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

October 23, 1868.] THE PHOTOGRAPHIC NEWS. 507 approval of the course taken by the committee, upon whom a troublesome and thankless task had fallen. Under these circumstances the committee Lave not felt concerned to notice the false reports, raised for mischievous purposes, in sham letters, by unscrupulous men, who avoid the risk ofdetection and punishment by writing anony mously. That any one so high-minded and straight forward as the correspondent who makes the above munifi- dent offer should for a moment be misled, is a temporary evil 'Very readily rectified. Anonymous slanders cannot in any way injure the gentlemen against whom they are directed ; hut they may in some degree effect other mischief, by tem porarily nar0wing or retarding the stream of benevolence, and bywdering able—and therefore generally busy—men indisposed to subject themselves to false statements and offensive inuendoes by undertaking the onerous duty of initiating and managing such an organization. Our correspondent will see, however, although at first glance it might seem desirable that the balance of a fund raised for a specific benevolent purpose should be applied to a benevolent project of similar aim, but wider scope, despite the injurious suggestions as to motive made by malignant persons, yet those to whom the funds were entrusted have no power to make such application. The money belongs to the subscribers, and is only held in trust until the proper moment arrives for returning it to its rightful owners. THE PROPORTION OP SALT EMPLOYED IN ALBUMINIZING PAPER. A question which “ crops out ’’ at intervals amongst photo graphers was raised at the last meeting of the North London Photographic Society, and is again referred to in our pages in the present number. The question is: Is it im portant that albuminizers should state what proportion of chloride is employed in conjunction with albumen in prepar ing photographic paper? The question is simple enough, and it might be imagined that no discussion whatever need arise on the subject, but that it would be answered without a moment’s hesitation, whether the information were of value or not. But, oddly enough, the question is not answered: a circumstance which has induced some photographers to ask the question put by a correspondent in our columns this week : Is there some occult reason for this reticence? Is it possible that albuminizers work so much by rule of thumb that they are uncertain of the proportion of salt employed ? We do not think that any such reason for reticence exists, or that any reasons exist at all beyond a certain amount of indifference, and an impression that the informa tion is not really required by the public. Mr. Hart stated at the North London meeting that few photographers had any interest in such information, or could make any use of it if they possessed it; and he suggested that those who were anxious to know the proportion of salt could easily dissolve the albumen and salt off a quarter of a sheet of paper, and, by precipitating the chloride by means of a standard solution of nitrate of silver, obtain means for esti mating the proportion of salt present. In making this sug gestion Mr. Hart overlooks the fact that, apart from the deli cacy of the operation to persons non-familiar with chemical manipulations, it is the trouble to which they are put which is the ground of protest on the part of photographers. They complain that with a fresh sample of paper they have no guide to the mode of treatment required without some ex periment ; and, as a remedy, Mr. Hart suggests an experi ment which, to many of them, will be far more troublesome. We know Mr. Hart to be a skilful, intelligent, and con scientious manipulator, and that all his operations are based on sound chemical knowledge of his subject, and careful consideration of the wants of photographers, neither guess work or chance governing his operations. We do not imagine for a moment that the operations of any albumin- izer are conducted so loosely, or so much by rule of thumb, that he could not give a tolerably accurate statement of the proportion of salt used. From a variety of causes we need not dwell on, exact precision in the statement might not be easy, but a very near approximation might be given, quite suffi cient for the purposes of photographers. Very few photo graphers now prepare their own paper: with all the uncer tainties of which we occasionally hear complaint, it is found, as a rule, easier and better to buy albuminized paper ready for use than to prepare it at home. At a time, however, when photographers did albuminize for themselves, we re member that it was the custom of some of the most able men to prepare two distinct kinds—-a heavily-salted paper for vigorous negatives, and a lightly salted paper for soft nega tives. Why' should not albuminized peper-makers do the same, and state that the strongly salted paper contains from 10 to 12 grains of (say) chloride of sodium to an ounce of albumen solution, and requires exciting on a 60 or 70-grain bath ; and that the other contains 6 or 8 grains of the chloride, and requires a 30 or 40-grain bath ? There could be no great difficulty in this ; and the information would be acceptable to many, and might be useful to all. Mr. Hart, plausibly enough, asks, Why photographers do not ask the constitution of the collodion?, Two or three answers to the question arise at once. It might be first replied, that they have often done so, and the more intelligent of them would always be very glad to have some idea of what they are using. It might be replied, in the next place, that such information is often, at least in a modified form, supplied. Manufacturers generally willingly state whether a collodion is simply iodized or bromo-iodized, and also whether it con tains an extra proportion of bromine. But the most im portant answer is found in the fact that variations in the proportion of salt in albuminized paper produce greater variations in result, less under the control of the photo grapher, than the slight variations which exist in commer cial samples of collodion. In printing, very much of the quality of the picture as to vigour or weakness depends on the preparation of the paper, and the photographer has not much facility in modifying this, except so far as it can be done by altering the strength of the silver solution. With collodion the case is different; the control possible in the developing and intensifying operations renders the original tendency of the collodion of far less importance. Mr. Hart said—and, we are satisfied, truly—that photo graphers could generally obtain the information by asking for it of the manufacturer. Would it not be well that it should always be given in general terms without asking, and that in future a C-grain or a 10-grain paper be as fami liarly spoken of as a Rive paper or a Saxe ? o FAILURE OF PHOTOGRAPHING THE ECLIPSE IN INDIA. It is a matter for deep regret and mortification that the photographic part of the operations of the Expedition sent out from England to India to observe the late solar eclipse was a comparative failure. Some weeks ago the members of the Royal Astronomical Society received copies of a letter sent by Major Tennant to the Astronomer-Royal, recording the results obtained at Guntoor on the 18th of August. The photographic portion of the report was so unsatisfactory, or even humiliating, that we felt little inclination to publish it. An extract secured from a second letter, although re cording that the results were better than were at first believed, does not serve to redeem the operations from the stigma of comparative failure. The first letter of Major Tennant opens as follows : — Guntoor, August 18, 1863. This morning was very promising, and if it had followed the course of its predecessor, we should have had a magnificent clear sky; but it clouded over the east with thin cumulostrati, which, while hardly stopping vision, interfere very much with the photo graphic energy; and the result was that every negative was under.