Science Siftings

New Zealand Tablet, 6 July 1911, Page 1267

Science Siftings

BY ‘VOLT*

The Luminosity of the Sky. The luminosity of the sky on a starlit night, says an astronomer who has been carrying on extensive researches along these lines in Germany, is attributable in part to the direct light of the stars, in part to some ether source which he styles earth-light, which he thinks may be a permanent aurora. A measuring cf the light shows that it varies not only on different nights but also at different periods of the same night. French Coinage. The French Coinage Commission has rendered an adverse decision on the adoption of an aluminium coinage, claiming that neither the pure metal nor its alloys' offer sufficient resistance to blows or friction. An aluminium bronze is recommended, consisting of 90 per cent, of copper and 10 per cent, of aluminium. Coins of this composition have a beautiful yellow hue, and to prevent any confusion, the committee recommends that the coins be pierced with central orifices so as to prevent their being mistaken for gold. . . Sterilisation of Water. The investigations by the English Government into the sterilisation of water by bleaching powder are not only interesting from a scientific standpoint, but also promise to replace processes hitherto reckoned efficient, sate, and economical. Analyses have shown that one part of available chlorine to from 7,000,000 to 8,000,000 parts of water completely destroys all non-sporing organisms within 20 minutes, leaving neither smell nor taste to the water. Manufacturers of domestic filters are examining how they can utilise this method. A Substitute for Radium, Prof. Otto Hahn is under contract to deliver to the French Academy of Science within the next few months 250 milligrams of a new substance which is expected to be a fair substitute for radium. The new radio-active material is a by-product * of the manufacture of thorium gas mantles, and is known as mesothorium. When in combination with bromide it is whitish in color and has the same properties as the corresponding salts of radium. Its price is about a third of that of the rarer salts. It is claimed that Germany alone can produce ten grams of mesothorium in a year, which is in excess of the entire world’s supply of radium salts. Cables of the World. The various governments of the. world own together 880 cables, having a total length of 14,480 miles, and containing 21,560 miles of conductors (says the Chicago Journal). The French Government, which'takes the lead as to length of cables, has 3460 miles in fifty-four cables. As to number, the Norwegian Government comes first, with 255 cables, having a total length of 248 miles. Finally, as to the length of conductors, the English Government comes first, with 5468 miles of conductors, divided among 115 cables, having a total length of 1588 miles. Private companies to the number of twenty-eight own 288 cables, having a length of 126,864 miles and containing 127,632 miles of conductors. The French companies, only two in number have eighteen cables,, with a total length of 7249 nautical miles. The most important of the private companies is the Eastern Telegraph Company, which operates seventy-five cables, with a total length of 25,347 miles. The total number of cables in the world is 1168, with a total length of 140,344 miles and 149,193 miles of conductors. This is not sufficient toreach to the moon, but would extend more than half wav there. The Soudan Sandstorms. * The sandstorms which occur in the Soudan would be interesting if they were not distinctly disagreeable. The premonition is a stifling sensation of breathing hot air, and a stillness, which makes itself felt ; then one looks for a coming storm, which is first seen in the form of a huge mountain in the distance. In about an hour it will be close at hand; meanwhile doors and windows are tight l y closed, and one remains at the last open door as though fascinated, watching the mighty wall of storm cloud till it reaches the opposite side of the road. This gives ample time for retreat, and then the tempest envelops the house in darkness and the trees bend and crack before the furious wind. When it has passed, the air is cool and one lives again; but in spite of closed doors and windows, everything is brown, and covered with a fine, sandy dust, which, however-, is easily removed, as it does not 'stick. It may be described as silky, silvery sand, and should it have fallen on a sheet of paper left on the table, it will pour off, and leave no trace nor require further dusting. The heat in summer is terrific, being often 110 deg. in the shade (and sometimes up to 118 deg.), but the dry atmosphere prevents this from being insupportable, . and the mitigating feature is the fact that the nights are cool in comparison, as the thermometer generally drops to 30 deg. before sunrise.