The Optical Magic Lantern Journal (November 1894)

The Optical Magic Lantern Journal and Photographic Enlarger. only common air passed through, in which he evidently made a mistake, and did not discover j| that the proportion of nitrogen had been reduced. He, like others, had difficulty in fastening the edges of films of india-rubber to the mouths of tubes and glass vessels so that gases could not get in through the joint; the leakages, however he finally prevented by setting fire to a piece of india-rubber, and | daubing the semi-fluid material on that part of the glass round which the string was to pass ; then, on tightly. binding the barrier, it came into perfect contact with the glass and was retained there by the sticky material, no leakage whatever taking place unless some part of the arrangement burst. Dr. Draper described another plan of getting a mixture of nitrogen and oxyger, much richer than cornmon air, by taking advantage of the ' absorption of certain gases by water. If water, withall the gases it normally dissolves, have them boiled out of it, and then be at once exposed to common air, in a few hours it takes up oxygen and nitrogen gases, in the proportion of one| third oxygen instead of the one-fifth contained in our atmosphere. He says that by taking advantage of this, it is possible to obtain oxygen from the atmosphere. If a volume of atmospheric air be agitated with boiled water in a close vessel, it will be found that a rapid absorption of oxygen ensues, while but little nitrogen is imprisoned among the pores of the liquid. The gas, by the action of heat, may be driven off from the water, and being subjected to another washing, may be rendered still more pure; by successively washing and rejecting the nitrogen left, a gas so rich in oxygeo may be procured as to be equal to some | that has been obtained by other processes, as | by the action of sulphuric acid upon peroxide of manganese. This interesting book contains much about photographic subjects, and the action of light on chemical substances. In it Dr. Draper empha sises the fact that he was the first to take a | portrait by the Daguerreotype process, as published in Lhe Philosophical Magazine for June, 1840, page 535; he also gives the details of how he quickened the original Daguerreotype process for the purpose. Dr. Draper says that hydrochloric acid gas will pass through gold leaf intoa vesscl containingcommon air, when the gold leaf is so thin as to uniformly transmit green light. This may be of interest to Mr. J. W. Swan, who recently exhibited at the Royal Society some leaves of gold leaf abnormally thin, which transmitted green light freely. Dr. 195 Draper's scarce and interesting book should be in every photographic library, if copies can now and then be obtained. ——:0:— Mr. H. P. Caanbier, the club lanternist, is doing excellent work in connection with the entertainment of clubs in general, and cycle clubs in particular. On the 17th ult., at The Talbot, London Wall, we were present at one of these social evenings, and had an enjoyable time. Gathered together under the patronage of the leading cycling clubs, over three hundred members and their friends listoned to a good selcction of songs, mostly by. professionals, and also enjoyed an hour with the lantern, during which time Mr. Chandler projected on the screen a large number of slides from negatives taken during several outings. The pictures were of great variety, including portraits of the captains of many clubs, reminiscences of the outings during the past sumer, not forgetting a few cycle breakdowns, which elicited rounds of applause. :0:——_ New Apparatus. NEGATIVE RACK. The Birmingham Photo Co. have introduced several spccialities, amongst them being a drying rack for negatives. The sketch shows the style of same, and the manner in which the negatives are inserted. We have found this rack handy in our office as a letter rack. A DUSTING BRUSH, for use with either negatives or paper having wings, so that the brush portion is prevented from touching the table (by the same firm) will also be found convenient. A NEGATIVE BOX (PARTITIONED) to hold a dozen quarter-plate negatives is a handy and economical way of storing negatives. Other novelties are about to be brought out by this firm, one being a dark room box, of which we hope to speak when they are manufactured, ; ELECTRIC TRIPLE LANTERN, Tn introducing thislantern, Mr.J. H. Steward, of 406, Strand, W.C., has kept in mind all those ideas which assist to make the manipulation of a triple lantern a simple matter. This lantern is fitted with Davenport’s hand-fed lamp, there of course being three, whilst, so as to allow of the various currents of electricity