SCIENCE NOTES.

Otago Witness, Issue 3017, 10 January 1912, Page 76

SCIENCE NOTES.

—The Ivory Supply.— In view of the rapid disappearance of the herds of elephants which formerly roamed in Africa, and the limited number of those animals remaining in Asia, attention has been called to the enormous supply of ivory whicii exists in the frozen tundras of Siberia,-and which, it is thought, will probably suffice the world s consumption for many years to come. This uory consists of the tusks of the extinct species of elephant called mammoths. The tusks of those animals were of great size, and are wonderfully abundant at some places in Siberia, where the frost has perfectly preserved them, and in many cases has preserved the flesh of the animals also. —Electricity from Peat. — The Canadian Government, wishing to arouse interest in the utilisation of peat, has built a plant at Ottawa and secured a peat bog of 500 acres near Alfred, Ontario. The plant is equipped to make produoor gas from the peat, which will be used in a 50-horse power four-cycle gas engine, directly connected to a 50-kilowatt dynamo. It is estimated that there aio 36 000 square miles of peat in Oanada which would yield 28,000,000,000 tons of air-dried peat, which would be equivalent to 14,000.000,000 tons of coal. To demonstrate’ the commercial practicability of utilising peat for power purposes a building adjoning the Ottawa plant will be fitted up as an ore-dressing laboratory, and will bo operated by the electricity generated from the peat. —Nature’s Pa~achutes. — Careful examination has been made of the heads of Oanada thistle-downs, in order to determine their effectiveness as parachutes, carrying the t-eed of the plant to great distances through the air. The results of this examination are quite remarkable. Calculation shows that a thistledown starting from an elevation of 20ft, ih still air, would require two-thirds of a minute to reach the ground. With a wind blowing 20 miles an hour it would be carried, on the average, about a fifth of a mile. The total surface exposed to the air in an average thistle-down is, on account of the great number of hairlcts, a little more than one-third of a square foot. Another well-known and very beautiful example of Nature’s parachutes is furnished by the light silken threads with the aid of which the little gossamer spider makes long aerial voyages —To Remove Tattoo Marks.— Once tattooed, always tattooed, was formerly the rule; but a French army surgeon, Dr Tranchant, his discovered a method of removing tattoo-marks, whether made with India ink or lampblack. According to La Nature, the process consists of first rubbing the ekin until a thin layor of the surface is worn away, then applying a mixture of lime, slaked just before use, and powdered phosphorus. The tattooed part having been coated with this paste, a piece of gauze is laid over it, covered) with a bandage. The dressing is removed after 48 hours. The ecab is allowed to dry in the air, and comes away in about a fortnight, without leaving a scar. If any trace of the tattooing then remains, the treatment is repeated. Dr Tranchant claims to have applied this treatment in a great many cases with perfect success. —Separation of Metals from Complex Ores. A process for separating metals from complex ore that is applicable to any mixture in which one of the metals is more easily reducible than the other, has been patented in England by II L. Sulman and xl. F. K Pickard. The Mining and Engineering World states that in the case of a mixture containing the oxides of zinc and lead the ore is crushed ami heated with carbon, or in an atmosphere of reducing gas, to about 600dcg C., when the lead alone is reduced to rnetal, distributed in small particles through the mass. The product is cooled, under conditions preventing reoxidation and then conee «?Vated by vanning or flotation, to separate the lead narticlos; the zinc and silica being left in the watery pulp. Sulphide ores must first bo calcined; should any sulphite of the more easily reducible metal be oxidised to sulphate, it will be again reduced in the final reduction and an easy separation can be acomplished.—Queensland Government Mining Journal. —Elasticity of the Skull.— Fortunately the human skull, although composed of bones is elastic —much more eo than one would think. The average male adult skull, in fact, is so elastic that it may bo compressed laterally in diameter by a blow or by pressure, applied at the centre of area, at right angles to the surface at that point, by about sixtenths of an inch, recovering its origfhal diameter and form, without breakage. The material of which our bones are made Is so highly resistant that a cylindrical piece only 0.00155 square inch in area (i.c., only C. 044 inch in diameter) has a tensile strength of 331 b avoirdupois, figuring out at about 21.3001 b per square inch. As a matter of fact, bone ha-s 50 per cent, more tensile strength than hard wood, and a single bone fibre is shown in the Hygiene Exhibition, Dresden, supporting a weight of 111 b avoirdupois.

—Electric Light for Sterilising Milk.— According to Consul Mahin, of Amsterdam, a local periodical refers to the effect of ultra-violet beams on 'bacteria and to the fact that such beams are abundantly developed by mercury incandescent lamps, and relates that through this medium milk may now be sterilised in a few minutes. An apparatus has been constructed, it is explained, whereby the milk flows in a tions must be conducted where there is monstrations were first made with water infected with different kinds of bacteria, and it is said that the water was purified in a few minutes, without appreciably increasing its temperature. The result is attributed to the ozone formed under the influence of the light, but the demonstrations must mo conducted whore there is sufficient room for the light to burn freely. This method of sterilisation, without heating or adding preservatives, is believed to have great hygienic value in respect to nursing children. —The Lost Art of Tempering Copper.— According to a writer in the Brass World, the Aztecs, Toltecs, and Tarascans are said to have possessed in prehistoric ages the art of tempering copper. Several archaeologists and ethnologists of Mexico City now deny they had such knowledge. Copper axes and knife blades found at Atoapotzalco are so soft they can he cut with an ordinary pocketknife. On the other hand, Tarascan copper-cutting implements from the Balsas River ruins in Guerrero were so hard that they would turn the edgie of a modern knife. Anahfiis showed that these different blades were of the same composition as the copper ores, found in the respective localities. The soft blades wore made from comparatively pure copper ores, while the hard, apparently tempered, blades from Guerrero, were made from the natural ores which existed in the hills, alloyed with nickel and cobalt : thus making the smelted metal (or alloy) almost as hard as steel. Hence the co-callod tempering was due to the natural alloy found in the ore, which when heated and sharpened gave a hard, cutting edge. On the other hand, where the ores wore practically pure copper, the implements made from such ores were soft, and remain so to this day. —Edible Birds’ Nests. — The uninitiated ,ar© apt to think of birds’ nest soup as a most disgusting stew of twigs, feathers, and what not. As a matter of fact, the nest used by the Chinese is a very delicate, semi-transparent, gelatinous substance, built by the swallow-like birds known as the ealangane. The nests are found in the islands about Siam and the Malay Archipelago, and the harvest in the year 1909 was 18,0001 b, valued at over IOO.OOOdoI. It used to bo thought that the neat was formed of inspissated saliva secreted by the highly-developed glands of the bind. Now it is known that the nest is made of a species of alga, gathered by the bird. The season for harvesting the nests lasts from April until September. It takes three months to build the first nest, and just before the eggs are laid the nest is stolen by the collector. The bird immediately sots about the building of a second nest, taking 30 days for the work. This is also stolen before the eggs are laid. The third nest, however, is unmolested, and the birds are permitted to raise their young, after which the nest is taken and sold The nests are built in most inaccessible spots, among the cliffs along the coast, and the natives must risk (heir lives to reach them. In preparing birds’ nest soup the nest is washed in cold water and then cooked for eight hours in a closed vessel, after which it is mixed with chicken broth, seasoned, and boiled for a quarter of an hour. This dish is considered a groat delicacy among the Chinese, and Occidentals who have tried the soup find it very palatable and much resembling chicken soup. —A New Material for Safes. — Safe-makers and safe-breakers are engaged in a contest similar to that of the makers of guns and armour plate. Safebreakers’ methods have lately been much improved, especially by use of the so-called autogenous welding process, which makes it possible to penetrate iron and steel plates of great thickness in a short time by means of the oxy-aoctylene flame. This advance in criminal practice lias produced corresponding improvements in the construction of safe's and vaults. Lately, the well-known armour plate makers, the Krupps of Essen,' have produced a new material which is especially suitable for the protection of safes and vaults, as it cannot bo fused or penetrated by the oxyhydrogen or oxy-acetylene burners now in asp, or at least it offers so great a resistance to fusion that an inordinately long time and enormous quantities of gas are required. The material Ls a variety of cast steel, which is extremely hard and resists the best boring tools, so that it affords security also against mechanical forcing. In order to make a hole 3.2 inches in a plate of this material 1.6 inches thick, with the oxy-acetylene burner, from six to 14 hours time, from 2750 to 4550 gallons of oxygon, and from 25C0 to 3700 gallons of acetvlene are required, according to the ’■■■suits of a number of experiments. The average safe-breaker has not so much time or so much gas at Ids disposal. One of the steel cylinders in which compressed gases are transported contains alaiut 1400 gallons of (uncompressed) gas, and weighs

about 1501 b. According to the most favourable results given at least four such cylinders would bo required, and their transportation, in addition to that of the other apparatus, is a task to stagger the boldest safe-cracker. The extraordinary hardness of the plates opposes no serious obstacle to working them in the shop, as the rivet holes required can bo made directly in the casting or they can bo bored in softer steel parts especially provided for that purpose. The only defect of the plates is the present impossibility of making them thinner than 1.6 inches. It appears not improbable that this difficulty will be overcome, for only a year ago it was impossible to make the plates of loss thickness than 6m, in which condition, of course, they were practically useless for the construction of safes and treasure vaults.