WONDERS OF LIQUID AIR.

Shannon News, 9 October 1923, Page 3

WONDERS OF LIQUID AIR.

Liquir air is so cold that ice is ex. tromely “hot” compared with it, and a kettle filled with it will boil on a lump of ice! If some be poured into an open dish, it looks as if it is being turned to steam, and quickly all disappears i It is much colder, as it were, than boiling water is hot, for water boils at 212 degrees F., but liquid air has a temperature of about minus 374 de* grees F.—over 400 degrees below freezing point! So not even a finger must be put in it, or severe frost bite will ensue. In preparing it ordinary air at high pressure, is forced through a verysmall nozzle, and is thus cooled. This cooled air is passed back over more incoming air, The latter is thereby cooled and then passed back as before, and so on, till the air gets so cold that it clondences in drops, just as steam condenses to water when cooled. Many wonderful experiments can be performed with liquid air, owing to its extreme coldness. A tube of milk placed in it becomes a solid block in a few seconds, and so does mercury. Grapes and flowers become hard, white, and brittle, so that they can easily be broken into fragments with a hammer A child’s indiarubber ball is hardened in the samo way, the air inside contract's and almost a vacuum is made, so that when trying to bounce it against a wall it explodes like an elec, trie lamp would. If o,ne end of a cigarette be dipped in the liquid and then a lighted match applied, it burns furiously like a squib; a cigar gives even a better effect. A biscuit behaves similarly, and cotton wool burns up instantly with a great flare. Liquid air evaporates int'o the atmosphere so quickly—about a pint an hour from a large jar—that it has to be kept in special vessels which fare |ust like thermos flasks; an ordinary cork or glass stopper is nb good, so cotton wool is used instead.