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502 THE PHOTOGRAPHIC NEWS. [October 17,1862. silver was the simplest, and best method of neutralizing it, as nothing was added but the proper constituents of the bath. But there were cases in which carbonate of soda was valuable, as performing another office besides neutralizing any free acid. It was well known, that the formation of an insoluble pre cipitate in any solution, had a tendency to throw down other particles of matter present, in suspension, or even in solution. In preparing metagelatine, for instance, the solution always re tained an opalescent turbidity, which no filtration would re move, until cleared by a method of this kind. The addition of a little white of egg, and then boiling, at once rendered the solu tion clear and transparent. The .coagulated particles of albu men were thrown down, and with them, the matter which caused the opalescence. It was so, he apprehended, with the addition of bi-carbonate of soda to the silver bath. Traces of organic impurity, which unfortunately, were sometimes present with commercial nitrate of silver, were precipitated with the in soluble carbonate of silver formed, and thus a bath was some times very easily purified by the use of bi-carbonate of soda. In reference to Mr. Leake’s remarks on albumenized paper and the importance of getting a substitute to supply its place for large prints, he cordially agreed with him, and might take this opportunity of calling attention to a dozen or two of the early experimental prints, taken by Mr. Cooper, on resinized paper, an account of which members had doubtless read in the pages of the Photographic News. Mr. Harman said that- reference had been made to some slight yellowness in the paper. By artificial light they could not see the exact tint. He asked Mr. Simpson if that were in- surmountable. Mr. Simpson said that in the benzoinized paper that tint was apparent. But in some subsequent experiments with frankin- sence and mastic, immunity from yellowness had been secured. Mr. Price had some of the prepared paper by him, which he was keeping in order to test, and it remained perfectly white. Mr. A. H. Wall had hoped to have brought with him a solar camera picture, taken on resinized paper, which would have illustrated its value. He thought it was a most important pro cess, especially in an artistic sense. Mr..Price said, in reference to the yellow tint in benzoin, he believed the first gatherings of the “tears ” were quite white. If these were kept separate instead of being mixed with the darker portions subsequently gathered, they would answer the purpose well. After some further conversation on the subject, in which several members spoke very hopefully of the promise of the resinized paper, Mr. Frank Howard said Mr. Leake’s paper was a very valuable one, dealing as it did with many minor points of importance. There were some parts of it, however, in which lie could not entirely agree with Mr. Leake. One was as to the use of plate glass. In his own practice he had used the crown glass for stereoscopic and other negatives, up to 5 by 4, without experiencing any of the disadvantages to which Mr. Leake had adverted. Again, as to adding to the bath a little of the iodizer of the collodion intended to be excited in it, he thought the plan was inconvenient and unnecessary, and in some cases, whore the nature of the iodizer was a secret, impossible. He thought there was no readier and simpler means of making a bath than that recommended by Mr. Simpson. He dissolved one ounce of nitrate of silver—always weighing it himself—in twelve ounces of common water. This of course caused a pre cipitate. To this quantity he added one grain of iodide of potassium, and after agitating at intervals for half an hour, he filtered through two thicknesses of paper, and. found the bath ready for use without further waiting. There was another point he would name in reference to exciting paper. A suggestion which appeared a short time ago in the News he had found most valuable. It was to the effect that if the paper were drawn very slowly from the surface of the silver bath there would be scarcely any waste of the solution, as the paper would come away without bringing more than a drop or two of solution running down its surface. He believed a saving of 25 per cent, might bo effected by this method.. Mr. Harman remarked that, if the drainings were caught in dishes it did not matter, as they were then saved. Mr. Simpson suggested, that Mr. Harman was looking at the matter from the professional photographers’ point of view, his operations being conducted on a large scale commercially, whilst Mr. Howard was looking at it as an amateur. It would scarcely answer the purpose of the amateur who was about to print, perhaps, a score of prints, to place dishes to catch the drippings from a few pieces of paper. Mr. Wall thought many mistakes and many discrepancies of opinion arose from the cause just adverted to : the difference between amateur and professional opinion. Take the question of glass, for instance. He (Mr. Wall), for economy, had thought he would get crown, and test it, as he had seen recommended, in the pressure frame, before using. Unfortunately, such a test was not always trustworthy, as he had found to his cost; for he had lost four or five guineas, only recently, by the breakage of a negative, on common glass so tested. He (Mr. Wall) thought professional photographers, to whom negatives were money, would find their account in using plate-glass. The Chairman asked to what such breakages were due ? Mr. Harman said, invariably to unequal pressure, from some cause. If the glass were quite flat, and perfectly even, no matter how thin it might be, there was no danger of breakage. Mr. Fitch said he used common glass up to whole-plate size, and never had breakages. Mr. Simpson said that, even if plate-glass were used, there would always be a certain percentage of breakages from various causes, where much printing was done. The fact, therefore, that a certain negative, or negatives, had broken and caused loss, was not, necessarily, an impeachment of crown glass. Mr. Foxlee said, that he thought the film on common glass, to which Mr. Leake had alluded, was caused by the effect of smoke condensed on the surface in the manufacture. He had found that, in cleaning glasses, this smoke could only be re moved by mechanical action. If well cleaned with tripoli he (Mr. Foxlee) thought the flattened crown was as good as patent plate. Mr. Simpson said, in reference to this foggy deposit, alleged to be caused by common glass, he (Mr. Simpson) thought it must be due to other causes, and for this reason :—Flatted crown was the glass universally used by positive operators for collodion positives, and, as was well known, the slightest fog or deposit in the shadows of a picture was far more fatal to its excellence than it would be in a negative, and much more easily detected. But collodion positives of the utmost brilliancy were constantly taken on flatted crown. Mr. Price said, that plate glass was not always of an even thickness. He (Mr. Price) had seen a piece of plate glass double as thick at one edge as the other. After some further conversation on the subject, Mr. Harman, in answer to the Chairman, said, that intense negatives required to be printed in the sun, and weak ones in the shade. Me. Wall said, that he had recently prints from the same negative—printed one in the sun, one in a diffused light, and one in the shade in a room ; the last was decidedly the best print. Mr. Simpson said, he thought it was well understood by practical photograpbers, that an intense negative required printing in direct sunlight, and a weak one in diffused light. But, other things being equal, it was generally a better class of prints which was produced in the shade. The reduction was slower, and the molecules of reduced silver seemed smaller. The print produced was more delicate in its detail, and even sharper looking. The Chairman asked, if the effect of temperature on print ing had been observed ? Mr. LEAKE thought it did not make much difference. Mr. Martin said, since heat augmented • the energy of most chemical reactions, he thought it would only bo fair to assume that it had some influence in printing. Mr. Howard said it was evident it had, as excited paper decomposed much sooner in warm weather than in cold. Mr. Price said he believed that sun-printed pictures were the first to fade. That opinion was put forth by the editor of one of the American journals some time ago—Mr. Snelling, ho believed, the paper was published some time ago in the News— that some prints were like over-quickly cooked steaks, the' out side was done before the rest was perfect, and ho believed that a want of permanence was the result. Mr. Howard referred to the causes of mealiness, which lie believed to be carelessness and haste in the washing before toning. W ashing in luke warm water he found beneficial in preventing it. Mr. Fitch preferred very slow toning, which was analagous in principle to the plan Mr. Howard had described. Mr. Harmer thought very thorough but rapid washing was important, the shorter the time prints were in the first washing