at your disposal must determine the proportions. Secure as much length as you conveniently can. J. C. G.—We cannot recommend the instruments of any maker by name here. If you will send us a list (you may find some in our advertising columns), distinguishing each by a number, we can advise you as to which is most suitable for your wants. T. S. (Biggleswade).—Water purified by the addition of a little nitrate of silver and sunning is suitable* for making silver baths, but not for other photographic purposes. It would not bo suitable, for instance, for making a toning bath, because the nitrate of silver remaining in solution would decompose the bath and throw down the gold. The yellow precipitate you describe is probably oxide of gold. M. Cage.—In the formula to which you refer, whore acetic acid simply is mentioned, glacial acetic acid, which is that commonly used in photography, is meant. It is only when a deviation from the usual standard is intended that the qualification need be stated; hence, when the weaker acid is intended, Beaufoy’s is mentioned. It is about one-third of the strength of the glacial acid. 2. The solu tion or paste of bees’-wax is used after the print is mounted on ordinary cardboard. Care must, of course, be taken to avoid touch ing the margin ; this is easily done. Mr. Blanchard has given up the commercial application of collodion to his prints, not because he lost faith in it, but because, printing extensively, his assistants complained of the effect of the ether. He now uses the wax instead. Any trace of iodine in collodion for prints would be injurious. The bees’-wax treatment is cheap. 3. We saw the portrait to which you refer, and noted, also, the want of honesty to acknowledge it. Such a copy, unacknowledged, is, of course, piracy. W. A. (Southampton).—We addressed the note and forwarded it. You are probably aware that the firm is passing through the Bankruptcy Court, which may account for the delay to which you refer. W. N. and S.—The ridge-roof form is best, placing the side towards the north. This is the form and position employed by the best men. 2. The decision as to the use of wood or iron depends upon circumstances. We should prefer wood to iron; or, if we employed iron, we should have it lined with wood. W. J. A. G.—You will find the additional particulars you require, beyond those given by Mr. Bolton, in our Year-Book for 1866. A 15-grain tannin solution may be used. The difficulty in sending out collodio-bromide of silver ready for use consists in the fact that it is apt to precipitate in process of time, and, as Mr. Bolton states, should not be prepared more than a few days before it is required for use. We are not aware that any maker prepares a collodion especially suited to the purpose, but should think that most good samples of plain collodion might be employed. It is probable that thebromized collodion might be kept ready for use, and the requi site amount of silver added when required. If highly rectified solvents were employed in preparing the collodion, silver might bo used in the form of a saturated aqueous solution, one ounce of nitrate of silver dissolved in one ounce of water. 2. The so-called moonlight scones produced by photography are generally instanta- ncous pictures by sunlight, kept in a low tone. Mr. Breese states that he has absolutely photographed a white statue by the light of the moon with a long exposure. X. Q. P.—The complete picture, and not every separate negative from which it was produceci, will need to be registered. You may describe it as you mention, and register it as one picture. The smaller copy of it will not need registration. It is the design you protect, and not the especial size in which it is produced. A copy in any size, without your permission, will be a piracy. J. L.—By proper precautions a wet plate may be kept a couple of hours between preparation and development.* By Mr. Blanchard’s method, recently described in our pages, he has succeeded in keep ing a plate longer than that. But although a plate may bo kept that time, it would be difficult to keep foliage still for half of that time ; and unless the attempt were made in a light unfit for the work, or with imperfect appliances, foliage should never need any thing like such an exposure by the wet process. You are probably right on the personal question; but it is better let alone. R. M. T.—The turbidity and precipitate formed in your collodion on the addition of more bromide of cadmium was probably bromide of potassium, which is very sparingly soluble in ether and alcohol. When a collodion is iodized with a potassium salt, the addition of bromide of cadmium will frequently form bromide of potassium, which, if in greater proportion than about half a grain to an ounce, will generally precipitate. After the collodion is settled it is better to pour off the clear portion than to filter. The collodion so prepared will probably give you great vigour and brilliancy, but a little less harmony than one containing more bromine. 2. The more bromide present in your collodion, the more nitric acid you may have in the bath, without loss of sensitiveness. OUT-OF-Focus.—In your description of your studio you have left all the dimensions blank, and so left us in ignorance of a great part of what you intended to state. Judging, however, from tho portraits and from the view of your studio, you arc suffering from insufficient light. It seems that you are so closed in that scarcely any direct light can reach your sitters. To satisfy yourself of this, place yourself in the position of the person standing for a portrait, and then look up and around, and ascertain how muck sky you can see, for that will enable you to estimate how much direct light from the sky reaches your sitter. We fancy that you will see very little. The staining of the interior woodwork is not a matter of much moment. After two o’clock in the afternoon of this season the light is fast waning, and under the best of cir cumstances tho light at that time would not be very good. We cannot give you any opinion of the lenses; they may be good, but those of most French makers, being cheap, are a little un certain. Varnish is disposed to have a good-natured laugh at Dr. Mann for regretting the loss of negatives by the adhesion of the paper to the varnished film when exposed to the roasting in the direct solar rays of South Africa. Certainly the test was a severe one, but one which, we fancy, a thoroughly good varnish made of la® would stand without becoming sticky. Many varnishes in the market will not stand the direct solar rays of our own temperate clime. Still.—The disagreeable smell emitted on first using your tin dis tilling apparatus arises from the oil and rosin used in tho manufacture of the tin plate and in soldering the joints. It is not wise to employ soda for removing them, since this alkali attacks the coating of tin, and renders the metal afterwards liable to rust. It is a common practice to boil a little bran -with the first water in new tin saucepans; but wo should advise the rejection of the first few gallons which come over, and rely upon ordinary use as tho best means of thoroughly purifying the apparatus from such adventitious matters. The cost of a 2-gallon tin still and condenser may be quoted at a guinea, or rather more, according to the substance* of the metal. Venator.—Thanks for a sight of the box. It appears admirably adapted to the conveyance of plates of various sizes. It would not pay you to protect it in any way, but you might show it to some dealer, and arrange with him to make it. GERMANICUS (Bangalore).—Your interesting letter, enclosure, and photographs duly received. Wo will examine tho prints and reply in detail shortly. Tho News, &c., shall bo duly forwarded. G. Lewis.—Our fourth volume is unfortunately quite out of print We are glad that you find our Art Lessons profitable. C. R. Lobb.—Thanks. Wo shall make use of your suggestions in our next. Tho prints arc good and interesting. J. S. (Glasgow).—We will ascertain, and communicate with you. A. B. C.—We should think it quite safe. J. B. N.—Thanks. Answer in our next. Several Correspondents in our next. Several articles in type are compelled to stand over until our next.