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18 THE PHOTOGRAPHIC NEWS. [January 11, 1867. out waste and loss is no trifling matter. The general principles are well known, but the subject, in practice, is beset with many little variations that cause vexation, annoyance, and failure. Though good formul be supplied, the experience derived from an endless number of experiments shows that every formula may occasionally be varied with advantage, according to the sample of paper used. The mechanical and chemical nature of the paper really forms an important part of any printing and toning process. The intelligent printer will, therefore, find much advantage in studying its nature, and adapting his chemicals to it. It is no use railing against paper and condemning formulae: they must both be used, and it is better to try and make them harmonize. Paper cannot be made to suit the chemicals, so chemicals must be modified to suit the paper. Well-prepared albumenized paper is one thing, and a good toning process another; and the skill of the printer is shown by blending them so as to produce first-rate prints. By recommending the use of vigorous negatives, by furnishing good working formula;, and by urging the propriety of slight modifications according to circumstances, the key is supplied for producing as perfect prints as the present knowledge of the art permits. A chapter of general hints and advice, concluding the elementary portion of the work, may be studied with advan tage by all photographers. - HINTS AND GENERAL ADVICE. Concentrate your attention on the production of a good clean negative; a professional printer may be employed to produce your prints. Never expect the faults of the negative to be corrected in the printing; a good print can never be produced from a bad negative. Take a pride in cleaning the glasses well; stains and smears always indicate slovenliness and inattention. Whenever you take a negative, take as good a one as you possibly can, even though it be a bad subject; almost anything looks well in a first-rate photograph ; moreover, it is excellent practice. Never be Contented with a medium picture if you can obtain a better one. “ I dare say it will do I” will not do at all in good photography. Obtain the most perfect apparatus that your means afford, and take a pride in keeping them clean and in good order. Wipevyour lenses, before using, with a soft chamois leather, and dust out the interior of your camera with a damp cloth. Wipe your dark slide dry after each plate; the accumulation of nitrate of silver at the bottom corners of the dark slide stains the plate, rots the wood, and denotes the careless operator. Carry your dark slide in a cloth when taking it from place to place (especially out of doors), and cover the top of the slide with it while the plate is being exposed. Keep your camera exactly level when perpendicular objects are to be represented. Get all parts of the picture into focus if you can; if not, make the principal objects the sharpest—in a portrait, the eye; in a group, the central figures ; in a landscape, the foreground, in pre ference to distant objects. Keep your nitrate bath always covered, and your bottles well corked or stoppered, as well as distinctly labelled. Wash your hands after taking one picture, before commencing another. Wash your developing-glass after each time of using. Keep a separate vessel for every solution, and a separate bottle and funnel for each distinct purpose. Much time and trouble in cleaning dishes and bottles will be saved, and no end of uncer tainty removed. Never open a bottle of collodion, ether, alcohol, or varnish near a flame, or an explosion may take place. Never allow the sun to shine on the lens when taking a picture. Never attempt landscapes on windy or misty days. Of the two errors, under-exposure is worse than over-exposure. Aim at good pictures rather than quick ones. There is more certainty in working a slow than a quick process. Learn one process thoroughly, so as to be able to depend on it; then, and not till then, amuse and instruct yourself by practising others. Don’t be led away by every fresh idea you hear. Don’t expect to succeed With every new process you read of, but don’t condemn it because it fails in your hands. Don’t believe every novelty to be an improvement. Don't hastily credit every new discovery. Make great allowance for the ex aggeration and enthusiasm of inventors, but keep your mind open and unprejudiced, to receive every new truth, from whatever quarter it may proceed, or in whatever guise it may appear, O— PHOTOGRAPHIC GLEANINGS FROM THE CONTINENT. STREAKS ON THE NEGATIVE. M. A. de Constant accounts, in the Archiv, for the forma tion of certain stains and streaks in negatives. He states that some time since, M. Reulbach, although unaware of the reason of the negative becoming stained, suggested an effective means for preventing the same, viz., by moving the plate to and fro in the silver bath immediately after its immersion. M. Constant now describes the cause of these streaked negatives, which give the plate the appear ance of having been rubbed over with a doth. If a plate has been cleaned in a dry, warm room, and is then taken into a damp laboratory to be coated, a slight condensation of moisture takes place on the glass, and any subsequent polishing or dusting of the plate will inevitably produce the stains in question. These stains are even sometimes formed on a plate by merely allowing it to remain for a few minutes in a damp atmosphere after it has received its final polish ; and if breathed upon, the lines of the polishing cloth are distinctly visible. If, however, the plate is dried immediately before coating, or before the application of the dusting brush, no staining of the negative takes place. Dr. Reissio’s COLLoDros. In the Hamburger Gewerbeblatt, Dr. Stinde refers to Dr. Reissig’s new collodion, which is stated to give most excellent results. The pictures produced with it are vigorous and brilliant, and the collodion remarkably sensitive. Its composition is as follows :— Iodide of potassium 1 drachm Bromide of cadmium 1 „ Iodide cf cadmium 2 drachms, dissolved in 11 ounces of alcohol. To this is added 1 drachm 4 scruples of pyroxyline dissolved in one ounce of alcohol and 12 ounces of ether. Gelatino-Iron Developer. Dr. Stinde likewise calls attention to the gelatine deve loper, which, besides producing clear and brilliant pictures, is, he states, a certain cure for fogging. The developer which gives the best results is composed as follows :—• Thirty parts of gelatine are dissolved in 90 parts of water, and to this are added 10 parts of pure sulphuric acid ; the mixture is boiled for a few minutes, and, when again cool, sufficient iron filings are added till gas ceases to be given off. This last operation should be conducted in a large vessel, owing to the tendency of the mixture to froth up ; and the iron filings, of which about six or seven parts are required, roust be added gradually in small quantities. Four parts of acetate of soda, dissolved in 375 parts of water, are finally added, and the whole carefully filtered. If the developer gives hard black pictures, it must be diluted with a weak solution of sulphate of iron, in the proportion of one part of the latter to twenty of water. PRACTICAL DETAILS OF CARBON PRINTING. BY JOSEPH W. SWAN. As a few weeks will elapse before the book on carbon printing which is in course of preparation is in the hands of the public, I think a brief sketch of the practical details of my process may be useful to some of your readers. Sensitizing the Carbon Tissue.—The sensitizing solution may consist of one part of bichromate of potash and twelve parts of water; if hot water is used to dissolve the bichro mate, the solution must not be used till quite cold. If the temperature of the solution is much over 60°, the gelatinous coating of the tissue is apt to “ run.” The solution may be used in a flat earthenware dish, such as is ordinarily employed in preparing photographic paper; a deeper trough is, however, better for large sheets; the trough may be of