The Optical Magic Lantern Journal (February 1901)

—Se— The following List, relating to current Patent Applications, is compiled expressly for the ‘‘ Optical Magic Lantern Journal” by W. P. Thompson & Co., Patent Agents, «f 322, High Holborn, London, W.C., to whom all enquiries for further information should be addressed. No. 20789. ReEcENT PaTENT APPLICATIONS. 17th November, 1900. Christian Heinrich Emil Adolf Miethe. An improved prcecess for projecting multi-colour photographs and apparatus therefor. 17th November, 1900. provements in apparatus for animated effecta. 19th November, 1900. Benjamin Wilkinson. Improvements in or relating to tripods for photographio cameras. 19th November, 1900. Herbert Holmes and George Houghton. An improved focusing device for photographic cameras. 19th November, 1900. Percy Fortunatus Coggin. An improved photographic retouching desk. 19th November, 1900. Frederick Herbert Sanderson. Improvements in photographic cameras. 19th November, 1900. George Houghton and William .Albert Edwards. An improvement adapted for photographic view finders. 19th November, 1900. Jean Schmidt. Improvements in electric lamps for use in photography. 20th November, 1900. Oswald Nather. ‘ holding cameras. Walter Gibbons. Im. producing 20818. 20828. 20860. 20861. 20862. 20863. 20868. 20932. Paul Rudolph and Improvements in roll(Complete.) Copies of the following specifications may be obtained by remitting 1/for each specification to W. P. Thompson & Co., Patent Agents, 322, High Holborn, London, W.C. SPECIFICATIONS PUBLISHED. 17165 of 1899. Thornton and Rothwell. Transparent photographic films and the manufacture thereof. 25404 of 1899. Clarke. Photograph developing tray rocker. 311 of 1900. Kamm. Arparatus for photographing and exhibiting cluematcgraphic pictures, 5583 of 1900. Laux and Kranz. Dark-blacks and holders therefor for taking successively several photographs on the same plate. 6093 of 1900. Hall. Lamps for use in photography. 16282 of 1900. Shipway. Apparatus for supporting photographic cameras when in use for taking photogrsphs. 16996 of 1900. Ross, Limited (Warner and Swasey). Means for adjusting and fixing the pri-ms in prismatic field and opera glasses and telescopes. 17044 of 1900. Augstein. Cameras. 17429 of 1900. Hall. Camera supports. 16535 of 1500. Goerz. Device for changing photographic plates or films in daylight. 23992 of 1899. N.tley and Frost. Lamps for burning hydrccarbon, oil, or spirit. i@— 5 | “hatch bb Z PATENT INTELLIGENCE. |g The Optical Magic Lantern Journal and Photographic Enlarger. ODE ase, 7 j\ . Détes and Queries. eS C T. R. (Oldham),—The only trouble from your description appears to be that you have not placed the illuminant at the correct distance from the condenser. Try this, and if not effectual write again. Scotta.—There is no duty on the goods coming to England. We thank you for your interesting letter, part of which we allude to elsewhere. W. C. Furnas.—Delighted to have your newsy letter,, and shall at all times be very glad to hear from you. Summer C. Wood.—The first jet to which you allude is practically a blow-through jet in the ordinary senee, although the oxygen nipple is set back somewhat, and surmounted by a cone-shaped orifice. .The second jet is on a totally different principle, and the difference in light obtainable is very great. W. B.—(1) Stretch the screen and give it a couple of coats of whitewash containing a little blue, or you can prepare it as instructed in this Journal for March, 1900, page 31. The present issue (page 19) also contains instructions. (2) Theoretically there might be a slight difference, but practically there is none if the lens is of any account; all the rays should go through the 2 inches. Gilbert Wood.—The event will be over by the time this issue reaches the public. Major Barrett—You will not be able to obtain a sufficient light under the conditions you name from acetylene. An ordinary commercial lantern combination and ordinary slides will answer well with acetylene, and you can count, roughly speaking, on getting a little better light than with the best oil lamp. F. H. Rowntree.—Lantern plates are not made to give the effects you enquire about. To make the paper for blue prints, take :—(1) Citrate of iron and ammonia, 2 ounces, water 8 ounces; (2) ferridcyanide of potassium, 1} ounces, water 8 ounces. Mix 1 and 2 in equal proportions just before using, and float ordinary stout paper on this for 3 or 4 minutes, and hang in the dark until dry. Expose under negative in the sun, and develop with water. Photophil writes:—I have failed in demonstration experiments to separate out the blue or viole' rays (either will do) of the spectrum on a screen. A sample of thick dark-blue glass I bave found best, but this letsa good deal of green pass. Ammonio-sulphate of copper seems generally mentioned for this purpose, but I have. not succeeded in preparing a solution which acts satisfactorily. Can you give me a recipe for its preparation ? Ans.—The ordinary dark-blue glass cf commerce (cobalt glass) lets through very much of the green. but if you back this gla:s by a piece of light manganese glass (amethyst colour), you will cut out the green. The manganese glass allows the two ends of the spectrum to pass, chit fly red and blue-violet. The cobals glass cuts ous the red. The combination, if the densities of the two glasses are rightly apportioned, is far more violet than ammoopio-sulphate of copper. To make the ammonio-sulphate solution, dissolve a quarter of an ounce of sulphate of copper in a piut of water, th-n add sufficient liquid ammonia to redissolve tha precipitate which ix first formed. A strong (saturat-d) solution of sulpbate of copper may be used ina flat sided glass cell, provid-d that you employ a rather weak solution of nitrate of cubalt tocut out the green. Sh