Volltext Seite (XML)
LDECENTDER 18, 1885. THE PHOTOGRAPHIC NEWS. 816 fully warranted in doing, judging from the very large audience he had the pleasure of presiding over on that occasion. The Halifax PHOTOGRAPMIC Society. The monthly meeting was held in Mr. Manley’s rooms, on the 4 th inst., Mr. Edward Gledhill in the chair. The minutes of the previous meeting were read and confirmed, after which the rules of the Society were revised, and the pro gramme for the coming season discussed. Several of the members brought specimens of their work for comparison and criticism. J. I. Learoyd exhibited a Pantascopic Camera for panoramic views, and explained its- working. It embraces a very wide angle, the camera revolving on the top of the stand, motion being given to it by clockwork mechanism which can be adjusted for short or long exposure. Experiments were also made with the " Eclipse ” oxy magnesium light, and a fairly successful negative was taken of the vice-president. Ualk in the Studio. PHOTOGRAPIIIC Society of Great Britain.—The next monthly technical meeting of this Society will be held on Tuesday next, December 22nd, at 8 p.m., at the Gallery, -5a, Pall Mall East; open at 7 p.m. for journals, &c. Annual Dinner of the PHOTOGRAPIIIC Club.—This took place on Wednesday, the 9th inst., at Anderton’s Hotel, Fleet S'reet, between forty and fifty persons being present. The chair was occupied by W. Ackland, and after dinner several of those present gave recitations and songs. India-Rubber Stereotypes from Phototype Blocks.—We have recently seen some excellent rubber stereos from Dallastint blocks, and, by using one of these, it becomes practicable to sign a letter with one’s portrait. Optical Lantern with Electric Light.—We have received the following :—“ I have at last succeeded in getting a battery to work my magic lanterns ; I have been trying for some time, and at last a friend of mine has got me one to do all I could wish. I showed on the Sth of this month at the Camera Club, and every one thought it a very good. I am the first person who has lit a magic lantern with a single liquid battery only weighing a few pounds (about twenty) when empty, and it takes one gallon of liquid to fill, the liquid costing about 3s. a gallon, and then it will burn all at once, or a time, say one hour, and then you can work it again for an hour and so on till the liquid is used up. It will last for about five hours, four for certain with a good light. You can lift your zincs, and when out it rests. The pair of lanterns are lit with an incandescent electric lamp, the current of which is supplied by a small primary battery. The battery consists of twenty-four sets of ordinary carbon zinc elements in twenty-four cells, the whole of which only measure twenty inches long, seven inches wide, and five inches high, and which are con tained in a handsome box, easily carried in one hand, which serves as a rest for the lamps. The cells are three parts filled with exciting liquid (which is the secret and is patented) quite white and entirely without smell. The current generated in this battery is sufficient to supply two Swan-Edison lamps of twenty volts each, burning from four to five hours, and is switched from one lamp to the other as the slides are changed. The light is very powerful, white, and perfectly steady. The great advantage is that one always has his lamp ready for use (as when at home he shows for an hour and puts on one side, lifting zincs out, and then it is ready till he wants to use again. No smell or danger, no heat, and only a few pounds to carry about. I think it a great step ahead in lighting for the magic lantern, and after the 28th I shall be glad to show it to anyone who comes down to me, letting me know a day or so before. AU intormation, &c., I can give to anyone who wishes.—A Dresser.” Abstract of Chapman Jones’s Lecture at the Birk beck Institute, December 16th.—Albumen is merely changed in form when it is coagulated; when dry, it may be heated to 100° C. without coagulation taking place. It is coagulated by strong alcohol, and by most acids, withont heating. Asphalte treated successively with alcohol, ether, and chloroform, yield three extracts, of which the first is practically not sensitive to light; the second is sensitive, and the third is much more so. Elder pith, manufactured cotton, linen, hemp, unsized white paper, are each of them almost pure cellulose. Cellulose is unalterable when pure, but readily decays when in contact with decomposing matter. Strong sulphuric acid dissolves it; strong hydrochloric acid does not change it, and strong nitric acid makes nitrates of it; these nitrates are pyroxyline or guncotton, the latter by very prolonged and more comple’e action of the acid. The sulphuric acid used merely helps the nitric acid. Gallic acid is prepared from gall nuts, and gallic acid, when suitably heated, gives pyro gallic acid. Pyrogallic acid is a more vigorous reducing agent or developer than gallic acid. Neither chemistry, nor optics, norboth, are photography, but a certain knowledge of these subjects is in dispensable to the student of photography. The Dundee and East of Scotland PHOTOGRAPHIC Exhibi tion.—Applications for space should be made at once to the Secretary, D. Ireland, junr., Commercial Street, Dundee. A large number of medals will be awarded, and we are told that a large number of exhibits arc to hand from abroad. Photographic Club.—The subject for discussion on Decem ber 23rd will be “ The Effects of Varying the Amount of Pyro in the Developer.’’ Uo Uorrespondents. *#* We cannot undertake to return rejected communication'!. €° As Christmas Day falls on the Friday, our next number will be published on Thursday, December 24. J. L.—If you give six or ten times the exposure, and weaken the developer suflicionly, it is probable that the prints will tone satis factorily. Tiie development should be decidedly slow. IGNORAMUS.—It is not customary for camera makers Io do as you suggest, and if you are working with a lens in which the foci differ, you must either let the camera maker know the extent of the difference, or you may make correction yourself by shifting the ground glass in its setting. A. Austin.—1. Leave it in a saturated solution of mercuric chloride until the image is throughly whitened, after which, thoroughly wash, and immerse in the potassic iodide solution—1 part of the iodide and 30 parts of water. George Dyson.—They are almost exclusively used now, and they make negatives which, in general estimation, are quite as good. Allen Selwyn.—Seep. G6 of our volume for 1884. J. M.—There is very little doubt that the spots arise from a chemically active dust which settles on the paper during some stage of the process. Be more careful as regards sweeping the rooms or other proceedings which may cause dust. Ebbw Vale.—1. About 300 or 600 double vibrations a second, according to which octave is taken. 2. The remark applies only in the case of a developer containing so much saline matter as to render the gelatine somewhat non-absorbent of water, and in no sense does it apply to the ordinary pyro and ammonia developer. 3. Considering that in the case of each lens the focus varies half an inch from that given in the list, and that in each of the instru ments this difference is in a contrary direction, bringing the foci of the two so near as to mike it scarcely worth while to take both lenses into the field, you are quite right in demanding others to replace them, or a return of your money. Of course one can not expect the focal length of a lens to be exactly as catalogued, but a variation of half an inchon an instrument which is supposed to have a focus of 54 inches, is altogether unreasonable. E. S. D.—1. Possibly the lens may be dirty ; a screen is useful in many cases, but not essential. 2. Proceed until it is well out at the back. 3. Try another thickness of yellow paper. 4. Very few are using it; they do not look as well as prints on albumen- ized paper. 5. If the glasses are misplaced, the instrument is useless. Ed. J. Hughes.—Judging from your description, you have a lan tern condenser. This, or any such arrangement as you describe, is quite useless for photographic purposes. Col. Biggs.—Thank you for the communication. R. J. Gorman.—Get Abney’s “ Instruction.” M. J. M. (Hants).—It may bethat the film has become veryhard and prone to repel aqueous fluids, and we should suggest that there is no alternative but to use the mercurial solution as strong as poRsibb, and leave the plates in for a still longer time. F. M. S.—It seems to us that the film has become loosened by the action of extreme cold on the wet paper. Uhe Agotographir Zews. SUBSCHIPTIoNS. Including Postage to any part of the United Kingdom:— Yearly ... 15s. Od | Half-Yearly ... 7s. 8d. | Quarterly ... 3s. KM To the United States, the Continent, and the Colonies:— Yearly ... 17s. 4d. | Half-Yearly ... 8s. 8d. | Quarterly ... 4s. M To India (Yearly) 19s. od. For Advertisement Scale, see page v.