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[July 18,186- THE PHOTOGRAPHIC NEWS. 348 expressed last week. Its products are not photographs, blit illustrations of a valuable application of photography to large portraiture, and as such worthy of much praise. New Method to Amalgamate Zinc.—To amalgamate zinc of electric batteries, Mr. Berjot uses the following process :— Dissolve 7 ounces 375 grains of mercury in 3 pints 4 ounces of nitre muriatic acid (nitric acid 1 part, hydrochloric acid 3 parts). Heat the mixture a little, and add to it 2 pints 4 ounces hydrochloric acid. It is sufficient to put the zinc a few seconds in this mixture to have it amalgamated. The process is very simple and not costly. The above amount of mercury is enough to amalgamate 150 to 200 cylinders of zinc. Gux-coTTON as a FILTER for Strong Acids.—Bottger recommends chemists to use gun-cotton as a filter for concen trated acids and liquids decomposable by organic matters. The author employs it with the greatest advantage for filtering con centrated nitric acid, fuming sulphuric acid, chromic acid, per manganate of potash, and even concentrated solutions of potash, and aqua regia. He says that properly prepared gun-cotton is only attacked at the ordinary temperature by acetic ether. NewExplosive PYROXYLINE.—The latest explosive material consists of the flour of starch, which, boiled in a peculiar way with nitric acid, possesses a far greater projective force than the gunpowder in ordinary use. It also has the great advan tage of not fouling the piece to any appreciable extent, and, from the nature of the materials used, is produced at a far cheaper rate. Another point in its composition which recom mends it especially for fortresses and magazines, is the facility with which the ingredients are mixed together, thus rendering it possible to keep them separate until wanted for actual use. MOI The ur process nent, ai knot i it least vhethel half as We two mo hently the ade tolutior be in tl cess, in “Mot been er less son Prom t retainer tannin, of Mr. answer surface lions, tl sensitiv numbel them, < it is q but an when t Lier Italy, i from t advant of bon tolatio simila It i bme tome < the wl modif and ol and ti were more had b At th than longe Beeme expec The tanni is sor whic seem does and Tl of 0 Ulk in tbe Studio. Copyright in Fine Arts.—The Copyright (Works of Art) Bill passed through committee, in the House of Lords, on Tues day evening. Royal Portraits.—We have pleasure in announcing that their Royal Highnesses tbe Princesses Helena and Louise honoured Mr. Jabez Hughes with sittings for portraits, at his studio, in the arcade, Ryde, by appointment, on Tuesday last. Several successful portraits, both single and grouped, were ob tained. Their Royal Highnesses were accompanied by Major Elphinstone and Lady Caroline Barrington. Large Angle.—We recently received from Major Gordon, of the Ilse of Wight, some 12 by 10 photographs, produced by a Voigtlander orthoscopic lens of lid in. focus. The pictures were very good indeed, and the definition pictorially sufficient to the edges. This, of course, includes a large angle, and with very satisfactory effect. M. CLAUDET’s Enlarged Drawings.—We received from Mr. Macandrew, a few weeks ago, a letter on M. Claudet’s en larged drawings, produced from a photographic negative by the aid of the solar camera, in which it was stated that a specimen exhibited at a meeting of the Photographic Society as produced in the manner described, was simply a painting, and whatever excellence it possessed was due only to the skill of the painter, who alleged that ho had erased the slight traces on the canvas before commencing work, as being more hindrance than aid. We declined to insert the letter, as it simply involved a question of personal veracity in some of the parties concerned, and not of photographic possibility, as, if the pictures wore not produced as described, they might have been ; and we did not wish to give publicity to gossipping on the part of this painter, which, to speak mildly, was at least very imprudent. As the letter appears, however, in two of our contemporaries, in one of which it is accompanied by a letter from M. Claudet, who has been courteously permitted an opportunity of vindicating his veracity in the same page in which it is called in question, we now notice the matter to remark that M. Claudet distinctly describes every picture of this kind which he exhibits in the International Exhibition as having been traced by himself in the manner described in his paper, and painted under his own eyes. The only portrait not so painted was that of Professor Faraday, in relation to which the painter’s assertion has been made. The true explanation of this matter is to be found, we fear, in a little of that jealousy in which so many artists indulge, and which in duces them to seize every opportunity of decrying the merit of the photographic drawing, and alleging their independence of its aid. Not every painter who even now condescends to earn money by colouring photographs, is like our friend Wall, an ardent and enthusiastic lover of photography, as well as a skilled artist with the brush. Our opinion of M. Claudet’s method was In this state the powder is non-explosive. The exgeri now in course of progress in Vienna and Berlin are said to an little doubt as to its general adoption in the Austria Prussian armies. Uo Gorrespondents. . a TEESDALE.—If you call upon us when you arc in town we will a" i 2. The “ halo ” of which you speak is most probably a reflection., 1ored perfect mounting of the lens. 3. Prints after washing are generallyi al to dry spontaneously. Many operators place them between blotting paper kept for the purpose, to remove excess of moistttGrims then leave them to dry. Some operators make it a point to dryfi mote by the fire, under the impression that rapid drying gives a -tu brilliancy. . ,_,pgoro- « Mr. Warner, of Ross,” presents his compliments to the editor ot core graphic News, and will thank him to state in his “ Notices to a pondents," that owing to the damp from the walls in the Internep “Sky Parlour, ” his specimens of enlarged photographs from Sma tives (for which he has just obtained an “Honourable Mention' ficate of Merit) have been taken down ; but that similar ones, Witl Ifte from the small negatives attached, may be seen at the exhibition South London Photoyrayhic Society, at the Crystal Palace, Sydenhalttrod C. A. R.—The deposit on the deep shadows of your negative, which er the light in printing, and cause parts which should be black.toh,d pale, is really a form of fog. You do not describe the details Oa manipulation’; but it is probable that you develop with iron, and steen with pyrogallic acid and silver, and it is in the course of the latte seo tion that this deposit takes place. If so, you will probably find the ’ citric acid in the pyro solution, instead of acetic acid, will aid in Prevcviste this deposit. Pouring a weak solution of tincture of iodine over thegi and then washing it off, prior to the application of pyro and silver also aid in preventing it. If these remedies do not apply, state yourge tions more clearly, and we will assist you further. Your other SPSShtbe has some good qualities, but it is a little hard, and the definition mi" better. A. B. C.—The general proportions of your proposed glass house apPttert very good. We should prefer nine feet dark over the head of the SFdr six, and about six feet at the sides, next the background, might W also. The amount of slope or “pitch” should be rather more thipjod propose, in order to prevent the slightest chance of water lodgin .jpe gradually soaking in. If the total height be 14 feet, let the sideshgsod or ten feet, which will make the slope more steep than you proi^'^ will rapidly throw off water in very heavy showers. If your posit* 01 be admit of placing the house so that the sitter will face the north, it" tle an improvement. Except for ventilating purposes, we do not se necessity of making any of the sashes to open. met’ W. Bartholomew.—A correspondent, who has not Mr. Bartho-hipe address, asks us to put the following questions relative to the morFvitb dry process, and will be glad if Mr. Bartholomew will kindly helpht‘ be a few hintsIs old or new collodion the best? Must the Pnatl perfectly washed, or only with a limited quantity of water? MYehatbi have made at the rate of 1 grain muriate of morphine to 10 ounces otbe is that enough or too much ? The plates I have tried have been less sensitive at the corners and edges: should this be so? Th. hof deposits a dark looking film on the glass bottle in which I keep 1‘ can I prevent this ?” d New Subscriber.—The specimens you enclose are very bad examP-es mealiness, and we regret to say that we cannot give you a certain Sue the defect. It arises from a variety and combination of causes ; Pr -joo we believe the paper is at fault, but a variety of causes will bring 12 when the predisposition is in the paper, and some modes of deneb mitigate, if they do not cure. In the first place, the use of a thinje) or fogged negative will materially aid in producing the defect," clean, brilliant negative, which permits perfect reduction in printil, largely prevent it. In many cases we ascertain that the use of a 13 of alkaline silver bath, or of the ammonia nitrate silver bath for e, the paper will prevent it. In some cases washing well with dhtill^J before toning will prevent it. In some cases the use of a bath of ace soda prior to toning will prevent it. It is a defect which has rarelyy occurred in our own hands, and therefore we can only record thesss rience of others as to its cure or prevention. A very great deal t peared in our pages on the subject during the last twelve monthstd chief remedies suggested are those we have just named. Good PAPgeb’ good negatives are of the chief importance. The fifth print is a; P a puzzler, we cannot assign any certain cause for the effectep) shadows turning red during intensifying is a circumstance we ig with. It will sometimes occur when intensifying, after fixing, in tThie *' When it occurs as you describe, after the fixed plate has, stood ft go” the light before intensifying, it may possibly, or may not,* be duo Istao way to that cause ; but we have seen it occur under these circutrces ° only when the plate has been imperfectly washed, and sometiged 2 cyanide of potassium, and perhaps of cyanide of silver, have the film. If the plate be thoroughly washed after fixing, and the y fying be done in yellow’ or subdued light, this red deposit will n°becn5 The Almanac, “ Manual of Colouring,” and back numbers have warded. Please state from whom your post-office order is made F ' , whether with your full name or initials only. ingw) J. Wilkinson.—The orange glass about which you enquire, regar"inforp)®" we made a favourable report to Photos, was obtained, we are of Messrs. Burfield and Rouch. mab00% Chromo complains that he cannot learn colouring satisfactorily It but ba A good manual of instruction is an invaluable aid to the studenn, depeQe far it will be sufficient without the aid of a teacher, must lar Kity, t2e upon natural capacity, &c. By all means, if you have oPPO. than ! lessons : you cannot have a more able or conscientious teacheniliar" Wall. His own practice is chiefly in oil, but he is perfectly w other methods. His address is 35, Westbourne Grove, Bayswan witbo, T. G. M. — You may add a bromide to your simply iodized couontosg, difficulty. Bromide of cadmium, at the rate of from half « 8 . orP to each ounce. It may be either added to the collodion “ ’ viously dissolved in a very small quantity of alcohol. Several Correspondents in our next.