Volltext Seite (XML)
S VoL. VII. No. 268.—October 23,1863. CONTENTS. PACK 510 511 512 513 514 515 515 515 516 516 5 or more grains 1 ounce 0} grain PAGE . 505 , 506 , 507 , 508 . 509 To Prevent Paper from Turning Red Correspondence— Photographic Notes and Queries—The Use of a Lens in Print ing-Substitution for Yellow Glass Talk in the Studio To Correspondents Photographs Registered during the past Week Gelatine Water... Bicarbonate soda pyro and water, and was completed in intensity in less than five minutes; sky printing through, and foreground corners vigorously brought out, thus evidently verging on over-expo- sure. I hope any prejudice existing to part of the formula may be laid aside, and a fair trial be made of it; after the manner of Mr. Sutton, allow me to recommend a trial of my process, which is to coat and sensitize a plate in my morphine bath, wash as in the tannin process, drain a little, and coat with a solution, of— The Triple Achromatic Lens. By J. II. Dallm eyer Proto-Acetate of Iron as a Developing Agent. By M. Me. A. Gaudin THE PHOTOGRAPHIC NEWS. One of the Causes of Pin-holes in Negatives. By J. W. Swan... 512 A Lesson in Photography.—No. 16.—Tannin Process A Rapid Dry Process The Photographic Exchange Club A Costly Lens Scientific Gossip . A Dozen Brief Hints to Portraitists Jottings from the Note-Book of a " Photographer's Assistant.’ No IV I....................... dissolved by heat and filter, then apply hot to the plate ; wipe the back and place to dry evenly, as usual; develop with pyro and water, and intensify with pyro, acid, and silver, as usual. I do not state positively a morphine bath is indispensable, not having compared results, except from memory; but I am led to believe that the sensitiveness is greater from these new trials.—Yours faithfully, Wk. BARTHOLOMEW. Egham, October 5th 1863. We received from Mr. Bartholomew a box of plates, which, on the first convenient occasion, we exposed and developed. How long they had been prepared we cannot tell; but they had been in our possession nine days. The light was un fortunately very poor, without direct sunlight, and a some what hazy atmosphere. We used a Dallmeyer’s No. 1 B lens, with various stops, and for the first exposure gave about double the time we should have judged necessary for a good wet plate with iron development. The plate was a little over-exposed. Sundry other exposures eventually decided us that about one-half longer than for wet collodion gave us the best results. With the lens in question, of about six inches focus, and a stop of half an inch, we got a good negative with an exposure of fifteen seconds, in a dull, diffused light, the subject a portrait and foliage. In development we proceeded as follows:—Having first moistened the film with common New River water, we then applied a three-grain solution of pyrogallic acid, with acid of silver : very rapidly an image appeared, distinct and red by reflected light, but feeble and phantom-like when ex amined by transmitted light. In the course of about a minute, all the detail being well out, we added a few drops of a solution, containing ten grains of citric acid and ten grains of nitrate of silver to an ounce of water. The required intensity was now easily and quickly attained; the whole process of development occupying little more time than would have been required for a wet plate. The deposit was of an extremely non-actinic colour, resembling a collodio- albumen plate, with the general tint by reflected light of a good pyrogallic acid negative. In some cases where the plates were not handled with sufficient care, there was a slight tendency to loosening and wrinkling of the film; but, with care, this was avoided, and there was no danger in any case of losing a film. Altogether, our experiments with the plates were decidedly satisfactory. A RAPID DRY PROCESS. We have recently had an opportunity of trying some dry plates of extraordinary sensitiveness and general excellence. We have tried two entirely different samples, by different processes and different persons, and both possess unusually good qualities. One lot was prepared by Mr. Bartholomew by a process which we give below ; the other by Mr. Hurst, of Mirfield, prepared by a process which we hope to publish, shortly. The latter gentleman called upon us a few weeks ago, and favoured us with a sight of some exquisitely fine stereo negatives, all taken with very rapid exposures, some possessing good clouds. He left a few of his prepared plates for our own testing, and promised, when he had quite satis fied himself as to the very best conditions, to give us further details. About the same time we received a note from our corre spondent. Mr. Bartholomew, which excited our interest. It ran as follows:— I have been using some dry plates of great sensitiveness lately, and I am sure they completely overthrow Mr. Sutton’s free nitrate principle, for they arc thoroughly and completely washed, and require about ten seconds' exposure for an open sunlit view, at 10 a.m. this month, Dallmeyer’s No. 1 triple lens, stop No. 2. If you can find any spare time to try a few 41X31, may I send some? J guarantee success! Cold pyrogallic development, and no bother about a moveable film (under reasonable treatment). Many of the recent tannin modifications are very good, but hero is a formula far easier of preparation, far more sensitive, and, I think, producing unsurpassed negatives. We subsequently received two or three other communi cations from Mr. Bartholomew, all of them speaking of con firmatory evidence as to the rapidity and excellence of the Process, and explaining that it was simply a modification "f the alkaline process he had proposed nearly two years ago. We prefer to state the matter in his own words, and subjoin, therefore, the following letter:— Dear Sib,—Your correspondent, “ Delta,” calls attention to my alkali ne-gelatine process, as involving the principle of alkaline development, which it certainly does, if plain pyro nnd Water is used to commence development. Curiously enough, his remarks have appeared just at the time when I have completed some trials of dry plates prepared by a plan I have long pro posed to myself, but hitherto forborne carrying out; in fact, I have shelved this alkaline process, and devoted more attention to the simply washed and dried film formula until now: the Present time, then, appears to mo rather apropos to say a few words on the matter. Well, these plates are with me the most sensitive dry films I have prepared, and stains, &c., are not present, I may say, in more than their fair proportion, being nearly absent altogether. f Ham afraid to speak of the exposure required, but will give a ait itul resunie of the time of one plate as a guide ; ten days ag0‘about), 98A.ar,, 74X5 plate. No. 1 triple lens, No. 2 stop, Nunt View of church, 15 seconds, cold pyro and water develop- men 451 owed by the usual silver and acid addition to inten- y, t us negative was visible directly on the application of the