SCIENCE NOTES.

Otago Witness, Issue 2323, 8 September 1898, Page 54

SCIENCE NOTES.

— The Revue Technique describes an explosive invented by T. Jewler, named " Promethee," which is manufactured on different lines from the explosives in ordinary mining use, being composed of separate solid and liquid elements in themselves non-explosive and only detonating when jointly combined. The solid portion is made up of the following : Chlorate of potash 56 per cent. , manganese dioxide 20 per cent., ferric oxide 24 per cent. This is triturated, mixed in a mill and filled into cartridges, a permeable cartridge paper being employed to facilitate the penetration of the oil," which consists of : Petroleum 50 per cent., oil of turpentine 40 per cent., oil of bitter almonds 10 per cent. This prepared liquid — which is not applied to the cartridges until just before use — is stored in metal flasks holding about onetenth of a gallon ; 2.'6i0 of the explosive c«iitains 1.651b of cartridge contents and .Si) of the oil, this Quantity being sufficient

to impregnate the cartridge. The cartridges, before they are steeped in the oil, are noninflammable and non-explosive, even by shock from steel plates. They are, it is Paid, unaffected by frost, moisture, or sud- ' den changes in the surrounding medium, and \ do not undergo any change diu'ing storage, i The oil is not readily inflammable, and, when ignited, burns quietly with a smoky ' flame. However, when impregnated with oil — which takes about 15 minutes — the cart- ' ridges, on ignition, burn quietly with a i brilliant flame, and disengage a large volume ' of gas. Pu'cnssiuii between two plates of j steel will explode them, as will also any ordinary detonator. No other means of , causing an explosion is possible, and cartxidges fitted with detonators mny be placed ' in the vicinity of others that are being exploded without themselves going off. More- ] over, when the impregnated cartridges are dried again, they return to then non-explo-sive condition. It is claimed that the dis- ] ruptive force exerted is at least as gi-ent as that of dynamite ; also that it is directed in the line of greatest resistance, and acts with equal efficiency in den&e rock, lightfis&ured rock, and in water. No soot is left on the walls of the boreholes, and direct experiment hos shown that the cartridges may be lived in presence of inflammable or explosive gases like fire-damp without danger. , — At the fifty-sixth annual meeting of the ' trustees of the Royal Southern Hospital, j Liverpool, Mr W. Adamson said he must allude to the continued success of the Rojitgen rays, which was daily becoming more apparent. The Royal Southern Hospital was the pioneer in this country and the first t general hospital in the world that piactised the straightening of hunchbacks — spinal curvature. Over 70 operations had been performed, inclusive of cases done a second time, and the results were most encouraging. The success had proved that in the future deformity need never occur. It was hoped that by this method persons might not only be rescued from deformity, but from early death. A large number of hunchbacks await treatment at the hospital. It seemed that the age of miracles had not ended. He had been permitted to watch one of these operations, and from the time the patient lelt his bed there appeai-ed to be no pain whatever, either before, during, or after the operation, the patient's only fear being that when able to rise and dress his clothes would be too short. — Most amateur photographers have occasionally met with ghostly markings on their gelatine plates, for which they could not account, and the manufacturer is generally blamed when such a spoilt plate is discovered. But it would seem from experiments lately conducted by Dr W. J. Russell, and described by him in the annual Bakerian lecture delivered before the Royal Society, that several substances, some organic, some metallic, will affect a sensitive plate by being kept near it, and not necessarily in contact with it. Wood kept near a plate in darkness for a few clays will picture itself on the sensitive surface, the image showing when the plate is developed. A sheet of perforated zinc will, in like manner, give up its pattern to tlie plate, and a nickel coin is especially active, giving an excellent copy of ( all its markings in a comparatively short [ time. Gum copal and printers' ink are two of the organic substances which are most active — a reminder to the amateur not to ' wrap his plates in newspaper. Dr Russell states that the general conclusion to be gathered f"om the experiments is, that the metals and substances under consideration , have the property of giving off vapours which affect the sensitive surface of a photo- ] graphic plate ; that these vapours will pass ' readily through such bodies as gelatine, eel- ! luloid, collodion, etc. ; and that the action I is greatly intensified by a rise of temperature. »Dr Russell will continue his experiments, and expresses the hope of being able to bring before the Royal Society further j developments of these curious and, at the present time, little understood actions. —In a recent number of the American Journal of Science, Mr H. V. Gill has an interesting paper on " The Theory of Singing Flames." The phenomenon of a gas jet burning inside an open tube emitting a musical note is one of those facts which, although known for "many years and much written about, has never been fully explained. Among the more interesting theories was that of De La Rive, who supposed the sound to be due to a periodic \ condensation of the water vapour produced in the combustion of hydrogen gas. Faraday showed the inadequacy of this theory by the use of a flame which did not form water vapour, and proposed in its stead the theory that the so-called singing was caused by successive periodic explosions of a mixture of gas and air. This was accepted by Tyndall. Another theory which has been proposed is that the sound is produced by vibrations maintained by heat, the heo.t being communicated to the mass of air confined in the sounding tube at a place where, in the I cour&e of vibration, the pre&sure changes. ; Sondhauss performed a series of experiments, his chief conclusion being that the condition | of tho column of gas in the supply tube had | an important influence on the phenomena. I Mr H. V. Gill sums up his conclusions as f ollows :— " We think we have made it clear | that the pressure on the gas plays an important part in this phenomenon, and that aI consideration of the reactions we have described will be found to explain the many ! facts noted in the case of a singing flame, : some of which we have alluded to. We look, therefore, on the chief cause as a mutual reaction between the pre&sure in the , tube and on the gas, the energy necessary to j sustain the note being supplied by the pressure on the gas and the action of the flame. We may compare the singing flame to the siren, in which the current of air causes the disc to rotate, the note being produced by the reaction of the disc on the current of air. . . . We have, then, three kinds of f singing flames, one depending on changes of pressure, another on air currents, and a third depending at once on both changes of pressure and on air currents." — Ozone-producing machines are said to j have just been invented by M. Andreoli. j They consist of glass vacuum tubes with a I metal rod running through them, and surrounded by metal rings with teeth turned , towards the glass. When the electric current is turned on ozone is formed between

these teeth and the glass. The invention is also likely to prove of great commercial value, as by it fats and oils can be purified, deodorised, and decoloured, wood seasoned, linen bleached, and wines and spirits mellowed in a few hours. — Professor S. H. Vines made a glycerine extract of the mucous membrane in the pitchers of the pitcher plant and found ifc to digest fibrin. The digestive action was disputed, but the professor has recently made further experiments, which tend to confirm, his earlier conclusions. — Spitzbergen is not an unbroken icesheet, as mony persons supposed it to be. Glaciers there* are in plenty, but there is much open ground- and fin,, m-mni^n scenery. Fogs arc prevalent, and Mr Garwood described a peculiar effect due to this condition of the atmosphere which does not seem to have been ever noted by alpine climbers. He has seen the face of a mountain covered with spieules of icr— a kind of exaggerated hoarfrost — some of the icicles standing out horizontally from the wall of a rock, and measuring as much as 18in in length. They are evidently generated by the action of fog — and grow by the constant addition of moist particles. Fogs will often continue for many days together, and they are so dense that one cannot see a companion who is more than two or three yards away.