The photographic news

• Bandzählung: 35.1891
• Erscheinungsdatum: 1891
• Sprache: Englisch
• Signatur: F 135
• Vorlage: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: Hochschule für Grafik und Buchkunst Leipzig
• Digitalisat: SLUB Dresden
• Rechtehinweis: Public Domain Mark 1.0
• URN: urn:nbn:de:bsz:14-db-id1780948042-189100009
• PURL: http://digital.slub-dresden.de/id1780948042-18910000
• OAI: oai:de:slub-dresden:db:id-1780948042-18910000
• Sammlungen: LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
• Sammlungen: Fotografie
• Strukturtyp: Band

• Digitalisat: SLUB Dresden
• Strukturtyp: Ausgabe

146 THE PHOTOGRAPHIC NEWS. Motes. At a meeting of the Physical Society last Friday, Professor Minchin gave a demonstration of the working of his cells, which cells have been already fully de scribed in these pages, for obtaining electrical energy by the agency of light. The “impulsion” cells were so delicate that the motion of the foot of an observer in the laboratory, or the vibrations set up by a passing cab, would frequently throw them into the insensitive state, or vice versa. A battery of the steadily working class of cells he connected with a quadrant electro meter, and when light fell upon the battery the needle of the electrometer moved and caused a platinum wire to touch a platinum plate ; this completed the circuit of an ordinary local battery, and caused a bell to ring. A suggestion has been made that this principle can be applied to the protection of bankers’ safes, so that when anyone enters the strong-room with a light a bell shall give the alarm ; burglars cannot readily work in dark ness. Professor Minchin stated that he hoped, and was disposed to think, that no chemical action was set up in the sensitive surface by light, but that a transforma tion of energy took place. He had kept up a deflection of the quadrant electrometer with one of them for a week, and no deterioration seemed to have taken place. Some of the cells had been made for several months, and had not deteriorated. If these sensitive surfaces do not undergo chemical change by the action of light, it is a strong point in favour of the dynamic hypothesis of the invisible photographic image. Some pretty experiments relating to the phenomena of colour were described last Friday at the meeting of the Physical Society by Dr. J. H. Gladstone, who, it may be remembered, many years ago painted invisible designs upon white paper with sulphate of quinine, which designs came out dark in a photograph of the sheet of paper, because of the fluorescence of the salt. Some of the salts of cobalt are used to form what are called “ sympathetic inks,” which come out of a pink colour when a sheet of paper written upon with them is held to the fire; the pink colour is due to a change in the state of hydration of the salt. Dr. Gladstone stated on Friday that when such a salt is dissolved in alcohol the solution is pink, but gradually changes to blue when sufficient water is added. A blue solution in a little water changes gradually to pink as more and more alcohol is added. A correspondent, who wisely omits to put his name thereunto, sends us the following:—“ Is it really true that a photographer who has a glass eye, which turns with the other one, occasionally replaces it by a small detective camera ? I was told that he used to walk about with the eyelid closed, and when he saw a suitable object with his working eye, he opened the eyelid of the other in a moment, and got the required exposure. But now he has added mechanism to the detective, and is able to have the eyelid open, like [February 20, 1891. other persons, and when he wants to photograph, he just winks in a particular way, which sets some interior mechanism a-whirring, whereby, as soon as the eyelid is again open, an internal screen is removed and then replaced; and so the photograph is taken. He can change the detective for the glass eye, or vice versa, while he pretends to be sneezing with his handker chief before his face. It is all too, too dreadful, but he must be ingenious.” Those who are fortunate enough to use the incan descent system of electrical illumination must be aware, to their cost, that the original estimate for their fittings is greatly enhanced by the somewhat frequent failure of the delicate carbon thread which forms the principal feature of the glow lamps. There is a tiresome un certainty about the life of these lamps which must be taken into account with the general outlay upon the fittings. A particular lamp may last for years, while another close by it, and on the same circuit, may give way after a few hours’ incandescence; and, owing to royalties to inventors, a lamp is an expensive item, and the replacement of several before they have yielded a fair amount of service is, to say the least of it, an aggravation hard to be borne. Hitherto a broken incandescent filament has re sembled Humpty-Dumpty in the inability of all the king’s mounted men being able to put it together again ; but a French inventor, M. Pauthonier, has recently de scribed a method by which reparation may be made, and large users of the pretty fairy lamps will welcome the discovery. The faulty lamp is placed in the hands of a glass-blower, who, by means of the blow-pipe, makes in the bulb a hole sufficiently large to extract the useless film, and to insert a new one. The new filament is attached to the stumps of the old one, and after the bulb has been filled with a liquid hydro carbon a current of electricity is applied which de composes the liquid, and makes the joints good by the deposition of solid carbon all round them. The glass is next bleached, to get rid of the dark carbon deposit which is commonly seen in lamps which have been long in use; it is then once more exhausted of air and sealed up. It is now as good as ever it was, and is ready to enter upon a new lease of life. The toning of lantern slides, by which operation various colours can be produced, is a recently intro duced modification of slide manufacture which will be found extremely useful in many branches of work. In lantern slides of microscopic objects, the colour of the original can be closely imitated, while the blue tone which can be obtained after fixation by means of the gold and sulphocyanide bath will give, for cer tain subjects, the effect of moonlight. All brilliantly illuminated sky and sea pieces, where bright lights sparkle on the waves, are fit subjects for this treat ment, while other pictures, where the lights and shadows are in strong contrast, are vastly improved by a blue tone.