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THE PHOTOGRAPHIC NEWS. Vol. XII. No. 505.—May 8,1868. CONTENTS. PAGE Camera Printing and Collodion Prints 217 Test for Bromides 218 Photographic Piracy 218 Photographic Reproduction of Old Engravings 219 Critical Notices 219 On the Occurrence of Hyposulphites in Mounting Cards. By John Spiller, F.C.S 220 Photographic Printing in Silver, Theoretical and Practical. By W. T. Bovey 221 Pictorial Effect in Photography. By II. P. Robinson 222 PAGE Observations on the Employment of Sulphocyanides. By M. Civiale 223 Collodio-Chloride. By William A. Terry 224 Proceedings of Societies—French Photographic Society—Old ham Photographic Society 225 Correspondence — Sei Clement—The Panoramic Stereoscope— Modified Honey Process—Photo-lithography—Sources of Success in Operating 226 Talk in the Studio 227 To Correspondents 228 CAMERA PRINTING AND COLLODION PRINTS. Since the publication in our last volume of a description of a simple means of producing very fine enlarged prints in the ordinary camera, using a collodion film to receive the image, and transferring the film subsequently to paper, we have received many communications on the subject, chiefly from correspondents who wanted help. The two sources of difficulty have been the toning and transferring, upon which we shall offer a few further hints. Before doing so, one or two further words of explanation as to the origin of this mode of working may be desirable. The method of producing prints on collodion in the camera, and afterwards transferring them to paper, was introduced many years ago by Dr. Moitessicr, but did not come into very general use. Some time ago M. Disderi adopted this system of printing, and introduced it into this country a couple of years since as the email process, the great beauty and delicacy of the prints generally winning admiration. Up to recently it has been chiefly employed as a means of producing prints the same size as the negative, or rather smaller, the process being regarded as a cubstitute for albu minized paper printing in the ordinary manner. Until last year no practical attempt seems to have been made to intro duce this process as a means of producing large prints from small negatives. Half-a-dozen years ago we produced some such enlargements, and transferred them to paper; but we could not, at the time, work the method fully out, and, leaving it for a more convenient season, overlooked it alto gether, Last year it was simultaneously and successfully worked out, without any concert, and unknown to each other, by several able photographers, and the general details, as derived from several of them and from our own practice, described in these pages. We have repeated these particulars because we have found that an impression prevailed in some quarters that the pro cess was patented, in others that important details were pre served as secrets; and we have heard that a description of the process described as a secret has been vended in the country at the price of a certain number of guineas. We wish our readers to understand that no restriction of any kind exists as to the practice of the process. As to whether other modes of effecting some of the operations than those we have described exist, we of course cannot say; but we know that the method of working we have described is, if properly carried out, efficient and simple, and is identical with the modes employed by many able men. It should, however, be borne in mind, that in this, as in every distinct branch of photography, skill can only come from practice. Experience brings familiarity with minuti, and success gradually seems to come naturally where failure used to result from the same operation, without the operator being able to say upon what essential point present success or past failure depended. The troubles as to the modes of toning are some what difficult to meet in any general statement, inasmuch as tastes differ considerably as to the best colour. The tone of M. Disderi’s published prints by this process, which are amongst the most successful examples of it, is generally black. It is produced by first whitening with bichloride of mercury, and then, after washing, applying an extremely dilute solution of hyposulphite of soda. The chief defect attending this method consists in a tendency to coldness and greyness. The best means of avoiding this consists in securing a tolerably vigorous image at the outset, aS it is difficult to obtain a deep black if the original deposit is thin and weak. A still warmer black may be obtained by supplementing the bichloride of mercury with a weak solution of sulphide of ammonia. We have seen some exceedingly rich sepia tones which were obtained by following the mercury treatment with ammonia-nitrate of silver. The richest black tones we have seen are those obtained by Mr. Burgess, of Norwich, in his Eburneum pro cess, in which a neutral gold solution is employed. The bichloride of palladium, as we have before explained, also gives a pure neutral black. It should also be remembered that warm tints are’most easily obtained in the toned and finished picture when the original deposit is warm in colour ; hence the substitution of pyrogallic acid with acetic acid in place of the ordinary iron development. The greatest difficulties appear to have been felt in the transferring process, many examples of excellent enlarge ment and fine toning having been sent to us spoiled only by failure in the transferring process. It is worthy of note that in almost every instance the failure has occurred where the print has been suffered to dry before removal from the glass, and the collodion employed has generally been of a kind unsuitable for transfer. There are three or four conditions imperatively necessary to uniform success. The collodion should be of good body, and yield a tough film. A sample yielding a thin, powdery, adherent film perils the success of the operation. An acid nitrate bath facilitates the film leaving the glass. After toning, if the plate be immersed for a short time in a 20-grain solution of citric acid, or a dilute solution of acetic acid, the operation of transferring is materially faci litated. The addition to each ounce of the collodion of a grain of white wax facilitates leaving the glass. The application to the glass of a solution of bees’-wax in ether, which on being wiped off with a clean cloth will leave an almost imperceptible film on the surface, the pre sence of which will aid the film in leaving the glass. The safest mode of proceeding is as follows:—After the picture has been toned and submitted for a few minutes