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252 THE PHOTOGRAPHIC NEWS. [May 22, 1868. spectively, and add to them 1 part of ordinary uniodized collo dion, and l-5th part of tincture of iodine. Spread this very thin film on the glass, and, when it has set, collodionize and sensitize as usual; this forming a perfectly chemically clean surface, it is natural that any dirt or stains which may lie beneath will not appear in the upper film. This proceeding is useful under certain circumstances, when the conditions of the atmosphere do not favour an easy cleaning of plates by the ordinary method. U0 Gorxesponents. J. STOTHARD.—To have made an acetate toning bath properly, the gold salt should have had the acid driven off by evaporation at the outset; but by careful management of the solution you have, in the manner we indicated, you will get, as you have doubtless found, very good warm black tones, especially with vigorous prints. The object of the various additions to the chloride of gold solution is to induce a tendency to decomposition, liberating the chlorine, and precipitating the gold in a metallic form. The colour of gold precipitated in this way is modified by the size of the particles, and the size of the particles is modified by the substances used to effect the decomposition. If the decomposition be rapid, as when carbonate of soda is used, and the prints be immersed at once whilst there is nascent chlorine in the solution, the prints are attacked and become mealy and grey. If from imperfect evapora tion of the acids in making the gold salt, as in your case, hydro chloric acid, or chlorine, is present in the solution, a similar result ensues. 2. For a strong developer for short exposures, avoid gela tine. Use a strong iron solution with a small portion of acetic acid. Try 40 grains of protosulphate of iron and 20 minims of acetic acid. Gelatine promotes vigour and cleanness, and, in short exposures, often tend to hardness. Thanks for your reminder as to the method of copying. We shall describe, shortly, your appli cation of it. Duffer.—It is legal to copy a picture in which there is no copyright. The registration at Stationers’ Hall docs not confer copyright, it is only a necessary record of the existence of copyright. If you possess the copyright of a picture it is necessary to register it at Stationers’ Hall, but such registration would not give you a copy right in something belonging to another. If your object be to ascertain whether by registering your copy of a non-copyright pic ture you acquire a copyright, the answer is, that you acquire a copyright in your copy, but that would not deprive anyone else, who had opportunity, of the right to copy the original picture. 2. If you send a description of the photograph in the form we have often described, together with fifteen stamps, to our Publisher, he will duly register it for you and pay the fee. 3. The printing bath turning white and turbid indicates that it is getting weak, and is dissolving the albumen and chloride from the paper floated thereon. 4. Excess of salt will redissolve a portion of the chloride of silver in the washing water, instead of precipitating it; but no proportion of salt can be given, because the proportion of silver present is unknown. Take care to add a little at a time for safety ; or, better still, use hydrochloric acid to precipitate the chloride, in which case there is no danger of adding excess. Ax Amateur.—It is very probable that the cause you suggest may have operated in your case, and that the use of excess of silver in your collodio-bromide may have been the cause of practical insen sitiveness. We scarcely agree with you that a process which is rendered worthless by want of precision in carrying it out is not worth pursuing. Precision is one of the first requisites in success ful photography. However, there is large choice of excellent dry processes open, and the gum process we know to be excellent. Thanks for your experience confirming the value of permanganate solution for rectifying the bath. Silex.—The occasional uneven toning of collodio-chloridc prints is due to the use of a repellent homy collodion, which prevents ready and even permeation of aqueous solutions. The white opaque effect in the shadows is also due to unsuitable collodion. The plain collodion used should dry quite clear and transparent when tried on a glass plate; some samples dry dull, opaque, or opalescent, and such will give dull, grey, opaque shadows when employed for collodio-chloride. We explained the reason why your questions frequently do not reach us. We never neglect to answer questions which do not seem important, because we know that the most trivial difficulty is important to one suffering under it. X. Y.—Spirits of wine 56 over-proof is not sufficiently highly rectified for making collodion; it should not be less than 60 over proof at weakest; it is usually used stronger than that. Spirit of 56 over-proof is about 837 sp. gr.; spirit of 60 over-proof is about 830 sp. gr.; and spirit of 63 over-proof is about 823 sp. gr. W. F. Morgan.—You are right in your statement of Mr. England’s practice; but as very little more silver solution need be used than is necessary to cover the plate, and as the solution poured off may be added to the residues, there need be little waste. The results are, as you observe, exceedingly perfect. W. H. Payne sends us a good 10 by 8 architectural photograph, to show how perfect a result may be obtained with a Jamin quarter plate lens. He does not state the focus of the lens; but the result is certainly good. II. W.—Mr. England generally uses distilled water for the firstand final washes, using common water for the copious washing. In his last Continental trip he wet with good rain water, which answered every purpose. 2. In mixing iodides or bromides with plain collodion, the quality of the latter determines the mode of proceeding. If it be too thick for use, then the salts must bo dis solved in a proper quantity of alcohol, and added ; but if a collo dion of considerable body be required, and the plain collodion bo of the desired thickness, the salts must be added direct, and dissolved by frequent agitation. For such a purpose, the most soluble salts, such as those of cadmium, should be chosen. S.—The formation of oxide of silver by the addition of lime water to nitrate of silver solution might be useful to the photographer; but, on the whole, we prefer the method we usually recommend; Namely, the addition of a little caustic potash to a solution of nitrate of silver. Thanks. II. S.—The residue you describe as obtained after boiling your bath to dryness and fusing, which you sent a week or two ago, we find to consist for the most part of reduced metallic silver, the appear ance of which was, however, much altered by the presence of sul phate of silver, together with some crystallized nitrate. Upon applying heat, we found no difficulty in dissolving the precipitate in nitric acid. W. J. A. G.—As a rule, the use of strong hyposulphite solution and short immersion is safer and better than the use of weak solu tion and long immersion. In some cases, especially in prints from weak negatives or with highly salted paper, the prints are some what reduced and weakened by using very strong hypo; but wo never like to use less than a quarter of a pound to a pint of water. The use of a warm hypo bath, except in extremely cold weather, is not desirable, as it will impoverish the prints and reduce the tone more, and heat facilitates decomposition in the hypo bath. 2. In the studio you describe you will find the use of a black or dark blue blind over half the top very desirable for securing shadow. See our recent notice of the studio of Mr. Williams. Much depends on the size of the room as to the best mode of sliding. If the room be small, let it slide from side to side; if large, and two or three blinds will be necessary to cover the sky light, let them slide from caves to ridge, using one or more down at a time as necessity may require. 3. Mr. England’s Rhine views were produced from dry plates. You can obtain them of Marion, Soho Square. P. S.—The heat of a common fire, unless kept up very high with bellows, is not sufficient for reducing residues. The best plan will be to break up the slag, add more flux, and apply the heat of a proper furnace. 2. The term “Ivorytype” has been given to several forms of photograph which have been made transparent; but generally with colour. Several such processes have been, patented, but we believe that none of the patents arc maintained. We have published several such processes in the News at differ ent times ; but we cannot, without more definite information as to which process you want, give details here. If you can let us Know more precisely, we can probably refer you to the information you require. R. Gillo and Kent.—Received. Thanks. In our next. Several Correspondents in our next. ?hotographs Aegistere. Mr. II. SWINSION, Gloster, Photograph of an Engraving of a Triumphal Arch at Gloster 1777. Mr. Gibson, Hexham, Photograph of Miss Burnett. Messrs. Calve and Osguthorpe, Sheffield, Photograph Group of Founders of Odd Fellows. Mr. H. Watson, West Bromwich, Photograph of Rev. H. Farrow. Mr. T. Annan, Glasgow, Photograph of Lord Bilhaven. Mr. TEOS. Forrest, Pont-y-pridd. Photograph of the late John Hewitt,
