SCIENCE, MECHANICAL INVENTIONS, ETC.

New Zealand Herald, Volume XXXVII, Issue 11538, 24 November 1900, Page 6 (Supplement)

SCIENCE, MECHANICAL INVENTIONS, ETC.

V THE BREAKING UP OF COMETS. ': We must regard it as established by observation that comets present no fixity in their form, dimensions, and brilliancy. It seems as if these little wandering nebulosities get into trouble when they enter ; our system." Captured by the large planets, which force them to revolve in elliptical orbits, they constantly undergo the action of the. planets and of the sun until the day comes when the disaggregation of the nucleus begins to manifest itself. The final state consists of a stream of particles extending all along the orbit and successively captured by the planets. Our own globe collects considerable streams of shooting stars. These celestial fireworks are an excellent proof that we have nothing to fear from these gaseous bodies. * Besides, it is now acknowledged that the probability of a collision between a planet and a comet coming from the depths of space is almost if not quite equal to zero.—A. Muller, in the Revue Scientifique. • - _. ' MILK PRESERVED FRESH BY PRESSURE. Heat, cold, and chemicals have all been used as means of preserving fresh milk for a long period, and the effect-of pressure has now been tried, the experiment being described in the United States Experiment Station Record. Several hundred samples of milk were subjected for various lengths of time to pressures from a few hundred pounds to 100 tons. In each experiment a duplicate sample received the same treatment in every respect except pressure, and the results in the two cases were cdmpared. At ordinary temperatures, pressures less than 10 tons to the square inch were, found not to delay the souring of milk as compared with the check samples. Pressures of 30 tons for one hour delayed the souring for 24 hours, and pressures from 79 to 95 tons for from five minutes to an hour delayed souring two to seven days. The best results from a practical point of view were obtained with pressures of 10 to 15 tons for about the same number of days. In none of the experiments, however, were the bacteria in the milk found to be completely destroyed by pressure. Germs of typhoid fever, tuberculosis, anthrax, and other diseases, which had been previously added to the milk, were not killed when subjected to pressures of 10 to 15 tons for eight days. KACHIN AS A DEVELOPER.The original form of kachin was introduced some 15 months back, -since when (writes E. W. Foxlee, in the Photographic News), I have had considerable experience with it, and can say a great deal in favour as a developer. . The chief objections raised to the original kind were that a caustic alkali caustic sodawas necessary as an accelerator, and that it has a tendency to render the fingers soft and unpleasant. There is another drawback to the caustic alkali namely, that in hot weather it was likely to render the gelatine, on some plates or films, soft and troublesome to deal with. In the new form of kachin the caustic alkali is not required ; carbonate of soda is the accelerator to be used. With this the new kachin is as energetic, or nearly so, as the old was with caustic. The latter can, however, still be employed if preferred. The new kachin, in itself, is a more powerful developing agent than the original one, for, on referring to the formula for that, it is seen that the proportions were equal parts of kachin and caustic soda. In the formula for the new, if the caustic alkali be used, the proportions are as 25 parts to 35 of kachin. The new form of kachin may be considered an almost universal developer, for its use is not restricted to plates . and films, as by slightly modifying the ormula it is excellent for the various development papers. Another great advantage that kachin possesses for amateurs is that the solutions may be used over and over again, and, even after that be kept for future use. I have, after developing several plates, put it away for three weeks, yet it still worked well, though naturally a little slower than at first. A well-used solution is really better for over-exposed plates than a new one, as, from the accumulation of bromide from the previous plates, it requires no restrainer. A further advantage is that kachin does not stain the fingers, and it has no injurious action on the skin, as is the case with some of the other new developers.

THE PLATINUM SUPPLY. Platinum is peculiarly the electrician's metal. Its quality of resisting oxidisation indefinitely, and its ability to make a tight joint with glass, when fused into the body of that material, or even through the thin wall of an X-ray tube, make it absolutely invaluable, and no other material can take its place for these uses. The largest part of the .world's supply of the metal comes from the Ural Mountains, perhaps as much as 95 per cent, of the platinum used in the arts being found in the Russian and Siberian mines or places deposits of that range. '1 he metal is found in grains and nuggets in the sands of rivers and creek deposits, and in the moraines of glaciers, and is either quite pure or in the form of an alloy with iridium or some of the allied metals of the platinum group, such as rodium or ruthenium. While the demand for it is steadily increasing, largely on account of the increasing manufacture of incandescent lamps, which use bits of platinum wire for leading in the current to the filament inside, the output is steadily keeping pace with it. In 1890 the Ural region produced only 63631b of the metal, while in 1899 the production was no less than 13,2421b. TO DETECT ANILINE BLUE IN FLOURS. As some flours give a bread of yellowish colour, the millers add a slight quantity of aniline blue to the flour during the bolting, which dissolves in making the bread and modifies the colour of it. Probably this admixture would never have been noticed if some granules had not at times remained undissolved, thus being plainly visible in the loaf. For the detection of aniline blue, Violette recommends to take a deep plate, laying a piece of filtering paper on it, and pouring a layer of water, 1 millimetre in height, on top. When a flour containing aniline blue is sprinkled on, soon little black dots appear, which quickly increase in size, changing into blue round spots, darker in the centre. A VENUS-RATS PHOTO. Professor William K. Brooks, who is the head of the big astronomical observatory at Geneva, New York, has recently extended his experiments to photography, and he succeeded in producing a remarkably clear picture of Mr. J. Fosdick, his assistant, by means of the rays of Venus alone. He selected the darkest hour of the night after the planet had risen, and carefully excluded all light except that which came from this single star through the open shutter of the observatory dome. He found the light much stronger than he had anticipated, and will continue his experiments with other planets of less brilliancy. DEEP-SEA SOUNDING. Dr. Mill, at a late gathering, described the Pettersson-Nansen insulating water-bottle. He said that Professor Pettersson had, in conjunction with Professor Nansen, completed a modification of his wellknown apparatus for obtaining samples of sea water without change of temperature. The purpose of the apparatus was to enclose a quantity of sea watei at any desired depth, to hold it securely, and to bring it to the surface without any change of temperature exceeding one-hundredth of a degree centigrade. The insulation, which was the essential feature ot the water-bottle, was secured by a serious of concentric chambers of non-conducting material, which were simultaneously filled with water and so protected the portion, measuring about two litres, which occupied the large central tube. During last August the water-bottle had been tested by Professor Nansen on board the Michael Sars in the sea between Iceland and Spitzbergen, and at,the greatest depth met with, 3000 metres, or 1670 fathoms, the insulation was perfect. On August 11 a sample was taken from 3000 metres, and when it caro'/>£p the thermometer re&d 1.285 degrees C. After live minutes it read 1.283, after nine minutes 1.270, and after eleven minutes 1.210. Professor Nansen considered it essential to use an included thermometer to secure exact results. Protessor Nansen had also experimented with a water-bottle in which the insulating material consisted, in addition tp the concentric water tubes, of a ring of eighty exhausted glass tubes similar to the vessels used by Professor Dewar for liquid gases. Its insulation was proved i to be perfect.