150 matured jfllMracles. 



expansion of the air. This cold air rus^s up 

 around the pipe containing the air to be lique- 

 fied and escapes at the top, thus absorbing the 

 heat until the temperature is reduced to 312 

 degrees below zero. Then the air liquefies and 

 runs into a receptacle, where it may be drawn 

 off at pleasure. 



It will be seen that a large part of the com- 

 pressed air is wasted in cooling the remainder 

 sufficiently to liquefy. 



The use to which liquid air may be put, ad- 

 vantageously, is an unsolved problem; but no 

 doubt it will have a place in time. All great 

 discoveries do. Electricity had to wait a long 

 time for recognition ; but what a part it plays 

 now in the everyday life of the whole civilized 

 world ! 



Curious effects are produced by this intense 

 cold. Meat may be frozen so hard that it will 

 give off a musical tone when struck. Here is 

 a pointer for the seeker of novelties in the line 

 of musical instruments. 



Liquid air furnishes a beautiful illustration 

 of the fact that a burning gas jet is continu- 

 ally forming water as well as giving out heat 

 and light. If we put liquid air into a tea 

 kettle and hold it over a gas jet, ice will form 

 on the bottom from the water created by the 

 flame, and it will freeze so hard that the flame 

 will make no impression upon it, other than 

 to make the ice cake grow larger. 



