Science Sittings

New Zealand Tablet, Issue 3, 6 August 1908, Page 35

Science Sittings

BY 'VOLT

," " " - ' Eighty" Degrees- of ".Frost. -- • .~ It is difficult for us to form .any conception of the degree of cold represented by the eighty degrees of frost recorded from certain parts of Russia (says the Dundee ' Advertiser '). Sir z Leopold, McClintock "tells how: in- "one of his* Arctic a sailor -was foolish enough, to do. some outdoor work at pre- ' ciseiy^ this temperature. His- hands froze, and when he rushed into the cabin and plunged one of- them into a basin of water, so -cold was the, haad;.that ,-the -water was... instantly converted « into block of ice: -At, twenty-five degrees, -.' Dr. Kane says, 'the - m%ustache and^ under lip form- pendulous" beads of dangling ice. Put "out your tongue', N and" it instantly freezes' to; this icy crusting. Your chin- has a trick of freezing to your upper jaw by the luting •aid of your b&ard." My-.-eyes have often- been so glued as to show that. even a wink was unsafe.' - The Discovery, of Dynamite. Alfred Nobel, as far back^as v >i : B'4B; during' residence in-France, produced the first nitroglycerine powder that' was .then known. It was in Hamburg that he discovered by chance dynamite guhr.. Some of Iris powder had trickled out of a cask on the damp soil and became" spoiled by the infusorial earth. This., was a'happy accident, for as soon as --the moisture had evaporated h"e found that one part of this earth to three parts of nitroglycerine not only improved its substance -as an explosive, but made' it safer for handling. 'In 1879 Nobel dissolved nitrocellulose in nitroglycerine, which gave, it a more gelatinous substance. After this he jfound that the more gelatinous- cellulose was mixed in.;;, the nitroglycerine the more solid it became and the more slowly." ' it burned", both of which were important discoveries. -"Of this substance he made" a fuse, only to find -that it was hardly satisfactory because it had not sufficient strength to act as a driving force. s Tantalum. ~ ' ■ . Ekeberg, the Swedish- discoverer of tantalum, gave that name" ■ to the metal because of the tantalising "difficulties that' he n encountered while investigating it. It; is only recently that tan- • talum has been obtained. in a state- of ' purity, and the rapidity with which it has been produced, in response -to the demands , of commerce and industry, is almost unprecedented. It furnishesan excellent filament for" electric lamps. Only a . little while ago the mineral from which tanalum is obtained was so- rare that not enough could be found to supply specimens. to all .the mineralogical - museums. , Now Australia alone produces more ' than 70 tons of tantalite a year. " This does not seem a very great quantity, but it is to be remembered that a single pound, of tantalum suffices to furnish 23,000 .lamps, each of* 25 candle power-. The metal is so hard that it is said that a diamond-", pointed borer making 5000 revolutions a minute produces" in it after' three days at work an excavation of only .one-fiftieth of "an - inch, in- depth.. "-- ' The Great Clock of Munich. An American tourist in a recent letter- gives a description of"' the great clock which has just been completed for the Rathaus of Munich. ' The clock,' says the writer, 'is only one of tha . features, . and not^one of the most wonderful. There is a monster' chime, and .moving figures- represent a- -combat between mounted- knights, a national dance, "an "ancient night watchman, an angel of peace, a clown and a- cock.\ After the hour has been- - sounded the.chimes, play a national- song-; -then-two. figures- which stand near the dial strike the hour- again with heavy sledges. Then- a second song is intoned on the bells, and the tournament begins. While this is in progress a third melody is played, and. the group of figures representing peasants go through the motions •of the Schaffler dance. The clown makes grotesque movements, and the cock crows. In the night hours the watchman • appears after the hour has been sounded. A lighted" lantern- is Jn his hand, and as he disappears around an angle "of the. tower his .bugle sounds- a w.ell-known call, :and with" its last note the angel - of peace" appears. ' - k ' - ' —- v .