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THE PHOTOGRAPHIC NEWS. [January 2, 1863. collodion process—a truly useful and practical one. which, even up to the present time, cannot be said to have received such aid from any single con tributor as to detect from the greatness of his first application. At what date Mr. Archer first used collodion is unknown ; but this much is certain, that he first explained the process to his friends on the 21st September, 1850, at which time he was as well acquainted with its valuable properties as he was at the time he published it in March, 1851, in The Chemist. Mr. Archer had been brought up at a silversmith’s, but, not liking his occupation, some friends succeeded in placing him in a position more con genial to his feelings. He commenced as a sculptor, and wishing to preserve for himself records of the works which he had executed, induced him to study photography. For some time he had used the calotype process of Mr. Fox Talbot, to which he was the first to apply the pyrogallic acid ; but he complained of the difficulty in procuring paper suitable for his work, and, with a view to form a finer surface to the paper, he first covered this iodized paper with collodion, and afterwards sensitized the paper by entire im mersion. The next thought was to combine an iodide direct with the collodion, and apply the collodion to glass. In his early instructions and practice, the col lodion film was always removed by Mr. Archer from the glass on which the picture was taken. It has been stated by some that M. Le Gray, in Paris, about the same time, and quite independently, also conceived the idea of improving the sur face of paper with collodion. Whatever question there may be about this application of it, there is none whatever that the application of collodion to glass alone was an original and prior thought and application of Archer's. Mr. Archer, although possessed of many gifts, did not possess that of delicacy of manipulation, and, at the same time, he was always more anxious for research than the taking of photographic pictures ; hence some of his friends succeeded far better than himself in obtaining satisfactory results from the process he had invented. It is satisfactory, as clearly establishing how little success had attended M. Le Gray’s practice, that Mr. Archer applied to a friend, in the early part of 1852, for some specimens to forward to Paris, to prove what good results might be obtained with collodion under ordinary care. (To be continued.) Uorxespoudence. FOREIGN SCIENCE. [from our special correspondent.] Paris, 31st December 1802. At the last meeting of our Photographic Society, a com munication from Dr. Sabattier was read, on the means of obtaining direct positives on glass. He says:—“ At the meeting of the Society in July last, when my note on direct positives obtained by the aid of diffused light was read, the President remarked, that in order to be able to judge of a process, an essential condition is to have its products before our eyes, and invited me to send some proofs in support of my communication. In reply to this invitation, I now send the Society a dozen of my pictures. It would have been easy for me to have sent a much greater number, but as it is sufficient to have well defined the circumstances under the influence of which is manifested a phenomenon which can be repeated indefinitely, it seemed to me that this dozen pictures will establish, indisputably, that we can constantly and regularly, by flooding it with light, convert a negative, sketched in the darkness of the operating room, into a positive. “ These pictures, are, it is true, not free from defects ; but the competent judges to whom I now submit them, will rdlily percieve that the defects must be attributed to the operator, and not to the process. “ In the handsof an operator better acquainted with photo graphic manipulations, the process will satisfy all the requirements of the art. A very few experiments will serve ''ice the most sceptical. • not too often repeat, that nothing can be easier and sin’ pier ban to make a direct positive, while at the same tin e.nothn g C an be more curious. As the materialsand the man pulations remain the same, without any new baths or washings, by merely giving access to diffused light at a certain moment, we suddenly convert the faint negative into posit! V e. “In my previous communication, I announced three condi tions as indispensably necessary to the manifestation of this phenomenon. “ 1st. To give access to diffused light before the negative arrives at its perfect state. “ 2nd. To sensitize with a perfectly neutral bath. “ 3rd. To develop with pyrogallic acid, to which acetic or other acid, not too energetic, is added. “ Recent experiments have shown me that the second of these conditions, deduced from misinterpreted facts, is not indispensable; that we can as easily obtain positives with an acid sensitizing bath, as with one that is neutral, which latter, however, gives the best results. “ Two conditions only are therefore essential, and they are easily fulfilled. For every photographer, who is not preju diced, but sensible of the attractions of the art or science he cultivates, can experiment, see with his own eyes, and touch with his hands, the most surprising phenomenon his art can show.” The pictures sent by Dr. Sabattier excited much interest, and the thanks of the Society were 'awarded to him for his communication. M. de Poilly exhibited to the Society a new system of ap paratus, permitting the working of wet collodion without exposing the plate to light. He remarks that— : “ Collodion, the basis of the photographic processes called instantaneoui, has not yet received its full extension outside the operating room : hence it follows that a tent has hitherto formed an indispensable piece of photographic luggage. “ To be able not only to lessen the material, but also to simplify photographic operations, so that the merest tyro may operate with the same certainty as the experienced artist; to be able to operate without a dark room of any sort, as well at home as abroad—such are the advantages pre sented by my apparatus. “ Hitherto travelling photographers have been obliged to operate under tents, and to carry with them a load which it is not always easy to transport from place to place, or suitably dispose of at the scene of operations. Wth my system of apparatus, wherever the camera can be planted, my new dishes find their place, and the operations proceed mecha nically, so to speak, and with remarkable celerity. “ To be able to operate without labaratory or tent, I have invented for each photographic operation a compound appa ratus, in as many pieces as there are operations to perform in obtaining a picture. “ Sensitizing Apparatus.—This is a bath employed in sensitizing the collodion film with nitrate of silver. Its form gives it many advantages over vertical and horizontal baths, without possessing any of their inconveni ences. Thus, it requires only the liquid of an horizontal bath while the plate is covered with nitrate, as instantaneously as with a vertical bath, and this is done with the aid of a handle which suspends this bath under the base of the camera obscura, and admits of its turning, so as to assume the necessary positions1st, for introducing the plate; 2nd, for its immersion ; 3rd, for draining it; 4th, for re moving and conveying it into the slide; all without any loss of liquid, and without its having received any photo genic light. In this and the succeeding operations the are not soiled, or stained by the solutions. This bath is suspended by its handle beneath the base of the camera, in an horizontal position; before immersing the plate it is placed vertically, and is fixed in this position by a hook. The quantity of solution judged necessary to introduce into the bath—a quantity, which must never exceed that requisite for an horizontal bath—collects at the lower end of the bath. While it is in this position the collodion plate is introduced, the collodion side towards the operator; the bath is then shut, the hook unfastened, and the bath imme diately resumes its horizontal position. The solution col lected at the bottom of the bath covers the collodion plate in an instant. The bath is then rocked, to allow the ether to evaporate, and when the plate is supposed to be nitrated, the bath is again placed in a vertical position, and held there by the hook. The solution now flows to the bottom of the bath again, and the plate is found in its first position, which permits it to drain before being passed to the slide. “ The slide.—In this position the slide of the camera is adapted to the bath by the aid of grooves; this done, the slide and the .bath are opened, and unhooked ; the