Bit. 149 



diately rushed out of the saucer and clung to 

 the magnet poles; showing that oxygen is 

 magnetic. 



Since that time other experimenters have 

 succeeded in making liquid air on a compara- 

 tively large scale, and the process is simple 

 when we consider some of the old methods. 



Mr. Tripler of New York, who has made 

 liquid air in great quantities, does it substan- 

 tially as follows: First, he compresses air to 

 about 2500 pounds to the square inch. Of 

 course the air is very hot when it is first com- 

 pressed because all the air in the tank has been 

 reduced in bulk about 166 times, and all the 

 heat that was in the whole bulk of air is con- 

 centrated into one-166th of the space it occu- 

 pied before it was compressed. It is 166 times 

 hotter. There are two sets of pipes running 

 from the compressor to a long upright tank 

 called the liquefier. These pipes pass through 

 running water, so that the compressed air is 

 quickly cooled down to the temperature of the 

 water (about 50 degrees Fahrenheit). The 

 pipes at least one set of them run the whole 

 length of the liquefier, and most likely are 

 coiled. This set of pipes contains the air to 

 be liquefied. A second set of pipes runs to the 

 bottom of the liquefier, where there is a valve. 

 By opening this valve a jet of compressed air 

 is allowed to play on the other set of pipes, 

 when intense cold is produced by the sudden 



