SCIENCE NOTES.

Otago Witness, Issue 3275, 20 December 1916, Page 65

SCIENCE NOTES.

—To "Wither Warts While You Wait."— The cry goes up, "What will cure warts?" A remedy has never proved itself sufficiently sure for lis to recommend, but a formula is put forward by a medical authority which "withers warts while you wait." Mix sulphur sub., sdr; concentrated acetic acid, Z£dr; glycerine, 2oz. Apply the paste to the warts on small pieces of linen or spread with a brush at night. Wash off the next' morning. liepeat till the warts drop. —How Fast Leaves Purify Air.— It has been calculated that a single tree is able through its leaves to purify the air from tho carbonic acid rising from the respiration of at least a dozen men. The volume of carbonic acid exhaled by a human being in the course of 24- hours, is put at about lOOgal; but a single yard of leafsurface, counting both the upper and the under side of the leaves, can, under favourable circumstances, decompose at least lgal of carbonic acid a day. One hundred square yards of leaf surface, then, would suffice to keep the air pure for one man, but the leaves of a tree of moderate size present a surface of many hundred square yards. —Aeroplanes and Ash Trees.—

A timber export states that the demand for ash has gone up so enormously since we went in for aeroplane construction on the present big scale that prices are fully three times what they were in pre-war days. Nothing but the very best English ash serves the purpose. "The finest in the world," is his verdict. Experiments with other wood, notably American spruce, have yielded most disappointing results, and it is a curious fact, due to climatic causes, that Irish ash is unsatisfactory too. But an ash tree cannot bo grown in a day. The timber is utterly worthless for aeroplane purposes unices it is at least 60 years old. It is all the better if it is double that age, when some of the trunks can show a clear straight run of 80ft or more. —Deadly Raindrops.—

The fiercest bombardment conceivable would not be nearly &o destructive to- human life as an ordinary shower if it were not for the protective covering of our atmosphere. We live, move, and have our being at the bottom of an air room 40 miles or more deep. Therefore, we are safe not only from falling raindrops, but from meteorites and other wandering bodies from outer space. But, supposing that' it were possible for human beings to exist in an atmosphere that rose only to a few feet above their heads, and that storm clouds could form in the region outeide such a low-grade atmosphere, then every raindrop ,would prove as fatal to earthly creatures as if it were a steel bullet fired from a (dynamite gun. As it is, however, the reBistanco of our atmosphere so materially reduces, the rate at which the raindrops fall that they are harmless; though, were it not for _ the hindrance they encounter from the air, each drop would fall with a velocity .great enough to penetrate the full length 01 a grown man's body. i—Light Your House in the Country from the Sewer. — The disposal of sewage is a serious matter, and must be properly safeguarded. Pollution of waterways by* sewage is serious, while polution of the air is unpleasant. It is a large question of expense, this matter of purifying sewage, before it reaches rivers and streams. Therefore, it is plain that every effort should be made to make its disposal as cheap as possible. If the byproducts of sewage purification can be sold jn some way to yield a profit, so much the better. The newest method for purifying (sewage is so cheap that progress in economy must be looked to from the sale" of fertilisers, gas, and other things from it. The newest and most promising of these economies is the sale of sewer gas for use in 'driving engines which furnish the power for lighting plants. Almost every purification scheme includes what are known as septic tanks, where the sewage is allowed to settle for hours and hours at a time. The liquid is then draw r n off at the top, while the heavy sewage falls to the bottom. In this process sewer gas is generated, which rises to the surface in bubbles, and it has been found practicable to use this gas in a gas engine. It is a power gas, and not an Illuminating gas. The odours of these gases are very offensive, and therefore before ergine-owncrs would use this sewer gas an invention was domanded to eliminate them. •This was done by making, the septic tanks oil-tight, with no outlet for the gases until the whole are consumed in the engine. In one experiment 16 h.p. engines are worked wholly by bcwcJl* gas generated from the works where sewage is undergoing purification. Even tho engine which drives the pump to raise the sewage some 35ft is a gewer-gas-driven engine The supply of sewer gas is so regular and certain that the engine can bo left running all night without attention. This saves fuel and wages enough to pay for a new engine in six months' time. It is claimed that this system will easily yield 150 h.p. in a town of 10,000 inhabitants, or enough to produce electricity for tho whole town. Many country houses havo their own sewage disposal works, and tho gas generated therefrom could be mado to give enough power and light for several nearby houses. —A Bullet proof Jacket.— What is claimed to be a bullet-proof Jacket to protect the fighting man against shrapnel bullets, bayoaet-thrusts, and awordlunjge3 is attracting somo attention. In a

recent invention the protective device does not constitute an addition to the ordinary uniform, but is ingeniously combined with tho clothing. So far it has only been adapted to the dress of officers. The jacket follows the accepted regulation lines, and in outward appearance does not differ m tho slightest detail from the ordinary pat tern. But the garment is lined with highlytempered steel in such a manner as not to offer the slightest hindrance to the wearer's free movement of the arms, and body. Moreover, owing to the system of fitting, the slight additional weight is so distributed as. to escape the notice of the wearer. Tho eteel employed is sufficiently strong to resist a .455 Government revolver bullet fired from a distance of 20 yards. Under these circumstances tho jacket should be able _to protect the wearer completely against flying splinters of shell or fragments of shrapnel, and to safoguard him against many wounds which at present are inflicted by shell-fire. These injuries may not prove fatal, but they are often sufficiently severe to incapacitate the officer for weeks.