SCIENTIFIC MISCELLANY

Otago Witness, Issue 3726, 11 August 1925, Page 67

SCIENTIFIC MISCELLANY

(Foe the Witness.) LIMIT OF SMOKING IN DISINFECTING. In experiments by Dr Georg Wolff contact with tobacco smoke prevented the development of disease germs on media upon which they had been inoculated, but failed to kill any but the most sensitive of the germs in fully-developed pure cultures. THE LEFT-HANDED. Left-handedness in 20 boys and 20 girls out of 6192 children examined has been reported by A. Kapustin, a Russian physician. The condition was hereditary m a third of the cases. There was no evidence of disease, but the left-handed-ness seemed simply to indicate predominant activity of the right hemisphere of the brain. Special training of the left hand was favoured, instead of any attempt to develop right-handedness. A FIRE-SCREEN HELMET. A novel German fireman's costume includes a waterproof coat and overalls and waterproof gloves, with a helmet that spouts a curtain of water completely surrounding the wearer. The water gives protection against heat that would be otherwise unendurable, and makes it possible to fight the fire at closer and more advantageous points. ROPE WITH FITTED STRANDS. A new type of wire rope has preformed strands, which fit together without bending or twisting, and are claimed to distribute strain evenly, giving to the ropes greater strength and increased durability. There is no fraying from broken or wornthrough strands. A steel fitting of special design is applied to the strands, and grips them securely, making it practicable and safe to use turn-buckles and shackles. SAFER GLASSES FOR MULTIPLE VISION. The new three-field lens for spectacles is claimed not only to give three fields of vision instead of two, but to remove the defect of bifocal glasses of showing steps and other objects in wrong position when viewed through the junction of the two lens surfaces. This gives the wearer greater security against falls. The new lens is a single* piece ground in four sections—the large one at the top for far sight, one of higher magnifying power at the bottom for reading, and one at either side covering an intermediate field at distances up to 4ft or sft. An instinctive side glance shows objects not clearly seen through the ordinary double-vision sections. NICKEL IN SUBMARINE TELEGRAPHY. In the recently-laid 2400-mile cable between New York and Rome a thin winding of permalloy, containing about 79 per cent, of nickel and 20 per cent, of iron, increases the capacity to 1500 signals per minute from the 300 hitherto possible. The core, of round copper wire, 0.146 in in diameter, is'enclosed in six spirally wound copper tapes, and the single tape of permalloy is wound spirally m a lubricating compound surrounding the copper, because it was found that differences in pressure would affect the magnetic properties of the alloy if wound on the bare copper. The over-all diameter of the cable’s metal is 0.195 in. The outside covering differs little from that of other cables, and consists of gutta percha and jute insulation in a protective armour of steel and tarred hemp. NEW OZONE THERAPY. While ozonised air has proven disappointing in the treatment of respiratory disease, a stable solution of ozone in alcohol and ether is reported to have given greater promise. The solution, it appears, has been prepared in France by Menou by passing powerful electric currents through tubes of oxygen circulating under pressure, the resulting ozone being absorbed by the alcohol-ether mixture, with a special fixative. The ozone is concentrated to a fourth of its normal volume. It is liberated at blood temperature, and its decomposition into vascent oxygen is claimed to have a direct effect on the blood itself, one statement having been that the solution, administered either by the mouth or by hypodermic injection, has produced an increase of red corpuscles as high as 50 per cent, in a month’s treatment. In tests in tuberculous disease French physicians are said to have obtained increase of weight, lessening of cough, and other favourable results. DIAMONDS AT WORK. The use of diamonds in the industries has greatly increased in recent years, according to Sydney 11. Ball in Engineering and Mining Journal Press, and tne value of carbonado, or black diamond, is said to have increased from 1 cent per carat in 1843 to 25 cent* in 1850-70, and a retail maximum above llOdol per carat in 1924. There are three well-defined varieties of diamonds, all of which are employed industrially. First is the crystallised or gem variety; second, bort, a round form with Tadiate or confused crystalline structure*; and, third, carbonado, an impure aggregate of-small diamond crystals, fn the trade bort includes even fragments and powder of gom stones, while especially . fine bort is known as ballas. No authentic figures representing the demand are available, but it is believed that the unmounted stones annually consumed in tho industries, most largely in the Unitech States, have a value of 6,000,000d0l to 8,000 OOOdol, of which 20 per cent, is by carbonado, an approximately equal amount by true bort, and tho rest by diamond dust and fragments. The price of bort averages about 25 per cent, of that of carbonado. Most im-

portant of the industrial uses is in lathe tools, and such tools set with bort and carbonado serve for a large number of purposes, more and more replacing alloysteel tools. Diamond dust of all varieties is a superior abrasive, of great importance in sawing, drilling, and polishing hard stones. Dies for wire-drawing are drilled from gem itones and some ballas, and average two years of service in producing wire of uniform size and high polish. Drills for mining and tools for glass-cut-ting are other chief uses of industrial diamonds.

LITTLE ROOM FOR WORLD GROWTH. Though the great masses of the world’s population are shown by a map of U.S. Commerce Reports to be concentrated chiefly in a few relatively tmall areas, the lands suitable for further growth are found to be mainly those of southern Siberia, southern Brazil, Argentina, southeastern Australia, and South Africa. Other sparsely peopled areas are hot or cold deserts incapable of supporting much human life. Three densely settled island areas stand out on the map—England, crowded from industrial development; Japan, peopled to near the limit through intensive cultivation; and Java, near the equator, with unusual soil and rainfall conditions for productive tropical agriculture. A dense population exists in three large continental areas—China, India, and most of Europe, exclusive of the northern and north-eastern parts. North-eastern United States, within a line drawn from Boston to Buffalo to Pittsburgh to Philadelphia, is the only comparable region in the western hemisphere. The dense populations of continental Asia are based on intensive agriculture and relatively low standards of living, with only a few small manufacturing centres in China and India. The crowded conditions in north-west Europe, and to some extent in Italy, have grown out of manufacturing, and as the people do not grow needed food and raw materials, here is the great import market of the world. The tropics in general are rather sparsely settled, such parts as India, Java, and some port cities having given an exaggerated idea oi population. The fewness of inhabitants over vast expanses on the map is impressive, hut most of these regions can support only a scattered population. The high, dry, cold desert of western China can provide for only a few nomads, while the greater part of Siberia and European Russia will remain sparsely populated. Arabia, the Sahara, south-west Africa, and interior Australia are deserts. Even South America offers little to encourage new population except in north-east Argentina.