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[May 23,186 THE PHOTOGRAPHIC NEWS. 25’2 Ualk in tbe Studio. Uo Gorxespoudents. m Poi Wo J. Jefferson.—So far as we know the authorities of the South Kensington Museum still publish their photographs. Their catalogue can be obtained at the Museum at the cost of a few pence. J. R. P. Frazer.—We are obliged by your letter and enclosures. As regards an instantaneous collodion, we cannot advise you to do better than follow the formula of Mr. England, given in our pages. W. W. B.—It is somewhat difficult to speak of the character of a lens from iodized collodion and iron development. Several correspondents in our next. If Or re W Pord Stan ° by I Ammonia Nitrate for ALBUMENIZED Paper.—Mr. G. R. P. Frazer, of New Glasgow, Nova Scotia, sends us the following formula for ammonia-nitrate of silver, to be used with albu- menized paper. Some fine-toned prints are enclosed as illus trations of the operation of the process:—Dissolve an ounce of pure nitrate of silver in eight ounces of water, pour off one-third of the solution into another bottle, and add aqua ammonia until the precipitate first caused is redissolved. Then add to this the remaining two-thirds, and add to the whole one drop of nitric acid to each ounce of solution. The paper should not be floated on this solution for more than a quarter of a minute. The tones are rich and brilliant, and the process considered by those who use it a decided improvement on the usual method. The Jurors in the Photographic Department of the Exhibition.—We learn from the Photographic Journal that Dr. Tyndal is acting as deputy chairman, and Dr. Diamond as secretary or reporter to the jury in the photographic depart ment. The jury have been requested to take under their adju dication all photographic apparatus, and chemicals designed for photographic use, whether in their own or other classes. The jurors are proceeding actively in their labours, and are summon ing, where it is deemed necessary, exhibitors to explain the de tails and claims of their contributions. The awards are to be made before the 15th of June. The following selections from the “ Instructions to Jurors,” explain the arrangements in re gard to medals: — Medals to be awarded, without reference to Nationality : The medals will be awarded for excellence only, without reference to countries, the Exhibition, so far as regards the juries, being considered as a whole, and not as consisting of a mere juxtaposition of separate displays by different nations. Number of Medals: The number of medals required by each class cannot be determined with precision before the examina tion of the objects. Guided by the experience of former exhi bitions, Her Majesty’s Commissioners have authorized the special commissioner to place a definite number of medals at the disposal of each jury, but have reserved the right of the council of chairmen to increase this number, ifindividual juries give reasons which are considered satisfactory by the council. All Medals of one hind: There are no gradations of medals, all being the same. The medals are to be awarded for merit, with out any distinction of degree, and without reference to compe tition between producers. It is not the best manufacturer, in any particular branch of industry, who should alone be rewarded by a medal, but all producers who shall show by their exhibits, that their products are excellent in their kind. No exhibitor, however, can receive more than one medal from one jury. General Instructions for the giving of Medals: The council of chairmen do not deem it advisable to issue formal and positive instructions as to the conditions under which medals should be awarded, but think it expedient to offer the following sugges tions to the juries, trusting in their ability to make rules for their separate guidance. The jury for Class XIII., Philoso phical Instruments, will reward novelty of inventions, or no velty in the whole or part of the instruments exhibited, inge nuity of construction, new application of old principles, applica tion of new priciples, improvements in beauty of form, increased durability, extended applications, excellence and precision in workmanship, economy of production. The jury for Class XIV., Photography and Photographic Apparatus, will reward the instruments of photography on the same considerations as are attached to the class of philosophical instruments. In re gard to photographic impressions, they will reward novelties in the mode of production, durability, excellence in the results obtained, and artistic merit. With reference to photographic materials, novelty or new applications, increased sensitiveness, or powers of retention, and facilities of operating should be favourably considered. Ea 90, Pen C0 Cas, , I had No Sui Wo, sib) duc 1tg Ptoy Vend W "ith Fant u the obje defe "If, Prof Bay theq bot % s he Oxa Arose "Co Pirac impr Tecog are, ‘ teser of. the specimens of its work sent; as whether the lens be a goodar2» one, better results might have been obtained with it. Thenemiggds you state considerably under-exposed, and the model is not we The image is not perfectly sharp or well defined at any Part,, may be a good one, and from the maker you name most probab ” it has a curved field, which accounts for the middle of a standyi? being out of focus when the head and feet are in. If a lensCoysco fectly, the falling off will'of course show at the edges, but as rega, tore of field, it entirely depends upon the focussing as to where mt • is most apparent. If you focus for the edges the centre will beo bably this may be an excellent lens for some purposes, but SCariev suited for card portraits with standing figures. A smaller ape reduce the evil. . top A. B.—Prints may be placed in the acetate of soda bath previous " direct from the printing frame. ,dionf Cantcar.—We have never tried the addition of bromide to the collgd name. It is possible that for some purposes, and with iron deve’sd it might improve it. It is not certain that it does not already contro The best mode of adding bromide would be to make a solution of of ammonia in alcohol, say 8 grains to the ounce, and then a"as drachm of the solution to an ounce of collodion, which would WJ rate of half a grain of bromide to the ounce of collodion. 2. The 9 in which you attempted to dissolve wax and failed, was probably’Jp varnish. Wax is very sparingly soluble in alcohol. You sho Mee benzine varnish, commonly sold as a “crystal varnish.” Wax soluble in benzine or in essential oils. Spirit varnish without Wahg cold, so as to chill, may sometimes be used instead of ground &dV transparencies. A thin solution of starch may also be used. LeacdA unaltered iodide of silver would not answer well, as it would be too and would probably eventually darken somewhat. M. A. 0.—We have not answered your letter until we had oppoded making some enquiry. From what we learn, the prints which wer® se to be ineligible for exchange were not the same as those of which"o favourably. You will readily perceive that the referees can hav6.to tive in the decisions at which they arrive, but a wish to do justifev and to elevate the art as much as possible ; and you must rememl in order to make their unremunerated labours tolerable, or even Pio the rules arrange that their decisions shall be final, and not Su question. We would recommend you, when one lot of prints isto to resolve to improve and send some better next time. We feec that the referees, whether we are present at their deliberations orts gladly give a favorable consideration to all contributions, and that they would rather err on the side of lenient judgment than otherwjs Troublesome.—The alkaline gold toning bath with acetate of sodaces) and successfully used. It is well, if the chloride of gold contain to add just sufficient carbonate of soda to neutralize it. 2. Filtentde) cyanide of silver precipitated in the silver bath, to which the CYAe• added by mistake. If there be any quantity, add more silver todet to restore its strength. The bath will not be injured if the cya2 s pure, except so far as its strength is reduced by the loss of silveotb have not found acetic acid cause pinholes in the negative. 4 -3 probably given your tannin plates too little exposure. You say, honey and tannin you got a picture, but it required five minutes 5d It entirely depends on the state of the light, and the focus and as" your lens, whether that was a long or short exposure. It might p short one. . 2 2 R. C. H.—Your lens would probably answer very well for enlarz size of the stop to be used will somewhat depend on the amount ofd given, the state of the light, &c. Probably about gths of an inche’A would be found to answer. 2. It is desirable in enlarging to reoht.S position of the lens. We are glad your glass house proves satisfas,E J. G. B., Huddersfield.—All the accounts we hear confirm the,npe that honey is a decided advantage in the tannin process. We28 used gelatine with plates so prepared ; but we see no reasontonaj that a two-grain solution would retard at all. Probably with will not need the gelatine coating. The experiments we descro I with collodion made by ourselves ; but we apprehend that any 0000 iodized sample would answer. In cases where you wish tofo ,o formula, without the trouble of making collodion, you will findisd nient plan to buy a good plain collodion, and then add such in, bromides as may be necessary. This is a better plan, and inyd, trouble, than purchasing pyroxyline. The negative from whiQep’ closed print was taken appears to be very good ; but three quar"j alone. . i - ge of 5 i R. Albury.—We are obliged by your letter. We will make us its suggestions shortly. .rye) B.—The exposure necessary for the interior of a church will Vgte"", with circumstances, such as the number, size, and aspect 01 j,,, and whether they are of plain or coloured glass, &c. You in ‛ and experience must guide you. The interiors of St. EtienlUse a Mr. England, received exposures of five or six minutes. hour is a frightfully long exposure for an open-air picture. 2od J. W. R.—We cannot tell in what point you have failed, but the Pyy% described in the work to which you refer is successfully practiseneV facturers in gelatinizing the covers of fancy boxes, &c. Remen. d is necessary that the glass should be prepared with ox gall, otthle oil or grease, so that the gelatine shall not adhere firmly. A ins tice, carefully observing all the instructions, will probably issue 0u J. G. L.—The “black stuff” enclosed, which had been scraped dj“i corners of ebonite dishes, appears to be simply some kind of ip, varnish. You will rarely find articles of this kind sent out turers chemically clean ; photographers should always take the I id, to thoroughly cleanse new vessels. 2. The formula for a solution would depend somewhat on the character of the pyro-dde the purpose for which the collodion is to be used. You canigid more bromide, using cither the bromide of cadmium or of amm0ss;), bromo-iodized collodion, if it tends to over-intensity or hardnofsy may procure plain collodion, and iodize it yourself with iodidfapd V 4 grains, and bromide of cadmium, from half a grain to a granjodiol according to the quality of the pyroxyline and use of the col cd . with iodide of ammonium or potassium, 2 grains ; iodide ,s gbo 2 grains ; and bromide of cadmium in the same proportion a tje " We think you will find the tannin and honey preferable " 3 alone €5
