The photographic news

• Bandzählung: 7.1863
• Erscheinungsdatum: 1863
• 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-id1780948042-186300004
• PURL: http://digital.slub-dresden.de/id1780948042-18630000
• OAI: oai:de:slub-dresden:db:id-1780948042-18630000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

370 THE PHOTOGRAPHIC NEWS. [July 31, 1863. Develop with the solution of sulphate of iron and ammo nium, according to M. Liesegang’s formula.” With regard to the solution for strengthening collodion negatives, recommended by M. Valentine Blanchard, in the Photoobafhic News, M. Liesegang remarks that the solution improves by keeping. It is employed in exactly the same manner as pyrogallic acid, adding to it a quantity of the nitrate of silver solution, and pouring the mixture upon the developed proof; its action is prevented until the negative has become sufficiently vigorous. The advantages of strengthening by means of iron compared with pyrogallic acid are, that the precipitate of silver is finer, that the solu tion keeps better, and never fogs the shadows. The solution may be employed before or after fixing. It would appear that this new method will be very advantageous for instan taneous negatives, which are frequently very feeble. Tartaric acid, as recommended recently by yourself may be advantageously substituted for citric acid, and, when mixed with nitrate of silver, remains clear until the neces sary intensity is obtained. Some operators recommend the saccharo-sulphate as giving much intensity to the proof. Our Paris Photographic Society is undergoing the same kind of transformation which photography itself has under gone, by acquiring a wholly scientific character. What makes a society is less the aim with which it is established, than the influence of the members composing it. Now the Society’s bulletin, of the 15th of May last, contains a list of its members, which, it must be recognised with pleasure, belong, for the most part, to the most intelligent and en lightened classes of society, both native and foreign. What is particularly remarkable, is the esteem and the great authority which attaches to some members whose scientific and practical works have made their names popular. As has been well remarked, this must have a considerable in fluence upon the future of the Society, and on the value of its labours. But a few years ago the French Photographic Society was surrounded with hostility ; at Paris, especially, it was feared that the spirit of clique would prevail, and it was seriously apprehended that the Society had no future Its works could not be placed in comparison not only with those of the Photographic Society of London, but also with many provincial societies in the United Kingdom. At the present day, every impartial person must admit that this Society, far from realizing the doubts prevalent at its debut, has, on the contrary, fully accomplished the mission it pro posed to itself, as much by the foundation of prizes intended to stimulate works upon subjects which interest photo- graphers, as by the authority it gives to a portion of its members most eminent by their intellectual acquirements. Its Bulletin has become an indispensable journal to every one engaged in photography, and we recognise with plea sure that its selections from foreign journals are well made, and without the least party spirit. We have only one objection to make to the French Photo graphic Society : its subscription is too high. We do not believe that we are singular in our view, for we have often heard it expressed, and we repeat the opinion of high autho rity when we say this. The amount of subscription should not be much more than the subscription to the Bulletin, for abroad the title of member of the Society brings no other advantage than the monthly receipt of the Bulletin. Now, to make members pay triple that amount is not good policy, and if the amount were reduced to one-half, in a very few years the number of its members would be increased tenfold. M.M. Davanne and Girard, as is well known, have pointed out an excellent means of preserving the sensitive ness of positive paper, and preventing it from turning black —by preserving it in a box containing chloride of calcium, or other desiccating substance. It may be well for those who employ these boxes to know that the paper should first be exposed to the air in a dark place in order to acquire a certain amount of humidity, without which it will darken but very slowly in the pressure frame. We can obtain great intensity in developing collodion plates by moistening them after cleaning, and covering them with albumen diluted with its volume of water.. The dried plates are covered with collodion, and developed in the usual manner. For studies of trees and landscapes generally, pyrogallic acid is preferable to sulphate of iron. DOES LIGHT ONLY EXIST IN THE EYE? Dear Sib,—There are one or two statements in the interest ing paper on light, under the head “ Scientific Gossip,” in your last number, to which, I think, exception may be taken without incurring the charge of hyper-criticism. The writer comes to the conclusion that the blue sky is yellow, sunshine red. &c. This may be the case if the eye were in those regions to see their colours, though they would not necessarily assume the tints fixed upon by your corre spondent. I notice this assertion, not to question it, but to remark that it is at variance with what follows, viz., “ All this universe is dark.” If it be correct to say the sky is blue or yellow, it is incorrect to assert that it is dark. Light and darkness arc both sensations (unless darkness be called the sensible absence of the sensation of light), and it requires the presence of the eye to decide how far either exist, and that place only can properly be termed dark in which an eye fails to perceive light. It is true that in one sense there may be said to be no light where there is no eye to behold it—that is, in every place external to the eye; but it is equally correct to say that in such places there is no darkness, both light and darkness being attributes of the optic sense, and not existing independent of it. It was, no doubt, the mean ing of the writer, that in the universe there was no light independent of the eye, but it docs not follow that the. universe is dark, and such an expression is incorrect. Equally so is it to say, “ Light exists only in the eye.” Light is not in the eye, or in the optic nerves, but in the optic sense or sensorium, whatever or wherever that may be. The eye is merely the material instrument, perhaps the first in a series of many, by means of which what arc called waves of light are prepared for their mysterious action on the sense of sight, and is as much a medium as the atmosphere through which the ethereal vibrations are propagated. Your correspondent will perceive that I do not criticise his statements, but the form in which he has put them; but when the usually received meaning of words is departed from, and they are used in an exact philosophical or metaphysical sense, the greatest care is requisite to preserve consistency in their significations, lest confusion of ideas should be introduced into the minds of those to whom it is endeavoured to convey abstruse knowledge.—Yours truly, M. A. SUCCESSFUL LIME TONING. Sib,—I was a most unfortunate man, but thanks to you, am, I hope, one no longer. Unlike " Cha-meal-ion," I have not hitherto been fortunate in getting the tone I required, i.e., black and white. Itwas, therefore, with great pleasure I read in your number of the 17th Mr. Parkinson’s method of obtain ing them. I instantly prepared a bath according to your directions, and having only the Saturday afternoon, at present, to experiment in, I have been through the week looking forward to that day with no small anxiety. You can imagine my dismay, then, at reading “ Cha-meal-ion’s " letter, for 1 had mixed my bath exactly as he described his. How ever, as I had some prints prepared on purpose, I thought I would try for myself, when, judge my surprise and joy at finding them gradually attain the long-desired rich warm black. I can, therefore, only fancy that my materials were better. Perhaps it would be better to describe accurately the way in which I proceeded :— I obtained from Messrs. Hopkinsand Williams a saturated solution of chloride of lime, into which I put some car.